CHEMICAL SAFETY REPORT
Chapters 9-10
Substance Name: sodium dichromate
EC Number: 234-190-3
CAS Number: 10588-01-9
Applicant's Identity: Boliden Mineral AB
Note 1: This document is the chemical safety report for the substance sodium dichromate. This CSR has largely
been generated automatically from the technical dossier by using the CSR plugin for IUCLID. The plugin has
automatically generated headings for several (sub-)chapters, for which there is no content. This can have several
reasons. The respective data can be not available and/or not applicable for scientific reasons and/or not formally
required for this substance/dossier. For editorial reasons, the empty sections are not always maintained and an
individual reason is not given.
Note 2: This CSR contains a site specific Exposure Scenario: “The use of sodium dichromate in copper/lead
separation in concentrators handling complex sulphide ores” and related risk characterisation for concentrators
located in Boliden Area and Garpenberg, Sweden.
EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Table of Contents
9. EXPOSURE ASSESSMENT (and related risk characterisation) ................................................................... 3 9.0 Introduction .............................................................................................................................................. 3 9.0.1 Overview of uses and Exposure Scenarios ........................................................................................ 3 9.0.2 Introduction to the assessment ........................................................................................................... 4 9.1 Exposure scenario 1: The use of sodium dichromate in copper/lead separation in concentrators handling
complex sulphide ores .................................................................................................................................. 12 10. RISK CHARACTERISATION RELATED TO COMBINED EXPOSURE ............................................. 29 2014-09-17 CSR-PI-5.5.2
CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
9. EXPOSURE ASSESSMENT (and related risk characterisation)
9.0 Introduction
This exposure assessment will be part of an application for authorisation and therefore the assessment is focused mainly
on the Annex XIV properties (carcinogenity). However, the assessment of environmental exposure and subsequent
assessment of man via the environment has also been carried out to elucidate exposure levels of the general population.
The substance, sodium dichromate (CAS 10588-01-9, EINECS 234-190-3) is manufactured outside the EU. The imported sodium dichromate is directly used in the flotation process for separation of copper and lead concentrates at two
industrial sites, Boliden Area and Garpenberg in Sweden. Sodium dichromate is subsequently only used by workers,
working in the industrial settings in copper/lead separation by flotation.
A certain fraction of the applied amount of chromium added to the process in the form sodium dichromate leaves the
site with the products in the Cr (III) oxidation state. The solid chrome (III) oxide/hydroxides goes to the concentrate
and finally to metals produced at the smelter or as spinels in smelter slag. The final concentrate is a substance handled
separately under REACH (exempt from registration). A soluble but smaller fraction follows the tailings to the tailings
pond for sedimentation.
9.0.1 Overview of uses and Exposure Scenarios
Tonnage information:
The assessed tonnage of sodium dichromate is 29 tonnes for the Boliden Area site and 15.6 tonnes for the Garpenberg
site.
These figures are based on;
For Boliden Area, the projected average sodium dichromate consumption over the 9 years of the mines supplying the
Boliden Area concentrator (2017-2025). They are expected to be operational in their current state for 11 years, however
the consumption is projected to be minimal for the final 2 years (2026-2027). Taking the 9 years from 2017-2025 ensures that the average (29 tonnes per year) is conservative. The actual average consumption over 11 years will be 25.6
t/year. This figure (29 tonnes) also represented real usage for the year 2014.
The figure for Garpenberg (15.6 tonnes) is the maximum expected volume needed in the coming years. This figure was
chosen as Garpenberg did not use any sodium dichromate in 2014. The actual average consumption in Garpenberg is
expected to be 12.6 tonnes per year over 17 years.
These masses contain 11.5 t and 6.2 t chromium consequently (39.7 % wt. chromium).
The physical state of the imported/used substance is an anhydrous solid. In exceptional circumstances the hydrated salt
is used (e.g. just in case of purchasing/delivery problems of anhydrous salt).
The following table lists and titles the scenario and site specific contributing environmental exposure scenario (ECS)
and worker exposure scenarios (WCS) and tonnage assessed.
Table 1. Overview of exposure scenarios and contributing scenarios
Identifiers*)
ES identi- Titles of exposure scenarios and the related contributing scenarios
fiers
Tonnage
(tonnes
per year)
ES
The use of sodium dichromate in copper/lead separation in concentra- 12.5 - 45
tors handling complex sulphide ores
IW
ECS1
Use in copper/lead separation (ERC4/SpERC)
IW
WCS1
Preparation of Sodium-dichromate solution (PROC 8b)
IW
WCS2
Use of chromium in flotation process (PROC2)
IW
WCS3
Maintenance and cleaning (PROC 8a)
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EC number:
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Identifiers*)
Sodium dichromate
CAS number:
10588-01-9
ES identi- Titles of exposure scenarios and the related contributing scenarios
fiers
Tonnage
(tonnes
per year)
*) Manufacture: M-#, Formulation: F-#, Industrial end use at site: IW-#, Professional end use: PW-#,
Consumer end use: C-#, Service life (by workers in industrial site): SL-IW-#, Service life (by professional workers): SL-PW-#, Service life (by consumers): SL-C-#.)
9.0.2 Introduction to the assessment
9.0.2.1 Environment
The assessment for the environment has been performed quantitatively for the compartments most relevant for man
exposed indirectly through the environment. This means that concentrations of Cr in the environment (PECs) has been
measured/estimated for the compartments/medium. Risk characterisation for the environment has been performed for
some of the compartments for which PNECs have been derived. In the case where measured release and/or concentration data is not available the EUSES (2.1) modelling tool has been also used to calculate the exposure to the different
environmental compartments.
The overall background concentrations of Cr (VI) in the environment are known to be very low/insignificant and the
possible toxic effects of natural background of Cr (VI) in risk characterisation are ignored. The added risk approach is
used by assuming that only the anthropogenic local released amount of the Cr (VI) substance is relevant for the effect
assessment.
The initial assessment, ERC 4 (Industrial use of processing aids in processes and products, not becoming part of articles), is the most appropriate for the industrial use of sodium dichromate in copper / lead separation. The substance is
applied in industrial use of copper and lead as processing aid in continuous processes or batch processes applying dedicated or multi-purpose equipment, either automated or operated manually. In initial assessments for this use, 29 tpa
have been employed as it was anticipated that this would be the maximum annual use volume of sodium dichromate for
either site (Boliden Area site). The use of sodium dichromate at Garpenberg site has been much less (< 5 tons per year),
but the use is expected to increase to > 10 t/a.
Measured data on environmental exposure, in terms of released volumes and/or environmental concentrations, have
been used as far as possible. Site specific information proved that the initial ERC 4 emission fractions to estimate emissions to the environment result in an unrealistic worst-case assessment for sodium dichromate. Based on all available
detailed information, there are only very limited releases of Cr (VI) to the environment. At both the sites, programs for
monitoring environmental release to the aquatic environment are in place to control releases of chromates.
Site specific process conditions
The separation process of copper and lead may take place at different pH levels depending on ore quality. This means
that the sodium dichromate behaves differently after the separation. This also means that chromium will either end-up
in the concentrate or remain dissolved in the aqueous solution, followed by discharge with the tailings to the tailings
pond for sedimentation. The precipitation process, for chromium and other metals, is managed by changes to the pH
after the separation process, but before pumping the water to the tailingsspond.
If the process works in the range of pH 7-8, i.e. almost neutral, at this pH-range dichromate falls out as chrome oxides,
Cr2O3(s) and chrome hydroxide, Cr(OH)3 (s) (aq). Any excess of Cr (VI) is reduced to Cr (III) with iron (II) sulfate,
added at the end of the flotation process, and will precipitate as Cr(OH)3 (s). Most of the chromate will appear as solids
and in the dewatering process it mainly ends up in the concentrate.
If the process is performed at a high pH, typically above pH 11, dichromate mainly acts as a reducing agent and remains
in solution. Iron (II) sulfate is added to the lead concentrate to reduce excess of Cr (VI) to Cr (III), which will precipitateas chrome hydroxides when the pH is adjusted.
The main outlet of all chromium constituents from the concentrator processes are in the end bound to
1) concentrate
2) tailings pond precipitate
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EC number:
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Sodium dichromate
CAS number:
10588-01-9
The solid chrome oxide in the concentrate ends up as refractory oxides (spinels) in the slag in the downstream usage at
the smelter. The final slag from the smelter is a product that is registered under REACH (Slags Copper refining (EC
266-970-4, CAS 67711-94-8)).
As a result, depending on process conditions and ore quality, chrome will either end-up in the concentrate and hence is
handled under REACH or in the wastewater and is directed to a tailings pond. The outlet of each tailings pond is analytically monitored for total chromium.
Scope and type of assessment:
The site specific exposure scenarios generated are intended to be part of an application for authorisation. Sodium dichromate is a carcinogenic substance and consequently the main focus is to assess and demonstrate the safe use of the
substance in relation carcinogenicity within humans, the Annex XIV property of the substance. Therefore, detailed
assessment and quantification of ecotoxicological risks has limited application.The importance of the environmental
assessment lies with the predicted (or measured) environmental concentrations of chromium in different environmental
compartments on a localised scale, since these PECs might have influence on the exposure of the general populations to
Cr (VI) via the environment.
Release of chromium (VI), from any source, is expected to be reduced to chromium (III) under normal environmental
conditions, resulting in the impacts of chromium (VI) being limited to the area around the source of release. This assessment therefore focuses on the local impact of emissions from handling and use at the concentrators and from the
waste generated.
The possible wider background emissions of chromium from other sources are not considered and hence the concentrations calculated in this assessment are local ones (as local concentrations (Clocal)) and the assessment is based on the
added risk which these may present.
The scope of exposure assessment and type of risk characterisation for the environment is described in the following
table based on the hazard conclusions.
Table 2. Type of risk characterisation for the environment
Protection target
Type of risk characterisation
Hazard conclusion (PNECs)
Freshwater
Quantitative assessment
Cr (VI) 3.4 μg/l (ECB 2005)
Cr (III) 4.7 μg/l (ECB 2005)
Sediment (freshwater)
Quantitative assessment (Cr (VI) is trans- Cr (VI) 0.15 mg/kg (wet weight) (ECB
formed to Cr (III) form in most sediments) 2005)
Cr (III) 31 mg/kg (wet weight) (ECB
2005)
Marine water
No assessment, no Cr (VI) release to sea
No hazard data located
Sediment (marine water)
No assessment, no Cr (VI) release to sea
sediment
No hazard data located
Sewage treatment plant
No assessment (no biological STP in use)
Air
Qualitative assessment
No hazard data available
Agricultural soil
Qualitative assessment, no direct Cr (VI)
release to agr. soil
PNEC for Cr (VI) in soil has not been
determined. All chromium in soil is
considered to be in the form of chromium (III).
Predator
Quantitative assessment
17 mg Cr (VI)/kg food
Environmental exposure modelling
It is preferential in the exposure assessment to use measured data instead of modelled data, though certain data gaps,
e.g. concentrations of chromium in relation to indirect human exposure via the environment, can be reasonably filled by
modelling. The predicted environmental concentrations of chromium in different environmental compartments in the
local/regional scale have been modelled using EUSES 2.1 model. Basic substance specific parameters used in the mod-
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EC number:
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Sodium dichromate
CAS number:
10588-01-9
elling is presented in Annex 1.
Comments on assessment approach:
Sodium dichromate and several other soluble chromium (VI) salts have harmonised Aquatic Acute 1 Aquatic Chronic 1
environmental classification, thus Cr (VI) is generally known to be hazardous to the aquatic environment.
Contrary to the differences in human health hazards between Cr (VI) and Cr (III), the aquatic fresh water PNEC values
generated for Cr (VI) and Cr (III) are very close to each others, so actually the reduction from Cr (VI) to Cr (III) may
have a rather small influence on risks for the most sensitive aquatic species. The risk characterisation for the environment is made primarily for illustrative purposes and supporting information for the analysis of alternatives part of the
AfA to show that general release level and also the environmental risks regarding releases of chromium to the local
environment are under control at the assessed sites.
Predicted No Effect Concentrations
The Predicted No Effect Concentration (PNEC) values as presented in this chapter are used in the environmental risk
characterisation. The PNEC values are adopted from the EU risk assessment of chromates (ECB 2005).
The PNEC value for fresh surface water using statistical extrapolation method for chromium (VI) has been estimated to
be 3.4 μg/l. For chromium (III) the PNEC 4.7 μg/l was derived by using assessment factor method.
For sediment, the PNECs have been derived through use of the equilibrium partitioning method. The vast majority of
chromium (VI) entering into sediment is known to be converted to chromium (III). For Cr(III) the PNECsediment of 31
mg/kg wet weight (ca 80 mg/kg on a dry weight basis) in acid conditions and 307 mg/kg wet weight for other conditions has been derived (ECB 2005). For chromium (VI), PNECsediment = 1.5 mg/kg wet weight for acid conditions,
and 0.15 mg/kg wet weight for other conditions has been derived.
A PNEC for chromium (VI) for micro-organisms has been derived, as 0.21 mg/l, and a value of 10 mg/l for chromium
(III).
A PNEC for Cr (VI) in soil has not been determined, since all chromium in soil is considered to be in the form of chromium (III).
There are no data on the toxicity of chromium (III/VI) to organisms in the environment through air exposure. As chromium is considered to be associated with particles in the air, it would be expected that any emissions to air would settle
to the soil.
A PNEC for Non-compartment specific exposure for predators of 17 mg Cr (VI)/kg food has also been reported (ECB
2005). The toxicity studies from which the PNEC is derived involved application through gavage or drinking water, so
there would be little conversion of chromium (VI) to chromium (III). In theory, in the rare scenarios where the concentration of chromium (VI) is known, the risks could be quantified (if calculated as chromium (III) are not relevant for
comparison with this PNEC).
Transformation reactions of Cr (VI/III) in the environment
Chromium (III) species dominate in nature, with high levels of chromium (VI) species generally only found as a result
of man-made pollution. Although chromium (VI) is thermodynamically stable only under oxidising conditions, the
kinetics of reduction to chromium (III) under certain conditions can be slow. The environmental fate processes, mainly
the oxidation-reduction reactions of Cr (VI) need to be known to evaluate certain environmental and indirect human
risks of Cr (VI). This has already been evaluated in the view of risk assessment in EU risk assessment report on chromates (ECB 2005). For risk assessment purposes, after literature review, it was assumed that for acidic (or neutral,
where high concentrations of reductants for chromium (VI) exist) soils, sediments and waters, chromium (VI) will be
rapidly reduced to chromium (III) and that approximately 3% of the chromium (III) formed will be re-oxidised to the +6
state. This means that, of the estimated chromium (VI) release to the environment, ca. 3% will remain as chromium (VI)
and ca. 97% will be converted to chromium (III) (ECB 2005).
Under less favourable conditions, e.g. alkaline conditions (~pH >8) and/or neutral conditions, where low concentrations
of reductants for chromium (VI) exist, it will be assumed that the rate of reduction of chromium (VI) to chromium (III)
is slow, with a long half-life of around 1 year. Such conditions are found in seawater, where a pH of around 8 is typical.
In groundwater the presence of manganese oxides would indicate oxidation of chromium (III) to the more soluble
chromium (VI). In the absence of significant concentrations of manganese oxides, the oxidation of aqueous chromium
(III) is unlikely to occur and all the chromium (III) present will be adsorbed and relatively immobile (Eary and Rai,
1987).
Adsorption-desorption behaviour
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EC number:
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Sodium dichromate
CAS number:
10588-01-9
Overall, chromium (VI) anions can be considered to be mobile in sediments in the environment, except possibly under
highly acidic conditions. Chromium (III) appears to be much more strongly adsorbed to soils and sediments than chromium (VI). At pH >5 chromium (III) is known to precipitate out of solution as the insoluble hydroxide, often in conjunction with iron. The adsorption of chromium (III) onto soil follows the pattern typical of cationic metals, it increases
with increasing pH and organic matter content of the soil, while decreasing when other competing (metal) cations are
present. The following partition coefficients (in m3/m3 form) derived in ECB (2005) for chromium (VI) under acidic
conditions are used in this assessment: Ksusp-water = 500 m3/m3, Ksed-water = 500 m3/m3, Ksoil-water = 75 m3/m3.
Bioaccumulation of Cr (VI)
For the risk assessment, a value for the BCF in fish was derived (ECB 2005). The available data indicated that the bioconcentration factor for chromium (VI) in fish is low at around 1 l/kg. Once in the organism, reduction of chromium
(VI) to chromium (III) appears to occur, resulting in an accumulation of total chromium in the organisms by a factor of
approximately 100 times the original concentration in water. Uptake of chromium (III) directly from water is likely to
be very low due to the limited water solubility and strong adsorption to sediment under most conditions found in the
environment.
High BCFs of up to around 9,100 l/kg (dry weight basis) for chromium (VI) and 2,800 l/kg (dry weight basis) for chromium (III) have been determined in mussels with BCFs of around 500 l/kg (on a cell dry weight basis) for chromium
(VI) and 12,000-130,000 l/kg (on a cell dry weight basis) for chromium (III) having been determined in algae. It is
possible that once taken up by the organism, chromium (VI) is reduced to chromium (III) in the tissues, resulting in a
build up of chromium (III) and hence would overestimate the true bioconcentration factor for chromium (VI). Transfer
of chromium via the alga ⇒ bivalve, and sediment ⇒ bivalve food chains appears to be relatively low. Non cultivated
bivalves are not normally used for human consumption in the Nordic countries.
Fate and existence of Cr in air
Chromium (VI) compounds are not volatile and so are found in the atmosphere associated with aerosols or particle
matter. In the atmosphere, chromium (VI) can be reduced to chromium (III) if suitable reductants are present however,
it is likely that in most situations, chromium (VI) will be relatively stable under the conditions present in the atmosphere. The chromium present on particle matter and in aerosols can be transported to land surfaces via wet and dry
deposition.
9.0.2.2 Man via environment
Scope and type of assessment:
The scope of exposure assessment and type of risk characterisation required for man via the environment are described
in the following table based on the reported hazard conclusions.
Table 3. Type of risk characterisation required for man via the environment
Route of exposure and type of
effects
Type of risk characterisation
Hazard conclusion
Inhalation: Systemic Long Term
Quantitative (cancer)
29 x 10-3 per µg Cr (VI)/m3
Oral: Systemic Long Term
Quantitative (cancer)
8 x 10-4 per µg Cr (VI)/kg bw/day
Comments on assessment approach:
The focus in this exposure assessment for general population is carcinogenicity.
Typically indirect exposure of Cr (VI) to humans via the environment occurs by consumption of food (fish, crops, meat
and milk) and drinking water, inhalation of air and ingestion of soil/dust. This assessment aims to estimate the human
daily intake levels and makes use of appropriate local or regional environmental concentrations, as appropriate. The
concentratons have been calculated by using the Euses model as already described in the previous chapters (Environmental exposure modelling).
In the case of chromium (VI), the man via environment assessment has limited focus, since chromium (VI) is reduced to
more stable oxidation state (III) once it is released to the environment. The reduction may take place relatively quickly
in typical Nordic fresh water aquatic environments, even if detailed transformation rate is always dependent on local
conditions. In addition the bioaccumulation potential of chromium is low. Therefore, the relevancy of exposure assessment to the general population via food is not regarded as being significant. Modelled concentrations in foodstuff give
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EC number:
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Sodium dichromate
CAS number:
10588-01-9
some indication of Cr levels for risk characterisation purposes. Exposure via drinking water is relevant and any assessment relies primarily on measured Cr (tot) and secondarily on modelled Cr (VI) concentrations in drinking water.
Exposure through inhalation is also regarded as relevant and highly important. Exposure of the general population
through this route needs to be assessed as handling and the use of the substance may result in emission of Cr(VI) to the
atmosphere to some extent.
Chromium (VI) has a harmonised classification for CMR properties. Cancer and mutagenicity endpoints have been
studied relatively well and non threshold mode of action has been recognised for carcinogenicity. The dataset/information on reproductive toxicity is more limited and it is not completely clear what is the mode of action of Cr
(VI) in reproductive toxicity. However, it is assumed in the risk characterisation that carcinogenicity is the most sensitive endpoint of the three CMR properties. Therefore, the other risks are assumed to be under control if risk levels for
carcinogenicity are at levels of low concern.
Cancer risk- dose responce for general population
For the risk characterisation a preliminary reference dose response relationship for carcinogenicity, has been given for
general population and workers by ECHA/RAC.
Lung cancer risk: For the general population the inhalative linear dose response relation of excess lifetime lung cancer
mortality risk estimate is 29 x 10-3 per µg Cr(VI)/m3. This estimate is based on an exposure for 70 years, 24h/day, every
day.
Intestinal cancer risk: For the general population an linear excess lifetime intestinal cancer risk = 8 x 10-4 per µg
Cr(VI)/kg bw/day has been given. The estimate is based on an exposure for 70 years (24h/day, every day) and an 89year life expectancy (and against a human background cumulative lifetime intestinal cancer risk of 9 – 16 per 1000 for
the German population).
To estimate intestinal exposure from intake of inhalable, but non-respirable particles, the exposure to Cr (VI) can be
converted into oral doses by applying the standard human resting breathing rate of 0.8 m3/hr and the standard average
human body weight default value of 60 kg.
9.0.2.3 Workers
Scope and type of assessment:
The scope of exposure assessment and type of risk characterisation required for workers are described in the following
table based on the hazard conclusions presented.
Table 4. Type of risk characterisation required for workers
Route
Inhalation
Dermal
Eye
Type of effect
Type of risk characterisation
Hazard conclusion
Systemic Long Term
Quantitative (cancer)
1μg/m3 (Cr (VI)) results in 4 x 10-3 excess lung cancer lifetime risk, linear
extrapolation to higher or lower concentrations
Systemic Acute
Qualitative
Acute Tox. 2 *)
Local Long Term
Qualitative
Resp. Sens. 1 *)
Local Acute
Qualitative
Corrosivity, Resp. Sens. 1) *
Systemic Long Term
Qualitative
*)
Systemic Acute
Qualitative
*)
Local Long Term
Qualitative
*)
Local Acute
Qualitative
corrosivity, Skin Corr. 1B *)
Local
Qualitative
corrosivity *)
*) For most of the dermal and inhalation route endpoints qualitative assessment applies. The relevant critical effects are
local and systemic effects, i.e. corrosivity, irritation and carcinogenicity. Sodium dichromate has the harmonized classification Ox. Sol. 2 Carc. 1B Muta. 1B Repr. 1B Acute Tox. 2 * Acute Tox. 3 * Acute Tox. 4 * STOT RE 1 Skin Corr.
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EC number:
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Sodium dichromate
CAS number:
10588-01-9
1B Resp. Sens. 1 Skin Sens. 1 Aquatic Acute 1 Aquatic Chronic 1 (ref: CLP ATP 3). Lung cancer is the most sensitive
effects in humans and also the main driver in setting OC/RMM and the low limits of exposure. Therefore, the operational conditions, engineering controls and personal protective equipment will minimize inhalation/dermal exposure and
be sufficient to protect from all other acute and/or systemic effects.
Comments on assessment approach related to toxicological hazard:
The focus in the worker exposure assessment is to clarify the occupational exposure in relation to the carcinogenicity
properties of Cr(VI) in the two industrial sites.
At the Garpenberg concentrator premises there are in total ca. 30 full time (8 hr shift/3 shifts per day) workers running
the concentrator. During normal office hours there are ca. 15 workers (process operators and service workers). There
are 10 people until 10 or 11 PM outside of normal office hours and 7 workers for the rest of the night. In total 40 workers are expected to have potential to be exposed to Cr(VI) when it is used as a process chemical at the Garpenberg concentrator.
In total, there are ca. 310 workers at the Garpenberg site (ca 195 in the mines and the rest in administrative and service
tasks).
At Boliden Area concentrator there are in total ca. 30 full time workers. Outside of office hours there are 10 people until
10 or 11 PM and 7 workers for the rest of the night.
In total, during the daytime, there are approximately 70-80 workers at the Boliden Area site (including laboratory and
administrative/office workers). In addition there are, depending on the needs, varying number of contractors working on
site.
Table 5. Average number of workers at the sites
Site (time of the day)
Concentrator
operators (at the
concentrator)
Maintenance
workers (at the
concentrator)
Other workers on
site (not at the concentrator premises)
Garpenberg (office hours)
15-20
1-10
310
Garpenberg (non-office hours)
8-10
0-10
195
Garpenberg (night time)
5-7
0-1
195
ca 35-40
1 (pers/a)
ca. 310
Boliden Area (office hours)
15-20
1-10
80
Boliden Area (non-office hours)
8-10
0-10
10
Boliden Area (night time)
5-7
0-1
10
ca 35-40
1 (pers/a)
ca. 80
Garpenberg totals
Boliden Areatotals
A quantitative assessment was carried out for long term systemic hazards via inhalation and skin. On-site measured
exposure information is used as far as possible. Risk assessments for the inhalation route should, as a default, use the
fraction of inhalable, but not respirable, particles (E(I)-E(R)). The risk arising from exposure to this fraction will be
assessed assuming exposure via the gastro-intestinal tract and thus using the risk estimates for that exposure route (ECHA 2012). In the case of these two concentrators, where the all measured Cr(VI) concentrations are low, the applicant
only provides data for the exposure to the inhalable particulate fraction. As a default, it will be assumed that all particles
where in the respirable size range.
The hazard level for qualitative assessment is assigned based on the classification of the substance. The assignment
rules are described in section E.3.4.4 of part E of the Guidance on Information Requirement and Chemical Safety Assessment. The hazard level determines the risk management strategy to be described in the exposure scenarios.
Sensitiser for skin and respiratory organs are properties that require sufficient skin and respiratory protection whenever
there is possibility of direct contact with Cr (VI).
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Reproductive toxicity and mutagenicity are known and classified properties of sodium dichromate. Currently it is unclear whether reproductive toxicity of Cr(VI) is a threshold property or not (insufficient data). However, risk management measures necessary to protect from cancer risk are expected to be sufficiently protective for these M/R properties
as well.
Cancer risk - dose response for workers
A reference dose response relationship for carcinogenicity of hexavalent chromium substances has been provided by
ECHA/RAC. The reference dose response relationships proposed by ECHA are only based on carcinogenicity arising
from the Cr(VI) ion.
(For an authorisation to be granted, the applicant must also demonstrate that there are no suitable alternatives available.
In this latter analysis it may be the case that other endpoints than those for which the substance was listed in Annex XIV
become relevant in order to demonstrate that there is no suitable alternative.)
Inhalation route: For workers a linear dose response relation of excess lifetime lung cancer risk has been given: 1μg/m3
(Cr (VI)) results in 4 x 10-3 excess lung cancer lifetime risk. This relationship is an excess lifetime (up to age 89) lung
cancer risk estimates for workers exposed at different 8h-Time Weighted Average concentrations of Cr(VI) for 40
years.
Intestinal cancer risk estimates for workers has also been given by RAC. An excess lifetime intestinal cancer risk = 3.3
x 10-4 per µg Cr (VI)/kg bw/day, based on a 40 year working life (8h/day, 5 days/week), the following risk estimates are
used:
Exposure to inhalable, non-respirable particles is first converted into oral doses by applying the standard worker breathing rate of 1.25 m3/hour, 8h per day, and the standard worker body weight default value of 70 kg. It is assumed that
there is 100% retention of particles that are inhaled (the gastro-intestinal absorption is not 100% and is reflected in the
oral risk estimates).
Worker exposure: Measured data
Chromium in air has not been analysed routinely at either of the two sites. In general, chromium is not known to generate gases (at NTP) and intrinsic volatilization behavior of chromic acid from the aqueous process solutions is expected
to be zero or extremely low. The raw materials processed in the concentrator do not raise concerns regarding chromium
in the air. Therefore, routine measuring of chromium concentration in workplace air has not been regarded as reasonable in the process halls in general.
Handling of dry chromium salts and/or generation of mists in the flotation unit are potential sources of chromium in the
working place air at the two concentrators. To be completely sure of sufficiently low worker exposure to chromium via
the inhalation route, measurements were performed during the years 2014-2015.
Exposure modeling
Where no measured data are available, modeling tools are used to estimate worker exposure. Exposure assessment tool
for metals and inorganic substances MEASE (1.0.2.01) (EBRC Consulting GmbH 2010) and Targetted risk Assessment
TRA v. 3.10 (ECETOC 2014) exposure assessment tools are used following recommendations of CSA R.14 guidance
for metals and inorganic substances.
Exposure estimates (8hr TWA) for three contributing worker scenarios applying variable working time, PPE/RPE and
substance combinations are given in the Annex 6 of this report "Exposure estimates for the concentrator workers based
on exposure models".
Comments on assessment approach related to physicochemical hazard:
Sodium dichromate is a hazardous chemical and physical chemical hazard properties meet the criteria to be classified it
as “oxidative solids” (Ox. Sol. 2 ). It is not classified related to its Explosive or Flammable properties. Sodium dichromate itself is not flammable and it cannot be ignited by a flame. However, dichromates may intensify fire on contact
with burning materials.
The reactivity of diluted chromates under controlled conditions in the actual concentrator process use does not pose any
specific physicochemical hazards that should be considered separately in the exposure scenario. The oxidative hazard is
not relevant for the reduced Cr (III) reaction product.
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CAS number:
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General information on risk management related to toxicological hazard:
For substances categorised as having a high hazard profile (i.e. category 1A and 1B carcinogens) a very high level of
containment, appropriate PPE together with automatic dosing/feeding to the process are recommended in occupational
settings in order to avoid exposure. Therefore, in this ES the use of protective and relevant PPEs are always seen as a
default in tasks where the substance is handled manually or where the potential for exposure is high.
When contact is possible with the solid, e.g. during mixing, Local Exhaust Ventilation should be standardly present
(RMM efficiency 90-95%, based on ECETOC 2009) while Respiratory Protective Equipment (RPE, efficiency 90%)
should be used. The pattern of use for this substance is non-dispersive, only certain groups of trained workers are handling the material directly and contact level would be incidental or none. For most workers the use is non-direct and
with a contact level of diluted process solutions or products at most is intermittent, but usually would be incidental or
none. Properly designed gloves should be used to minimize the dermal exposure as the substance is sensitising and may
be corrosive (depending on conditions).
General information on risk management related to physicochemical hazard:
The substance is stored in its original package in the reagent store at the industrial area of each concentrator. Health
hazards may be involved in use/storage of sodium dichromate with incompatible substances. The substance is classified
for oxidising properties. Chromium may undergo vigorous redox reactions from its +VI oxidation state to the +III oxidation state. Vigorous oxidative reactions may take place if the substance is mixed with incompatible materials. The
maximum amount of sodium dichromate stored on Boliden Area site is 10 t and on Garpenberg site 5 t at a time. Internal Emergency plans are available in compliance with legislation on chemical accidents (e.g. the Seveso directive) for
critical situations in which sodium dichromate may be involved in (leaks, spillages, fire, explosion, etc) and supplied to
the authorities to enable them to draw up external emergency plans.
9.0.2.4 Consumers
Scope and type of assessment:
The substance is entirely used in industrial installations in strictly controlled conditions. Consumer exposure is nil, since
the substance does not end up in any products entering the consumer market. Therefore exposure assessment and risk
characterization is not required here.
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CAS number:
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9.1 Exposure scenario 1: The use of sodium dichromate in copper/lead separation in concentrators handling complex sulphide ores
Description of the activities and technical processes covered in the exposure scenario:
Market sector: 0 Other (Processing aid)
Sector of use: 2a Mining
Article categories:
Environment contributing scenario(s):
ECS1 Use in copper/lead separation
ERC 4
Worker contributing scenario(s):
WCS1 Preparation of Sodium-dichromate solution
PROC 8b
WCS2 Use of chromium in flotation process
PROC 2
WCS3 Maintenance and cleaning
PROC 8a
Subsequent service life exposure scenario(s): 0
Exposure scenario(s) of the uses leading to the inclusion of the substance into the article(s): 0
Explanation on the approach taken for the ES:
Industrial use of sodium dichromate as processing aids in continuous technically controlled processes applying dedicated equipment match initially well with the environmental release category ERC4. Since the assessment is site specific,
there is detailed information available on the processes and measured and available data on actual releases from the
sites. In addition, industry sector specific release categories (SpERC) and release factors can be used, taking into account the following assumptions:
- Focus of is in chromium (VI), which is the most hazardous form of the metal
- In the long term, the majority of released Cr (VI) is reduced to Cr (III) form in the environment, but reduction rates
cannot be quantified and take into account in the local scale assessment
- The main outlets of chromium from the process is 1. concentrate 2. tailings pond sludge
- Waste collected during cleaning and maintenance operation are recycled back to process if possible or disposed off as
hazardous waste.
- Service life of articles is not applicable and the final product, the concentrate, is a substance handled separately under
REACH.
The actual use of the substance as a process aid chemical takes place in continuous wet process in dedicated equipment.
The concentration of chromium in the process solution is low (50 mg/l at maximum). Release of chromium to atmospheric environment is very low/insignificant and the releases of chromium to the environment takes place mainly to the
fresh surface water environment.
Sodium dichromate is a non volatile (vapour pressure of < 0.01 Pa) high melting (357 °C), water miscible (2355 g/l)
low dustiness solid salt. The mass of the anhydrous salt is 262 g/mol and it contains 39.7 % chromium. Emissions of
Cr(VI) into the air is no more than 0.03% following industry sector specific ERC. A suitable spERC (code 1.2.v2.1) is
available from Eurometaux (see details for spERC http://www.reachmetals.eu/). The spERCs for metals and metal
compounds characterize the environmental releases from manufacture, processing and downstream uses of the metal
compounds in the EU based on >1,300 recent (1993-2010) site-specific measured release factors to air and water for
chromium and 17 other metals and their compounds from various EU Member States.
Both of the concentrators are following environmental monitoring programs. No emission of the substance as gas is
predicted because of the intrinsic physical/chemical properties of chromium at the low (< 50 °C) process temperature.
Time scales of use
There is no need for the use of chromium at the concentrators if there is no need to make copper/lead separation, which
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is highly dependent on specifications of the ore raw materials during each “campaign”. In Garpenberg the separation
circuit is running continously and therfore chromium is used continously. In Boliden Area the separation circuit is running in campaigns depending on the specification of the ore. If the separation circuit is in operation chromium is used.
Handling of concentrated /pure sodium dichromate salt is a short term activity (WCS1). The transferring/mixing activities only account for up to a max 1 hour per shift/day. Transferring, charging and mixing takes place in a highly controlled way to minimize exposure.
Releases to the environment and related RMM‘s
Sodium dichromate is stored in its original package in the reagent store at the industrial area of each concentrator. Sodium dichromate is consumed during the process by chemical transformation from chromium (VI) to solid chrome (III)
oxide/hydroxides. The substance is used in closed continuous process (initially ERC 4 - Industrial use of processing
aids in processes and products, not becoming part of articles).
Environmental releases of pure solid sodium dichromate resulting from the use in copper/lead separation are minimal.
Potential release of the particulate substance is possible only during filling of the mixing tank. In the flotation process
dichromate Cr6+ ions are reduced to Cr3+ (for details see WCS2).
At the Boliden Area concentrator, the LEV of the chemical mixing station is attached to a wet scrubber to prevent emission to the local air. At the Garpenberg site the chemical mixing station LEV is connected to separate filtering equipment. Measurements taken have demonstrated low values of chromium in the air from the chemical mixing and process
halls. The Garpenberg concentrator in question is new and it has started its operation in the year 2014. The old concentrator of Garpenberg is no longer operational.
The aqueous process waste streams are collected in tailings ponds. Both of the concentrators are following environmental monitoring programs. The environmental permits of the tailings ponds are at a provisional condition for the outlet at
15 µg/L total content Cr. The spillway from the tailings pond is continuously sampled and analysed for Cr. The outlet of
the tailings pond is discharged into industrial Waste Water Treatment Plants (WWTP) at both Boliden and Garpenberg
area.
Waste management
Any chromium containing waste generated is disposed of according to local regulations and permissions and follow the
guidelines laid down in the EU legislation on waste and pollution prevention.
The principle that generation of waste is prevented in accordance with EU waste legislation (Waste Framework Directive 2008/98/EC) is followed. Where waste is generated, hazardous waste is managed in accordance with the following waste hierarchy and applied in priority order (in line with the WFD): 1) Prevention 2) Preparing for re-use 3) Recycling or, where that is technically and economically impossible 4) Disposal.
Chromium (VI) containing waste collected during cleaning and maintenance or other operations are recycled back to
process as far as possible. If that is not possible, dilute solutions can be pre-treated by adding Iron (II) sulfate to reduce
Cr (VI) to a less hazardous Cr (III) hydroxide precipite. The residues are disposed of as hazardous waste.
For more details of waste management is presented under the relevant contributing exposure scenarios.
9.1.1
9.1.1.1
Environmental contributing scenario 1- Use in copper/lead separation
Conditions of use
Product (article) characteristics
 Dry involatile solid Na2Cr2O7 salt, low dustiness, (Mp. 357 °C, Vp. 0.0001 Pa)
Amount used, frequency and duration of use (or from service life)
 40 t/a (ca. 17t/a Cr), use in continuous process (24 h/day, 150-365 d/year) , ca. 100 kg/day (total both sites)
Technical and organisational conditions and measures
 Use in dedicated equipment,
 Any excess of Cr(VI) is reduced to Cr(III) by adding iron(II)sulfate at the end of the process and chrome
precipitate out as chrome oxide/hydroxides. This solid fraction ends up in the final product (concentrate).
 Any release potential of the substance will only be possible when filling the sodium dichromate into the
mixing tank.
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 Emission control to air: A wet scrubber is used (Boliden area) and the liquid is returned to the process. At
Garpenberg a LEV and two stage LEV air filtering system (Absolent stoftfilter typ A.dust 4F) controls
chromate dust emission of the chemical mixing station.
Conditions and measures related to sewage treatment plant
 Waste waters are treated on site in industrial waste water treatment plants that reduce any of Cr (VI) to Cr
(III) and precipitation of Cr(OH)3 (s) to tailings ponds.

Conditions and measures related to treatment of waste (including article waste)
 Any hazardous Cr (VI) waste generated is treated off site by authorised contractors
 Secondary waste (eg. emptied chemical bags, used RPE filters etc.) are treated off site as hazardous waste.
Hazardous wastes from onsite risk management measures and solid or liquid wastes from use, cleaning and
maintenance processes should be disposed of separately to authorised hazardous waste treatment plants or
hazardous waste landfills.
 Type of external treatment aiming at final disposal of the waste: Solid waste retained in the tailings pond
(Boliden Area site) is tailingspond sludge (EWC code 01 03 05 other tailings containing dangerous substances). and EWC code 010304, acid-generating tailings (for Garpenberg, where the tailing is not stored
under water). The sludge is wasted under controlled conditions following local permissions (reclamation
with qualified covering) and EU waste regulations.
 Fraction of substance disposed of as secondary waste < 0.1% wt (estimate < 50 kg Cr per site).
Other conditions affecting environmental exposure
 Both of the concentrators (Boliden Area and Garpenberg) are following environmental monitoring programs.
 Fraction consumed in process/use > 0.99. The sodium dichromate (Cr(VI)) is consumed during the process
by chemical transformation to solid chrome oxide/hydroxides (Cr(III).
Additional good practice advice. Obligations according to Article 37(4) of REACH do not apply

9.1.1.2
Releases
The environmental releases are determined primarily by tonnage and the ERC, with conservative estimations and defaults being implemented. For the environmental assessment industrial categories and use types are chosen to best suit
the description of the industry sector and uses of sodium dichromate and emission defaults are those specified by the
ECHA Guidance on information requirements and chemical safety assessment: Chapter R.16: Environmental Exposure
Estimation. Parameters used in modelling exercises are presented in Annex 1.
Surface Water:
Regarding releases to surface waters the environmental permits of the tailings ponds at Boliden Area are at a provisional condition for the outlet at ≤ 15 µg/L total content of Cr. The spillway from the tailings pond is continuously sampled
and analysed for Cr. The outlet of the industrial WWTP is discharged into an tailings pond (for Boliden area) and for
the other site (Garpenberg) an WWTP started its operation in summer 2014.
The waste water flow rates are as follows: 31,200 m3/d at Boliden area, which volume is discharged to an WWTP. For
the Garpenberg site the flow rate is 9000 m3/d (A Fenton type reduction process).
The maximum calculated annual release of chromium to the WWTP influent at 1) Boliden Area site and 2) Garpenberg
sites are:
1) 31 200 m3/d * 15 mg/m3 * 365 d = 170.8 kg/year
2) 9000 m3/d * 15 mg/m3 * 365 d = 49.3 kg/year
The calculation does not take into account the fact that sodium dichromate is used periodically, but not throughout the
year and the actual releases are lower than the permission limits.
Release conditions to surface waters
Boliden Area: The discharge of water from the tailings pond was 31200 m3 per day (24 h) in the year 2013. No relevant
data on average concentration are available since the tailings pond was commissioned during 2012 and is still not in
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CAS number:
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equilibrium. The environmental permit of the tailings pond is a provisional condition for the outlet at 15 µg/L total
content Cr. The outlet of WWTP is directed to the tailings pond as a continuous flow (365 days/y) and subsequently to
the stream Brubäcken, which empties into the Skellefteå River. As no relevant monitoring data for the outlet of the
tailings pond was not available at the time writing this assessment, a worst case concentration of 15 µg/L influent in the
WWTP and 3 µg/L discharge from the WWTP was used applying no further dilution and a distribution in the WWTP of
80% to sludge and 20% to water (as specified in the EU RAR). Expressed as Na2Cr2O7 this corresponds to 7.5 µg/L
discharge from the WWTP. A further dilution factor of 3 is applied from the WWTP to the receiving water (stream
Brubäcken).
(Recent monitoring data: In Boliden Area there are recent analysis on specifically to Cr(VI) concentration sampled
tailings flow out to the tailings pond 440 µg/l (sp 6100), discharge to recipient <0.40 µg/l ( sp 6203) and also a monthly
flow weighted sample from the flow out of the tailings pond (to Hötjärn) <0.40 µg/l (sp 6205s). Boliden area has decided to continue monthly sampling and Cr(VI) analysis of these three sampling points (sp).).
Garpenberg: Data from 2012-2014 shows that the discharge of water from the tailings pond was, on average, 9000 m3
per day (24 h). Average concentration of Cr is 0.58 µg/L total and 0.29 µg/L dissolved. The environmental permit of the
tailings pond is a provisional condition for the outlet at 15 µg/L total content Cr. The outlet of the tailings pond is directed as a continuous flow (365 days/y) via a WWTP. The main purpose of the WWTP is to oxidize thiosulfate. In this
process iron sulphide is added as a catalyst, which leads to sludge formation due to iron hydroxide precipitation. The
overall flow through the WWTP will be higher starting from summer 2014, with approximately 27 000 m3/day. This is
however, not the flow leaving the sedimentation pond. The concentrators circulate about 60 % of the water as process
water, so the amount of water to the recipient is only about 10 000 m3/day. After the WWTP the water runs through a
sedimentation pond called Kongsjön, where the sludge is deposited. No sludge leaves the sedimentation pond. The
sedimentation pond is big enough to hold all sludge leaving the WWTP during its lifetime.
After the sedimentation pond at Garpenberg, the outgoing water is released to the recipient Lake Gruvsjön, which is a
part of the Dalälven River system. As the recipient Lake Gruvsjön is highly affected by old mine waste deposits, the
chromium level in the discharge water from the tailings pond will be at the same level or even lower than the chromium
level in the lake; therefore a worst case dilution factor of 1 is applied from the tailings pond to the receiving water. The
discharge to recipient is thus 1.45 µg/L expressed as Na2Cr2O7.
(Recent monitoring data: In Garpenberg there are recent 2014 sampling and analysis of specifically Cr(VI) concentration in the discharge to recipient (n=4, maximum 10 µg/l, average 5.1 µg/l, minimum 0.2 µg/l). There are significant
variability in the monitoring results, mainly because the new WWTP plant/tailings pond system is still in its operational
first year running-in phase).
Air:
The loss of chromium as a gas is not likely as sodium dichromate has a high melting point is not volatile and dustiness
is low. Handling of dry chromium salts is the only potential known source of chromium to the local air of the two concentrators. Generation of mists in the open flotation units could also be sources of chromium to the process hall air at
the two concentrators.
Emissions of chromium to air are not included to the local environmental permissions of the two sites as regulated pollutants (low relevancy). Therefore these emissions have not been monitored and have been evaluated by using industry
sector specific emission factors. The SpERC= 0.03% emission to air for the manufacture and recycling of metals and
metal compounds is considered to be most appropriate spERC for the use of sodium dichromate as processing aid at the
concentrators (for justifications see ANNEX 2 - Eurometaux SPERC (1.2.v2.1) – local emissions to air assessment).
The calculated annual release of Cr (VI) to the air by using release factor 0.03% in combination to maximum estimated
use volumes of Na2Cr2O7 at 1) Boliden Area concentrator and 2) Garpenberg concentrator are:
1) 13100 kg * 0.0003 = 3.93 kg/year
2) 6200 kg * 0.0003 = 1.86 kg/year
Soil:
Normal operation of the two concentrator sites does not have any direct releases to soil or ground water. Rare exceptions are possible accidents during chemical transportation/unloading operations.
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Table 6. Local releases to the environment
Release
Release factor estimation me- Explanation / Justification
thod
Water
Site specific data
Air
Industry sector specific ERC
(estimated loss of particulate
material to atmosphere)
Initial release factor: 100 % (ERC 4 - No RMM)
Final release factor: 0.03 %
Local release rate:
3.93 kg/year (0.0262 kg/day in 24 d/a) (Boliden Area)
1.86 kg/year (Garpenberg)
Explanation / Justification: The final factor is an spERC emission estimate for this industry sector (ref. Eurometaux see Annex2),
emission calculated based on annual use of Cr(VI) per each site.
Soil
Site specific data
Final release factor: 0%
Explanation / Justification:
No direct releases to soil or ground water
Initial release factor: nd...%
Final release factor: nd...%
Local release rates:
170.8 kg/year (Boliden Area) (1.139 kg/d in 150 d/a)
49.3 kg/year (Garpenberg)
Explanation / Justification: Release calculated based on waste
water flow rates and Cr (tot) permission limits in the effluents.
Releases to waste
A fraction of the initially applied amount of Cr is sent to external waste treatment. This is the sum of direct losses from
processes to waste, and the residues from onsite waste water and waste gas treatment.
Process waste
Residues from water and scrubber waste treatments are circulated effectively back to the process. A fraction of the Cr
(III) solid waste will be retained in the tailings pond under controlled conditions (reclamation with qualified covering).
The sludge is regarded as process waste. No sludge is leaving the tailings pond and there is no recovery of sludge for
agricultural or horticultural use from the Boliden Area or Garpenberg sites.
Secondary waste
Secondary waste means other than process waste. Generation of Cr(VI) contaminated secondary waste is rather small.
Secondary waste is disposed off following local regulations and sent to external waste treatment.
The bags containing the reagent are washed directly after emptying while they are still inside the compartment on top of
the mixing tankwhich then flushes into the mixing tank. After being cleaned the bags are wasted of by authorised waste
management company. Any PPE used (the protective rubber gloves, RPE filters etc.) are disposed of by an authorised
waste management company. The amount of secondary waste sent to external treatment (incineration/landfill/other
treatment) is <500-1000 kg/a per site. Working suits are washed on site and reused.
Release factor to waste from the process: A very rough estimate is that 30 % of used chromium (VI) is wasted and
enters the tailings ponds (the rest enters the concentrates in the form of Cr (III)).
Release factor to waste from on site treatment: All Cr (VI) is transformed to Cr(III) form in the on- site treatment
and thus the effectiveness of treatment is expected to be 100% and release factor is 0 (Effectiveness means here the
fraction after on-site treatment compared to the fraction entered into waste treatment).
9.1.1.3
Exposure and risks for the environment and man via the environment
Two separate iterative estimates Tier 0 and Tier 1 are given for indirect human exposure. The first evaluation has the
most conservative approach and the second is expected to give more realistic estimates for the sites.
The assessment is based on measured site specific data in combination with modelled exposure data. Justifications for
specific selections made in the assessment and approach taken in the iteration phase has been given in Annex 3 Site
specific iteration from Tier 0 to Tier 1.
Table 7. Modelled exposure concentrations and risks for the environment and man via environment
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Protection target
Exposure concentration
Risk characterisation
Freshwater
1.5 µg/l (effluent 15 µg/l + dilution 10)
0.44
Sediment (freshwater)
24.1 mg/kg (wwt) (modelled)
0.77
Marine water
nd (no release to marine water)
Sediment (marine water)
nd (no release to marine water)
Sewage treatment plant
nd (no STP)
Man via Environment - Inhalation
Air (Boliden) modelled
5 * 10-7 mg/m3 [Na2Cr2O7 as Cr (VI)]
-7
3
n.d.
Air (Garpenberg) modelled
3 * 10 mg/m [Na2Cr2O7 as Cr (VI)]
n.d.
Air (Garpenberg) measured
Cr (VI) < 0.002 mg/m3, measured data (at
the emission source )
n.d.
Agricultural soil
7 * 10-5 mg/kg (wwt) as Cr (VI)
n.d.
Man via Environment - Inhalat- 5 * 10-4 µg/m3 (modelled,1st tier)
ion
Man via Environment - Oral
5.4 *10-3 µg/kg/d (modelled, 1st tier)
Man via environment - combined routes
5.4 *10-3 µg/kg/d (modelled, 1st tier)
1.4 *10-5 (lung cancer risk)
4.3 * 10-6 (intestinal cancer risk)
Lung cancer risk: For the general population inhalative linear dose response relation of excess lifetime lung cancer mortality risk
estimate 29 x 10-3 per µg Cr(VI)/m3. This estimate is based on an exposure of 70 years, 24h/day, every day.
Intestinal cancer risk: For the general population linear excess lifetime intestinal cancer risk = 8 x 10-4 per µg Cr(VI)/kg bw/day. The
estimate is based on an exposure for 70 years (24h/day, every day) and an 89-year life expectancy.
Further and more detailed information is given in Annex 3 on the calculated man via environment concentrations of
Cr(VI) in food, drinking water and air and the contribution/fractions of these different sources in building up the estimated daily dose.
In summary the estimated lung and intestinal cancer risks for the general population are:
Lung cancer risk via inhalation route:
1.4 *10-5
Intestinal cancer risk via oral route:
4.3 * 10-6
Remarks on man via the environment from local contribution
Concentrations of Cr(VI) in the local environment
Drinking water
In general, naturally occurring chromium is almost always present in trivalent form, while hexavalent chromium is
derived from human activities (IPCS, 1988). One identified environmental concern worldwide is landfill sites of chromite ore processing residues (COPR). Chromium from these landfills is being leached to groundwaters predominantly
in hexavalent form in high concentrations (Merian et al. 2004). This may be problematic for the general population
locally if groundwater is used for human consumption.
There have not been problems with elevated concentration of chromium in drinking water in the local communities of
Boliden and Garpenberg. Total chromium (Cr (III) + Cr (VI)) is analysed at least annually.
Boliden belongs to the Skellefteå municipality and total chromium is analysed in drinking water. Latest controls on
water from Boliden water utilities are from 2014-02-04 with a total chromium content of 0,052 µg/liters. Latest extended controls for Skellefteå water utility, Abborrverket, was 2014-06-24 with a total chromium content of 0,071 µg/liters.
Garpenberg belongs to Hedemora municipality and total chromium is analysed once each year. The concentration has
been below 0,1 µg/l with the last analysis taking place in December 2013 giving a result of 0,064 µg/l.
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Background chromium concentrations in air and fresh surface waters
For comparison to the measured and calculated on-site concentrations, general background levels of chromium can be
given. Generally, worldwide chromium (total) concentrations in air are in the range 10-50 ng/m3 in urban areas, with
lower levels (annual means <10 ng/m3) found in rural areas. Most of the chromium in air is associated with the particle
phase (Bencko, 1985).
Regarding total chromium concentrations in (fresh) surface waters in the Nordic countries a very comprehensive study
was performed in 1995, Norway, Sweden and Finland with regard to heavy metal concentrations in lakes. Nearly 3,000
lakes were sampled. The study found a median Cr concentration of 0.070 μg/l in Norway, 0.13 μg/l in Sweden and 0.29
μg/l in Finland respectively (Skjelkvåle et al., 1999).
Conclusion on risk characterisation:
It can be concluded that risk levels for human health are at levels of low concern (1.4 *10-5 — 4.3 * 10-6) at the local
level. The same conclusion can be drawn for the environment (no risk (RCR < 1) for the evaluated protection targets).
9.1.2
Worker contributing scenario 1, Preparation of Sodium-dichromate solution (PROC
(8b))
Task for transportation, unloading/mixing of Na2Cr2O7 with other materials. Sodium-dichromate is dissolved in
water in the reagent mixing tank. Solution preparation is carried out in dedicated dissolving station for sodium dichromate at both concentrators.
The chromate product is delivered in Big Bags (1000 kg). When mixing the reagent with water the Big Bags are emptied in a bin on top of the mixing tank. The bags are emptied from bottom by cutting up automatically with stationary
knifes inside the bin. After the dissolution/mixing stage Na-dichromate solution is automatically pumped from the mixing tank to a consumption tank and diluted to proper strength (2.0-8.5 %).
The task includes also supervising the work and cleaning of the dissolving station and cleaning of the unloading/mixing
working area. PPE is the same for all work in the reagent mixing area. Cleaning is done with a water hose.
The detailed procedure in preparation of the solution is as follows:
Site 1 & 2:
Steps for dissolving Na2Cr2O7
When the solution in the dissolving tank is reduced to a fixed minimum level (this can be seen on the monitor in the
control room) the following steps are done by the mixer employee:
 The employees have to use the required personal protective equipments.
 Transporting reagents with truck or traverse to the temporary storage location. The chromate product is delivered in Big Bags (site 1 & 2) (se pictures of the equipment in ANNEX 5).
When mixing the reagent with water the Big Bags are emptied in a bin on top of the mixing tank. First lifting the reagents sack with traverse or truck from the ground floor to floor 1 (the reagent mixture), then lowering it onto a knife in
the funnel or scale.
The employee opens the suction hood (LEV) of the dissolving tank (the system is under negative pressure).
It is ensured that the sack is secured properly to the lifting hook of the forklift truck when it is lifted above the mixing
tank and slowly lowered it onto the fixed knife so that minimum dusting occurs. The bags are emptied from the bottom
by cutting automatically with stationary knives inside the bin. The knife valve will open and drain the whole refilling
funnel. It should be empty after each mixing.
After the sack has been emptied, it is put into the package compressor and compressed, after which time it is wasted.
Na-dichromate is automatically pumped from the mixing tank to a consumption tank and diluted to proper strength (2.08.5 %).
9.1.2.1
Conditions of use
Method
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CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Method
Product (article) characteristics
 Na2Cr2O7 coarse salt grains (mm), Substance as such, low dustiness
Site-spec.
Amount used (or contained in articles), frequency and duration of use/exposure
 At Boliden Area: One worker 1-3 times per month, duration <30 min per time.
 At Garpenberg: Two workers, 2-6 occasions each year with 1 big bag of sodium chromates,
duration <30 min per time.
Site-spec
Technical and organisational conditions and measures
 Indoors at normal room temperature, good general ventilation
 Local exhaust ventilation in use
Site-spec
Conditions and measures related to personal protection, hygiene and health evaluation
 Respiration Protective Equipment is always used: Halfmask ABEK1 + prefilter,
Site-spec
 Skin and body protection: Protective suit (washable or disposable overalls), safety boots, chemical goggles or face shield, chemically resistant gloves (Nitrile rubber, chloroprene rubber, butyl
rubber or other suitable gloves, complying with the requirements of EN 374 (breakthrough time:
480 min); Specific activity training in relation to use and maintenance of the gloves must be
provided) [Effectiveness Dermal: 95%]
 Work under a high standard of personal hygiene. Wash hands and face before breaks.
Other conditions affecting workers exposure
 Training of employees on how to safely work with the substance, incl. how to use the necessary Site-spec
personal protection equipment.
 If an operator comes in contact with the sodium dichromate he/she has to change clothes and
take a shower as soon as possible.
 All information about how to undertake the mixing steps and regulations for each reagent chemical is available in the company IT system (ABB system).
 The employees who are allowed to handle sodium dichromate are authorized to handle the substance. Work instructions and risk analysis covering e.g. the operating instructions and action in
case of spilling are available for the personnel.
 The operators have always access to written work instruction documents for mixing and handling of reagents (example list of documents from Boliden site)
 G1A Operating instruction of Reagent mixing
 G1A Checklist of Reagent mixing
 G1A Action in case of spillage of chemicals
 G1A Risk analysis of Reagent mixing
 New chemicals may not be purchased or used without prior approval of the Local Chemical
Group (Lokala kemikaliegruppen; LKG).
Additional good practice advice. Obligations according to Article 37(4) of REACH do not apply
 Work under a high standard of personal hygiene. Wash hands and face before breaks. When
using the product, do not eat, drink or smoke.
9.1.2.2
Site-spec
Exposure and risks for workers
The station for preparation of the Na2Cr2O7-solution is connected to a LEV and further to the central suction system to a
wet scrubber (Boliden) and attached specific LEV filter (Garpenberg). Exposure to workers is minimised by effective
containment.
Chromium can occur as particles. The concentration of Cr(VI) in workplace air has been measured.
Measurements:
At the Garpenberg concentrator the measurements of chromium (VI) in the working place air occured in the reagent
mixing area. The exposure has been measured by stationary (2 times) and portable dust collectors (1 time). The summary results are below:
Garpenberg:
2014-09-17 CSR-PI-5.5.2
CHEMICAL SAFETY REPORT
19
EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Cr (VI) < 0,002 mg/m3 (stationary, Air Check XR2000, open filter) (10. Jan 2013, 06.40 – 08.00 (80 min.))
Cr (VI) < 0,0003 mg/m3 (portable) (time: 24 Nov. 2013, 06.00 – 14.10 (490 min))
Cr (VI) <0,0008 mg/m3 (stationary Air Chek XR2000, open filter) (24 Nov. 2013, 06.00 – 08.20 (140 min))
Boliden Area:
At the Boliden Area concentrator the measurements of chromium (VI) in the working place air of the reagent mixing
area have been carried out by stationary (1 times) and portable dust collectors (1 time). The summary results are below:
Cr (VI) <0,0005 mg/m3 (stationary sampler Air Chek XR5000) (reagentmix G1A, 18 Mar. 2015, (292 min))
Cr (VI) <0,0005 mg/m3 (personal sampler, Air Chek XR5000) (reagentmix G1A, 18 Mar. 2015, (292 min))
At both sites the chemical bags are emptied to dissolving tank and the chromium salt is dissolved in water. A RPE mask
ABEK1 is always used by the worker carrying out the task. The working area is flushed with water at the end of each
work shift. The concentrator is running in three shifts per day and operates ca. 1700 hours per year. In total ca. 40
workers could be exposed to variable concentrations through the breathed air.
Chemical storehouse: Stationary measurements of Cr(VI) concentration in air at the Garpenberg chemical store (reagenser lager sampling point 11). Storehouse (reagenser lager): sampling date: 2014-06-17 by “Air check 2000” equipment (sampling time 6.1 hours (in total 0.723 m3) result of analysis < 0.4 µg/m³.
Modelling exposure
Preparation of sodium-dichromate solution has been assigned the PROC 8b category, which means: Transfer of substance or preparation (charging/discharging) from/to vessels/large containers at dedicated facilities. The description of
8b and the conditions in Boliden Area concentrator are expected to match well with each other.
A proper selection might also be PROC 26 (handling of solid inorganic substances at ambient temperature). The
MEASE tool can be used for evaluating exposure for PROC26 since the TRA tool does not currently support this
PROC.
The operational conditions (TRA): PROC 8b, industrial use, substance as such, low dustiness, 15-1hr duration of activity, indoors with good general ventilation, RPE in use 90% efficiency, gloves APF20. TRA (3.1) modeling results: long
term inhalative 1 µg/m3 in air and 1.37 mg/kg/day dermal.
For more details of the modeled exposure levels see Annex 6. Exposure estimates for the concentrator workers based on
exposure models.
Table 8. Exposure concentrations and risks for worker
Route of exposure and type of Exposure concentration
effects
Risk characterisation
Inhalation, systemic, long-term 0.00005 mg/m3 (TWA8) 15-60 min task, (RPE
95%) low dustiness, LEV, modelled TRA 3.1
Inhalation, systemic, acute
0.001 mg/m3 short term estimate modelled TRA 3.1
Inhalation, local, longterm(Garpenberg)
0.002 - 0.0008 mg/m3 measured,1hour stationary
sampler
Inhalation, local, long-term
0.0003 mg/m3 (8 hr full shift, Garpenberg) measured, portable/personal sampler)
1.2 x 10-3 excess lung
cancer risk
(dose 0.5 µg/kg (bw)/d)
Inhalation, local, acute
1*10-3 mg/m3 modelled TRA 3.1
Dermal, systemic, long-term
0.14 mg/kg/day modelled TRA 3.1
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CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
Route of exposure and type of Exposure concentration
effects
CAS number:
10588-01-9
Risk characterisation
Dermal, systemic, acute
Dermal, local, long-term
Dermal, local, acute
10 µg/cm2 modelled TRA 3.1
Eye, local
Combined routes, systemic,
long-term
0.19 µg/kg (bw)/d
0.6 x 10-4 excess intestine cancer risk
Combined routes, systemic,
acute
Remarks on exposure data:
There are some exposure measurements available for the concentrators for tasks related to preparation of sodiumdichromate solution, three results for Garpenberg ( (Aug. 2014) and Boliden Area (Mar. 2015). These show low exposure to Cr (VI) in the breathed air.
The few measured concentrations in the working place air seem to be in line with the modelled results. The high level
of containment of workers, automation and other technical measures (e.g. LEVs, high capacity big bags and storage
tanks, automatic dosing/feeding to the process), together with the use of appropriate PPE to limit exposure is at a high
level at both sites. The measured exposure levels of Cr(VI) in the breathing zone and in the vicinity of the mixing tank
during unloading of the bags and solution preparation are low. The arrangement of the mixing stations is the same at the
both concentrators.
Conclusion on risk characterisation:
Based on the information available risk to workers for this contributing worker scenario can be considered to be controlled to a risk level of low concern if the recommended risks management measures and PPEs outlined in this contributing scenario are implemented by the users.
9.1.3
Worker contributing scenario 2, Use of chromium in flotation process (PROC 2)
This contributing worker scenario covers actual use of chromate (Cr2O72- - ions and/or CrO42- - ions) in the flotation and
metal separation process in manufacturing copper and lead concentrate.
This use falls in the general PROC 2 category “use in closed, continuous process with occasional controlled exposure”.
The activities take place indoors in a standardized way, under controlled conditions with dedicated equipment.
Use in the process - The dichromate solution is automatically dosed into the separation circuit of the froth flotation
process as a depressive agent. The solution is pumped through pipes, which are connected to the primary thickener
tanks. The thickeners are large several meter wide tanks. Thickeners are open to the process hall from the top, so the
whole process system is rather a semi-closed than completely a closed system.
Using a depressant increases selectivity of the flotation process, with the depressive effect of the chromate ion taking
the form of a chemical attachment to the galena (PbS) mineral surface.. Thus a depressant prevents one mineral from
floating, while other minerals to float unimpeded and collect in the froth. Use of Cr (VI) in the process results in hydrated mineral surface. Instead of floating, sedimentation of the lead mineral occurs. The addition of sodium dichromate
solution to the separation circuit is made automatically by reagent pumps.
In the flotation process dichromate, Cr6+ is reduced to Cr3+ by oxidation of Pb-xanthates into dixanthogen and the sulphide on the surface of PbS into SO42-. When dichromate, Cr2O72-/ CrO42-, is reduced from Cr6+ to Cr3+ it can form
chrome dioxide, Cr2O3 (s) and chrome hydroxide, Cr(OH)3 (S), (aq) or it can form chrome hydroxide complexes,
Cr(OH)4-/ Cr(OH)x, depending on the pH.
Reaction formula of the chromate:
2014-09-17 CSR-PI-5.5.2
CHEMICAL SAFETY REPORT
21
EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
3PbS + 11 CrO42- + 16H+ = 3PbCrO4 + 4Cr2O3 + 3SO42- + 8H2O
3 PbS + 5HCrO4- + 5H+ = 3PbCrO4 + Cr2O3 + 3S0 + 5H2O
The Boliden process often works at a high pH, above pH 11. In this pH-range dichromate mainly acts as an oxidizing
agent and remains in solution. Iron (II) sulfate is added (when needed) to the lead concentrate to reduce excess Cr (VI)
to Cr (III), which precipitate as chrome hydroxides when pH is adjusted.
Because Cr is solvated in an aqueous solution it remains in water during the dewatering process and some ends up in the
tailings pond. In the tailings pond the potential Cr(OH)x complexes are sensitive to pH-drop since this might cause it to
precipitate out as Cr3+ ions.
The dewatering of the Pb-concentrate occurs in two steps, thickening and vertical plate pressure filters. The underflow
from the primary thickener is dewatered in a filter while the overflow is sent to the secondary thickener. Underflow
from the secondary thickener goes back to the primary one while the overflow is sent to the tailings pond. Most of the
chromate will appear as Cr (III) and remains in solution and ends up with the waste water in the tailings pond. However,
some solid chrome oxides/ chrome hydroxides may occur and end up in the concentrate.
9.1.3.1
Conditions of use
Method
Product (article) characteristics
 Substance in aquatic solution (2-8%) at room temperature, in concentrates and in waste water
 Depending on processed ore, the process liquids are either neutral (7-8) or alkaline (pH 11)
Sitespec
Amount used (or contained in articles), frequency and duration of use/exposure
 At maximum 28t/a (11.5 t/a as Cr), continuous use in process (24 hr) during campaigns, full shift Siteexposure
spec
Technical and organisational conditions and measures
 The dichromate solution is automatically fed to the continuous froth flotation process
Site Cr (VI) acts as a depressant in the separation circuit and Pb mineral sedimentation takes place in spec
the flotation cells and separated from the liquids in thickeners and dewatering units
 The underflow from the primary thickener is dewatered in filters
 Most of Cr (VI) is reduced to Cr (III) in the process
 Chromium enters to the concentrate product and/or to the tailingss pond
 The process is remote controlled by the operators. Working time in the process hall may typically
be < 2 hr/shift.
Conditions and measures related to personal protection, hygiene and health evaluation
 Skin and body protection: Wear a protective suit (washable or disposable overalls), safety boots
 Eye protection: Wear chemical goggles or face shield in the processing area.
 Wear chemically resistant gloves (Nitrile rubber, chloroprene rubber, butyl rubber or other suitable gloves, complying with the requirements of EN 374 (breakthrough time: 480 min); Specific
activity training in relation to use and maintenance of the gloves must be provided)
Personal respiratory protection equipments are not needed in normal working conditions.

Sitespec
Other conditions affecting workers exposure
 Training: concentrator employees are trained on how to safely work with the substance, incl. how Siteto use the necessary personal protection equipment.
spec
 Work under a high standard of personal hygiene. Wash hands and face before breaks. Do not eat,
drink or smoke in the working area.
Additional good practice advice. Obligations according to Article 37(4) of REACH do not apply
 Work under a high standard of personal hygiene. Wash hands and face before breaks. When using
the product, do not eat, drink or smoke.
2014-09-17 CSR-PI-5.5.2
CHEMICAL SAFETY REPORT
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EC number:
234-190-3
9.1.3.2
Sodium dichromate
CAS number:
10588-01-9
Exposure and risks for workers
Measurements
Some measured concentrations of chromium in working place air in the concentrator halls of the two sites are available
and will be used in risk estimation.
Boliden Area: Stationary measurements of Cr (VI) in Boliden Area concentrator flotation hall were made (7.Nov. 2014)
under the normal production and ventilation conditions. Sampling time was 398 minutes (SKC Airchek 52 sampler,
PVC dust filter), analysis by EPA-method (modified) 200.7 (ICP-AES) and 200.8 (ICP-SFMS).
Process hall: Cr (VI) < 0.31 µg/m³.
Until now, Cr(VI) has not been monitored systemically in workplace air. A decision has been made, that there will be
two annual measurements on Cr(VI) in the Boliden Area concentrator process hall in the future. The intention of these
measurements is to check that all ventilation/purification systems are working properly and the Cr(VI) levels in work
place air will in all conditions be kept at a level of low concern.
Garpenberg: Stationary measurements of Cr(VI) concentration in air at the Garpenberg concentrator hall (reagenser
övre/botten plan sampling points 12/13), were taken under the normal production and ventilation conditions at three
different sampling points (in the process area of reagent mixing and flotation (3411 FA)). The measurements have been
carried out to ensure that Cr (VI) is not present in the air at measurable concentrations. The analysis results were below
the detection limit.
Flotation unit: sampling date: 2014-07-31 by “Air check 2000” equipment (sampling time 8.5 hours (in total 1.275 m3),
weather conditions of the day: + 25 oC, sunny). The result was Cr6+ <0.3 μg tot. in sampling filter which means:
Process hall: Cr (VI) < 0.235 µg/m³.
Since the number of measurements is limited, modelled results are used to support the conclusions that risks are controlled to a risk level of low concern.
Table 9. Exposure concentrations and risks for worker
Route of exposure and type of Exposure concentration
effects
Risk characterisation
Inhalation, systemic, long-term Cr (VI) < 0. 235 µg/m³ (TWA 8 hr, measured
Garpenberg) (dose < 0.04 µg/kg (bw)/d)
< 1 x 10-3 excess lung
cancer lifetime risk.
Inhalation, systemic, long-term Cr (VI) < 0.30 µg/m³ (TWA 8 hr, measured Boliden)
Inhalation, systemic, long-term Cr (VI) < 1 µg/m³ (TWA 8 hr, modeled MEASE) < 4 x10-3 excess lung cancer lifetime risk.
Inhalation, systemic, acute
Inhalation, local, long-term
Inhalation, local, acute
Dermal, systemic, long-term
0.002 mg/day (total dermal exposure) MEASE
0.03 µg/kg (bw)/day
Dermal, systemic, acute
Dermal, local, long-term
Dermal, local, acute
Eye, local
Combined routes, systemic,
2014-09-17 CSR-PI-5.5.2
< 0.07 µg/kg (bw)/day
CHEMICAL SAFETY REPORT
< 0.2 x10-4 excess intestine
23
EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Route of exposure and type of Exposure concentration
effects
Risk characterisation
long-term
cancer lifetime risk
Combined routes, systemic,
acute
Remarks on exposure data:
The measured concentrations are all below the detection limits of the used sampling time (up to 8 hours) and sampling
methods (particle filter) and analytical instrumental methods (EPA-methods (modified) 200.7 (ICP-AES) and 200.8
(ICP-SFMS)). The measurements at Garpenberg have lower detection limits (sampling time longer) and were, therefore,
selected as the most representative measurements for risk characterisation purposes.
Conclusion on risk characterisation:
Based on the information available risk to workers for this contributing worker scenario can be considered to be controlled to a risk level of low concern (< 1 *10-3 excess lung cancer lifetime risk).
Please note that the estimated risk levels are smaller than “<” values, since the detection/quantification limits have not
been reached in the measurements. Therefore the detection limits (sampling time and/or sampled air volume) has become the limiting factors in determining the risk levels.
The cancer risk relationship used is an excess lifetime (up to age 89) lung cancer risk estimates for workers exposed at
different 8h-Time Weighted Average concentrations of Cr(VI) for 40 years.
9.1.4
Worker contributing scenario 3, Maintenance and cleaning (PROC 8a)
Maintenance tasks include some procedures which must be performed occasionally (pump breaks etc.) or tasks which
must be carried out systematically following a predefined schedule (e.g. changing filters, maintenance of process control devices).
Industrial maintenance of process equipment can be divided into different types: Preventive Maintenance (PM), Predictive Maintenance (PdM), Corrective Maintenance (CM), Situational Maintenance (SIT) (i.e. based on analysis results,
special events, etc.)).
Maintenance also includes cleaning/emptying of process equipment e.g. emptying and cleaning of tanks and pipings
prior to maintenance. Cleaning of equipment before it is repaired may be carried out by day shift workers or maintenance workers.
Maintenance at the concentrators
Regular maintenance activities at the two concentrators include pre-scheduled Preventive /Predictive maintenance tasks:




Maintenance of valves
Maintenance of pumps
Maintenance of reagent vessels
Maintenance of reagent dosing equipment
The estimated total time needed for the first three tasks is equivalent of two workers, one day every third year. Maintenance frequency of reagent dosing equipment is approximately once a year one hour for one worker. All these tasks are
carried out by the company own staff.
Operational conditions in WCS3
Before the start of PM/PdM maintenance work the equipment is shut down, emptied and cleaned thoroughly by the
operator using proper safety equipment according to safety data sheets and other in house instructions to avoid exposure
to chemicals.
Before performing maintenance in the area where chromium (VI) compounds may appear in the process liquids or solids, all equipment has to be cleaned by an authorized and skilled person. This applies particularly for aggregates, fittings
and measurement devices that have to be dismounted and treated externally or in the workshop.
2014-09-17 CSR-PI-5.5.2
CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Maintenance and cleaning, i.e. removal of residues from thickeners or pipes may be necessary at longer intervals (e.g.
during annual break off) or occasionally in the case of corrective maintenance after breaking of equipments. For these
tasks, there may be a need to follow special precautionary procedures and more stringent safety measures need to be
taken. Cleaning of chemical tanks and thickeners where Cr(VI) may appear (as dust or mist) is a task of high exposure
potential necessitating the use of a chemical safety suit, full face mask and full skin protection.
Waste management in WCS3
The risk management measures in an exposure scenario should cover waste management measures to reduce or avoid
exposure during waste disposal and/or recycling. Chromium containing waste requiring external treatment is not normally generated during these maintenance tasks. The liquids separated from the process in a controlled manner prior to
maintenance can normally be circulated back to process. However, if hazardous Cr (VI) waste is generated in WCS3
tasks, These waste fractions are pretreated as appropriate (e.g. reduction of Cr (VI) to Cr (III) and precipitation) and
disposed off according to local regulations and permissions and follow the guidelines laid down in the EU legislation on
waste and pollution prevention.
Process category
In general these maintenance tasks are expected to be best covered under the process category PROC 8a: “Transfer of
substance or preparation (charging/discharging) from/to vessels/large containers at non-dedicated facilities and with the
explanations: Sampling, loading, filling, transfer, dumping, bagging in non- dedicated facilities. Exposure related to
dust, vapour, aerosols or spillage, and cleaning of equipment to be expected.”
Exposure to substances in aqueous solutions having very low vapour pressure (<0.0001 Pa/very low fugacity) may be
underestimated by most of the PROCs e.g. PROC 8a. Mist generation is always possible in those cases where process
liquids need to be handled manually (changing pumps, filters, gauges, depressurising pipings and joints etc.).
Certain PROCs take the mist generation into account by default (PROC 7,11,12 and 18). PROC7 covers industrial
spraying and substances can be inhaled as aerosols. The energy of the aerosol particles may require advanced exposure
controls. The PROC 7 is expected to be an additional process category in the modelling of exposure of maintenance
worker to Cr (VI) if mists are generated.
PROC 8a is expected to describe best the ordinary pre-scheduled preventive/predictive maintenance work. Additionally,
PROC 7 would better describe modelling of some of the more complicated occasional corrective maintenance situations
where aerosol and mist generation might occur (e.g. in instant correction of equipment breaks). On the other hand, it is
quite clear without any modelling excercises should Cr (VI) containing aerosol/mist may be generated, sufficient protective PPE must always be selected as a precaution.
9.1.4.1
Conditions of use
Method
Product (article) characteristics

Chromium (VI) containing equipment (dry solids, solutions, precipitates, filtrates)
Amount used (or contained in articles), frequency and duration of use/exposure







Variable tasks and amount of substances, in total 2 persons (duration of specific mainte- Site specifc
nance tasks 15 min-8h/d per person) 0-5 occasions per year.
Maintenance of reagent vessels, 2 person 1 time per three years for 1 day
Maintenance/changing pumps: 2 person 1 time per three year for 1 day
Maintenance/change valves 2 persons for 1 day 1 time per three years
Maintenance of reagent dosing equipment, once a year one hour for one worker.
Maintaining/changing sensors and other control equipments, occasionally
.
Technical and organisational conditions and measures


Variable tasks, conditions are not always anticipatable
Before performing maintenance in the area where chromium (VI) may exist all equip-
2014-09-17 CSR-PI-5.5.2
CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Method

ment has to be cleaned by an authorized and skilled person. This applies particularly for
aggregates, fittings and measurement devices that have to be dismounted and treated externally or in the workshop.
In cleaning and maintenance of silos, tanks and pipings where Cr(VI) compounds may
appear strict conditions and measures has to be followed. Get instruction for proper procedures for emptying, waste handling and cleaning of the equipments from the work supervisor or the plant manager.

Conditions and measures related to personal protection, hygiene and health evaluation




Regular preventive/predictive maintenance: Protective glasses, protective clothing and
gloves, be prepared to use RPE whenever needed/anticipated
For expected or known high exposure tasks, i.e. corrective maintenance after equipment
breaks, high exposure potential to dust/mist: full face mask P3 (APF = 40) chemical protective gloves (APF 20) chemical protection suit (EN 468) and safety shoes, chemically
resistant gloves (Nitrile rubber, chloroprene rubber, butyl rubber or other suitable gloves,
complying with the requirements of EN 374 (breakthrough time: 480 min);
In tanks/thickeners independent respirators need to be used to avoid risk of too low oxygen level (work in closed container)Avoid any dust/mist formation by technical means
e.g. avoid handling of dry dusty waste, use RPE whenever dust/mist is generated.
If instructions for proper procedures for the work are not available, sufficiently protective PPEs must always be selected in use by way of precaution
Other conditions affecting workers exposure



Variable conditions: physical form of the substance may be solid/dust/liquid/mist,
pure/mixture at ambient or slightly elevated temperature
When carrying out special work (e.g. cleaning tanks, chemical silos) a work protocol has
to be filled in and checked by operation manager.
All regular maintenenace tasks are normally carried out by Boliden staff. If outsourced
personnel is needed in some specific maintenance tasks and prior to the maintenance
cleaning tasks. All requirements, conditions and measures related to personal protection
apply also to outsourced personnel.
Additional good practice advice. Obligations according to Article 37(4) of REACH do not apply


9.1.4.2
Training and awareness; Identify training needs to ensure that all personnel whose work
may significantly affect the environmental impacts and worker safety in the waste management activities have received appropriate training and have sufficient technical
skills/practical experience of hazardous waste management. Awareness of the importance in using proper and sufficient PPE/RPE whenever needed is key elements of
the worker safety.
The employer and self-employed outsourced maintenance and cleaning persons have
legal responsibilities for the maintenance and issue of personal protective equipments
and respiratory protective devices if needed and the management of their correct use in
the workplace including training of the workers.
Exposure and risks for workers
Use of skin/eye protection is always required – due to corrosive, irritant, sensitising and toxic properties of sodium
dichromate. Therefore quantitative assessment of dermal exposure or exposure to eyes is not always regarded as relevant. Use of skin protection is always recommended, even if hand protection requirements may often be difficult to
comply with due to the nature of some of the maintenance work (e.g. in some mechanical engineering and assembly
work).
Table 10. Exposure concentrations and risks for worker in maintenance and cleaning work
2014-09-17 CSR-PI-5.5.2
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
Route of exposure and type of Exposure concentration
effects
Risk characterisation
Inhalation, systemic, long-term 5 µg/m3, (TWA 8) PROC 8a, task 1560 min, low dustiness solid (100%)
RPE 95%, (TRA 3.1)
excess lung cancer risk
20*10-3
(exposure is intermittent, not
continuous or daily)
(Dose 6.8 µg/kg (bw)/d)
Inhalation, systemic, long-term 1 µg/m3, (TWA 8) PROC 8a, task 1560 min, liquid (< 1% Cr(VI) direct
handling, contact level intermittent,
(MEASE 1.02)
excess lung cancer risk
4*10-3 (exposure is intermittent, not continuous or daily)
(Dose 1.3 µg/kg (bw)/d)
Inhalation, systemic, long-term 3 µg/m3, (TWA 8) PROC 8a, task
>4hr, liquid (< 1% Cr(VI) direct handling, contact level intermittent,
(MEASE 1.02)
5 µg/m3, (TWA 8) PROC 7, task 15-60
min, liquid (mixture< 1% Cr(VI)) RPE
95%, direct handling, contact level
intermittent, (MEASE 1.02)
Inhalation, systemic, acute
Inhalation, local, long-term
Inhalation, local, acute
Dermal, local, acute
Dermal, systemic, long-term
0.34 *10-3 mg/kg/d, PROC 8a (task
>4hr, liquid < 1% Cr(VI)) contact level
intermittent, cloves (MEASE)
Dermal, systemic, long-term
0.07*10-3 mg/kg/d, PROC 7 (task: 1560 min, liquid < 1% Cr(VI)) contact
level intermittent, cloves (MEASE)
Eye, local
Combined routes, systemic,
long-term
<1.3-6.8 µg/kg (bw)/d
< 4.3-22 *10-4 excess intestinal
cancer risk
Combined routes, systemic,
acute
Remarks on exposure data:
Maintenance work typically contains tasks which may lead to significant exposure if sufficient PPE are not used. In
practice, the operational conditions may not always be completely justified in advance. Exposure may sometimes be
sudden and unexpected and therefore PPE in use may not always be sufficient. Modelling worker exposure from
maintenance work includes significant uncertainties. When Cr (VI) is in aqueous liquid, the TRA predicts mainly the
vapour phase exposure and exposure by aerosols is not taken into account. If aerosol formation is relevant as it is in this
case here, other information or models must be used.
Measured data is not available for the maintenance work. However, the modelled information (applying PROCs 8a, 7)
gives clear indication that normal PPEs and also RPE is needed to keep worker exposure levels at sufficiently low level
whenever the process chemicals and liquids containing Cr (VI) is involved in the maintenance task.
In practice, if mists and aerosols are generated in the air, a full face RPE mask and chemical protective suit is recommended to keep the worker exposure levels controlled to a risk level of low concern,
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CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
In the Annex 6 – “Modelled Exposure estimates for the concentrator workers” it can be seen the effect of different
combinations of process category, working time, composition of the substance and PPE in use on the 8 hr TWA exposure levels for maintenance workers. If certain short duration 15-60 min tasks with sufficient PPE/RPE combination is
prolonged to > 4hr or full shift, exposure levels may rise to unacceptable levels.In practice it may be difficult to keep
exposure levels completely under control in the cases where equipment breakages may lead to unfavourable exposure
situations. However, these situations are occasional/rare and in long term the exposure levels of individual maintenance
workers may be as low as they are for the process operators.
Conclusion on risk characterisation:
Based on the information available, risk to workers for this contributing worker scenario can be considered to be controlled to a risk level of low concern if the recommended risks management measures and PPE outlined in this contributing scenario are implemented by the users.
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CHEMICAL SAFETY REPORT
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EC number:
234-190-3
Sodium dichromate
CAS number:
10588-01-9
10. RISK CHARACTERISATION RELATED TO COMBINED
EXPOSURE
In situations where the same person is exposed to the same substance in the same setting via different routes of entry
and via the environment, exposure scenarios reflecting these concomitant exposures should be assessed in the exposure
estimation. These scenarios – typically related to workplaces and aggregated exposure – need specific attention in the
risk characterisation step (ref: CSR guidance E.3.5.1).
Separate calculations are performed for the different populations, workers and the general population.
In environmental assessment, where exposure occurs to a substance as well as to several very closely related and similar
acting chemical substances (e.g. different salts and forms of chromium VI) in the environment and background levels
and the exposure evaluation and risk characterisation should reflect this aspect. The issue can be addressed in a qualitative way, since Cr (VI) is known to be transformed in the environment to Cr (III) form. The reverse reaction back to Cr
(VI) form is known to happen, but the environmental conditions for this reaction must be specific. Therefore natural
background levels of Cr (VI) are extremely low and can be deemed negligible in this context.
Relatively rapid transformation of Cr (VI) in the environment to less toxic form makes historical contamination by
chromium a smaller problem in comparison to many other metals. Historical contamination by Cr (VI) is not reported to
be an environmental problem at the two industrial sites under consideration. Chromium has not been mined at the two
mining areas or chromium ore concentrated at the two sites.
A combined risk characterisation can be performed by combining the current risk levels derived for the local population
to the risk levels derived for workers. The combined exposure is relevant for persons living in the communities located
close to the concentrators and at the same time being workers at the concentrator.
Table 11. Summary of estimated cancer risk levels for different populations
Exposed group
Excess lung cancer risk
Excess intestinal cancer risk
Worker WCS1
1.2 x 10-3
0.6 x 10-4
-3
Worker WCS2
< 1 x 10
< 0.2 x10-4
-3
Worker WCS3
<4-20 (10 )
4.3-22 (10-4 )
-5
General population
1.4 x 10
4.3 x 10-6
Duration of exposure
max 24 days/a
8 hr/d, ca.300 days/a
max 10 days/a
24 hr/day
For the worker scenario WCS2 measured exposure data is available. However, the sampling methods have not been so
effective/sampling time short that the detection and quantification limits of the instrumental analytical methods have not
been reached. Therefore, in these cases, the detection limit determines the result and the risk levels are given as “<“
(i.e. the actual risk estimate is below the given risk level).
For the worker scenario WCS1 and WCS2 the duration of exposure is several days per year (10 to 24 days per year) but
not continuous.The cancer risk estimates given for WCS1 and WCS are TWA8 values for those working day the tasks
are carried out. If the risk estimates are given on annual basis, the risk levels remain at significantly lower level. The
estimated annual risk would be ca. 1/10 lower for WCS1 and ca. 1/30 lower for WCS3 than the estimated TWA8 daily
risk (Table 22).
Table 22. Summary of excess risk levels and corresponding duration of exposure (Table 7 of the SEA)
Exposed group
Excess lung cancer risk
Excess intestinal cancer risk
Duration of exposure
Worker WCS1
1.2 x 10-4
0.6 x 10-5
max 24 days/a
Worker WCS2
< 1 x 10-3
< 0.2 x10-4
8 hr/d, ca.300 days/a
Worker WCS3
<1.3-6.7 x 10-4
1.4-7.3 x 10-5
max 10 days/a
-5
General population
1.4 x 10
4.3 x 10-6
24 hr/day
It can be seen from the risk levels that the estimated lung cancer and intestinal cancer risk levels for the general population are about two orders of magnitude lower than for workers. As a conclusion, the Cr (VI) exposure via the environment to workers of the concentrators are so low that it can be regarded as negligible in comparison to occupational
exposure. Risk characterisation related to combined exposure has not been investigated further
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