H
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April 2017
F E T Y AT
R
VINYL CHLORIDE (CAS NUMBER 75-01-4)
SA
O
Workplace Exposure
Standard (WES) Review
&
TABLE OF CONTENTS
01
INTRODUCTION3
02
PHYSICAL AND CHEMICAL PROPERTIES
03
USES7
04
HEALTH EFFECTS OF VINYL CHLORIDE
5
9
4.1
Non-cancer10
4.2
Cancer10
4.3
Absorption, distribution, metabolism and excretion
11
4.4
IARC evaluation and rationale
12
4.5
SCOEL evaluation
12
EXPOSURE STANDARDS AND GUIDANCE VALUES
IN USE AROUND THE WORLD
05
13
5.1
New Zealand
15
5.2
ACGIH® 15
5.3
SCOEL15
ANALYTICAL METHODS FOR THE ASSESSMENT
OF AIRBORNE VINYL CHLORIDE
06
07
DISCUSSION AND RECOMMENDATION
16
18
APPENDICES20
Appendix 1: Glossary
21
Appendix 2: Methods for setting OELs
23
Appendix 3: References
26
TABLES
1
Chemical and physical properties of vinyl chloride
2
Exposure standards for vinyl bromide from around the world
6
14
01/
INTRODUCTION
3
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
This WorkSafe New Zealand (WorkSafe) review considers
whether the WES for vinyl chloride needs to be changed.
It considers, among other things, the potential for exposures to vinyl chloride in New Zealand,
the health effects and risks, exposure standards in other jurisdictions and the practicability of
measuring vinyl chloride exposures given currently available analytical methods.
The review includes a recommendation to change the current WorkSafe WES, which is currently
set at a WES-TWA of 5 ppm (or 13 mg/m3), as published in the Special Guide Workplace
Exposure Standards and Biological Exposure Indices, 8th Edition (WorkSafe New Zealand, 20161).
In New Zealand, vinyl chloride carries a 6.7A notation for carcinogenicity. This means it is a
known or presumed human carcinogen – the substance is either carcinogenic to humans, or
the data indicate sufficient evidence in animal studies to demonstrate a causal relationship
between human exposure and the development of cancer, or an increase in tumours.
>> Terms that are bold (first occurrence only) are further defined in the Glossary.
>> Concentrations have been converted to ppm from mg/m3 (using the conversion factor
in Table 1) unless the latter is specified as an occupational exposure standard.
>> Synonyms: Vinyl chloride; Chloroethylene; Chloroethene; Monochloroetheylene; Vinyl
chloride monomer.
4
02/
PHYSICAL AND
CHEMICAL
PROPERTIES
5
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
Vinyl chloride is a colourless, highly flammable gas with
an ethereal odour.
Chemical and physical properties include:
Molecular weight
62.5
Specific gravity
0.9106 at 20 °C
Formula; Structure
C2H3Cl; CH2=CHCl
Boiling point
-13.4 °C
Vapour pressure
2530 torr (3.329 atm) at 20 °C
Vapour density
2.15 (air = 1)
Solubility
Soluble in alcohol or ether. Slightly soluble in water.
Conversion factors
1 ppm = 2.56 mg/m3; 1 mg/m3 = 0.39 ppm at 25 °C and 760 torr
Reactivity
Vinyl chloride polymerises in light or in the presence of a catalyst. It is highly
flammable. LEL = 3.6%, UEL = 33%.
HSNO classifications
2.1.1A , 6.1D (All), 6.1D (O), 6.1E(I), 6.5B, 6.6A , 6.7A , 6.9A (All), 6.9A (I), 9.3B
Table 1: Chemical and physical properties of vinyl chloride
6
03/
USES
7
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
Ninety five percent of vinyl chloride produced worldwide
is used as a raw material in the manufacture of polyvinyl
chloride (PVC), and its associated polymers.
PVC is used to manufacture automotive parts and accessories, furniture, packaging materials,
pipes, wall coverings and wire coating. Vinyl chloride production is often located on the same
site as the production of PVC.
In 2007, 7.2 million tonnes of vinyl chloride were produced in the EU and Norway in 30-40 plants
located in 13 EU Member States. It has been estimated that in the EU, about 20,000 workers
are potentially subject to high exposures to vinyl chloride across the vinyl chloride and PVC
manufacturing industries, in the manufacture of rubber and plastic products, and in the water
transport industry and supporting and auxiliary transport activities (European Commission, 20162).
The numbers of persons exposed or potentially exposed in New Zealand is not expected to
be high due to vinyl chloride not being widely used in New Zealand.
Statistics New Zealand 2015 data indicated that 6900 New Zealand workers were working in
the areas of basic polymer manufacturing, polymer film and sheet manufacturing, rigid and
semi-rigid material manufacturing, the manufacture of polymer foam products. The number
potentially exposed to vinyl chloride cannot be inferred from these figures.
8
04/
HEALTH EFFECTS
OF VINYL
CHLORIDE
In this section:
4.1Non-cancer
4.2Cancer
4.3Absorption, distribution,
metabolism and excretion
4.4IARC evaluation and rationale
4.5SCOEL evaluation
9
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
4.1
NON-CANCER
HUMANS
Immediate signs or symptoms of acute exposures have been listed as follows:
>> Following inhalation – weakness, ataxia, inebriation, headache, fatigue, numbness,
paraesthesiae, nausea, vomiting, epigastric pain, visual and auditory disturbances,
narcosis and death.
>> Following dermal exposure – irritation, pain and burns. Rapid evaporation may produce
local frostbite.
>> Following ocular exposure – irritation, pain, possible frostbite and corneal injury
(UK Health Protection Agency, 20083).
In addition to its carcinogenicity, vinyl chloride has been shown to be clastogenic in humans and
is hence a mutagen. Frequencies of chromosomal aberrations, micronuclei and sister chromatid
exchanges in the peripheral blood lymphocytes of workers exposed to high levels of vinyl
chloride have been shown to be increased compared to controls (International Programme
on Chemical Safety, 19994).
ANIMALS
Investigators have reported anaesthesia in rats exposed for six hours per day, for one or five
days at 10% vinyl chloride (Jaeger et al., 19745), possible ataxia in mice exposed for one hour at
50,000 ppm (Hehir et al., 19816), 11 deaths among 20 mice exposed for six hours per day for five
days at 30,000 ppm vinyl chloride (Anderson et al., 19767), and death in 17% of pregnant mice
exposed at 500 ppm, for seven hours per day on days six through 15 of gestation (John, 19818).
In a two-generational reproductive toxicity study in rats exposed to concentrations up to 1100
ppm, no adverse effects on embryo-foetal development or reproductive capacity were observed
at any exposure level over two generations (Thornton et al., 20029).
4.2
CANCER
HUMANS
In 2015, the ACGIH® stated that numerous case reports and epidemiological studies have
demonstrated an association between occupational vinyl chloride exposure and angiosarcoma
of the liver (ACGIH®, 201510). They further stated that some studies have also reported statistically
significant increases in mortality among vinyl chloride workers due to brain and lung cancer, and
cancer of the lymphatic /haemopoietic system.
According to the National Toxicology Programme 13th Ed. (US Dept of Health and Human
Services, 201411), the strongest evidence that vinyl chloride causes cancer in humans is based on
numerous epidemiological studies and case reports that show its association with cancer of the
blood vessels of the liver (hepatic angiosarcoma), which is a very rare tumour.
Gokel reported that exposure to vinyl chloride causes hepatocellular carcinoma (Gokel et al., 197612).
10
SECTION 4.0 // HEALTH EFFECTS OF VINYL CHLORIDE
ANIMALS
The literature on cancer in experimental animals, due to vinyl chloride is extensive and the
following summaries of relevant research represent a sample of the reports available.
Mice exposed to 50 or 500 ppm vinyl chloride by inhalation for 52 or 26 weeks were sacrificed
and subjected to pathologic examination (Holmberg, B. et al., 197613). All animals exposed to
500 ppm, and the majority exposed to 50 ppm developed tumours. Two animals from eight
sacrificed at 26 weeks had lung adenomas. Of the remaining 24 animals, alveologenic adenomas
were found in 13, one of which had a secondary haemangiosarcoma in the lung originating
from a primary subcutaneous tumour in the throat region. Subperitoneal heamangiosarcomas
were found in 14 of the animals. Subcutaneous tumours occurred in five animals, all
bearing haemangiosarcomas in brown fat or other sites. One of these also had a mammary
adenosarcoma. Rhabdomyosarcoma of the left thigh was found in one case. Among other
pathological changes, rupture of haemangiosarcomas causing haemocoelia occurred in eight
animals. The frequency of all the tumours, the number of tumour foci and the size of the foci
in both treatment groups suggested a dose-dependent carcinogenic effect for vinyl chloride.
Swiss mice were exposed to 0 to 10,000 ppm vinyl chloride for four hours per day, 5 days per
week, for 30 weeks (Maltoni et al., 198114). Exposures resulted in an increase in the incidences
of liver angiosarcomas, extra angiosarcomas, lung tumours and mammary gland carcinomas.
Fischer rats were exposed to 0 to 100 ppm vinyl chloride for six hours per day, five days per
week, for up to 24 months (Drew et al., 198315). Exposures resulted in an increasing incidence
of liver haemangiosarcomas, haemangiosarcomas (all sites), mammary gland adenocarcinomas
and hepatocellular carcinomas with exposure duration.
Golden hamsters were exposed to 0 to 10,000 ppm vinyl chloride for four hours per day, five
days per week, for 30 weeks (Maltoni et al., 198114). Exposures resulted in an increase in the
incidences of liver angiosarcomas, skin epitheliomas, forestomach papillomas and acanthomas,
and leukaemia.
4.3
ABSORPTION, DISTRIBUTION, METABOLISM AND EXCRETION
Vinyl chloride is readily and rapidly absorbed via inhalation, ingestion and through the
skin. At room temperature it is a gas, so inhalation is the major route of exposure. Following
absorption, it is distributed through the body, with the highest concentrations found in the liver
and kidneys, followed by the lungs and spleen. Vinyl chloride is mainly metabolised in the liver
by cytochrome P450 enzymes into reactive metabolites and is mainly excreted in the urine as
thiodiglycolic acid (UK Health Protection Agency, 20083).
Volunteers exposed for 6 hours to vinyl chloride concentrations of 2.9 to 23.5 ppm retained,
on average, 42% of the inhaled substance, regardless of exposure level, after 30 minutes
(Krajewski, 198016).
Dermal absorption to airborne vinyl chloride, excluding direct application of the liquid, as
determined with a Rhesus monkey model, was found to be insignificant (Hefner et al., 197517).
11
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
4.4
IARC EVALUATION AND RATIONALE
In 2012 the IARC concluded there is sufficient evidence in humans for the carcinogenicity
of vinyl chloride (IARC, 201218).
They further concluded there is sufficient evidence in experimental animals for the
carcinogenicity of vinyl chloride.
IARC’s overall conclusion is that vinyl chloride is carcinogenic to humans (Group 1).
In making the overall evaluation, the IARC working group took account of a substantial volume
of data in humans, including:
>> An excess of angiosarcoma of the liver in exposed workers was reported by Mundt et al.
(Mundt et al., 200019). IARC made the point that this type of cancer is extremely rare in the
general population.
>> Suggestive evidence for neoplasms of connective and soft tissue derived from the multicentre
study by Mundt et al., in which a more than twofold statistically significant overall increase
in mortality from these neoplasms was observed (Mundt et al., 200019).
The IARC also took account of a large body of evidence for cancers, including extrahepatic
angiosarcomas, lung adenomas, mammary carcinomas, mammary gland tumours,
haemangiosarcomas, nephroblastomas, hepatomas and benign pulmonary tumours in
experimental animal models.
4.5
SCOEL EVALUATION
SCOEL assessed the risk of hepatic angiosarcoma at 3 x 10-4, 6 x 10-4 and 9 x 10-4 (1 in 3,333,
1,667 and 1,111) for working life continuous exposures to vinyl chloride concentrations of 1, 2
and 3 ppm respectively (SCOEL, 200420). It is noted that these risk assessments are consistent
with risk assessments of WHO (1987, 1999, 2000) and of Clewell et al. as reported in SCOEL/
SUM/109 final.
12
05/
EXPOSURE
STANDARDS
AND GUIDANCE
VALUES IN USE
AROUND THE
WORLD
IN THIS SECTION:
5.1New Zealand
5.2ACGIH® 5.3SCOEL
13
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
Table 2 below shows the lead exposure standards from around the world, as published
by the Institute for Occupational Safety and Health of the German Social Accident Insurance
(Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung) and available at
http://limitvalue.ifa.dguv.de
JURISDICTION OR ADVISORY BODY
8-HOUR LIMIT VALUE
ppm
mg/m3
Australia
5
13
Belgium
3
7.77
Canada – Ontario
1
Canada – Quebec
1
2.6
Denmark
1
3
EU
3*
7.7
Finland
3
7.7
SHORT-TERM LIMIT VALUE
ppm
mg/m3
2
6
Hungary
7.77
Ireland
3
7.7
Italy
3
7.7
Japan
2
New Zealand
5
13
Poland
5
China
10
Singapore
5
South Korea
1
Spain
3
7.8
Sweden
1
2.5
Switzerland
2
5.2
The Netherlands
13
5
13
7.77
Turkey
3
UK (HSE)
3
USA – OSHA
1
ACGIH® (1999)
1
SCOEL (2004)
30
7.77
5
None set
Table 2: Exposure standards for vinyl chloride from around the world
* It is noted that in May 2016 the European Commission proposed changing the OEL for vinyl chloride from 3 to 1 ppm
(European Commission, 201621).
14
SECTION 5.0 // EXPOSURE STANDARDS AND GUIDANCE VALUES IN USE AROUND THE WORLD
There are no biological exposure indices (BEIs) in place either in New Zealand, or other
jurisdictions or advisory bodies such as the Health and Safety Executive, SafeWork Australia,
ACGIH® etc.
It is noted that the only organisations from whom we have obtained information as to how and
why they set occupational exposures standards are ACGIH® and SCOEL.
5.1
NEW ZEALAND
WorkSafe’s WES for vinyl chloride has been unchanged since adoption in 1994. In 1999, ACGIH®
revised its TLV-TWA from 5 to 1 ppm, and assigned a notation of A1, to reflect its classification
as a Confirmed Human Carcinogen.
5.2
ACGIH®
ACGIH® TLVs® are health-based guidelines or recommendations to assist in the evaluation and
control of potential workplace health hazards. The ACGIH® TLV® of 1 ppm for vinyl chloride
is intended to minimise the potential for liver cancer, particularly angiosarcoma. The ACGIH®
applies a notation of A1 to vinyl chloride – Confirmed Human Carcinogen. For an A1 notation
the carcinogenicity to humans is based on the weight of evidence from epidemiologic data.
Sufficient data were not available to recommend SKIN or SEN notations or a TLV-STEL.
The most recent review of the TLV® for vinyl chloride by the ACGIH® was conducted in 1997
with the TLV-TWA of 1 ppm and A1 carcinogenicity classification published in 1999.
5.3
SCOEL
No threshold mechanism is supported for vinyl chloride. Where there is no threshold established,
SCOEL does not set a health-based OEL, and uses the risk assessment set in Section 4.5
(SCOEL, 201322). Consequently, SCOEL have found it ‘not feasible’ to set an OEL.
SCOEL has not made a recommendation in relation to notations for sensitisation nor for the
potential for absorption through the skin.
15
06/
ANALYTICAL
METHODS
FOR THE
ASSESSMENT
OF AIRBORNE
VINYL CHLORIDE
16
SECTION 6.0 // ANALYTICAL METHODS FOR THE ASSESSMENT OF AIRBORNE VINYL CHLORIDE
A common practice in New Zealand to measure
airborne vinyl chloride based on NIOSH Method
1007 (NIOSH, 199423).
Using this method, an air sample of 0.7 to 5 L is collected onto tandem solid sorbent tubes, each
with 150 mg of activated coconut charcoal, using a sampling train set at a flow rate of 0.05 L
of air per minute. Following desorption of analyte from the adsorbent using carbon disulphide,
the analysis is carried out by gas chromatography using FID detection. The estimated limit of
detection of this method is 0.04 g of vinyl chloride per sample. This would allow a minimum
airborne concentration of 8 g/m3 (0.003 ppm) to be detected.
In practical terms this method would allow compliance to be assessed against a WES-TWA
as low as 0.02 ppm and still allow for extended shifts of 12 hours per day.
It is noted that this method would allow compliance to be assessed against a WES-TWA of 1 ppm.
17
07/
DISCUSSION AND
RECOMMENDATION
18
SECTION 7.0 // DISCUSSION AND RECOMMENDATION
In 2016 the European Commission discussed their proposal
to improve workers’ protection against cancer-causing
chemicals (European Commission, 201621).
In brief, they propose new EU-wide OELs for 13 priority chemical agents identified through
a consultation process involving scientists, employers, workers, Member State representatives
and labour inspectors. Their proposed new OEL for vinyl chloride is listed as 2.6 mg/m3
(equivalent to 1 ppm), and this value, if adopted, would replace the current EU OEL of 3 ppm.
WorkSafe considers the current WES-TWA of 5 ppm is unacceptable. As discussed, SCOEL20
have assessed the hepatic angiosarcoma risk for vinyl chloride at 3 x 10-4 (1 in 3,333) for a lifetime
of exposure to a concentration of 1 ppm. The risk of hepatic angiosarcoma could be expected to
be much higher than 1 in 3,333 and possibly of the order of 1 in 667, at the current New Zealand
WES-TWA.
It is proposed that WorkSafe New Zealand lower the WES-TWA to 1 ppm to minimise the
potential for increases in the incidence of hepatic angiosarcomas and hepatocellular carcinomas,
based on epidemiological cohort studies of workers in vinyl chloride industries in Europe.
At this concentration, the risk of hepatic angiosarcoma could be expected to be in the order
of 1 in 3,333. This value of 1 ppm, if adopted, will bring the WorkSafe WES-TWA into line with
other jurisdictions and advisory organisations including Ontario, Quebec, South Korea, Sweden,
OSHA and ACGIH®.
19
APPENDICES
IN THIS SECTION:
Appendix 1: Glossary
Appendix 2: Methods for setting WES
Appendix 3: References
20
APPENDICES
APPENDIX 1: GLOSSARY
TERM
MEANING
ACGIH®
The American Conference of Governmental Industrial Hygienists (ACGIH®) is a 501(c)(3)
charitable scientific organization, established in 1938, that advances occupational and
environmental health. Examples of this include their annual edition of the TLVs® and BEIs®
book and Guide to Occupational Exposure Values.
BEI
Biological Exposure Index (BEI) (plural indices) is a guidance value for assessing biological
monitoring results. A BEI indicates a concentration below which nearly all workers should
not experience adverse health effects from exposure to a particular substance.
FID
Flame Ionisation Detection – a detection method used in conjunction with gas
chromatography.
IARC
The International Agency for Research on Cancer – an agency of the World Health
Organisation, whose mission is to coordinate and conduct research on the causes of human
cancer and to develop scientific strategies for cancer prevention and control.
LEL
Lower explosive limit, usually expressed as % volume/volume
mg
Milligram or one thousandth of a gram.
mg/m3
Milligrams of substance per cubic metre of air.
NIOSH
The National Institute for Occupational Safety and Health (NIOSH) is the United States
federal agency responsible for conducting research and making recommendations for
the prevention of work-related injury and illness. NIOSH is part of the Centers for Disease
Control and Prevention (CDC) within the U.S. Department of Health and Human Services.
OEL
Occupational Exposure Limit.
ppm
Parts of vapour or gas per million parts of air.
SCOEL
The Scientific Committee on Occupational Exposure Limits is a committee of the European
Commission, established in 1995 to advise on occupational health limits for chemicals in the
workplace within the framework of Directive 98/24/EC, the chemical agents directive, and
Directive 90/394/EEC, the carcinogens at work directive.
SEN
A notation indicating the subject substance is a sensitiser. DSEN and RSEN are used in
place of SEN when specific evidence of sensitisation by the dermal or respiratory route,
respectively, is confirmed by human or animal data. An ACGIH® term.
SKIN
Skin absorption–applicable to a substance that is capable of being significantly absorbed
into the body through contact with the skin.
TLV®
Threshold Limit Value (see TLV-STEL and TLV-TWA below). An ACGIH® term.
TLV-STEL
TLV-Short-Term Exposure Limit; a 15 minute TWA exposure that should not be exceeded at
any time during a work day, even if the 8-hour TWA is within the TLV-TWA. An ACGIH® term.
TLV-TWA
TLV® – Time-Weighted Average; the TWA concentration for a conventional 8-hour workday
and a 40-hour workweek, to which it is believed that nearly all workers may be repeatedly
exposed to, day after day, for a working lifetime without adverse effect. An ACGIH® term.
UEL
Upper explosive limit, usually expressed as % volume/volume
g
Microgram, or millionth of a gram.
21
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
22
TERM
MEANING
WES
Workplace Exposure Standard – WESs are values that refer to the airborne concentration
of substances, at which it is believed that nearly all workers can be repeatedly exposed
to, day after day, without coming to harm. The values are normally calculated on work
schedules of five shifts of eight hours duration over a 40 hour week. A New Zealand term.
WES-TWA
The average airborne concentration of a substance calculated over an eight-hour working
day. A New Zealand term.
WHO
World Health Organisation.
APPENDICES
APPENDIX 2: METHODS FOR SETTING OELs
ACGIH® STATEMENT OF POSITION REGARDING THE TLVS® AND BEIS®
The American Conference of Governmental Industrial Hygienists (ACGIH®) is a private notfor-profit, nongovernmental corporation whose members are industrial hygienists or other
occupational health and safety professionals dedicated to promoting health and safety within the
workplace. ACGIH® is a scientific association. ACGIH® is not a standards setting body. As a scientific
organization, it has established committees that review the existing published, peer-reviewed
scientific literature. ACGIH® publishes guidelines known as Threshold Limit Values (TLVs®) and
Biological Exposure Indices (BEIs®) for use by industrial hygienists in making decisions regarding
safe levels of exposure to various chemical and physical agents found in the workplace. In using
these guidelines, industrial hygienists are cautioned that the TLVs® and BEIs® are only one of
multiple factors to be considered in evaluating specific workplace situations and conditions.
Each year ACGIH® publishes its TLVs® and BEIs® in a book. In the introduction to the book,
ACGIH® states that the TLVs® and BEIs® are guidelines to be used by professionals trained in
the practice of industrial hygiene. The TLVs® and BEIs® are not designed to be used as standards.
Nevertheless, ACGIH® is aware that in certain instances the TLVs® and the BEIs® are used as
standards by national, state, or local governments.
Governmental bodies establish public health standards based on statutory and legal frameworks
that include definitions and criteria concerning the approach to be used in assessing and
managing risk. In most instances, governmental bodies that set workplace health and safety
standards are required to evaluate health effects, economic and technical feasibility, and the
availability of acceptable methods to determine compliance.
ACGIH® TLVs® and BEIs® are not consensus standards. Voluntary consensus standards are
developed or adopted by voluntary consensus standards bodies. The consensus standards
process involves canvassing the opinions, views and positions of all interested parties and then
developing a consensus position that is acceptable to these parties. While the process used to
develop a TLV® or BEI® includes public notice and requests for all available and relevant scientific
data, the TLV® or BEI® does not represent a consensus position that addresses all issues raised
by all interested parties (e.g., issues of technical or economic feasibility). The TLVs® and BEIs®
represent a scientific opinion based on a review of existing peer-reviewed scientific literature
by committees of experts in public health and related sciences.
ACGIH® TLVs® and BEIs® are health-based values. ACGIH® TLVs® and BEIs® are established by
committees that review existing published and peer-reviewed literature in various scientific
disciplines (e.g., industrial hygiene, toxicology, occupational medicine, and epidemiology).
Based on the available information, ACGIH® formulates a conclusion on the level of exposure
that the typical worker can experience without adverse health effects. The TLVs® and BEIs®
represent conditions under which ACGIH® believes that nearly all workers may be repeatedly
exposed without adverse health effects. They are not fine lines between safe and dangerous
exposures, nor are they a relative index of toxicology. The TLVs® and BEIs® are not quantitative
estimates of risk at different exposure levels or by different routes of exposure.
23
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
Since ACGIH® TLVs® and BEIs® are based solely on health factors, there is no consideration given
to economic or technical feasibility. Regulatory agencies should not assume that it is economically
or technically feasible for an industry or employer to meet TLVs® or BEIs®. Similarly, although
there are usually valid methods to measure workplace exposures at TLVs® and BEIs®, there can
be instances where such reliable test methods have not yet been validated. Obviously, such a
situation can create major enforcement difficulties if a TLV® or BEI® was adopted as a standard.
ACGIH® does not believe that TLVs® and BEIs® should be adopted as standards without full
compliance with applicable regulatory procedures including an analysis of other factors
necessary to make appropriate risk management decisions. However, ACGIH® does believe that
regulatory bodies should consider TLVs® or BEIs® as valuable input into the risk characterization
process (hazard identification, dose-response relationships, and exposure assessment).
Regulatory bodies should view TLVs® and BEIs® as an expression of scientific opinion.
ACGIH® is proud of the scientists and the many members who volunteer their time to work on
the TLV® and BEI® Committees. These experts develop written Documentation that include an
expression of scientific opinion and a description of the basis, rationale, and limitations of the
conclusions reached by ACGIH®. The Documentation provides a comprehensive list and analysis
of all the major published peer reviewed studies that ACGIH® relied upon in formulating its
scientific opinion. Regulatory agencies dealing with hazards addressed by a TLV® or BEI® should
obtain a copy of the full written Documentation for the TLV® or BEI®. Any use of a TLV® or BEI®
in a regulatory context should include a careful evaluation of the information in the written
Documentation and consideration of all other factors as required by the statutes which govern
the regulatory process of the governmental body involved.
POLICY STATEMENT ON THE USES OF TLVS® AND BEIS®
The Threshold Limit Values (TLVs®) and Biological Exposure Indices (BEIs®) are developed as
guidelines to assist in the control of health hazards. These recommendations or guidelines are
intended for use in the practice of industrial hygiene, to be interpreted and applied only by a
person trained in this discipline. They are not developed for use as legal standards and ACGIH®
does not advocate their use as such. However, it is recognized that in certain circumstances
individuals or organizations may wish to make use of these recommendations or guidelines
as a supplement to their occupational safety and health program. ACGIH® will not oppose
their use in this manner, if the use of TLVs® and BEIs® in these instances will contribute to the
overall improvement in worker protection. However, the user must recognize the constraints
and limitations subject to their proper use and bear the responsibility for such use.
The Introductions to the TLV®/BEI® Book and the TLV®/BEI® Documentation provide the
philosophical and practical bases for the uses and limitations of the TLVs® and BEIs®. To extend
those uses of the TLVs® and BEIs® to include other applications, such as use without the judgment
of an industrial hygienist, application to a different population, development of new exposure/
recovery time models, or new effect endpoints, stretches the reliability and even viability of the
database for the TLV® or BEI® as evidenced by the individual Documentation. It is not appropriate
for individuals or organizations to impose on the TLVs® or the BEIs® their concepts of what the
TLVs® or BEIs® should be or how they should be applied or to transfer regulatory standards
requirements to the TLVs® or BEIs®. (Approved by the ACGIH® Board of Directors on March 1, 1988.)
24
APPENDICES
Special Note to User: The values listed in the book are intended for use in the practice of
industrial hygiene as guidelines or recommendations to assist in the control of potential
workplace health hazards and for no other use. These values are not fine lines between safe
and dangerous concentrations and should not be used by anyone untrained in the discipline
of industrial hygiene. It is imperative that the user of this book read the Introduction to each
section and be familiar with the Documentation of the TLVs® and BEIs® before applying the
recommendations contained herein. ACGIH® disclaims liability with respect to the use of the
TLVs® and BEIs®.
EUROPEAN SCIENTIFIC COMMITTEE ON OCCUPATIONAL EXPOSURE LIMITS (SCOEL)
SCOEL adopts a case-by-case approach to setting OELs. Wherever possible SCOEL will
attempt to establish a ‘health-based’ OEL, using the following general procedure:
>> assemble all relevant data on the hazards (experimental information, data on physical
properties etc)
>> determine whether the database is adequate for the setting of an OEL
>> identify adverse effects that may arise from exposure, and establish those that are crucial
in deriving an OEL
>> identify, and review relevant human and animal studies
>> establish whether the substance acts via a non-threshold mechanism or whether a
conventional (threshold) toxicological model can be used. Where non-threshold mechanisms
are involved, SCOEL considers that ‘health-based’ OELs cannot be established and different
considerations apply (such as applying a numerical risk assessment process)
>> assess dose/response data for each key effect, establish ‘no observed adverse effect
levels’ (NOAELs) where possible, or ‘lowest observed adverse effect levels’ (LOAELs),
or benchmark doses
>> decide whether a STEL is required in addition to an 8-hour TWA limit
>> decide whether a biological limit value (BLV) might be established, and what it will be
>> establish a numerical value for an 8-hour TWA OEL at or below the NOAEL (or LOAEL
as the case may be), incorporating an appropriate uncertainty factor
>> establish a numerical value for a STEL and for a BLV, if required
>> document the process so the rationale for the OEL is clear
>> assess the technical measurement feasibility of the air and biological values.
25
WORKPLACE EXPOSURE STANDARD (WES) REVIEW: VINYL CHLORIDE
REFERENCES
26
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exposure to carcinogens or mutagens at work.
3
UK Health Protection Agency (2008) www.gov.uk/government/uploads/system/uploads/attachment_data/file/338284/
hpa_vinyl_chloride_toxicological_overview_v1.pdf
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Jaeger, R.J. et al. (1974). Acute hepatic injury by vinyl chloride in rats pretreated with phenobarbital. Nature 252, 724 – 726.
6
Hehir, R.M. et al. (1981). Cancer induction following single and multiple exposures to a constant amount of vinyl chloride
monomer. Environ Health Perspect. 41, 63 – 72.
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Anderson, D. et al. (1976). Vinyl chloride: Dominant lethal studies in male CD-1 mice. Mutat. Res. 40, 359 – 370.
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68, 207-219.
10
American Conference of Governmental Industrial Hygienists (ACGIH®), (2015). Vinyl chloride. Documentation of the
Threshold Limit Values and Biological Exposure Indices. 7th Edition, ACGIH®, Cincinnati, Ohio. Copyright 2015. Reprinted
with permission.
11
National Toxicology Programme (2014). Report on Carcinogens: Vinyl halides (selected) 13th Ed. (US Dept of Health and
Human Services) https://ntp.niehs.nih.gov/ntp/roc/content/profiles/vinylhalides.pdf
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Gokel, J.M. et al. (1976). Hemangiosarcoma and hepatocellular carcinoma of the liver following vinyl chloride exposure.
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Holmberg, B. et al. (1976). The pathology of vinyl chloride exposed mice. Acta. Vet. Scand. 17, 328 – 342.
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experimental basis. Environ. Health Perspect. 41, 3 – 29.
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Drew, R.T. et al. (1983). The effect of age and exposure duration on cancer induction by a known carcinogen in rats, mice
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Hefner, Jr. et al. (1975). Percutaneous absorption of vinyl chloride. Toxicol. Appl. Pharmacol. 34, 529 – 532.
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20
SCOEL (2004) Recommendation from the Scientific Committee on Occupational Exposure Limits: Risk Assessment for
Vinyl Chloride, SCOEL/SUM/109.
21
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chemicals, Brussels.
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23
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24
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Cincinnati, Ohio. Copyright 2016. Reprinted with permission.
DISCLAIMER
WorkSafe New Zealand has made every effort to ensure the information contained in this publication
is reliable, but makes no guarantee of its completeness. WorkSafe may change the contents of this guide
at any time without notice.
This document is a guideline only. It should not be used as a substitute for legislation or legal advice.
WorkSafe is not responsible for the results of any action taken on the basis of information in this
document, or for any errors or omissions.
Published: April 2017 Current until: 2019
PO Box 165, Wellington 6140, New Zealand
www.worksafe.govt.nz
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