Development of Interim CCME PCB Soil
Quality Guidelines for Missing Pathways of
Exposure for the Protection of Human
Health and Ecological Receptors
By: Karl Bresee, B.Sc., PBD, P.Biol.
Intrinsik Environmental Sciences Inc.,
January 15th 2016
Fairmont Palliser, Calgary
Outline
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Project background
CCME* requirements
What guidelines are available and missing
Project-specific requirements
Toxicity of PCBs**
Methods
Interim guidelines
Other considerations
* Canadian Council of Ministers of the Environment
Guideline summary
** Polychlorinated Biphenyls
Project Background
Project Background
CCME Requirements
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Chemical classification important at identifying pathways of exposure:
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Chemical Properties of PCBs:
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Organic / inorganic
Volatile / non-volatile
Soluble / non-soluble
Biomagnify / non-biomagnify
Molecular Weight = 291.99 g/mole
Log(Kow) = 7.1
Vapour Pressure = 0.000494 mm Hg
Henry’s Law Constant = 0.000415 atm-m3/mol
Solubility = 0.7 mg/L
PCBs are persistent, bio-accumulative and can bio-magnify
PCBs are highly toxic causing adverse effects on the immune, reproductive,
nervous and endocrine system.
CCME Requirements
• Protects human and ecological receptors
• Includes aquatic and terrestrial pathways
• Designed for various land uses or exposure
scenarios
• Applicable across Canada
• Generic and designed to be conservative
CCME Requirements - Ecological
CCME 2006
CCME Requirements - Ecological
Interim from 1991 ???
Route of Exposure
Agricultural
Residential / Parkland
Commercial
Industrial
Guideline [mg/kg]
0.5
1.3
33
33
Soil Contact
Soil Nutrient Cycling
Processes,
Soil Invertebrates,
Crops/Plants,
Livestock/Wildlife
Soil Nutrient Cycling
Processes,
Soil Invertebrates,
Plants, Wildlife
Soil Nutrient Cycling
Processes,
Soil Invertebrates,
Plants, Wildlife, Offsite
Migration
Soil Nutrient Cycling
Processes,
Soil Invertebrates,
Plants, Wildlife, Offsite
Migration
Soil and Food
Ingestion
Herbivores,
Secondary and
Tertiary Consumers*
Herbivores,
Secondary and
Tertiary Consumers*
Not Applicable
Not Applicable
Ingestion of
Contaminated Water
Livestock
Not Applicable
Not Applicable
Not Applicable
Contact with
Contaminated Water
Freshwater Life, Crops
Irrigation
Freshwater Life
Freshwater Life
Freshwater Life
CCME Requirements – Human Health
No Guideline Available
Route of Exposure
Agricultural
Residential / Parkland
Commercial
Industrial
Soil Contact
Direct soil ingestion,
Direct soil dermal
contact, direct soil
particulate inhalation
Direct soil ingestion,
Direct soil dermal
contact, direct soil
particulate inhalation
Direct soil ingestion,
Direct soil dermal
contact, direct soil
particulate inhalation
Direct soil ingestion,
Direct soil dermal
contact, direct soil
particulate inhalation
Indirect Soil Exposure
Indoor vapour
inhalation,
Consumption of
produce, meat and
milk*
Indoor vapour
inhalation,
Consumption of
backyard garden
produce
Indoor vapour
inhalation, Offsite
migration
Indoor vapour
inhalation, Offsite
migration
Protection of potable
water
Ingestion of
groundwater
Ingestion of
groundwater
Ingestion of
groundwater
Ingestion of
groundwater
Project Specific Requirements
Description
Will be calculating
human guideline for
Agricultural
Land Use
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•
Will be calculating
ecological guideline for
•
Residential/Parkland
Land Use
Commercial
Land Use
Industrial
Land Use
Direct soil ingestion,
soil dermal contact,
soil particulate
inhalation
Consumption of
produce, meat and
milk
Direct soil ingestion, soil
dermal contact, soil
particulate inhalation
Direct soil ingestion, soil
dermal contact, soil
particulate inhalation
Not calculating
Not calculating
Direct soil ingestion,
soil dermal contact,
soil particulate
inhalation
Consumption of
produce, meat and
milk
•
Soil and food
ingestion for cattle
Not calculating
•
CCME Guideline available for
primary consumer but based
on the chicken
Total Exposure – All Sources Included
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•
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Exposure limit or
Toxicity Reference Value; or
Reference Dose
Residual
Portion Allocated to
Soil Guideline
Background
CCME 2006
Estimated Daily Intake - Background
• Health Canada Total Diet Studies available from Cities
across Canada from 1992 to 2002
• Included Toronto, Montreal, Halifax, Winnipeg
Vancouver, Ottawa, Whitehorse, St. John’s and
Vancouver
• Food items obtained from 3 to 4 different supermarkets
within each city
• Combined with estimates of Canadians’ food intake rates
Estimated Daily Intake - Background
Age Groups
(Males and Females)
Minimum Daily
Intake (µg/kg
bw/day)
Maximum Daily
Intake (µg/kg
bw/day)
Average Daily
Intake (µg/kg
bw/day)
Infant
0.00174
0.0514
0.0138
Toddler
0.0018
0.0359
0.013
Child
0.00456
0.0178
0.00966
Adolescent
0.00231
0.013
0.006
Adult
0.00116
0.0936
0.0040
Tolerable Daily Intake - TDI
0.13
Bolded values represent the average daily intakes of PCBs that were used in the assessment
Tolerable Daily Intake - TDI
• PCBs were administered to female rhesus monkeys through their
diet
• Critical effect involved monitoring various aspects of locomotor
activity in the offspring of females (Bowman et al. 1981)
• Highest dose at which no adverse health effects were seen was 13
µg/kg bw/day
• TDI = NOAEL / uncertainty factor (UF) of 100
• Interim TDI = 0.13 µg/kg bw/day (Health Canada 2010)
*NOAEL – No Observable Adverse Effects Level
Soil Ingestion Guideline
=
×
+
−
×
×
×
×
+
×
×
Variable
Units
Description (toddler)
Tolerable Daily Intake (TDI)
µg/kg/d
0.13
Estimated Daile Intake (EDI)
µg/kg/d
0.013
Soil Allocation Factor (SAF)
Unitless
20%
Absorption Factor Gut & Lung (AFG & AFL)
Unitless
100%
Absorption Factor Skin (AFS)
Unitless
14%
Soil Ingestion Rate (SIR)
mg/day
80
Inhalation Rate Soil (IRS)
mg/day
0.0071
Soil Dermal Contact Rate (SR)
mg/day
69
Exposure Term 1 & 2
Unitless
1
+
Soil Ingestion Guideline
Description
Agricultural
Land Use
Direct Contact PCB Soil
Quality Guideline [mg/kg]
Alberta Direct Soil
Contact Guideline [mg/kg]
•
Commercial
Land Use
Industrial
Land Use
4
Residential/
Parkland
Land Use
4
7
75
22
22
33
160
Current Alberta guideline based on older Health Canada (2004) TDI of 1 µg/kg/day, which was based on the
LOAEL* from the study by Bowman et al. (1981)
*LOAEL – Lowest Observable Adverse Effect Level
Consumption of Produce, Meat & Milk
=
×
×
+
×
−
×
×
×
×
+
! ×
Variable
Units
Description (Agricultural – Toddler)
Proportion of Produce Home-Grown (PH)
Unitless
50%
Produce Consumption Rate (PC)
Kg/day
0.172
Biotransfer Factor for Produce (BV)
Days/kg
0.0031 = 10(
Proportion of Meat Home-Produced (MH)
Unitless
50%
Meat Consumption Rate (MC)
Kg/day
0.086
Meat Biotransfer Factor (BP)
Days/kg
0.021 = 10()*.*33×(,-./01 )
Soil Ingestion Rate for Cattle (SIRC)
Kg/day
0.9
Proportion of Milk Home-Produced (MKH)
Unitless
100%
Dairy Product Consumption Rate (MKC)
Kg/day
0.592
Dairy Product Biotransfer Factor (BM)
Days/kg
0.0045 = 10()*.*33×(,-./01 )
.'(()*.'+(×,-./01 )
4
"×
(Travis and Arms 1988)
5 .*+×,-./01 ) 6.'7)
4
! ×
×
5 .*+×,-./01 ) 6.'7)
×
8
(RTI 2005)
"
(RTI 2005)
+
Consumption Guideline
Description
Consumption Guideline
[mg/kg]
•
Agricultural
Land Use
0.11
Residential/
Parkland
Land Use
7.4
Assumes no spatial averaging or foraging by cattle
Commercial
Land Use
Industrial
Land Use
Not
Applicable
Not
Applicable
Primary Consumer Guideline
=
•
•
•
0.75 ×
×
×
+(
×
)
Daily Threshold Effects Dose (DTED) based on NOAEL of 1.67 mg/kg/day derived from
study by Willett et al. (1987), which consisted of:
• Three dose groups exposed to Aroclor 1254 including a control
• 4 Holstein cows per group exposed for 180 days
• Dosing occurred through lactation and non-lactation phase
• No apparent effect on health and productivity of cows and calves
• Divided NOAEL of 1.67 mg/kg/day by uncertainty factor of 30 to derive DTED of
0.056 mg/kg/day
The PCB ingestion guideline for the protection of cattle was derived to be 31 mg/kg, which
is close to the existing CCME guideline of 25 mg/kg based on the chicken.
Cows appear to be less sensitive to PCB exposures than chickens
Other Considerations
• Bioavailability
• Food preparation
• Area use factor
Other Considerations: Bioavailability
• Soil bio-availability of PCB in rats ranged from
66 to 99% (NEPI 2000)
• Assumed a mid-point value of 83%
Relative
Bioavailability for
PCBs in Soil (%)
Ingestion of Contaminated Produce, Meat, and
Milk PCB Soil Quality Guidelines (SQGFI) (mg/kg)
Agricultural Land Use
Residential/Parkland
Land Use
83%
0.12
7.4
100%
0.11
7.4
Other Considerations: Bioavailability
• Milk bio-availability of PCB in goats was 51%
(Feidt et al. 2013)
Relative Bioavailability
for PCBs in Milk (%)
Ingestion of Contaminated Produce, Meat, and Milk
PCB Soil Quality Guidelines (SQGFI) (mg/kg)
Agricultural Land Use
51
0.17
Residential/Parkland
Land Use
7.4
100
0.11
7.4
Other Considerations: Food Prep.
• Approximately 27% of PCBs are lost during cooking (US
EPA 2003)
• Approximately 24% of PCBs are lost after cooking (US
EPA 2003)
• The total percent retained is 0.73 × 0.76 = 0.55, or 55%
Percent Retained During
and After Cooking (%)
55
100
Ingestion of Contaminated Produce, Meat, and Milk PCB
Soil Quality Guidelines (SQGFI) (mg/kg)
Agricultural Land Use
Residential/Parkland
Land Use
0.13
7.4
0.11
7.4
Other Considerations – Combined
• Soil bioavailability
• Milk bioavailability
• Food preparation
Percent Retained
During and After
Cooking (%)
Ingestion of Contaminated Produce, Meat, and
Milk PCB Soil Quality Guidelines (SQGFI)
(mg/kg)
Agricultural Land Use
Residential/Parkland
Land Use
Revised
0.21
7.4
Original
0.11
7.4
Other Considerations: Area Use Factor
• The AUF is defined as the ratio of the area that
is contaminated (A) to the home range size (HR)
such that AUF = A/HR (Suter et al. 2000)
Proportion of Site
Impacted by PCBs (%)
Ingestion of Contaminated Produce, Meat, and Milk PCB
Soil Quality Guidelines (SQGFI) (mg/kg)
Agricultural Land Use
10
20
30
40
50
60
70
80
90
100
1.1
0.56
0.37
0.28
0.22
0.19
0.16
0.14
0.12
0.11
Residential/Parkland Land
Use
74
37
25
18
15
12
11
9.2
8.2
7.4
Ingestion Guideline for
Cattle (mg/kg)
Agricultural Land Use
311
156
104
78
62
52
44
39
35
31
Summary of PCB Guidelines [mg/kg]
Soil Guideline
Agricultural
Residential / Parkland
Commercial
Industrial
4
4
7
75
0.11
7.4
NA
NA
Soil Contact
33
33
33
33
Primary Consumer (Chicken)
25
25
NA
NA
Primary Consumer (Cow)
31
31
NA
NA
Secondary Consumer
1.8
1.8
NA
NA
Tertiary Consumer
1.3
1.3
NA
NA
CCME Guideline
0.5
1.3
33
33
Revised Guideline
0.11
1.3
7
33
Human Health
Soil ingestion
Produce, meat and milk
Ecological
Guidelines
Yellow highlights project-specific soil quality guidelines that were calculated.
References
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Bowman et al. 1981. Locomotor hyperactivity in PCB-exposed rhesus monkeys. Available at: http://www.ncbi.nlm.nih.gov/pubmed/6798510
CCME (Canadian Council Of Ministers of the Environment). 2006. A Protocol for the Derivation of Environmental and Human Health Soil Quality
Guidelines.
Feidt, C., Ounnas, F., Julien-David, D., Jurjanz, S., Toussaint, H., Jondreville, C. and Rychen, G. 2013. Relative bioavailability of soil-bound
polychlorinated biphenyls in lactating goats. J. Dairy Sci. 96:3916-3923 http://dx.doi.org/10.3168/jds.2012-6319
Health Canada. 2004. Contaminated Sites Program, Federal Contaminated Site Risk Assessment in Canada; Part II: Health Canada Toxicological
Reference Values (TRVs).
Health Canada. 2010. Part II: Health Canada Toxicological Reference Values (TRVs) and Chemical-Specific Factors, Version 2.0.
NEPI (National Environmental Policy Institute). 2000. Assessing the Bioavailability of Organic Chemicals in Soil for Use in Human Health Risk
Assessments.
RTI Research Triangle Institute). 2005. Methodology for Predicting Cattle Biotransfer Factors. Prepared for U.S. Environmental Protection Agency (EPA)
Office for Solid Waste. EPA Contract No. 68-W-03-042. August.
SRC (Syracuse Research Corporation). 2014. PCBs. Available at: http://esc.syrres.com/fatepointer/webprop.asp?CAS=1336363
Suter G.W. II, Efroymson, R.A., Sample, B.E. and Jones, D.S. 2000. Ecological Risk Assessment for Contaminated Sites. Lewis Publishers, CRC Press.
Boca Raton, FL.
Travis, C.C. and A.D. Arms. 1988. Bioconcentration of Organics in Beef, Milk, and Vegetation. Environmental Science and Technology. 22:271-274.
US EPA (United States Environmental Protection Agency). 2003. Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin
(TCDD) and Related Compounds National Academy Sciences (NAS) Review Draft, Volume 3: Site-Specific Assessment Procedures, Chapter 2:
Estimating Exposure and Risks.
Willett, L.B., Liu, T-T.Y., Durst, H.I., Smith, K.L. and Redman, D.R. 1987. Health and Productivity of Dairy Cows Fed Polychlorinated Biphenyls.
Toxicological Sciences. 9(1):60-68.