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., April 26, 2016 Le Centre Sheraton, Montreal
Outline • Project background • CCME* requirements • What guidelines are available • What guidelines are missing • Project-specific requirements • Toxicity of PCBs** • Methods • Interim guidelines • Other considerations • Guideline summary * Canadian Council of Ministers of the Environment ** Polychlorinated Biphenyls
Project Background
Project Background
CCME Requirements • Chemical classification important at identifying pathways of exposure: – Organic / inorganic – Volatile / non-volatile – Soluble / non-soluble – Biomagnify / non-biomagnify • Chemical Properties of PCBs: – Molecular Weight = 291.99 g/mole – Log(Kow) = 7.1 – Vapour Pressure = 0.000494 mm Hg – Henry’s Law Constant = 0.000415 atm-m 3 /mol – Solubility = 0.7 mg/L • PCBs are persistent, bio-accumulative and 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 Soil Nutrient Cycling Soil Nutrient Cycling Soil Nutrient Cycling Processes, Processes, Processes, Processes, Soil Invertebrates, Soil Invertebrates, Soil Invertebrates, Soil Invertebrates, Crops/Plants, Plants, Wildlife Plants, Wildlife, Offsite Plants, Wildlife, Offsite Livestock/Wildlife Migration Migration Soil and Food Herbivores, Herbivores, Not Applicable Not Applicable Ingestion Secondary and Secondary and Tertiary Consumers* Tertiary Consumers* Ingestion of Livestock Not Applicable Not Applicable Not Applicable Contaminated Water Contact with Freshwater Life, Crops Freshwater Life Freshwater Life Freshwater Life Contaminated Water Irrigation
CCME Requirements – Human Health No Guideline Available Route of Exposure Agricultural Residential / Parkland Commercial Industrial Soil Contact Direct soil ingestion, Direct soil ingestion, Direct soil ingestion, Direct soil ingestion, Direct soil dermal Direct soil dermal Direct soil dermal Direct soil dermal contact, direct soil contact, direct soil contact, direct soil contact, direct soil particulate inhalation particulate inhalation particulate inhalation particulate inhalation Indirect Soil Exposure Indoor vapour Indoor vapour Indoor vapour Indoor vapour inhalation, inhalation, inhalation, Offsite inhalation, Offsite Consumption of Consumption of migration migration produce, meat and backyard garden milk* produce Protection of potable Ingestion of Ingestion of Ingestion of Ingestion of water groundwater groundwater groundwater groundwater
Project Specific Requirements Description Agricultural Residential/Parkland Commercial Industrial Land Use Land Use Land Use Land Use Will be calculating • Direct soil ingestion, • Direct soil ingestion, Direct soil ingestion, soil Direct soil ingestion, soil human guideline for soil dermal contact, soil dermal contact, dermal contact, soil dermal contact, soil soil particulate soil particulate particulate inhalation particulate inhalation inhalation inhalation • Consumption of • Consumption of produce, meat and produce, meat and milk milk Will be calculating • Soil and food Not calculating Not calculating Not calculating ecological guideline for ingestion for cattle CCME Guideline available for primary consumer but based on the chicken
Total Exposure – All Sources Included • 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 • Included dairy and beef products • Combined with estimates of Canadians’ food intake rates
Estimated Daily Intake - Background Age Groups Minimum Daily Maximum Daily Average Daily Intake Intake Intake ( µ g/kg bw/day) (Males and Females) ( µ g/kg bw/day) ( µ g/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 young rhesus monkey offspring (Bowman et al. 1981) • Highest dose at which no adverse health effects were seen was 13 µ g/kg bw/day • TDI = NOAEL / uncertainty factor (UF) of 100 • Interim TDI = 0.13 µ g/kg bw/day (Health Canada 2010)
Soil Ingestion Guideline Soil Allocation Residual 𝑇𝑅𝐻↓𝐸𝐼 = ¡ (𝑈𝐸𝐽 − 𝐹𝐸𝐽) × 𝑇𝐵𝐺 × 𝐶𝑋/[(𝐵𝐺↓𝐻 × 𝑇𝐽𝑆) + (𝐵𝐺↓𝑀 × 𝐽𝑆↓𝑇 × 𝐹𝑈↓ 2 ) + (𝐵𝐺↓𝑇 × 𝑇𝑆)] × 𝐹𝑈↓ 1 ¡+ 𝐶𝑇𝐷 Soil Dust Dermal CCME 2006
Soil Contact Guideline Description Agricultural Residential/ Commercial Industrial Land Use Parkland Land Use Land Use Land Use Direct Contact PCB 4 4 7 75 Soil Quality Guideline (SQG DH ) [mg/kg] Alberta Direct Soil 22 22 33 160 Contact Guideline [mg/kg] • Current Alberta guideline based on older Health Canada (2004) TDI of 1 µ g/kg/day, which was based on the LOAEL from the study by Bowman et al. (1981)
Consumption of Produce, Meat & Milk Residual Soil Allocation 𝑇𝑅𝐻↓𝐺𝐽 = ¡ (𝑈𝐸𝐽 − 𝐹𝐸𝐽) × 𝑇𝐵𝐺 × 𝐶𝑋/(𝑄↓𝐼 × 𝑄↓𝐷 × 𝐶↓𝑊 ) + ¡ (𝑁↓𝐼 × 𝑁↓𝐷 × 𝐶↓𝑄 × 𝑇𝐽𝑆↓𝐷 ) + ( 𝑁𝐿↓𝐼 × 𝑁𝐿↓𝐷 × 𝐶↓𝑁 × 𝑇𝐽𝑆↓𝐷 ) ¡+ 𝐶𝑇𝐷 Vegetation Soil Milk CCME 2006
Consumption Guideline Description Agricultural Residential/ Commercial Industrial Land Use Parkland Land Use Land Use Land Use Consumption 0.11 7.4 Not Not Guideline SQG FI Applicable Applicable [mg/kg] • Assumes no spatial averaging or foraging by cattle
Primary Consumer Guideline 𝑇𝑅𝐻↓ 1 𝐷 = ¡ 0.75× 𝐸𝑈𝐹𝐸↓ 1 𝐷 × 𝐶𝑋↓ 1 𝐷 /(𝑇𝐽𝑆↓ 1 𝐷 × 𝐶𝐺) +( 𝐺𝐽𝑆↓ 1 𝐷 × 𝐶𝐷𝐺↓ 1 ) ¡ CCME 2006 • 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 • No apparent effect on health, productivity or 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% • Milk bio-availability of PCB in goats was 51% (Feidt et al. 2013) • Approximately 27% of PCBs are lost during cooking and 24% after cooking (US EPA 2003).
Other Considerations – Combined • Soil bioavailability, Milk bioavailability & Food preparation Guideline Ingestion of Contaminated Produce, Meat, and Milk PCB Soil Quality Guidelines (SQG FI ) (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 Ingestion of Contaminated Produce, Meat, and Milk PCB Soil Site Impacted Quality Guidelines (SQG FI ) (mg/kg) by PCBs (%) Agricultural Land Use Residential/Parkland Land Use 10 1.1 74 50 0.22 15 100 0.11 7.4
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