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Modelled Ecological No-Effect Soil Concentrations for Cattle, Sheep and Deer: Safe for Humans? Shannon Bard, Ph.D. Jennifer Trowell, M.ET. Topics: • Toxicity Reference Value (TRV) derivation • Calculation of Ecological No-Effect Soil Concentrations (EcoNECsoil) • Calculation of Human Health No-Effect Soil Concentrations (HHNECsoil) • Conclusions and Applications Background • Consider… • In mining regions, soils can be naturally elevated in metals – exceed current standards • Remediated soils have to be “cleaned-up” – concentrations of metals and/or hydrocarbons have to be below a set standard • Required: a set of guidelines for screening soils as hazardous or not for wildlife and domestic grazing receptors • Dilemma: Currently there are no federal standards and few provincial standards (Alberta is the exception) for soil concentrations of metals or hydrocarbons in “Wildlands” Background • Protection goals: • Deer and other wildlife ungulates • Domestic ungulates (Cattle, Sheep) • Human consumers of deer, cattle and sheep • Developed Risk-Based Ecological NoEffect Soil Concentrations based on: • Relevant Toxicity Data • Ungulate Biology Definitions • Toxicity reference value (TRV) • An exposure concentration or dose that is not expected to cause an unacceptable level of effect in receptor(s) exposed to the contaminant of potential concern. • Ungulate • “hoofed animal” • Ungulates = Ruminants Toxicity Evaluation of ecotoxicology datasets Exposure Determine oral exposure from soil Toxicity Reference Values (TRV) derived Determine oral exposure from dietary components Determine daily oral dose in deer from exposure pathways Food Ingestion Rate (FIR) Maximum Allowable Soil (Csoil) Calculated: "↓$%&' = )*+/-.*∗((/↓$ ∗0↓$ )+(∑(/↓2 ∗3"-↓2 )+(/↓5 ∗3"-↓5 )…)) TRV derivation - Species Relatedness Wildlife & Domestic Ungulates Pigs (Order Artiodactyla) Herbivores All Mammals (Rodents) TRV derivation – Selection Criteria • Growth/development, reproduction or mortality endpoints • No-observed adverse effects levels (NOAELs) selected • Conservative • Protective • Effect Size of NOAEL selected à10% or less NOAEL and LOAEL Example Control 10 mg/kg/ day TRV 50 mg/kg/ day 100 mg/kg/ day No Observable Adverse Effect Level (NOAEL) Low Observable Adverse Effect Level (LOAEL) TRV derivation – Selection 90 80 Highest NOAEL 70 lower than Lowest LOAEL Dose (mg/kg/day) TRV 60 50 NOAEL 40 LOAEL 30 20 11.1 10 10 0 Reproduction Growth ENDPOINTS Mortality Exposure Toxicity Determine oral exposure from soil (6↓7 ∗8↓7 ) Evaluation of ecotoxicology datasets Determine oral exposure from grasses (6↓9 ∗:;<) Percent of soil in diet (Ps) Percent of grasses in diet (Pg) Bioavailable fraction (fs) of metals (1) or hydrocarbons (variable) Toxicity Reference Values (TRV) derived Bioconcentration factor (BCF) Determine daily oral dose in deer from exposure pathways <=>∗((6↓7 ∗8↓7 )+(6↓9 ∗:;<)) @ABACD EF%G&HIG (@E)=)= -.*∗"↓$%&' ∗((/↓$ ∗0↓$ ) +(/↓? ∗3"-)) /)*+ Food Ingestion Rate (FIR) Maximum Allowable Soil (Csoil) Calculated: "↓$%&' = )*+/-.*∗((/↓$ ∗0↓$ )+(/↓? ∗3"-)) Calculate Oral Exposure Deer Food Ingestion Rate Cattle Sheep 0.035 mg/ 0.029 mg/ 0.023 mg/ kg/d kg/d kg/d Percent grass in diet (Pg) 9% 100% 100% Incidental Soil Ingestion (Ps) 2% 18% 30% • Concentration of contaminant in grass relative to concentration in soil= Bioconcentration Factor (BCF) • [grass]/[soil] • Availability of contaminant in soil = fs -.*∗((/↓$ ∗0↓$ )+(/↓? ∗3"-)) 1.0E+06 1.0E+05 Risk-based No-Effect Soil Concentrations Deer - EcoNECsoil Cow - EcoNECsoil Sheep - EcoNECsoil 1.0E+04 1.0E+03 1.0E+02 1.0E+01 1.0E+00 Standards developed for 19 metals and 17 hydrocarbons Above – representative metals and PAHs Safe for Humans? Calculate exposure from eating meat Pathway exposure factor Human intake of meat Proportion of meat in diet -↓DJ = (.↓J ∗ /↓J )∗(KL-∗[(/↓$ ∗0↓$ )+(3"-↓? ∗/↓? ∗0↓? )]∗3↓J ) Site Use Factor Assume = 1 Dietary uptake from soil Ps – incidental soil ingestion fs – bioavailability in soil From MacKone and Ryan, 1989 Biotransfer Factor – ungulate diet to meat Dietary uptake from grass BCF – bioconcentration factor Pg – proportion of grass in diet fg – bioavailability in grass Oral Exposure Deer Cattle Sheep Human intake of meat (kg/kg BW/d) 0.00256 0.00185 0.00185 Proportion of meat consumption 100% 51% 15% Average consumption rate - First Nations wild game consumers Richardson, 1997 Average consumption rate of meat and eggsCanadian general public Richardson, 1997 Conservative assumption Proportions of beef and “other” (assumed 100% lamb) Yang and Nelson (1986) in McKone and Ryan (1989) Oral Exposure Deer Cattle Sheep Human intake of meat (kg/kg BW/d) 0.00256 0.00185 0.00185 Proportion of meat consumption 100% 51% 15% Percent grass in diet (Pg) 9% 100% 100% Incidental Soil Ingestion (Ps) 2% 18% 30% Chemical-specific parameters -↓DJ = (.↓J ∗ /↓J )∗(KL-∗[(/↓$ ∗0↓$ )+(3"-↓? ∗/↓? ∗0↓? )]∗3↓J ) No-Effect Soil Concentration for Humans @ABACD EF%G&HIG (@E)=) = @@OP"↓$%&' ∗(.↓J ∗ /↓J )∗(KL-∗[(/↓$ ∗0↓$ )+(3"-↓? ∗/↓? ∗0↓? )]∗3↓J )/@FJAI @HA'GQ )*+ @@OP"↓$%&' = @FJAI @HA'GQ )*+/(.↓J ∗ /↓J )∗(KL-∗[(/↓$ ∗0↓$ )+(3"-↓? ∗ Risk-based No-Effect Soil Concentrations Deer - EcoNECsoil Cattle - HHCsoil 1.0E+07 1.0E+06 1.0E+05 1.0E+04 1.0E+03 1.0E+02 1.0E+01 1.0E+00 1.0E-01 1.0E-02 1.0E-03 Deer - HHCsoil Sheep - EcoNECsoil Cow - EcoNECsoil Sheep - HHCsoil @@"↓$%&' = @FJAI @HA'GQ )*+/(.↓J ∗ /↓J )∗(KL-∗[(/↓$ ∗0↓$ )+(3"-↓? ∗/↓ Change Site-Use Factor (SUF) • Restrict or limit cattle/ sheep from grazing on contaminated soil • Minimize spread area of remediated soil relative to a deer’s home range/ seasonal use to limit contact Conclusions • Goal: Develop soil concentration guidelines that are protective of grazing wildlife and domestic ungulates • Conservative assumptions à Protective guidelines Conclusions • Goal: Develop soil concentration guidelines that are protective humans consuming ungulate meat • More conservative than EcoNECsoil • Can be refined • Proportion of diet • Site Use Factor • Use to set consumptive limits Soil Management • Useful as a Management tool • Soil “clean-up” guidelines/ Screening guidelines • Select guidelines for use based on management goals • Will consumption of ungulate grazers be an issue? • Is the meat consumed “sole sourced” from the contaminated area?
