Table 749-4
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Wildlife Exposure Model for Site-Specific Evaluationsa

Plant
KPlant Plant uptake coefficient (dry weight basis)
Units: mg/kg plant/mg/kg soil
Value: chemical specific (See Table 749-5)
Soil Biota  - Surrogate receptor: Earthworm
BAFWorm Earthworm bioaccumulation factor (dry weight basis)
Units: mg/kg worm/mg/kg soil
Value: chemical-specific (See Table 749-5)
Mammalian Predator  - Surrogate receptor: Shrew (Sorex)
PSB(Shrew) Proportion of contaminated food (earthworms) in shrew diet
Units: unitless
Value: 0.50
FIRShrew,DW Food ingestion rate (dry weight basis)
Units: kg dry food/kg body weight-day
Value: 0.45
SIRShrew,DW Soil ingestion rate (dry weight basis)
Units:  kg dry soil/kg body weight-day
Value: 0.0045
RGAFSoil,shrew Gut adsorption factor for a hazardous substance in soil expressed relative to the gut adsorption factor for the hazardous substance in food.
Units: unitless
Value: chemical specific (See Table 749-5)
TShrew Toxicity reference value for shrew
Units: mg/kg-day
Value: chemical specific (See Table 749-5)
Home Range 0.1 Acres
Avian Predator  - Surrogate receptor: American Robin (Turdus migratorius)
PSB(Robin) Proportion of contaminated food (soil biota) in Robin diet
Units: unitless
Value: 0.52
FIRRobin,DW Food ingestion rate (dry weight basis)
Units: kg dry food/kg body weight-day
Value: 0.207
SIRRobin,DW Soil ingestion rate (dry weight basis)
Units:  kg dry soil/kg body weight-day
Value: 0.0215
RGAFSoil,Robin Gut adsorption factor for a hazardous substance in soil expressed relative to the gut adsorption factor for the hazardous substance in food.
Units: unitless
Value: chemical specific (See Table 749-5)
TRobin Toxicity reference value for Robin
Units: mg/kg-day
Value: chemical specific (See Table 749-5)
Home Range 0.6 Acres
Mammalian herbivore  - Surrogate receptor: Vole (Microtus)
PPlant,Vole Proportion of contaminated food (plants) in vole diet
Units: unitless
Value: 1.0
FIRVole,DW Food ingestion rate (dry weight basis)
Units: kg dry food/kg body weight-day
Value: 0.315
SIRVole,DW Soil ingestion rate (dry weight basis)
Units:  kg dry soil/kg body weight-day
Value: 0.0079
RGAFSoil,Vole Gut adsorption factor for a hazardous substance in soil expressed relative to the gut adsorption factor for the hazardous substance in food.
Units: unitless
Value: chemical specific (See Table 749-5)
Home Range 0.08 Acres
Soil concentrations for wildlife protectionb
(1) Mammalian predator:

SCMP=(TShrew)/[(FIRShrew,DW x PSB(Shrew) x BAFWorm) + (SIRShrew,DW x RGAFSoil,Shrew)]

(2) Avian predator:

SCAP=(TRobin)/[(FIRRobin,DW x PSB(Robin) x BAFWorm) + (SIRRobin,DW x RGAFSoil,Robin)]

(3) Mammalian herbivore:

SCMH=(TVole)/[(FIRVole,DW x PPlant,Vole x KPlant) + (SIRVole,DW x RGAFSoil,Vole)]

Table 749-4  Notes 

a    Substitutions for default receptors may be made as provided for in WAC 173-340-7493(7).  If substitute species is used, the values for food and soil ingestion rates, and proportion of contaminated food in the diet, may be modified to reasonable maximum exposure estimates for the substitute species based on a literature search conducted in accordance with WAC 173-340-7493(4).  Additional species may be added on a site-specific basis as provided in WAC 173-340-7493(2)(a).  The department shall consider proposals for modifications to default values provided in this table based on new scientific information is accordance with WAC 173-340-702(14).

b Use the lowest of the three concentrations calculated as the wildlife value.

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