Home > Environmental & Workplace Health > Reports & Publications > Contaminated Sites > Federal Contaminated Site Risk Assessment In Canada Part I: Guidence on Human Health Preliminary Quantitive Risk Assessment (PQRA)

Federal Contaminated Site Risk Assessment In Canada Part I: Guidence on Human Health Preliminary Quantitive Risk Assessment (PQRA)

Table 5

Recommended General Equations to Be Used to Estimate Doses
Note : Presented below are generalized equations; actual equations presented by individual contractors may vary according to the manner in which different variables are presented, the units used, and the precise presentation of exposure frequency, exposure duration and averaging times.
Inadvertent Ingestion of Contaminated Soil
The predicted intake of each contaminant via soil ingestion is calculated as:

Where:
C_S = concentration of contaminant in soil (mg/kg)	D₂ = weeks per year exposed/52 weeks
IR_S = receptor soil ingestion rate (kg/d)	D₃ = total years exposed to site (to be employed for assessment of carcinogens only)
AF_GIT = absorption factor from the gastrointestinal tract (unitless)	BW = body weight (kg)
D₁ = days per week exposed/7 days	LE = life expectancy (yr) (to be employed for assessment of carcinogens only)
Inhalation of Contaminated Soil Particles
The predicted intake of each contaminant via inhalation of dust entrained into the air is calculated as:

Where:
C_S = concentration of contaminant in soil (mg/kg)	D₂ = days per week exposed/7 days
P_Air = particulate concentration in air (kg/m³)	D₃ = weeks per year exposed/52 weeks
IR_A = receptor air intake (inhalation) rate(m³/h)	D₄ = total years exposed to site (to be employed for assessment of carcinogens only)
AF_Inh = inhalation absorption factor (unitless)	BW = body weight (kg)
D₁ = hours per day exposed (h/day)	LE = life expectancy (yr) (to be employed for assessment of carcinogens only)
Inhalation of Contaminant Vapours
The predicted intake of each contaminant via inhalation of vapours is calculated as:

Where:
C_a = concentration of contaminant in air (mg/m³)	D₃ = weeks per year exposed/52 weeks
IR_A = receptor air intake (inhalation) rate (m³/h)	D₄ = total years exposed to site (to be employed for assessment of carcinogens only)
AF_Inh = inhalation absorption factor (unitless)	BW = body weight (kg)
D₁ = hours per day exposed (h/day)	LE = life expectancy (yr) (to be employed for assessment of carcinogens only)
D₂ = days per week exposed/7 days
Note: C_a may be directly measured or may be estimated from soil-borne or groundwater-borne concentrations of volatile COPCs using methods discussed in the text.
Ingestion of Contaminated Drinking Water
The predicted intake of each contaminant via ingestion of contaminated drinking water is calculated as:

Where:
C_W = concentration of contaminant in drinking water (mg/L)	D₂ = weeks per year exposed/52 weeks
IR_S = receptor water intake rate (L/d)	D₃ = total years exposed to site (to be employed for assessment of carcinogens only
AF_GIT = absorption factor from the gastrointestinal tract (unitless)	BW = body weight (kg)
D₁ = days per week exposed/7 days	LE = life expectancy (yr) (to be employed for assessment of carcinogens only)
Dermal Contact with Contaminated Soil
The predicted intake of each contaminant via dermal contact with soil is calculated as:

Where:
C_S = concentration of contaminant in soil (mg/kg)	D₁ = days per week exposed/7 days
SA_H = skin surface area exposed (cm²)	D₂ = weeks per year exposed/52 weeks
SL_H = soil loading to exposed skin (kg/cm²-event)	D₃ = total years exposed to site (to be employed for assessment of carcinogens only)
AF_Skin = dermal absorption factor (unitless)	BW = body weight (kg)
EF = exposure frequency (events/d)	LE = life expectancy (yr) (to be employed for assessment of carcinogens only)
Ingestion of Contaminated Produce, Fish, Game or Other Food
The predicted intake of each contaminant via ingestion of contaminated produce, fish and/or game is calculated as:

Where:
C_Food I = concentration of contaminant in food I (mg/kg)	D₂ = total years exposed to site (to be employed for assessment of carcinogens only)
IR_Food i = receptor ingestion rate for food i (kg/d)	BW = body weight (kg)
RAF_GITi = relative absorption factor from the gastrointestinal tract for contaminant i (unitless)	365 = total days per year (d/yr)
D_i = days per year during which consumption of food i will occur (d/yr)	LE = life expectancy (yr) (to be employed for assessment of carcinogens only)

Back


Last Updated: 2006-02-01		Important Notices