Public Health Assessment Public Comment Release
Fish Ingestion
Exposure doses for ingestion of fish downstream of the site were calculated using the average
concentration measured in fish tissue samples, in mg/kg or ppm, multiplied by the 95th percentile
ingestion rate for recreational fishers of 25 grams per day (g/day). An ingestion rate of 12.5
g/day was assumed for children. The calculated value was also multiplied by a conversion factor
of 0.001 kilograms per gram. The multiplication product was divided by the average weight for
an adult (70 kg or 154 pounds) or a one-year-old child (10 kg or 22 pounds) to obtain the
exposure dose in mg/kg/day.
Soil Ingestion
maximum concentration measured in soil, in milligrams per kilogram (mg/kg), or parts per
million (ppm). This maximum concentration is then multiplied by the soil ingestion rate for
was divided by the average weight for an adult, 70 kg (154 pounds). The resulting dose was then
multiplied by a factor of 5/7, because the exposure was assumed to occur five days a week
throughout the year. For exposure of child trespassers, the body weight used was 36 kg (80
pounds) and the exposure factor was 2/7 (2 days a week throughout the year).
Surface Water Ingestion
Exposure doses for surface water ingestion were calculated by use of the maximum
concentration for a surface water contaminant, in milligrams per liter (mg/L). This maximum
concentration was then multiplied by an incidental surface water ingestion rate of 0.2 L/day for
adults or 0.1 L/day for children. These ingestion rates are 1/10th of the EPA default drinking
for a 10-year-old child (36 kg). The resulting dose was then multiplied by a factor of 4/7,
because the exposure was assumed to occur four times a week throughout the year.
Sediment Ingestion
maximum concentration measured in the sediment, in mg/kg or ppm, multiplied by 1/10th of the
default soil ingestion rate--10 mg/day for adults or 20 mg/day for children. The multiplication
product was divided by the average weight for an adult (70 kg) or a 10-year-old child (36 kg).
The resulting dose was then multiplied by a factor of 4/7, because the exposure was assumed to
occur four times a week throughout the year. The calculated value was also multiplied by a
conversion factor of 0.001 kilograms per gram.
Noncancer Health Effects
The calculated exposure doses are then compared to an appropriate health guideline for that
chemical. Health guideline values are considered safe doses; that is, health effects are unlikely
below this level. The health guideline value is based on valid toxicological studies for a
chemical, with appropriate safety factors built-in to account for human variation, animal-to-
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