fundamentals of engineering supplied-reference handbook - Ventech!
fundamentals of engineering supplied-reference handbook - Ventech!
fundamentals of engineering supplied-reference handbook - Ventech!
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Risk<br />
Risk characterization estimates the probability <strong>of</strong> adverse<br />
incidence occurring under conditions identified during<br />
exposure assessment.<br />
Carcinogens<br />
For carcinogens the added risk <strong>of</strong> cancer is calculated as<br />
follows:<br />
Risk = dose × toxicity = daily dose × CSF<br />
Risk assessment process<br />
Noncarcinogens<br />
NO THRESHOLD LINEAR<br />
AT LOW DOSE<br />
CARCINOGENIC DOSE<br />
RESPONSE CURVE.<br />
Dose is expressed as the mass intake <strong>of</strong> the chemical<br />
normalized to the body weight <strong>of</strong> the exposed individual and<br />
the time period <strong>of</strong> exposure.<br />
NOAEL = No Observable Adverse Effect Level. The dose<br />
below which there are no harmful effects.<br />
CSF = Cancer Slope Factor. Determined from the<br />
dose-response curve for carcinogenic materials.<br />
For noncarcinogens, a hazard index (HI) is calculated as<br />
follows:<br />
HI = chronic daily intake/RfD<br />
155<br />
ENVIRONMENTAL ENGINEERING (continued)<br />
Reference Dose<br />
Reference dose (RfD) is determined from the<br />
Noncarcinogenic Dose-Response Curve Using NOAEL<br />
RfD = NOAEL<br />
UF<br />
and<br />
NOAEL*W<br />
SHD = RfD* W =<br />
UF<br />
where<br />
SHD = safe human dose (mg/day)<br />
NOAEL = threshold dose per kg test animal (mg/kg-day)<br />
from the dose response curve.<br />
UF = the total uncertainty factor, depending on nature<br />
and reliability <strong>of</strong> the animal test data<br />
W = the weight <strong>of</strong> the adult male (typically 70 kg)
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