Deterministic Risk Index for Hazardous Chemical Constituents

4 Deterministic Risk Index for Hazardous Chemical Constituents. In accordance with Equation 6.5, the risk index for all substances in the waste that induce deterministic responses is 

As indicated in Table 7.6, all hazardous chemicals in electric arc furnace dust are assumed to induce deterministic responses. The possible responses include renal toxicity, effects on the cardiovascular system, dermal or ocular effects, decrease in body weight, hepatic toxicity, and respiratory toxicity. Decrease in body weight is not a response in a particular organ but is assumed to be a health effect of concern. All deterministic responses are assumed to be induced by more than one chemical in the waste. Furthermore, some of the chemicals (barium, beryllium, chromium, and lead) are assumed to induce all responses. 

The results in Table 7.8 indicate that the organ- and endpoint-specific risk indexes are about 0.7 to 0.8 in all cases, due mainly to intakes of lead. The maximum risk index for any organ or endpoint is about 0.8. Truncating this result using the INTEGER function, as indicated in Equation 6.5, gives a risk index for all deterministic hazardous chemicals in the waste of zero. This result means that the calculated dose in all organs and for all endpoints due to exposure to all deterministic substances that cause deterministic responses in the waste is less than the assumed acceptable dose of 10 times RfDs. Therefore, based only on consideration of substances that 

Toxic Element Renal Cardiovascular Ocular Decrease Hepatic Respiratory 

5 Stochastic Risk Index for Hazardous Chemical Constituents. Calculation of the risk index for all hazardous chemicals in the waste that cause stochastic effects is performed in the same manner as in the previous examples for radioactive wastes. The calculated risk for each such substance, based on the assumed exposure scenario, is summed and then divided by the acceptable lifetime risk of 10 3 for classification as low-hazard waste (see Table 7.1). The risk for each chemical is calculated by multiplying the arithmetic mean of the concentration in the waste given in Table 7.5 by the intake rate from ingestion, inhalation, or dermal absorption per unit concentration discussed in Section 7.1.7.3 and 10 percent of the appropriate slope factor in Table 7.7 (see Section 7.1.7.1) adjusted for the exposure time. Since the slope factors assume chronic lifetime exposure, they must be reduced by a factor of 70 based on the assumption that the exposure scenario at the hazardous waste site occurs only once over an individual s lifetime. In addition, a simplifying assumption is made that whenever more than one slope factor is given for a hazardous substance in Table 7.7, the higher value was applied to the total intake rate by all routes of exposure of about 4 X 10 8 mg (kg d) 1 per ppm. This assumption should be conservative. 

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