Comparison of USEPA and NYSDOH Indirect Risk Assessment Guidance for Combustors. D. J. Marino, Eastman Kodak Company, 1100 Ridgeway Ave., Rochester, NY 14652
In 1991, the NYSDOH issued draft indirect risk assessment guidance for municipal waste combustion units. The guidance is based on site-specific methodology developed by the USEPA and published in 1990. Potential risks from consumption of contaminated homegrown fruits/vegetables, locally produced beef and milk, and recreationally caught fish are calculated for adult and child residents. In 1994, the USEPA issued Screening Guidance for hazardous waste combustors. This methodology is based on assessment of potential high-end risk activities including subsistence farming and subsistence fishing, and includes evaluation of potential impacts on adult and child residents. The Screening Guidance specifies use of the maximum combined wet and dry deposition and maximum ambient air impacts for assessment of potential risks unless there is site-specific information to dictate otherwise. Besides differing receptor types and characteristics, the NYSDOH and USEPA methodologies also differ with regard to specified algorithms, input values including consumption rates and exposure parameters, and contaminant physical/chemical properties. In order to compare the two approaches, theoretical risk estimates were developed using an emissions dataset and air dispersion model results derived from EPA guidance documents or the scientific literature. Risk estimates were developed for all metals and organics listed in the NYSDOH Guidance using available EPA IRIS or HEAST oral toxicity values. The constituents were arsenic, beryllium, cadmium, chromium VI, lead, mercury, nickel, B(a)P, PCBs, and TCDD. Calculated risk estimates for the subsistence farmer (4.3E-07) and subsistence fisher (2.0E-06) using EPA’s Screening Guidance exceeded estimates for the NYSDOH adult resident (3.1E-07). Estimated contaminant intakes of B(a)P in fish drove risk estimates for the subsistence fisher, and contaminant intakes of TCDD in milk and beef drove risk estimates for the subsistence farmer. Risk estimates for the EPA adult resident (1.2E-09) and child resident (1.3E-09) were lower. For non-cancer evaluations, a similar pattern was evident. Hazard indices for the subsistence fisher and the subsistence farmer were 1.4E-03 and 3.1E-04, respectively. In comparison, the NYSDOH child resident yielded a hazard index of 2.4E-05. These results indicate that, for potential maximum impact areas, EPA’s Screening Guidance yields higher potential cancer and non-cancer risk estimates than the NYSDOH Guidance.