The evaluation of stack metal emissions from hazardous waste incinerators: assessing human exposure through noninhalation pathways.

Abstract

Potential public health effects associated with exposure to metal emissions from hazardous waste incinerators through noninhalation pathways were evaluated. Instead of relying on modeling the movement of toxicants through various environmental media, an approach based on estimating changes from baseline levels of exposure was employed. Changes in soil and water As, Cd, Hg, Pb, Cr, and Be concentrations that result from incinerator emissions were first determined. Estimates of changes in human exposure due to direct contact with shallow soil or the ingestion of surface water were then ascertained. Projected changes in dietary intakes of metals due to incinerator emissions were estimated based on changes from baseline dietary intakes that are monitored in U.S. Food and Drug Administration total diet studies. Changes from baseline intake were deemed to be proportional to the projected changes in soil or surface water metal concentrations. Human exposure to metals emitted from nine hazardous waste incinerators were then evaluated. Metal emissions from certain facilities resulted in tangible human exposure through noninhalation pathways. However, the analysis indicated that the deposition of metals from ambient air would result in substantially greater human exposure through noninhalation pathways than the emissions from most of the facilities.

Site-specific health risk assessment of dioxins and furans in an industrial region with numerous emission sources

“…The predicted carcinogenic risk is an estimated value of potential risk associated with the exposure scenarios. A risk from a single emission source was calculated by summing the carcinogenic risk of the PCDD/Fs to each exposure pathway [20] and the total risks in the region comprised the individual risks from 17 emission sources.…”

Residence location as a measure of environmental exposure: a review of air pollution epidemiology studies

“…Exposure to a pollutant may result from several exposure pathways. Especially for persistent and bioaccumulative pollutants, indirect exposure pathways (ingestion, dermal permeation ) can account for a significant fraction of total uptake (e.g., Polissar et al, 1990;Sedman et al, 1994;Kimborough et al, 1995;Wohl et al, 1996 ) . If the primary exposure pathway is not inhalation, then indicators designed to represent air pollution levels are unlikely to adequately represent total exposures.…”

“…First, recent studies show the influence of inhalation, ingestion and dermal exposure pathways, and significant variations between outdoor, indoor and microenvironmental conditions ( Lippmann and Lioy, 1985;Michael et al, 1990;Polissar et al, 1990;McKone, 1991;Wartenberg, 1992;Guthe et al, 1992;Stallones et al, 1992;Covello and Merkhofer, 1993;Briggs and Elliot, 1995;Kimborough et al, 1995 ). Exposures from an``indirect'' pathway (e.g., air to soil to food ) can greatly exceed contributions from thè`d irect'' inhalation pathway (Sedman et al, 1994 ). In such cases, the use of residence location that primarily represents inhalation exposures will account for only a small fraction of the total exposure.…”

Addressing Emerging Risks: Scientific and Regulatory Challenges Associated with Environmentally Persistent Free Radicals

“…, via water, foliage, soils, etc. —levels observed in those sources are likely more reflective of ordinary ambient air exposures [ 65 ]. Nevertheless, given that combustion-derived metals may exist as a component of an EPFR, these metal-pollutant complexes may exhibit toxicities that are much greater than, or “more-than-additive”, compared to that of their metal and organic components, per se.…”