Cohen, S.Z. October 23, 2007.
Environmental Chemistry in an Environmental Risk Assessment Context: Case Studies of Dibromochloropropane, Pentachloronitrobenzene, and Organoarsenical Pesticides. Presentation before the Department of Chemistry & Biochemistry, University of Maryland, Baltimore County.
Environmental risk assessment of organic chemicals requires a consideration of toxicity and exposure. The mechanism of toxicity can help focus the exposure assessment on particular sensitive receptors (e.g., trout, humans) and potential exposure pathways (e.g., runoff to cold water streams, leaching to aquifers that supply water to wells). A characterization of exposure requires an understanding of chemical mobility and persistence. The latter requires an understanding of multiple potential pathways for chemical degradation as well as metabolism to potentially toxic degradates. 1,2-Dibromo-3-chloropropane (DBCP) was a mobile and persistent chemical that is still present in drinking water aquifers years after last use. The molecular structure of pentachloronitrobenzene (PCNB) might lead one to initially believe that it bioaccumulates and it is extremely persistent, but lab and field data indicate otherwise. Organoarsenical (R-As) herbicides contain arsenic, but they have low acute toxicity and they are not carcinogenic. However, the regulatory risk assessment focus on the potential for conversion to toxic inorganic arsenic has introduced many complications to the exposure assessment of R-As.