Publication Abstract

Toxic equivalency factors for PAH and their applicability in shellfish pollution monitoring studies

R.J. Law, C. Kelly, K. Baker, J. Jones, A.D. McIntosh and C.F. Moffat

Fish and shellfish are exposed to a wide range of PAH following oil spills, and can become contaminated as a result. Finfish have a more effective mixed-function oxidase enzyme system than shellfish, and are therefore able to metabolise and excrete PAH more effectively. The major contamination by high-molecular weight PAH, including those with carcinogenic potential and so of concern with regard to human consumers, is therefore usually observed in shellfish, and particularly bivalve molluscs. Oil spills are not the sole source of these compounds, however, as parent PAH are also generated by a wide range of combustion processes. In this paper we consider monitoring data gathered following recent oil spills (both of crude oil and diesel fuel), alongside data from other studies. These include studies conducted around a former gasworks site and downstream of an aluminium smelter in the UK, and from mussel monitoring studies undertaken in the UK and the USA (including the Exxon Valdez oil spill and the National Status and Trends programme), and in other countries in Europe. For comparative purposes the PAH concentrations are summed and also expressed as benzo[a]pyrene equivalents, their relative concentrations being weighted in relation to the carcinogenic potential of individual PAH compounds using toxic equivalency factors. Our aim was to assess the utility of this approach in fishery resource monitoring and control following oil spills. Certainly this approach seems useful from the data assessed in this study, and the relative ranking of the various studies seems to reflect the relative degree of concern for human consumers due to the differing contamination sources. As a simple tool for control purposes it is equally applicable to PAH derived from both oil spills and combustion sources.

Reference:

R.J. Law, C. Kelly, K. Baker, J. Jones, A.D. McIntosh and C.F. Moffat, 2002. Toxic equivalency factors for PAH and their applicability in shellfish pollution monitoring studies. Journal of Environmental Monitoring, 4: 383-388.