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Submitted to: Journal of Pure and Applied Chemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/1/1999 Publication Date: N/A Citation: Unsworth, J.B., Wauchope, R.D., Klein, A.W., Dorn, E., Zeeh, B., Yeh, S.M., Akerbloom, M, Racke, K.D., Rubin, B. Significance of the long range transport of pesticides in the atmosphere. J. Pure Appl. Chem. 71:1359-1383. 1999. Interpretive Summary: This report summarizes the findings of an IUPAC task force that examined all the scientific research that has been reported on the long-range transport of pesticides in the atmosphere. What are the sources? How much transport occurs? Is it significant as a source of pollution? What concentrations and reactions occur in the atmosphere? Almost 200 references were found and the results are summarized and recommendations are presented which have been endorsed by the IUPAC Commission on Agrochemicals in the Environment. In general observed concentrations in air and atmospheric water are much smaller than those which are biologically active, with two exceptions: the auxin-type herbicides have been shown to impact sensitive higher plant, and in arctic regions there is possible bioaccumulation in mammalian milk due to temperature effects on both bioaccumulation and persistence. Recommendations highlight research needs, including (a) the need for a greater understanding of cloud chemistry of organic chemicals, and (b) the development of a risk assessment scheme to limit registration of pesticides with higher concentrations and longer lifetimes in the atmosphere. Technical Abstract: Monitoring results show that traces of pesticides may undergo long range transport and be deposited considerable distances away from the treatment areas, including remote areas such as the Arctic and Antarctic regions. Pesticides have been found in air, rain, cloud water, fog and snow. Whilst volatility of pesticides can be linked to their Henry's Law constant this is very much a simplification since it is also influenced by the surfaces treated, e.g. soil or leaves, and by the extent to which aerosols are formed during the application. The disappearance of pesticides from the atmosphere is due to hydrolysis, indirect photolysis via OH radicals and deposition in rain. The use of fugacity models has been shown to be a useful approach to predict concentrations in air. Under most conditions the presence of pesticides in air, or rainwater, has no significant effects on non-target systems, including direct and indirect effects. Exceptions to this are damage by auxin-type herbicides to sensitive plants and persistent organochlorine pesticides in Arctic regions where, due to the very oligotrophic nature of the Arctic ocean, they are more liable to bioaccumulate and be transported in the food web giving enhanced levels in mothers' milk. |
