Publication Summary

Composting of yard debris and other organic wastes is a very important component of Washington′s solid waste management system, and large quantities of compost are applied to the land under various scenarios of use. There are 25 permitted facilities in the state, which produce more than 500,000 cubic yards of finished compost annually. Most of the major facilities process yard debris and/or other waste materials from urban areas. There are many additional composting operations processing agricultural waste as well as backyard composting which occurs at many private residences across the state.

Composting of yard debris and other organic wastes is a very important component of Washington′s solid waste management system, and large quantities of compost are applied to the land under various scenarios of use. There are 25 permitted facilities in the state, which produce more than 500,000 cubic yards of finished compost annually. Most of the major facilities process yard debris and/or other waste materials from urban areas. There are many additional composting operations processing agricultural waste as well as backyard composting which occurs at many private residences across the state.

Recently there has been increasing interest regarding the potential presence of dioxins, or polychlorinated dibenzo para dioxins (PCDDs) in compost. The initial objective of this study was to conduct a screening survey of dioxin concentrations in compost samples from several facilities. Almost from the beginning of the project, however, the decision was made to include the polychlorinated biphenyls (PCBs) and polychlorinated dibenzo furans (PCDFs), since these are both similar to dioxins in their chemical properties. During the analyses for PCBs, it was found that organochlorine pesticides (such as Chlordane, Lindane, Dieldrin and DDT) were also present in the compost samples. The decision was then made to include these pesticides in the scope of analyses. Therefore, Ecology quantified PCDD/PCDF, dioxin-like coplanar PCBs, aroclor PCBs and organochlorine pesticide concentrations in the final screened products from selected compost facilities in the state. It was also determined that the sampling would be blind, which means that the sources of the compost would not be identified with the analytical results. For more information on PCDD/PCDF, PCBs and the project description, see Bennett, J., and Wescott, H., 2001 (a), (b).

This study is intended to be an initial assessment of the range and magnitude of dioxins and related compounds in composts produced in Washington State. The results add to the existing information about the presence of dioxin and similar chemicals in Washington′s environment.