Dioxin releases from US chemical industry sites manufacturing or using chlorine

摘要

This paper reports on an intensive study into releases of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from 19 chemical production facilities in the United States producing, or using, large volumes of chlorine. Releases on-site to air, water and to landfill were assessed as were transfers off-site in materials for disposal or additional treatment. The primary purpose was to develop estimates of releases on a site-specific basis that could be used in the US EPA inventory of dioxin-like compounds, it also serves to increase the database on releases from this industry which are comparatively poorly studied. Releases varied considerably and a prime conclusion of the study is that the presence of multiple processes using different technologies and common wastewater treatment facilities often found on integrated chemical sites means that sector-level approaches in inventory estimates will not give appropriate estimates at the site level. A more detailed study is required using site-specific data where possible. Transfers of data should only be carried out when fully justified on the basis of process characteristics. The largest estimated flows were in residues being transferred off-site for treatment (incineration) or disposal, generally in secure landfills. Releases to water varied widely from essentially non-detectable amounts to more than 5 g of PCDD/F (as I-TEQ) annually. Where sites took measures to upgrade processes, air pollution controls and wastewater treatment systems, substantially reductions in releases were observed.