Dioxin releases from US chemical industry sites manufacturing or using chlorine

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.