Public health assessment of hexachlorobenzene

Recently, hexachlorobenzene (HCB) was proposed for inclusion in the system of toxicity equivalency factors (TEFs) currently used for dioxin-like compo unds. In this paper, we explore the practical implications of the propositi on to the Agency for Toxic Substances and Disease Registry (ATSDR) programs by comparing respective health guidance values for 2,3,7,8-tetrachlorodibe nzo-p-dioxin (TCDD) and HCB (expressed as total toxicity equivalents [TEQs] ), reviewing possible interactions between HCB and dioxin-like chemicals, a nd by providing information on actual co-existence of HCB and dioxin-like c hemicals at hazardous waste sites. We found a good correlation between the TEF-adjusted oral exposure guidance values for HCB and guidance values for TCDD. The combination of HCB and other dioxin-like compounds was not found in soil, air, or water media at hazardous waste sites.;Based on this fact, it is not necessary to include HCB in the total TEQ count at hazardous wast e sites at this time. (C) 2001 Elsevier Science Ltd. All rights reserved.