Derivation of Biomonitoring Equivalent (BE) Values for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds: A Screening Tool for Interpretation of Biomonitoring Data in a Risk Assessment Context

Abstract

Recent efforts by the U.S. Centers for Disease Control and Prevention and other researchers have resulted in a growing database of measured concentrations of dioxins and related compounds in blood samples taken from the general population. However, few tools exist to assist in the interpretation of the measured values in a health risk context. Biomonitoring equivalent (BE) values are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline, and are derived by integrating available data on pharmacokinetics with existing chemical risk assessments This study reviews available health based exposure guidance values for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds from a variety of agencies including the World Health Organization Joint Expert Committee on Food Additives (JECFA), the European Commission Scientific Committee on Foods (ECSCF), the United Kingdom Committee on Toxicology (UKCOT), and the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) to estimate corresponding BE values for dioxin-like compounds in blood on a serum lipid-adjusted basis. Based on data from the animal studies underlying the exposure guidance values, a serum lipid-adjusted dioxin toxicity equivalent (TEQ) concentration of approximately 15 ppt is consistent with the ATSDR minimal risk level (MRL) for dioxins. Serum lipid-adjusted TEQ concentrations of approximately 31 to 74 ppt are consistent with the tolerable intakes estimated by the other three agencies. These values may be used as screening tools for evaluation of biomonitoring data for dioxins in the context of existing risk assessments and for prioritization of the potential need for additional risk assessment efforts for dioxins.