Derivation of Biomonitoring Equivalents for cyfluthrin

Recent efforts worldwide have resulted in a growing database of measured concentrations of chemicals in blood and urine 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 Equivalents (BEs) 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 cyfluthrin from Health Canada, the United States Environmental Protection Agency (USEPA), and the World Health Organization/Food and Agriculture Organization. BE values corresponding to the oral reference dose (RfD), or acceptable daily intake (ADI) estimates from these agencies were derived based on data on excretion fractions of the urinary metabolite 4-fluoro-3-phenoxybenzoic acid (FPBA), which is a metabolite specific to cyfluthrin. These values may be used as screening tools for evaluation of biomonitoring data for cyfluthrin as the metabolite FPBA in the context of existing risk assessments and for prioritization of the potential need for additional risk assessment efforts for cyfluthrin relative to other chemicals.