Biomonitoring Equivalents for deltamethrin

Measured concentrations of chemicals in blood or urine in biomonitoring studies provide an integrated reflection of exposures to chemicals via multiple routes and pathways. The potential significance of the measured concentrations of chemicals in the context of existing toxicology data and risk assessments can be assessed if chemical-specific quantitative screening criteria are available. This work presents the derivation of Biomonitoring Equivalents (BEs) for deltamethrin, a synthetic Type II pyrethroid. BEs are estimates of biomarker concentrations that are consistent with risk assessment-based exposure guidance values such as reference doses or acceptable daily intakes. BE values were derived for deltamethrin based on two biomarkers: deltamethrin in plasma and 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA), a specific metabolite, in urine. BE values for deltamethrin in plasma were based on extrapolation from measured deltamethrin concentrations in plasma in rats under conditions consistent with the Point of Departure in the critical study underlying the USEPA RfD. BE values for DBCA in urine were derived based on pharmacokinetic data from a study in human volunteers on the urinary excretion of deltamethrin and metabolites. BE values for deltamethrin in plasma corresponding to the USEPA RfD for adults and children are 20 and 2 μg/L, respectively. BE values for DBCA in urine corresponding to the adult and child-specific RfDs are 50 and 7 μg/L, respectively. The urinary BE value corresponding to the ADI established by the European Commission and the Joint Meeting on Pesticide Residues is 60 μg/L (as DBCA in urine). These values can be used to screen biomonitoring data in the context of current risk assessments for detlamethrin.