An oral dose of the pyrethroid insecticide deltamethrin was administered to five volunteers at the acceptable daily intake (ADI, 0.01 mg/kg). Total urine was collected from the volunteers at timed intervals for 60h post-exposure. The metabolites 3-(2,2-dibromovinyl)-2,2-dimethyl-(1-cyclopropane)carboxylic acid (DBVA) and 3-phenoxybenzoic acid (3-PBA) were quantified in hydrolysed urine using GC-MS analysis. Both metabolites exhibited rapid elimination half-lives of 3.6 and 7.1h, respectively. Levels of DBVA quantified in urine were approximately 5 times greater than 3-PBA. Mean metabolite levels found in 24h total urine collections, normalised for a 70 kg individual, were 42.8 μmol DBVA/mol creatinine (range 34.6-63.2; CV=28%) and 8.7 μmol 3-PBA/mol creatinine (range 6.6-12.7; CV=31%). We calculate that a 70 kg person receiving a dose of deltamethrin at the ADI would be expected to have a 24-h total urine collection level of 32-53 μmol DBVA/mol creatinine (95% confidence interval). Analysis of 336 samples from adult UK residents with no known exposure to deltamethrin derives an upper reference value (95th percentile) of 0.5 μmol DBVA/mol creatinine (maximum 4.2 μmol DBVA/mol creatinine), demonstrating that general population exposure to deltamethrin in the UK is very low and well within levels expected at the ADI.
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