The levels of cis-DCCA, trans-DCCA, and 3-PBA were adjusted by urinary creatinine concentrations to avoid the influence of different urine dilutions on the measurement of pyrethroid metabolites. Urinary creatinine was measured by the modified Jaffe colorimetric method using automated Beckman Coulter analyzers (Beckman Coulter, Fullerton, CA, USA) ( Mazzachi et al., 2000).