Biological monitoring of exposure to pyrethrins and pyrethroids in a metropolitan population of the Province of Quebec, Canada

Pyrethroid and pyrethrins are neurotoxic insecticides widely used to control agricultural and domestic insect pests. The general population is potentially chronically exposed through food consumption, but the actual exposure is poorly documented in Canada. This study aimed at obtaining an indication of the absorption of those insecticides in residents of Montreal Island, the largest metropolitan area of the Province of Quebec, Canada. We randomly recruited 120 adults and 120 children aged 18–64 and 6–12 years old, of which 81 adults and 89 children completed the study. The absorption of pyrethroids and pyrethrins was assessed through measurements of six urinary metabolites: chrysanthemum dicarboxylic acid (CDCA), cis- and trans-2,2-(dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acids (cDCCA and tDCCA), cis-2,2-(dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA), 3-phenoxybenzoic acid (PBA) and 4-fluoro-3-phenoxybenzoic acid (FPBA). Metabolites were determined in 12-h urine collections for children and 2-consecutive 12-h collections for adults, and were analyzed by gas-chromatography/mass spectrometry. In both adults and children, the relative distribution of the various metabolites was as follows: tDCCA>PBA>cDCCA>CDCA>DBCA>FPBA. In adults, median (95th percentiles) cumulative amounts of these metabolites were 12.0 (231.1), 8.2 (177.9), 5.0 (110.1), 0.3 (8.2), 0.1 (4.7) and 0.1 (0.5) pmol/kg bw, respectively, in nighttime 12-h urine collections. Corresponding values in children were 12.6 (207.7), 10.2 (73.2), 5.1 (59.6), 2.1 (14.2), 0.1 (4.9) and 0.1 (0.8) pmol/kg bw. The main metabolites observed are indicative of exposure mainly to permethrin and cypermethrin and amounts absorbed are in the same range in adults and children. The distribution levels of the main metabolites in our sample also appeared similar to those reported in the US population.