Background/aim Organophosphate (OP) and pyrethroid (PYR) pesticides have a strong potential to disrupt the brain and nervous system of insects. This neurotoxic effect is not highly selective and therefore the compounds are also toxic to other non-target species, including humans. Once in the human body, OP and PYR pesticides are typically metabolised and excreted in urine within 4–48 hours after exposure.

Methods A new analytical methodology for the quantification of OP and PYR urinary metabolites has been developed taking into account the wide range of concentrations of these compounds in humans from general and highly exposed populations (e.g. rural or agricultural areas). Six biomarkers of OP pesticides and two biomarkers of PYR compounds have been quantified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). This methodology has been externally checked-out by participation in rounds of the G-Equas programme.

A total of 125 urine samples from two adult Spanish populations have been analysed: farmworkers (n=45) and individuals living in urban and rural areas (n=80) from Catalonia and Galicia.

Results The most abundant OP metabolites were PNP (metabolite of parathion and methyl paration, found in all samples analysed), followed by TCPY (metabolite of chlorpyrifos, found in 95% of the samples) and DEAMPY (metabolite of pirimiphos, 77% of detection), with median concentrations of 1.8 ng/ml, 1.1 ng/ml and 3.2 ng/ml, respectively. None of the samples had MDA (metabolite of malathion), and a few of them (<5%) had detectable concentrations of IMPY and CMHC (metabolites of diazinon and coumaphos, respectively).

Concerning PYR metabolites, 3-PBA (metabolite of several commercial pyrethroids) was found in 81% of the samples (median concentration of 1.5 ng/ml) and 4-F-3-PBA (metabolite of cyfluthrin) was found in half of the cohort, with a median concentration of 0.076 ng/ml.

Conclusion Metabolites of OP and PYR pesticides were observed in both farmworkers and general populations living in rural and urban areas, the former showing twofold average concentrations of OP metabolites than the second. These differences are consistent with occupational activity. The results show that both populations are generally exposed to pesticides such as chlorpyriphos, pirimiphos and parathion.