Assessment of occupational exposure to pesticides with multi-class pesticide residues analysis in human hairs using a modified QuEChERS extraction method, case study of gardening areas in Burkina Faso

Pesticides have been proved to potentially cause multiple adverse health effects. The present study is part of a global project focusing on pesticides impacts on the environment and human health in gardening in Burkina Faso. In absence of existing monitoring, the present study aims at proposing a comprehensive indicator of occupational exposure to 48 pesticides identified during field campaigns. As a noninvasive and safe indicator of long term exposure, increasing interest is being observed in hair analysis for biomonitoring of human exposure to pesticides. In order to dissociate occupational and environmental exposure in the study area, two study populations have been randomly selected: fifty gardeners (operators) and fifty non users (reference population). The Ethics Committee of the Burkina Faso approved this study and written informed consent was obtained from all donors. Multiresidue extraction procedure using a modified QuEChERS extraction method has been developed and applied to the collected samples. Briefly, hairs were cut on the posterior of the head, subsequently cut in small pieces and spiked with appropriate 13C- or deuterated surrogates. After overnight incubation, they were extracted in acetonitrile, cleaned-up by Dispersive SPE (dSPE), concentrated and separated prior analysis on GC-MS and LC-MS/MS. Each sample was accompanied by a questionnaire on hair care practices. Different incubation, extraction methods and dSPE sorbents have been tested (temperature, type, volume, etc.). The best method was found to be a modified AOAC 2007.01 QuEChERS procedure, including 12h incubation at 37°C followed by dSPE clean-up with Supelco Z-sep/C18® sorbent. The substances detected in collected samples include pesticides commonly used in the study area such as acetamiprid, imidacloprid, cypermethrin, profenofos but also dieldrin a banned persistent organochlorine. These pesticides were detected in hairs of the gardeners but also in the samples of the reference population indicating the occurrence of passive contamination. This study presents a comprehensive assessment of sample preparation, extraction and clean-up procedure for multi-class pesticide residues analysis in human hairs. The modified QuEChERS extraction procedure proposed offers a simple and robust tool suitable to developing countries for monitoring human exposure and evaluation of compliance with policies. The study design, including comparison between reference and operators populations allowed to dissociate the influence of environmental exposure and direct occupational exposure. Results indicate that potential carcinogen, endocrine disruptor, neurotoxic and persistent pesticides have been detected in collected hairs.