Impact Assessment of Pesticides Applied in Vegetable-Producing Areas in the Saharan Zone

The present thesis aimed at characterizing the extent of the pesticide contamination and resulting impacts on the environment and the human health in market garden-ing areas in Burkina Faso. Analytical procedures were developed and validated for multi-class pesticide analysis in water, soils, sediments, and human hair. Passive samplers were deployed and grab samples were collected during a three-year investi-gation period. Results indicated that pesticide levels in surface water exhibited sea-sonality patterns. During the dry season, pesticide levels were generally low ( 0.1 µg L-1). Hazards were also identified for fish, cladocerans, and benthic invertebrates all year round but mainly during gardening activities. The assessment of the dietary intake of pesticides via vegetables and water consump-tion also outlined hazardous situations. Exposure levels to chlorpyrifos, dieldrin, and lambda-cyhalothrin presented acute and chronic risks for children and adults. The present work also proposed a novel approach for the quantification of 37 multiclass pesticides in hair using a modified QuEChERS procedure. In addition to the simpli-fication of sample treatment, this method offers a robust and sensitive tool for the biomonitoring of population exposure to pesticides. Hair samples collected from local populations were found positive to 17 active substances. For certain pesticides used in gardening such as acetamiprid, cypermethrin, and lambda-cyhalothrin, occupa-tional exposure was found to be the main source of exposure. However, for other substances such as imidacloprid and deltamethrin, similar exposure between occupa-tionally and non-occupationally exposed individuals suggested the prevalence of other sources of exposure (e.g. dietary intake, vector control activities, etc.). Levels detected in hairs are of concerns, as they were higher than reported in some other areas of the globe and indicated exposure to endocrine disrupting chemicals and probable carcinogens. Finally, the potential risk reduction of various mitigation measures was assessed using three international risk exposure assessment models. Simulation results indicated that training the operators to comply with pesticide recommendations of use and using suitable protective equipment was not sufficient. Additional behavioral changes and regulation adaptations are needed to reduce the exposure of the individuals present in gardening areas (operators, workers, and by-standers). More incentive on regulation enforcement and compliance with the good agricultural practices are necessary to improve the sanitary conditions in rural areas.