Food Safety and Environmental Stewardship Program

Organizations and developing countries that attempt to assess pesticides and other environmental contaminants face many challenges of how to measure them, such as, the remoteness of sites and subsequently the difficulty of transportation and stability of chemicals in samples from these sites.  The Sahel region of Western Africa has many highly engineered agriculture-based irrigated systems that generally have three cropping cycles per year.  The need to assess changes in contaminants at these sites requires tools that can characterize contaminants at high spatial and temporal resolution.  Modification of farming pest management practices face the challenge of how to measure success; how to assess the changes in bioavailability of contaminants.  They need quantitative tools that can characterize contaminants and predict their risk to local organisms and humans.  To address these issues we have further developed passive sampling devices (PSDs) that can sequester thousands of bioavailable chemicals.  These devices can help organizations and developing countries to evaluate changes in pest management that may produce or release chemicals.  PSDs can help organizers characterize exposure more accurately.  We are using PSDs to capture relevant non-polar and semi-polar pesticides and other chemicals of interest at multiple sites in Western Africa.  PSDs do not require power, transport easily and are easily extracted with organic solvent. We deployed PSDs in irrigation canals at seven agricultural sites in Senegal, Mali, and Mauritania agricultural stations. We were able to screen the PSD extracts for nearly 1,200 potential contaminants with gas chromatography mass spectrometry through the use  of libraries we have further developed based on software, including automated compiled mass spectral de-convolution and identification system libraries that contain numerous classes of chemicals of concern (pesticides, PCBs, PAHs, pharmaceuticals, industrially related chemicals, etc.). The results for all sites combined showed positive hits of six PCB congeners, 11 pesticides, 21 PAHs and two legacy pesticides including ethiolate, p’p’ DDD and its breakdown products.  Furthermore the compound pentachloroanisole a breakdown product of pentachlorophenol was detected in Mauritania. PSDs coupled with GC-MS screening tools offer a powerful technology to identify persistent organic pollutants present at agricultural sites in three countries in the Sahel region of Western Africa.