Estimation of Surface Water Contamination by Pyrethroids and Glyphosate in the Kerou and Pehunco Cotton Growing Areas of Northeastern Benin

Abstract

With the use of pesticides in cotton production areas, environmental components, including water bodies intended for consumption, become exposed. The study aims to assess the level of contamination of water bodies by pyrethroids and glyphosate in the Kerou and Pehunco cotton-growing areas in Benin. To do this, through a sampling campaign, water samples were taken in triplicate, followed by analysis of nutrient salts on the one hand, and of pesticide active ingredients on the other, by spectrophotometry and chromatography. The nutrient salts NH4+, NO3-, NO2-, PO43-, Cl- and SO42-, although globally in low levels, are more concentrated in the waters in agglomerations than in the cotton production zone. On the other hand, the water has very high levels of cypermethrin (18 mg/L), deltamethrin (41 mg/L) and glyphosate (11 mg/L) in the cotton-growing zone, sometimes quadrupling the pesticide levels in the urban areas, particularly in the areas of Gando-Baka, Marékpo and Pehunco-Gah. These results indicate that mineral salts in the Kérou and Pehunco plans have a dual origin, namely chemical fertilizers and, above all, animal droppings and other domestic discharges from the agglomerations. In addition, the pesticides come mainly from the dispersion in cotton growing areas with risks of gastric, nervous and dermal health problems. These results are an alert that should reorient agricultural policies in order to preserve the health of the population.