Risks Assessment of Organochlorines, Organophosphates and Pyrethroids Pesticide Residues in Water within River Benue and Lake Gerio Basin of Adamawa State, Nigeria

Abstract

Nigerian farmers particularly from Adamawa state in their quest to increase agricultural production led to increase in the use of pesticides, herbicides, rodenticides and fungicides. These persistent organic chemicals have become integral part of Nigerian farmers. A study on pesticide residue risk assessment in water and farmers in Adamawa state, Nigeria was conducted in four areas of study that comprised of Chigari, Dasin-Hausa, Gurin and lake Gerio respectively, with  three objectives. The water samples were analyzed for pesticide residues, hence 19 different residues of organochlorine, organophosphates and pyrethroids were detected by the use of GC-MS device. Recommended chemicals such as HPLC grade Acetone and Acetonitrile and n-hexane were used as solvents while NaCl₂ (99.6%) of aqueous solutions and dichloromethane as extrants were utilized. Disperse Liquid-Liquid Extraction Method (DLLME) was used in samples extraction.  The most contaminants detected are cypermethrin, permethrin, DDT, bifenthrin and Malathion, and the concentrations of each residue was determined. Generally, about three of water samples from the study areas were found above the EU MRL, only sample obtained from Dasin-Hausa had most of the residues below EU MRL. Therefore, 75% of the samples were found above EU MRL status. The EDI was determined by the use of the Expected Daily Intake  formula; EDI = ∑_C × F / D × W. HRI indicated that there is high risk in consuming water for a life time in the study areas. Anova analytical indicated significant association of pesticide and residues across the study areas. Farmers were exposed to these variant residues through oral means which results to high mortality rate among the famers in the study areas due to reported cases of High Blood Pressure, Gastro-intestinal complications, severe fever and frequent dihorrea especially among the old and the young members of the farming communities. Reduce this abstract to a maximum of 250 words.