Occurrence of organochlorine pesticide residues in dairy cattle feeds, milk, urine and water from lactating cows in some selected farms in Gauteng Province

M.Tech. (Biotechnology)Abstract: The health risks associated with organochlorine pesticide (OCP) residues in both animals and humans remained major public health concerns which require some serious attention especially in South Africa with high consumption rate of cattle and cattle products. However, review of literature revealed that, there seems to be no studies conducted to establish estimated levels of dairy cattle exposure to OCP by estimating levels in dairy cattle feeds, milk, urine, and water, in South Africa. Therefore, this present study was carried out to analyse the possible presence of OCP residues in cattle/ bovine feed, milk, water and urine samples. The samples analysed included, milk (24 samples), urine (12 samples), water (12 samples) and feed (36 samples) which were collected into 50 mL sterile capped bottle from 12 selected farms in Gauteng province of South Africa. Six different OCP residues namely, endosulfan I, endosulfan II, dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethylene (DDE) and endrin were analysed. The samples preparation method for OCP involved the use of liquid-liquid extraction (LLE) and solid phase extraction (SPE) procedure, while separation and quantification was done using a two-dimensional gas chromatography time-of-flight with mass spectrometer (GCXGC TOF MS). The results of the perception study revealed that out of the 12 farms, 41.7% practice chemical method and 58% practice biological method of pest control. The majority of farmers (75%) were found to be aware of pesticide residues risks but (92%) neither tested for pesticide residues nor attended any food safety training on pesticide uses. Moreover, the results from GCXGC TOF MS analysis revealed that urine samples were contaminated with OCP residues with high concentration of endosulfan I ranging from 0.03 to 0.05 mg/kg, while DDT and its isomers ranged from 0.01 to 0.02 mg/kg. Milk also showed high levels of endosulfan I (range: 0.05 to..