Levels and Health Risk Assessment of Organochlorine Residues in Vegetables from Rivers Niger-Benue Confluence in Lokoja, North Central, Nigeria

Organochlorine pesticide residues, OCPs are group of synthetic chemicals containing chlorine, hydrogen, carbon and are highly hydrophobic, slowly biodegradable. They are commonly used as insecticides, herbicides, fungicides and can accumulate in plants and animals with a potential to long range transport. These chlorinated hydrocarbons are persistence, toxic, hazardous and have been linked to various environmental contaminations and health challenges such as cancer, neurological damage, immunological disorder and reproductive problems. This study aimed at determining the levels of OCPs and their health risk in order to ascertain the status of consuming these vegetables from this part of Nigeria. The study investigated the levels and health risk of organochlorine pesticides (OCPs) residues in vegetables (spinach, jute leaf, pumpkin leaf, okro, tomatoes, garden egg and cucumber) cultivated around rivers Niger-Benue confluence in Lokoja, North Central, Nigeria. Concentrations of OCPs were determined in vegetable samples collected from major markets in five local government areas in the vicinity of the confluence after extraction by sonication using 1:1 dichloromethane – hexane mixture as solvent followed by clean–up with activated silica gel. Recovery test was carried out to ensure the accuracy of the method. Gas Chromatography – Mass Spectrometry (GC-MS) was used in the determination of the OCPs. The health risk indices (HRI) (which is a technique used to assess and communicate the level of risk posed by environmental pollutants) of consuming the analysed vegetables were assessed according to the USEPA guidelines, whereby the estimated daily intake (EDI) was compared with the acceptable daily intake (ADI). The average recovery of 76% was obtained. The highest non carcinogenic health index values of 8.33, 6.32 and 4.61 were found for dieldrin, heptachlor epoxide and heptachlor in jute leaves while the highest potential carcinogenic health index value of 37.020 was found for dieldrin also in jute leaves. The HRI values of heptachlor, its epoxide and dieldrin obtained exceeded the standard limits (1 mg/kg). The values of OCPs detected in analyzed samples were very much higher than standard limit of 1 mg/kg established by USEPA and are likely to pose a threat to human health.