Analysis of Aldrin, Endosulfan and Heptachlor epoxide in Cowpea from South-West Nigeria

Background: Pesticides are applied on cowpeas to reduce the losses incurred to the attack by Callosobruchus maculatus which adversely affect its production and storage. Objectives: This study aims to evaluate the mean concentration of heptachlor epoxide, aldrin and endosulfan in randomly collected cowpeas obtained from local markets in South-West states of Nigeria and compare the mean concentration with the maximum residual limit (MRL) set by the regulatory body. Method: Seventy-six samples of cowpeas were collected from from local markets within the study area, pulverised, extracted with dichloromethane, cleaned-up and analysed by Gas Chromatography-Mass Spectroscopy (GC-MS) for aldrin, endosulfan and heptachlor epoxide. Results: The experiment showed that aldrin, endosulfan and heptachlor epoxide are widely used in South-West for preservation of cowpea. Mean concentration of aldrin (406.8±0.12 μg/kg) in Bodija market, Oyo state, was observed to be the highest. The market in Ile Epo market, Lagos state, was observed to have the highest mean concentration for endosulfan (315±0.164 μg/kg) while Okitipupa market, Ogun state, recorded a mean concentration for heptachlor epoxide (156±6.23 μg/kg), which is the highest. Conclusion: This shows that aldrin, endosulfan and heptachlor epoxide are used in the storage of cowpeas long after they were labelled probable carcinogens and their mean concentrations were above the MRL set by USEPA. Thus there is need for regular monitoring to be conducted on cowpeas for organochlorines.