Assessment of average exposure to organochlorine pesticides in southern Togo from water, maize (Zea mays) and cowpea (Vigna unguiculata)

Abstract

Drinking water, cowpea and maize grains were sampled in some potentially exposed agro-ecological areas in Togo and analysed for their contamination by some common organochlorine pesticides. A total of 19 organochlorine pesticides were investigated in ten subsamples of maize, ten subsamples of cowpea and nine subsamples of drinking water. Analytical methods included solvent extraction of the pesticide residues and their subsequent quantification using gas chromatography-mass spectrometry (GC/MS). Estimated daily intakes (EDIs) of pesticides were also determined. Pesticides residues in drinking water (0.04–0.40 µg l⁻¹) were higher than the maximum residue limit (MRL) (0.03 µg l⁻¹) set by the World Health Organization (WHO). Dieldrin, endrin, heptachlor epoxide and endosulfan levels (13.16–98.79 µg kg⁻¹) in cowpea grains exceeded MRLs applied in France (10–50 µg kg⁻¹). Contaminants’ levels in maize grains (0.53–65.70 µg kg⁻¹) were below the MRLs (20–100 µg kg⁻¹) set by the Food and Agriculture Organization (FAO) and the WHO. EDIs of the tested pesticides ranged from 0.02% to 162.07% of the acceptable daily intakes (ADIs). Population exposure levels of dieldrin and heptachlor epoxide were higher than the FAO/WHO standards. A comprehensive national monitoring programme on organochlorine pesticides should be undertaken to include such other relevant sources like meat, fish, eggs and milk.

Keywords:

• drinking water
• maize (Zea mays)
• cowpea (Vigna unguiculata)
• organochlorine pesticides residues
• estimated daily intake (EDI)

Acknowledgements

This study was financially supported by the Service de Coopération et d’Action Culturelle du gouvernement français à Lomé. The authors wish to thank Dr Mianikpo Sogbedji (Fulbright Research fellow at Cornell University) for his precious contribution, and Damien Devault and Carole Castaing for their helpful technical assistance.