Assessment of pesticide residues and trace element contamination in market gardens of Togo

Abstract

All intensive agriculture, like periurban agriculture, uses massive inputs such as agrochemicals. This study aims to assess the environmental impacts of agrochemical use in periurban agriculture in Togo. It was based on the chemical analyses of soil, water and vegetable samples. These analyses were carried out by gas chromatography on extracts from soil, water and vegetable samples. In soil samples, the concentrations of pesticide residues are lower than 20 ìg/kg of dry material. For water samples, contamination levels vary from 0.02 to 1.1 ìg/L of dry material with the highest levels for metalaxyl M (1.1 ìg/L) and for dimethoate (1 ìg/L). In vegetables, the concentrations measured are between 0.01 and 0.1 mg/kg of dry material. All these concentrations are affected by a positive factor of the maximum limits of residues. These agrochemicals, coupled with periurban environmental management led to the high concentrations of trace elements. Lead and cadmium concentrations in water are 10 and 21 times respectively higher than the maximum concentration allowable for drinking water by the WHO. The study showed that inappropriate use of agrochemicals in Togolese periurban agriculture creates ecological disturbances that could affect produce quality.

Key words: Togo, periurban agriculture, agrochemicals, pesticide residues, trace element.