Soil and water contamination with carbofuran residues in agricultural farmlands in Kenya following the application of the technical formulation Furadan

Abstract

This study was undertaken to determine the concentrations of carbofuran residues in water, soil and plant samples from selected sites in the farmlands in Kenya and to demonstrate the impact of Furadan use on the local environment. Soil, water and plant samples obtained from agricultural farmlands where the technical formulation Furadan has been used extensively showed high environmental contamination with concentrations of carbofuran and its two toxic metabolites 3-hydroxycarbofuran and 3-ketocarbofuran, separately, ranging from 0.010-1.009 mg/kg of dry surface soil, 0.005-0.495 mg/L in water samples from two rivers flowing through the farms and bdl-2.301 mg/L in water samples from ponds and dams located close to the farms. Maize plant samples contained these residues in concentrations ranging from 0.04-1.328 mg/kg of dry plant tissue. The significantly high concentration levels of carbofuran and its metabolites, 3-ketocarbofuran and 3-hydroxycarbofuran, found in various matrices demonstrate that Furadan was used extensively in the two areas and that there was environmental distribution and exposure of residues in water which posed risks when used for domestic purposes or as drinking water for animals in two wildlife conservancies where the dams and ponds are located. Surface soil contamination was also high and posed risks through run-off into the dams and rivers as well as through secondary exposure to small birds and mammals.

Spatial Distribution and Temporal Trend in Concentration of Carbofuran, Diazinon and Chlorpyrifos Ethyl Residues in Sediment and Water in Lake Naivasha, Kenya

“…Meanwhile, previous studies by Anderson et al (2003) and Ensminger et al (2011) detected diazinon in sediment between the range of 0.1-13.1 ng g -1 dw in an exclusively agriculture areas. Elsewhere, carbofuran and its metabolites were detected in water sampled from surface waters adjacent to agricultural farms where mean levels of carbofuran of 11-59.2 lg L -1 (3-ketocarbofuran) and 11.8-68.0 lg L -1 (3-hydrocarbofuran) were reported (Otieno et al 2010). Levels were below detection limit in the analyzed matrices could be attributed to their volatilization, degradation, hydrolysis, and photolysis in the environmental medium before our sampling.…”

Biodegradation of carbofuran in soils within Nzoia River Basin, Kenya

“…[1][2] It belongs to the Nmethylcarbamate class that is extensively used in pest control. It is widely used in the control of pests such as corn root worm, wire worms, boll weevils, mosquitoes, alfalfa weevils and white grubs.…”

“…It was used in Isiolo and Laikipia districts to control agricultural pests and its residues were found in the soils, plants and water sources in such areas. [2] Carbofuran has also been used in Nzoia River Drainage Basin, especially in Bunyala Rice Irrigation Schemes nuclear estates. [5] A study done by Kimosop [6] in the same area on the dissipation behavior of carbofuran in the soil established that residual levels of carbofuran ranged from 0.01-1.08 mg g ¡1 in the soils, indicating environmental contamination.…”

Tropical surface water quality studies: Implications for the aquatic fate ofN-methyl carbamate pesticides

“…To our knowledge, there are no other reports that compare the half-lives of these three specific NMCs under identical conditions. [13,[54][55][56] Carbaryl (Sevin) is a broad spectrum pesticide [57] that is moderately toxic to aquatic organisms and highly toxic to many non-target insects, such as honeybees. [58] The compound has the potential to migrate to groundwater (K ow D 71).…”

“…NMCs are used in Kenya in plantation-scale agriculture, small subsistence holdings and on livestock, and the pesticides have been detected in rivers and streams and attributed to agricultural run-off. [9][10][11][12][13] Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.…”