Abstract
The levels of organochlorine pesticides (OCPs) in water, sediment, Nile Tilapia and African Catfishes were assessed to estimate possible consumer exposures and potential health implications from the Volta Lake, Ghana using gas chromatography equipped with 63Ni electron-capture detector. In agreement with their lipophilic nature, higher levels of OCPs were measured in fish samples than water and sediment samples. Heptachlor was the highest level of OCP measured with concentration of 37.75 ng/g in tilapia gill followed by δ-HCH in tilapia muscle and catfish muscle respectively. All OCP residues in tilapia muscle and catfish muscle did not differ significantly (p<0.05). The highest total OCP load of 66.70 ng/g was measured in tilapia muscle, followed by 63.44 ng/g for tilapia gill. This observation however, contradicts the lipophilic nature of OCPs since the fat content of tilapia gill (14.49%) was five times that of muscle tissues (2.80%). Gill tissues however, may be serving as channels to absorb and distribute OCPs to various fatty tissues in the anatomy and physiology of fish. In water a sample δ-HCH was the highest OCP determined with concentration of 0.669 μg/L. DDT was not detected in both water and sediment samples but was however measured in fish samples. This could be attributed to historical use since DDD and DDE were measured in higher concentrations. From the consumer exposure analysis, the water from the lake is relatively safe for domestic, agricultural and ranching since the acute risk ratio for all detected OCP residues were less than one. The Nile tilapia and African catfishes from this lake are also comparatively safe for human consumption because the estimated dietary intakes from this study are far below the corresponding acceptable dietary intakes for various OCPs. This study therefore shows a declining trend on the environmental burden of OCPs in the middle section of the Volta Lake.
Highlights
The World Health Organisation (WHO) says pesticide poisoning is the probable cause of 18 mysterious deaths in south-western Nigeria [1]
The main objective of this study is to evaluate the organochlorine pesticide residues in water, sediment, African Catfish and Nile tilapia from the Volta Lake; evaluate the suitability of the water and fish for continuous human consumption
Fifteen organochlorine pesticide (OCP) residues namely β-HCH, γ-HCH, δ-HCH, p,p'-DDT, p,p'-DDD, p,p'-DDE, heptachlor, aldrin, dieldrin, endrin, γ-chlordane, α-endosulfan, β-endosulfan, endosulfan sulphate and methoxychlor were considered in this study
Summary
The World Health Organisation (WHO) says pesticide poisoning is the probable cause of 18 mysterious deaths in south-western Nigeria [1]. In less than two decades of their use, synthetic pesticides have been so thoroughly distributed throughout the animate and inanimate world that they occur virtually everywhere They have been recovered from most of the major river systems. Residues of these chemicals linger in soil to which they may have been applied a dozen years before They have entered and lodged in the bodies of fish, birds, reptiles, domestic and wild animals so universally that scientists carrying on animal experiments find it almost impossible to locate subjects free from such contamination. They have been found in fish in remote mountain lakes, in earthworms burrowing in soil, in the eggs of birds and in man himself. For these chemicals are stored in the bodies of the vast majority of human beings, regardless of age [2]
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