ABSTRACT

This study examined the use of pesticides in smoke-dried fish preservation in Nigeria and its health implications.

The study was conducted in some major smoke-dried fish production and marketing centers viz Niger-Benue comprising of Jebba (Kwara State) Tatabu and New Bussa, Fakun (Niger State) and Makurdi (Benue State). The North-East comprised of Maiduguri metropolis, Doro Baga and Baga motor park all in Borno State. The South, comprised of Illushin in Edo State. Questionnaire-based surveys were conducted in the study areas involving stratified and randomly selected populations consisting of the processors, retailers, consumers and supported with focus group discussions (FGD). Broad spectrum instrumental analysis of randomly purchased smoke-dried fish samples was carried out using A Gas chromatograph equipped with mass spectrophotometer (GC/MS) was used to identify chemicals in the fish samples. Histological and haematological studies of rabbits, Oryctolagus cuniculus exposed to the identified chemicals “otapiapia” (Aluminium phosphide), Gammalin 20R (Lindane) and 2’ 2’ Dichlorovinyl dimethyl phosphate (DDVP 1000EC) at concentrations of (2%, 5%, 10%, 20%) for 24 hours and 14 days respectively; was also carried out. All data collected were subjected to Analysis of variance (ANOVA) at (P < 0.05).

The smoking kilns used in all the zones range from the Chorkor smoker to the Half and Full drum smokers with their fish either gutted before smoking or smoked whole. Processors packaged smoke-dried fish with cartons of various sizes or sacks weighing between 35-50kg. The average quantity of smoke-dried fish sold per day varied from 31-40kg/wholesaler. Consumption figures from all the zones showed that 3.25kg/week of smoke-dried fish is consumed on the average by each of the responding consumers. The Niger/Benue Zone was highest with an average of 3.89kg/week, followed by the South Zone with an average of 3.75kg/week and lastly by the North-East Zone with an average of 2.45kg/week. The results of the surveys showed that “otapiapia” a locally formulated pesticide and Gammalin 20^R were in use mostly in the North-East Zone. Gammalin 20^R, kerosene (DPK) and Aerosol “Shelltox” were used in the Niger-Benue Zone. The pesticide residues extracted from the treated fish, were Lindane (C₆H₆C₁₆), Pyrazine (C₁₄H₂₂N₂O₂), P’ P’ dioctyldiphenyl amine (C₂₈H₄₃N) and organometallic compounds of Tungsten, phosphorous and silicon with the formular (C₂₁H₂₆BO₅PsiW). The major components of the fish were esters, which were usually 6, 7, 8 and 20 carbon atoms either saturated or unsaturated or as methyl esters namely; n-Hexadecanoic acid; 6,9,12,15, Docosatetranoic acid methyl ester; 5, 8,11,14-Ecosotetranoic acid ethyl ester; and 9-octadecanoic acid methyl esters. These esters were present in all the spectra. Histological and haematological analyses of rabbits exposed to the pesticides indicated negative impacts on the kidney, liver and stomach of the animals. Comparison showed that the effects of the pesticides increased as the concentration increased through feed intake. There was a general reduction in the packed cell volume (PCV), white blood counts (WBC), and platelet counts (PC). In some cases the animals presented moderate to severe anemia together with leucopenia and thrombocytopenia.