ABSTRACT

Recent time there has being tremendous increase in the impairment of organs in human body. From all indication it has being attributed to toxicants mainly pesticides. The major route of entrance is through food and people eat stockfish raw and pesticide are used to preserve stockfish. Hence there is need to determine the pesticide residues used in stockfish preservation and heavy metals that accumulated on the stockfish from water source.  Thirty-nine (39) stockfish heads samples of Gardus morhua were purchased from the major market in Awka. Three of the samples were used to determine the background residue before the treatment and was used as control, while the remaining thirty-six (36) samples were treated with dichlorvos (DDVP) and kept for three (3) weeks, after which they were used to determine for pesticide residues and heavy metals in stockfish. The experiment was laid in completely randomized design (CRD) in three replicates. Residues of pesticides in the samples were determined using Gas Chromatography (GC-ECD), while heavy metal concentrations in the samples were determined using Atomic Absorption Spectrometer Varian AA240. The results obtained from the experiment, were compared with USEPA/WHO safe limit and control. All the treatment levels of dichlorvos exceeded 0.004mg/kg USEPA safety limit with the residue concentration of 2.59±0.67mg/kg, 2.71±0.20mg/kg and4.44±0.74mg/kg for treatment 2(250mg/kg), treatment 3(500mg/kg) and treatment 4(1000mg/kg) respectively, except for treatment 1(0mg/kg) which was the control. Chlorpyrifos residue also exceeded standard of 0.0100mg/kg except at treatment 1 (0mg/kg) with residue of 0.00mg/kg. DDT results complied with the safety limit of 0.0200mg/kg in all the levels. The results obtained from DDE test were also within the safety limit of 0.0200mg/kg, while the DDD residue in all treatments except treatment 1 exceeded the safety limit of 0.0200mg/kg and that of control 0.0048mg/kg.  g-HCH at all levels complied with the limit of 0.01mg/kg and that of the control of 0.0010mg/kg. a-HCH residue obtained in all the levels exceeded the control and standard except that of treatment 3. HCB residue obtained exceeded the control of 0.0009mg/kg and safety limit of 0.01mg/kg, except that of treatment 2 with the value of 0.00mg/kg. All the results for g-chlordane and the control exceeded the standard of 0.001mg/kg. Also all the residues obtained for glyphosate were above control with the value of 0.0227mg/kg. Residues concentration for t-nonachlor were above control of 0.0007mg/kg except at treatment 2 with the residue value of 0.00mg/kg. Results obtained from the heavy metals test indicates that concentration of Cd, Pb and Sn at all level complied with the standard limit of 0.5mg/kg, 0.5mg/kg and 14mg/kg respectively by WHO. Hg concentration in treatment 1(0.7263±0.163mg/kg) and 2(0.093±0.0635mg/kg) exceeded WHO safe limit of 0.001mg/kg and the control. Ni concentration in all the treatment levels were above both the control and the standard limit. This study showed that several pesticides were used to preserve stockfish traded in the market and most of these pesticides hardly degrade over time. Based on the research findings to achieve best sustainable methods for preserving stockfish, government should periodically and comprehensively monitor stockfish traded in the market to ensure that these contaminants don’t exceed the acceptable limit for consumption.