Heavy Metal Contamination of Singed Cattle Hides in Nsukka Abattoir, Enugu State, Nigeria.

Abstract

This research was carried out to investigate the possible heavy metal contamination of hides due to the various methods of singeing. A total of 60 cattle were used to carry out this study. Hides of cattle that were unsinged and singed were analysed for lead (Pb), cadmium (Cd), nickel (Ni), copper (Cu) and iron (Fe) using buck scientific atomic absorption spectrophotometer (AAS) model 210 VGP. AAS was also used to determine the concentration of heavy metals in abattoir waste water effluent. Bioassay was carried out on brine shrimp (Artemia salina) for 48 hours by exposing them to waste water effluent from washing of singed hides. There was substantial high level of these heavy metals in the unsinged cattle hide. The mean concentrations of heavy metals in unsinged hides were 5.65 + 0.70, 1.93 + 0.39, 9.88 + 1.11, 10.45 + 1.20 and 1.95 + 0.12 for Pb, Cd, Fe, Cu, and Ni respectively. These values were above the maximum permissible level (MPL) of 0.01 for Pb, 0.05 for both Cd and Ni, 0.1 for Fe and but below MPL of 20 mg/kg for Cu set for heavy metals in food animals. There was noticeable increase in the concentration of Fe, Cu and Ni upon singeing by 54.25%, 9.57% and 26.14% respectively. The values increased from 9.88 + 1.11 in USH to 21.60 + 3.52 in SH (P = 0.001) and 1.95 + 0.10 in USH to 2.64 + 0.21 in SH (P = 0.007) respectively. Copper also increased by 9.57% from 10.45 + 1.20 in USH to 12.77 + 1.06 in SH (P = 0.127) but was not statistically significant. Singeing reduced the level of Pb by 22.83% from 5.65 + 0.70 in USH to 4.36 + 0.79 in SH (P = 0.353) which was not statistically significant. The value gotten in the singed hides was also above the MPL. The sequence of decrease was thus Cd > Fe > Cu > Ni > Pb. The mean concentration of Cd was also decreased by 23.32% from 1.93 + 0.39 in USH to 1.48 + 0.28 in SH (P = 0.068). This was also not statistically significant. The reduction in the values of Fe by 61.7% from 21.60 + 3.52 in SH to 8.27 + 0.66 in SWH (p = 0.007) and Cu by 52.4% from 12.77 + 1.06 in SH to 6.08 + 0.56 in SWH (p = 0.002) was statistically significant, while the reduction in the mean concentration of Pb by 4.8% from 4.36 + 0.79 in SH to 4.15+ 0.35 in SWH was not significant (p = 0.87). The mean concentration of Cd reduced by 69.6% from 1.48 + 0.28 in SH to 0.45 + 0.07 in SWH (p = 0.105); this reduction was not statistically significant. For Ni, the mean concentration reduced by 15.2% from 2.64 + 0.21 in SH to 2.24 + 0.23 in SWH (p = 0.258) and this reduction was not statistically significant. Statistical analysis revealed positive correlation between nickel, cadmium, copper and lead in USH while singed treatment of hides produced a positive correlation between copper, nickel and iron. The results of the effect of brine shrimp lethality test of waste water showed that the LC 50 was 7316 ppm at 95% confidence interval. Finney Probit analysis using SPSS gave LC 50 of 7316 + 2.32 ppm.The results of this study proved that the environment and singeing processes may be responsible for the heavy metal contamination of hides in Nsukka abattoir. It also proved that the waste water from washed hides is toxic.