HUMAN HEALTH RISK ASSESSMENT OF HEAVY METALS IN FOODSTUFFS PROCESSED WITH DIESEL POWERED METALLIC DISC GRINDERS IN UMUAHIA, NIGERIA

Authors

  • J. C. Nnaji
  • B. I. Iweha
  • I. Ogbuewu

Abstract

This study determined the effect of locally fabricated, diesel powered metallic disc grinding machines on metal concentrations in foodstuffs. Five heavy metals (Pb, Fe, Cr, Cd, Ni) were analysed in beans (Vigna angularis), maize (Zea mays), wheat (Triticum aestivum), soybean (Glycine max L) and bambara nut (Voandzeia subteranean). Samples of these foodstuffs were purchased from the three major local markets in Umuahia (Orie Ugba, Ubakala and Ubani) and were each divided into two parts; one part was pulverized with wooden mortar and pestle and served as the control while the other part was pulverized using a metallic grinding machine. The samples (wooden mortar samples, WMS and metal mill samples, MMS) were digested in triplicates with concentrated HNO3 and analyzed for metals using Flame Atomic Absorption Spectrophotometry (FAAS). The result showed enrichment of the foodstuff samples with the metals from the use of the metallic grinders for milling since metal concentrations were higher in all metallic milled samples (MMS) than the wooden mortar samples (WMS). Cd was not detected in all the samples while Ni was detected only in bambara nut, soybean and wheat with mean concentrations of 2.27±1.14, 2.19±0.78 and 1.86±2.32 mg/kg respectively. Cr was below detection limit in wheat but the highest mean Cr concentration was detected in bambara nut (11.26±9.06 mg/kg) and the lowest in soybean (7.54±6.119 mg/kg). Mean Pb concentrations in soybean was significantly higher (P<0.05) than concentrations in other foodstuffs and mean values for all foodstuffs were considerably higher than the WHO/FAO limit of 0.2 mg/kg. Fe concentrations ranged from 405.542±135.919 in maize to 646.67±282.840 mg/kg in soybean. Mean Fe concentrations in the foodstuffs followed the profile soybean>wheat>beans>maize>bambara nut; mean Pb had the profile soybean>bambara nut>beans>maize>wheat, mean Cr had the profile bambara nut>maize>beans>>soybean while mean Ni concentrations followed the order bambara nut>soybean>wheat. The estimated daily intake (EDI) values for the individual heavy metals in each foodstuff were all below the respective reference oral dose (RfD) values. The health risk indices (HRI) for Cr and Pb in beans, maize, bambara nut and soybean were all >1 while that of Fe in soybean was also >1 indicating that the consuming population in Umuahia may be exposed to health risks arising from the consumption of these foodstuffs which are ground in the markets with metallic disc grinders. The hazard index (HI) for beans and wheat were >1 indicating the possibility of non-carcinogenic human health hazards arising from their consumption after milling with the metallic disc grinders. Target carcinogenic risk (TCR) were within the acceptable range (10−6 – 10−4) for cancer risk but the cumulative TCR values were above 10-4 in all the foodstuffs. Keywords: Foodstuffs, grinders, metals, hazard quotient, carcinogenic risk

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Published

2020-05-23