Evaluation of heavy metals in some locally produced food seasonings in Katsina State Nigeria

This study was conducted to determine the heavy metals concentration in seeds used as raw materials in producing local food seasonings (Locust bean, Soya beans and seed of Hibiscus subdariffa) and the produced local seasonings (Daddawar Kalwa, Daddawar waken Soya and Daddawar Botso) in Katsina state Nigeria. The objectives were mainly to detect the presence of heavy metals in some local seeds used in the preparation of local seasonings and their processed products used in food seasoning in the study area, compare the effect of processing on concentration of heavy metals in samples in relation to the permissible limits specified by WHO/FAO/USEPA Standards. Samples of seeds used in local processing of food seasonings were collected in the year 2017 from the selected area. Analysis for the concentration of these heavy metals; Cr, Cd, Fe, Ni, Mn, Pb and Zn was conducted by the use of AAS (by Atomic Absorption Spetrophotometry) method. The difference between concentrations of heavy metals in unprocessed and processed seed samples was performed by the use of T-test statistical analysis. Results from this study has shown that concentration values of Cu, Cr, Cd, Fe, Ni, Mn and Zn in the samples were generally lower than the USEPA, WHO/FAO maximum permissive limits. The results have indicated that the estimated daily intake of the heavy metals were lower than the tolerable daily intake limit set by the USEPA (2013) in both samples and the health risk index (HRI) for all the heavy metals were <1. The target hazard quotient (THQ) for the samples was in the decreasing order Cd>Pb>Mn>Fe>Ni>Zn>Cr, with the heavy metal Cd having a value of more than 1 which is a cause for concern. Key words: Soya beans, Heavy metals, Katsina, seasonings, locust beans