ASSESSMENT OF SOME TOXIC HEAVY METALS IN RICE AND BEANS SOLD IN BENIN CITY, NIGERIA

ABSTRACT

Determination of the level of some heavy metals in varieties of rice and beans samples obtained

from an open market in Benin city was studied, collection and preparation were carried out

using atomic absorption spectrophotometer (A.A.S). According to the analysis of the bean and rice samples in this study, the levels of heavy metals ranged from 0.013–0.067 mg/kg for Pb, 0.02-0.043 mg/kg for Cr, 0.003-0.367 mg/kg for Mn, 0.263–1.017 mg/kg for Zn, 0.30–0.933 mg/kg for Fe, and 0.01–0.023 mg/kg for Cu, with Cd being the only metal below the detection limit. Statistical analysis using a T-test showed that there was no significant difference between the levels of the selected heavy metals analysed among the bean samples and those analysed among the rice samples. If these heavy metals are used as benchmarks for measuring the product's quality, local rice would be considered to be of higher quality than foreign rice, according to statistical analysis using a correlation matrix that showed a nearly identical heavy metal composition between local and foreign rice. The concentration of all the metals studied was observed to be present at tolerable levels lower than the maximum permissible limit as given by the World Health Organisation (WHO). Based on the research findings, the rice and bean samples studied are safe for human consumption.