**8. Conclusions**

Heavy metals enter the human body through a variety of routes, including drinking water, air, food, and, on rare occasions, dermal exposure. Following absorption, heavy metals are retained and accumulate in the human body. When the research findings are compared to WHO standards, it indicates that the level of contamination in the Romi river with some heavy metal concentrations such as (Iron 0.89 mg/L and Nickel 0.36 mg/L) has exceeded the WHO maximum standard limits (Nickel 0.02 mg/ L and 0.030 mg/L). The mean concentrations of the metals: Chromium, Iron, Nickel, and Zinc with the standard deviation was found to be:<0*:*01 � 0*:*1 *mg=L*, 0*:*89 � 0*:*1 mg*=*L, 0*:*06 � 0*:*1 mg*=*L, and0*:*20 � 0*:*1 mg*=*L. This study found that the mean concentrations of chromium and zinc were lower than the World Health Organization's acceptable limits, while the higher concentration values of nickel were higher 0ð Þ *:*06 � 0*:*01 mg*=*kg and iron 0ð Þ *:*89 � 0*:*01 mg*=*kg was discovered to be

*Environmental Impact of Heavy Metals DOI: http://dx.doi.org/10.5772/intechopen.108973*

greater than the WHO standard acceptable limits for heavy metals. This contamination is attributed to the Kaduna Petrochemical and Refining Company's effluent discharge into the river.
