Evaluation of Pollution and Carcinogenic Risk of Heavy Metals in Agricultural Soil, Wheat and Flour in Bijar City

The purpose of this study was to investigate the level of pollution and concentration of heavy metals in agricultural soil, wheat and flour and to evaluate the consequent health risks in the residents of Bijar city in 2021.

To determine the total content of heavy metals, after acid digestion, the dry soil samples were converted into powder and prepared according to the steps of acid digestion for reading by graphite furnace atomic absorption spectrometry (GFAAS). Extraction from the samples was also done by acid digestion method. In the flour sample, direct acid digestion was done. For non-carcinogenic risk assessment studies, two routes including direct consumption (ingestion) and dermal absorption of heavy metals were considered. To calculate carcinogenic and non-carcinogenic risks, we considered heavy metals including cadmium, lead, zinc and arsenic.

The concentrations of heavy metals studied in the soil, wheat and flour samples of four regions were similar to one another and no significant differences were observed. The results of the risk assessment showed that the soil samples of all four studied areas were in class III (moderate risk) in regard to the carcinogenic risk of arsenic. Also, the soil samples of all four regions showed a low cancer risk in relation to cadmium. All other samples showed a low risk less than 10-6. In all of the samples of flour, wheat and soil from the four regions, we found no risk higher than 10-4 and, thus they were considered safe.

The results of this study showed non-carcinogenic risk in relation to zinc, lead, arsenic, and cadmium based on the results of examined samples, but the concentration of some of these metals, such as arsenic, is close to the risk level for the vulnerable populations such as children, and appropriate measures should be taken to evaluate and reduce these heavy metals concentrations.