Heavy Metal Health Risk Assessment in Sediments of Western and southwestern rivers of Urmia Lake

Urmia Lake, with more than 51,000 Km2 area​​, is one of 6 main Iran’s catchments. Nazluchai, Shaharchai, Bazandozchai, Gadarchi, Mahabadchai and Siminehroud located in west and southwest of Urmia Lake are among the most important rivers supplying the lake. This study aims to evaluate heavy metals health risk including cadmium, lead, nickel, cobalt, arsenic and chromium in surface sediments of western and southwestern rivers of Urmia Lake, for which 22 sediment samples from depth of 0-10 cm was randomly taken and after analyzing by ICP-OES method, non-carcinogenic risk for all studied elements and carcinogenic risk for elements with definite carcinogenicity (cadmium, nickel and chromium) were calculated. According to results, the highest concentrations of nickel, cobalt and chromium were recorded in Baranduzchai and Gadarchai, the highest arsenic concentration was recorded in delta and downstream of Nazluchai and Mahabadchai and the highest cadmium concentration was recorded in Nazluchai delta and downstream of Siminehrood. In mentioned cases, heavy metals concentration is much more than the other parts. Average daily doses of studied heavy metals for children and adults were measured as follows: cadmium <lead <arsenic <cobalt <chromium <nickel. Results also showed that the highest non-carcinogenic risk for children was related to cobalt, chromium and nickel, respectively, while non-carcinogenic risk of cobalt (0.51) and chromium (0.215) is close to the threshold. The overall risk (HI) of all studied heavy metals for children is also close to threshold. Total risk of chromium and cobalt is close to the threshold in 5 and 4 samples, respectively, and in only one sample located in downstream of Baranduzchai, total risk of cobalt has exceeded threshold value. Carcinogenic risk of cadmium and nickel in studied samples does not threaten human health, while carcinogenic risk of chromium is close to threshold and consequently total carcinogenicity risk is close to threshold.