Health risk assessment of inhalational exposure to heavy metals in drivers working in an urban desert city in the Middle East

Heavy metals are threatening the lives of people around the world. This study aims to quantify the adverse health risks of seven heavy metals, including arsenic, cadmium, cobalt, chromium, lead, manganese, and nickel in taxi drivers in an urban desert city, Yazd, Iran. The exposure concentrations were determined through air sampling in the breathing zone of 40 randomly selected intercity taxi drivers, 20 in winter and 20 in summer, in 2019. An ICP-MAS spectrometer was applied to measure the elements. Target hazard quotient (THQ) and excessive cancer risk (ECR) indices were applied to calculate the non-cancer and cancer risks based on the United States Environmental Protection Agency (USEPA) guidelines, respectively. The results showed that arsenic and lead had the highest exposure concentrations among the seven measured heavy metals while cobalt and chromium metals had the lowest concentrations. Arsenic, cadmium, manganese, and nickel would probably cause some adverse non-carcinogenic health problems (THQ > 1) in the drivers over their working life. The percentile 95% ECR of measured heavy metals was 1.3E - 03 in total, which is much higher than the value of 1E - 06. The concentration of arsenic and nickel was higher in winter than in summer. Taxi drivers in Yazd city are at considerable health risk; therefore, swift and serious controlling measures should be taken by responsible authorities. Besides, the taxi drivers should be educated about heavy metals' health effects and their protective behaviors.