Inhalational exposure to heavy metals: Carcinogenic and non-carcinogenic risk assessment

Occupational exposure to heavy metals (HMs) in various activities might pose a severe risk to human health. A systematic review was undertaken to gather relevant studies on occupational exposure to HMs in various professions without time limitation and included all studies up to February 5, 2023. This study aimed to identify workplaces exposed to HMs, examine HM concentrations in different occupations, and assess the carcinogenic (CR) and non-carcinogenic (HQ) risks of inhalational exposure to these chemicals among employees. A systematic search in the Scopus, Web of Science, and PubMed databases using standard keywords yielded 423 studies, 17 of which were included in the analysis. The present review included studies that met the requirements of the Population, Exposure, Comparator, and Outcomes (PECO) criteria. The results indicated that the mean concentrations of HM in occupational environments were lower than the National Institute for Occupational Safety and Health (NIOSH) thresholds. In the reviewed studies, the unacceptable CR values were related to work environments such as temples, tobacco cafés, barbeque restaurants, and subways. Cr showed the highest contribution to the CR, followed by Cd > As > Co > Ni > Pb. Also, HQ values in activities related to the subway stations, surgical instrument production industries, and workplaces studied in Alexandropolis were higher than the acceptable level of 1. The most significant HQ values were associated with Ni. Therefore, according to the HQ and CR calculated, which were higher than the permissible values (1 for HQ and 1 × 10^–6 to 1 × 10^–4 for cancer risks) in the investigated jobs, biomonitoring of HMs in the body of employees is recommended.