Inhalational exposure to formaldehyde, carcinogenic, and non-carcinogenic risk assessment: A systematic review

Formaldehyde is one of the most widely used substances in a variety of industries, although it was classified as a human carcinogen by the International Agency for Research on Cancer (IARC). The present systematic review was conducted to retrieve studies related to occupational exposure to formaldehyde until November 2, 2022. Aims of the study were to identify workplaces exposed to formaldehyde, to investigate the formaldehyde concentrations in various occupations and to evaluate carcinogenic and non-carcinogenic risks caused by respiratory exposure to this chemical among workers. A systematic search was done in Scopus, PubMed and Web of Science databases to find the studies done in this field. In this review, studies that did not meet the criteria specified by Population, Exposure, Comparator, and Outcomes (PECO) approach were excluded. In addition, the inclusion of studies dealing with the biological monitoring of FA in the body and review studies, conference articles, books, and letters to the editors were avoided. The quality of the selected studies was also evaluated using the Joanna Briggs Institute (JBI) checklist for analytic-cross-sectional studies. Finally, 828 studies were found, and after the investigations, 35 articles were included in this study. The results revealed that the highest formaldehyde concentrations were observed in waterpipe cafes (1,620,000 μg/m3) and anatomy and pathology laboratories (4237.5 μg/m3). Carcinogenic and non-carcinogenic risk indicated the potential health effects for employees due to respiratory exposure as acceptable levels of CR = 1.00 × 10-4 and HQ = 1, respectively were reported to be exceeded in more than 71% and 28.57% of the investigated studies. Therefore, according to the confirmation of formaldehyde's adverse health effects, it is necessary to adopt targeted strategies to reduce or eliminate exposure to this compound from the occupational usage.