Introduction N-N-dimethylformamide (DMF) which could induce to liver toxicity was the most common chemicals attributing 27.3% of the intoxication accidents of which 33% involved the migrant workers at workplace. Occupational health studies of the migrant workers at risk of exposure to DMF are rare despite their social vulnerabilities due to the lack of information owing to the deficiencies in the national monitoring system.

Objectives The aim of this study is to assess the urine concentration of N-methylformamide, a biological monitoring index (BEI) of DMF, among the migrant workers at risk of exposure to DMF by comparing with the native workers in manufacturing industry.

Methods This cross-sectional study was designed to target employees aged 20 and more, who were eligible to participate in the special health examination for DMF exposure in 2014–2019. Data were obtained from the workers’ special health examination (WSHE) and Work Environment Measurement (WEM) database of 2014–2019, managed by the KOSHA. We assessed the fundamental characteristics known to affect DMF exposure and its metabolism in human body including demographics (sex, age), companies where the subjects are employed (number of workers, types of industries), and DMF exposure factor (Time weighted average(TWA), years of employment). The Mann-Whitney U test and Pearson’s chi-squared test were used to compare the baseline characteristics between the native and migrant workers.

Results 60.6% of the migrant workers exposed to DMF were employed in small and medium sized company, while 19.6% of the native workers were. 21.6% of the migrant workers were exposed to TWA of DMF exceeding Threshold Limit Values, which significantly high compared with the native workers (6.3%). The mean concentration of urine N-methylformamide in the migrant workers (1.37 mg/L) was significantly higher than in the native workers (0.47 mg/L, p < 0 .001).

Conclusions The migrant workers at risk of DMF exposure in manufacture industries were in highly vulnerable environment at workplace.