Biological monitoring of workers exposed to dimethylformamide in a textile polyurethane unit

Dimethylformamide (DMF) is a universal solvent noted for its solubility in both aqueous and lipid media. It is hepatotoxic, and there are concerns about its carcinogenicity. Our objective was to determine the correlation between air monitoring measurements and biological measurements of a suitable metabolite of DMF in a cohort of operatives in a polyurethane production unit. This was done with a view to assessing how much the inhalation route contributed to total DMF exposure, mainly for control purposes. We investigated the relationship between personal air sample measurements of DMF and biological measurements of N-methylformamide (NMF) in nine adult subjects, recruited across the shifts, with varying levels of exposure to DMF. Personal exposure monitoring was carried out with a low-flow-rate Model 222-4 SKC pump, while post-shift urine samples were obtained for further analysis. Operatives were asked to abstain from consuming alcohol for 24 h before the designated shift, as advised by the laboratory responsible for the analysis of urine samples. We found a very strong statistical association between air sample measurements of DMF and NMF in the urine of the sample population (R(2) = 0.95, P < 0.0001). This study suggests that airborne exposure contributes significantly to elevated levels of NMF and, therefore, indicates that efforts should be concentrated on engineering controls in reducing workplace DMF exposure.