Total body burden arising from a week's repeated dermal exposure to N,N-dimethylformamide

Background: Hazardous chemicals and their metabolites may accumulate in the body following repeated airborne exposures and skin contact. Aims: To estimate the contribution of skin absorption to total body burden of N, N-dimethylformamide (DMF) across a working week in two groups with similar levels of respiratory exposure but dissimilar skin contact. Methods: Twenty five workers in a synthetic leather (SL) factory, 20 in a copper laminate circuit board (CLCB) factory, and 20 age and sex matched non-DMF exposed subjects, were recruited. Environmental monitoring of DMF exposure via respiratory and dermal routes, as well as biological monitoring of preshift urinary N-methylformamide (U-NMF), were performed for five consecutive working days. Results: Environmental and biological monitoring showed no detectable exposure in controls. The average airborne DMF concentration ( geometric mean ( GM) 3.98 ppm, geometric standard deviation (GSD) 1.91 ppm), was insignificantly lower for SL workers than for CLCB workers ( GM 4.49, GSD 1.84 ppm). Dermal DMF exposure and U-NMF values, however, were significantly higher for SL workers. A significant pattern of linear accumulation was found across a five day work cycle for SL workers but not for CLCB workers. Conclusions: Dermal exposure to DMF over five consecutive days of occupational exposure can result in the accumulation of a significant DMF body burden. The long term exposure response under both repeated and intermittent conditions of substantial skin exposure is worthy of note.