Sperm function in workers exposed to N,N-dimethylformamide in the synthetic leather industry

Objective: To determine whether occupational exposure to N,N-dimethylformamide (DMF) for men has adverse effects on sperm function. Design: Cross-sectional study. Setting: A synthetic leather factory in Taiwan. Patient(s): Twelve DMF-exposed workers in a synthetic leather factory and 8 socioeconomically matched control workers from another non-DMF-exposed manufacturing plant in the vicinity were recruited. Intervention(s): None. Main Outcome Measure(s): Breathing-zone monitoring of DMF exposure covering the full work shift was implemented on each participant. Urine specimens were collected from each worker immediately after their work shift in parallel with environmental sampling. Environmental DMF and urinary N-methylformamide (NMF) levels were measured by gas chromatograph. Analysis of semen samples was performed to measure semen volume, sperm concentration, morphology, and motility in accordance with World Health Organization criteria. Result(s): Both conventional microscopy and computer-assisted semen analysis showed that sperm motility in DMF-exposed group was significantly reduced from that in controls. Motility parameters were related to urinary NMF in a dose-response manner but were not related to airborne DMF. Conclusion(s): Workers occupationally exposed to DMF could be at risk of sperm motility perturbation. The responsible toxicant for the alterations of sperm function could be the active NMF metabolite instead of DMF, but this conclusion warrants a further complete investigation.