Incidence of dimethylacetamide induced hepatic injury among new employees in a cohort of elastane fibre workers.

OBJECTIVE

To investigate the incidence of N,N-dimethylacetamide (DMA) induced hepatic injury among new elastane fibre workers and to explore factors relating to DMA induced hepatic injury.

METHODS

Elastane fibre workers exposed to DMA were monitored for hepatic injury. Four hundred and forty new workers employed from 1 January 2002 to 31 July 2004 were included as study subjects. DMA exposure estimates were based on urinary N-methylacetamide (NMA) concentrations.

RESULTS

There were 28 cases of DMA induced hepatic injury. The overall incidence of DMA induced hepatic injury among new elastane fibre workers was 0.089/person-year. Incidence rates were 7-10 times higher in high exposure groups than in low exposure groups. Fewer DMA induced hepatic injuries occurred among workers employed for a longer period. Workers whose exposure duration was more than seven months showed no hepatic injury in either the high or low exposure groups. Exposure category and duration of employment were significant variables in the multiple logistic regression analysis.

CONCLUSIONS

Results suggest the existence of dose dependent DMA induced hepatic injury. The inverse relation between the incidence of DMA induced hepatic injury and duration of employment may reflect a type of healthy survivor effect or tolerance to DMA induced hepatic injury.