DNA adducts in coal miners: association with exposures to diesel engine emissions

The potential carcinogenic effects of exposure to diesel engine emissions (DEE) are of growing concern. Due to the use of diesel equipment in underground mines, DNA adducts in peripheral blood mononuclear cells have been measured using the (32)P-postlabelling technique in workers from two coal mines (A, B)in NSW, Australia, before and after a period of more intense exposure (long wall change out, LWCO). DNA adducts were readily detected in all workers. At Mine A, in the 89 participants before LWCO, no significant difference was found among the groups categorized by exposure levels. However, significantly higher concentrations of total DNA adducts were observed in the specific job categories, 'miners and loadmen', and 'machinemen, drivers and shiftmen' and in the smoking group. On comparing total DNA adducts before and after LWCO in a small number of workers, a significant increase was also found. At Mine B, before or after LWCO, the total DNA adduct levels showed no significant difference among groups categorized by exposure conditions, smoking status, job categories and job time length. However, the total DNA adducts for the 61 subjects were significantly increased (geometric means) from 297 to 389 amol lg(-1) DNA after LWCO (p < 0.0001, paired t test). Some individual adducts were also elevated to a greater extent (p < 0.05, paired non-parametric test, Wilcoxon signed rank test). Furthermore, using generalized estimating equations for adjusting all factors across the observation period, no particular factor showed any significant interactive effects. Given the association of exposure to DEE with lung cancer and the apparent increase in adducts during a period of intense DEE exposures it would be prudent to pay particular attention to keeping exposures as low as possible, especially during LWCO operations.