Retrospective cohort mortality study of dry cleaner workers using perchloroethylene.

To evaluate the carcinogenic potential from occupational exposure to perchloroethylene (PCE), a retrospective cohort mortality study of workers employed in the dry cleaning industry was conducted among 1,690 workers from four labor unions. The majority of the cohort had potential exposure to petroleum solvents as well as to PCE while working in the dry cleaning industry. Mortality from primary cancer of the liver was of particular interest, due to the findings of excess liver cancer in mice exposed to PCE. Other sites of cancer were also of interest. A total of 493 deaths were observed, whereas 575.5 were expected based on US mortality rates. Mortality from all cancers combined was greater than expected (142 observed v 122.9 expected). No deaths due to liver cancer were observed. Urinary tract cancer was the only specific site where there was a statistically significant excess in observed deaths (12 observed v 4.7 expected). There was some consistency in these findings across the four individual unions and across race/sex groups. A subcohort of workers who were employed only in dry cleaning shops that used PCE as their primary solvent was identified from the union records. There was only one death from urinary tract cancer, whereas 1.3 deaths were expected in this subcohort.