Estimation of risk of developing bladder cancer among workers exposed to coal tar pitch volatiles in the primary aluminum industry

Abstract

To confirm the relationship between exposure to coal tar pitch volatiles and bladder cancer among primary aluminum production workers, we carried out a case-control study among blue-collar workers who had worked more than 1 year between 1950-1979 in a major plant using mostly the Soderberg process in the Province of Québec. Cases of bladder cancer (ICD code 188) diagnosed between 1970-1979 (n = 69) were mostly included in a previously reported study. To these were added cases diagnosed between 1980-1988 (n = 69). Each case was matched to three controls on date of birth, date of hiring, and length of service at the company. Smoking habits were assessed from the medical records at the company. Benzene-soluble matter (BSM) and benzo(a)pyrene (BaP) were used as indicators of environmental exposure to coal tar pitch volatiles in the workplace. The estimated risk for current smokers was 2.63 (95% C.I. 1.29-5.37). Estimates of risk by occupational exposure were adjusted for smoking. Men who had worked in the Soderberg potrooms were at higher risk of developing the disease, the risk increasing with the time spent in these departments. Similarly, a strong association between risk and cumulative exposure to BSM or to BaP was observed. The risks associated with cumulative exposure to BSM (mg/m3-years) and to BaP (microgram/m3-years) were described with mathematical models. Using a linear model (1 + bx) and lagging 10 years before the diagnosis, BaP cumulative exposure was a better indicator of risk than BSM cumulative exposure. The risk for each year of exposure to BaP at a concentration of 1 microgram/m3 increased by 1.7% (0.8%-3.2%). Using the same model for BSM, a worker exposed to the current threshold limit value of 0.2 mg/m3 for 40 years will sustain a risk of 2.22 (1.56-3.48). Comparison of risks according to different periods of diagnosis (1970-1979 vs. 1980-1988) did not reveal any significant temporal changes on risk estimates.

Long-term follow-up study of mortality and the incidence of cancer in a cohort of workers at a primary aluminum smelter in Sweden

“…Unlike most studies in the aluminum industry, we did not find an association between bladder cancer and work in the aluminum industry (8,(16)(17)(18)(19). Perhaps the absence of any association is due to smoking, which implies that the real risk of lung cancer would be higher than observed in our study if we had been able to control for smoking.…”

“…Friesen et al (14) found a moderate association between exposure to PAH and acute myocardial infarction for aluminum smelter workers. As regards the incidence of cancer, the most consistent finding in previous studies has been an increased incidence of bladder cancer (8,(14)(15)(16)(17)(18)(19)(20). Cancer of the lungs (11,14,17,21,22) , pancreas (18), kidneys (15,17,18), lymphoma (17), stomach (17), and brain (23) has also been found to be associated with workers in aluminum plants, but these findings are less consistent.…”

Integrating Field Analyses with Laboratory Exposures to Assess Ecosystems Health

“…Tobacco smoking did not confound the relationship. Tremblay et al (1995) expanded the previous study and included 138 cases of bladder cancer, 66 cases of the previous study, 69 cases diagnosed between 1980 to 1988 and three additional cases diagnosed before 1980. Three matched controls were taken from the previous studies or selected from a subcohort of 1138 men enumerated by Armstrong et al (1994, see below) drawn mainly from the same subcohort.…”

Cancer in belugas from the St. Lawrence estuary.

“…Further support for PAH carcinogenicity in humans has been provided by epidemiologic studies such as those carried out in aluminum workers of the Saguenay-Lac Saint-Jean region of Canada (6)(7)(8). In these studies, the epidemiologic association between exposure to PAHs and lung and urinary bladder cancers has been strong enough to warrant the compensation of affected workers by the Quebec Health and safety Workers Compensation Board (6)(7)(8).…”

“…In these studies, the epidemiologic association between exposure to PAHs and lung and urinary bladder cancers has been strong enough to warrant the compensation of affected workers by the Quebec Health and safety Workers Compensation Board (6)(7)(8).…”