The primary exposure is to polycyclic aromatic hydrocarbons (PAHs). A Group 1 carcinogen: cancer of the bladder and lung; [Reference #1] "Bladder cancer incidence was not increased at B(a)P exposures below 40 ug/m3-yr." [Reference #2] Lower coal tar pitch volatile (CTPV) exposure occurs in prebake potrooms. "The initial epidemiologic studies of aluminum workers that reported evidence of increased risk of bladder cancer in the work-force were predominantly conducted in Soderberg smelters where exposure to CTPV was historically high. Recent follow-up studies of these worker cohorts have shown a significant reduction in the risk of bladder cancer." [
PMID 25525927] "These evaluations were typically produced at a time when the available data provided a clear indication of increased cancer risk in an occupational group, but not enough information to identify a causal agent. While such broadly defined carcinogenic agents can lead to general industrial hygiene interventions, provide support to compensate exposed workers and stimulate research to identify specific causes, they have limited utility for informing specific prevention activities and may be affected by changes in process, materials and exposure levels over time." [
PMID 29769352] See the process "Aluminum Producing."