Researchers have found evidence suggesting that men who work in microelectronics and business machine facilities may have an increased risk of dying from certain cancers, including non-Hodgkin lymphoma (NHL).
Their study, published in the American Journal of Industrial Medicine, was designed to assess the effects chemical exposure might have on the incidence of diseases and worker mortality.
The results showed that hourly male workers, who were more likely than other employees to be exposed to the chemicals studied, had a 1.5-fold increased risk of death from NHL.
However, the investigators did not observe a significant relationship between NHL and any of the chemicals studied.
This research originated from concerns about the release of trichloroethylene (TCE), perchlorethylene (PCE), and other industrial chemicals through groundwater and air emissions from several industrial facilities in a town in upstate New York.
Previous studies suggested the chemicals were associated with increases in the incidence of kidney, lung, and testicular cancer in the community. So researchers initiated a study of current and former workers of the local microelectronics and business machine facility.
Patient population
Sharon R. Silver, of the National Institute for Occupational Safety and Health in Cincinnati, Ohio, and her colleagues examined health outcomes among 34,494 former workers employed at the facility for at least 91 days between 1969 and 2001.
Machining workers were exposed to dust, noise, solvents, and metals. And “wet” process workers were exposed to chemical solutions used in manufacturing circuit boards and their substrates. The facility also had employees in non-production roles, including sales and office support, as well as computer programming.
The researchers evaluated the relationship between health outcomes and the estimated cumulative extent of potential chemical exposures, stratified according to gender and pay code.
Of the 34,494 workers, 69.7% were male. Among males, 15,447 were hourly workers, and 8590 were salaried. Among females, 8934 were hourly workers, and 1523 were salaried.
Chemical exposure
A previous study of this population revealed the use of 6 chemical agents (fiberglass, lead, methylene chloride, methyl chloroform, PCE, and TCE), 6 chemical classes (acid-base, aromatic hydrocarbons, chlorinated hydrocarbons, other hydrocarbons, chlorofluorocarbons, and metals), and general chemicals (including unspecified).
The potential for exposure to a chemical agent or class was much more common among hourly workers than salaried workers. Among males, 65.7% of hourly workers and 20% of salaried workers were exposed to at least 1 of the chemicals studied. Among females, exposure rates were 58.5% and 13.9%, respectively.
“Other hydrocarbons” was the chemical class that male hourly workers were potentially exposed to most often (60.5%). At least one-third of workers in this group had potential exposure to chlorinated hydrocarbons, lead, and acids and bases. TCE and PCE were the least common exposure agents among male hourly workers, with 13.9% and 15.1% exposed, respectively.
Cancer mortality, incidence
The investigators used mortality rates from the US population, as well as New York State (excluding New York City), to calculate the number of expected deaths among study participants. The standardized mortality ratio (SMR) is the ratio of observed to expected deaths.
The average follow-up was 25.7 years. By the study end date, 5966 workers (17.3%) had died. Workers employed less than a year at the facility (n=8397) comprised 363 of these deaths.
Both all-cause mortality (SMR=0.67) and all-cancer mortality (SMR=0.74) showed a statistically significant deficit for the entire workforce. Most of the individual cancers and other conditions studied were not associated with an increased risk of death.
There were significant increases in death for certain cancers among males, but there was no significant increase in a specific cause of death among females belonging to either pay code.
There was an increased risk of death from NHL among male hourly workers but not salaried workers, with SMRs of 1.49 and 0.68, respectively. The same pattern occurred for rectal cancer, with SMRs of 1.71 and 0.71, respectively.
The study also revealed an elevated incidence of pleural cancers in salaried males, mesothelioma in hourly workers, and testicular cancer in salaried males.
The increase in mesothelioma and pleural cancers was seen only in workers hired before 1969, which would support a link between the cancers and asbestos exposure. However, the researchers could find no evidence that asbestos was used in manufacturing at the facility.
Similarly, the investigators found no significant link between exposure to specific chemicals and the increased mortality from NHL or rectal cancer. And there was no significant link between exposure and testicular cancer.
Although these results do not suggest a strong role for occupational chemical exposures in cancer incidence and mortality, the researchers said risks from occupational exposures cannot be ruled out due to limitations of this study and the relative youth of this patient cohort.
