Workers at a fiberglass manufacturing plant in Ontario were exposed to higher than normal risks of lung cancer during the 1950s and 1970s, a new study suggests.
Lead researcher Harry Shannon of McMas…
Workers at a fiberglass manufacturing plant in Ontario were exposed to higher than normal risks of lung cancer during the 1950s and 1970s, a new study suggests. Lead researcher Harry Shannon of McMaster University in Hamilton, Ontario observed 42 fatal lung cancer cases in plant-only workers, a figure above the expected number of 26 deaths identified by Statistics Canada in the general population for the period. The study examined 2,557 men who worked at Fibreglass Canada in Sarnia, Ontario for at least 90 days between 1955 and 1977. The individuals included plant-only workers, office-only workers, and employees who worked in both environments at the plant, which operated from 1948 and 1991. Thirty-one of the 42 deaths involved individuals who first started working at the plant before 1960. “We don“t know a lot about what was going on in the “50s, which is probably the period of most concern in this particular project,” says Shannon, whose study appears in the current issue of Occupational Medicine. The high mortality for lung cancer is of greater concern because of what Shannon calls the “healthy work effect”, i.e. that the working population is generally somewhat healthier than the general population. The study uses a standardized mortality ratio (SMR), with 100 indicating the expected number of deaths. Lung cancer for plant-only workers showed an SMR of 163. Other agents found at the plant besides glass fibers may have played a role in the incidence of lung cancer. Although the company conducted exposure measurements for ammonia, formaldehyde, phenol, carbon monoxide and similar agents from 1977 to 1990, there was not enough data on those exposures to include in the study. “There could have been things other than the fibers that caused the increase in this particular plant,” Shannon says. “We raised the question as to whether it“s necessarily fiberglass or other contaminants in the work environment.” The concentration of fiberglass at the plant was an average of 0.03 fibres per cubic centimeter, significantly below the legal limit of 1 fiber per cubic centimeter for glass wool fibers currently in force in Ontario. John Oudyk, an occupational hygienist with the Occupational Health Clinics for Ontario Workers in Hamilton, says the International Agency for Research on Cancer considers glass fibers a grade 3 carcinogen, meaning it is not classifiable or the agency is unsure as to its carcinogenicity to humans. “If fibreglass does cause cancer, it“s not nearly as potent as something like asbestos,” he says. “So if it does, it“s not a very strong carcinogen,” Oudyk says. Glass fibers are too large in diameter to inhale and do not survive long inside the human body. The most common complaint resulting from exposure to fiberglass is skin irritation, while some people develop dermatitis from exposure to resin coated fiberglass. The study of workers at the Sarnia plant also found a higher-than-expected incidence of kidney cancer. The SMR for kidney cancer was 146. The researchers noted that the result merits further study, and it may be only a chance finding or reflect exposures to contaminants other than glass fibers.