A long-awaited study of almost 225,000 Pratt & Whitney workers from the 1950s to the early 2000s found a slightly higher rate of brain cancer among workers at a former North Haven plant than for the Connecticut population as a whole.
But the study, conducted by researchers at the University of Pittsburgh, says the higher rate is "not statistically significant" and could have been caused by factors not related to the plant. Two additional studies expected by 2010 will try to determine causes for the cancers.
Cancer-related deaths among all Pratt employees who worked at eight current and former Pratt facilities in Connecticut from 1952 to 2001 occurred at the same or lower rates than for the United States and for Connecticut, according to the study.
Begun in response to concerns about a potential cancer cluster at the North Haven plant, this first of the studies is scheduled for publication next month in the Journal of Occupational and Environmental Medicine. The study began in 2002.
Pratt, a unit of United Technologies Corp., will pay a total of $12 million for the three studies.
East Hartford-based Pratt said it is "encouraged" by the findings.
"We're encouraged that the data available today indicates that there's no clear association between the Pratt & Whitney workplace and brain cancer," company spokeswoman Jennifer Whitlow said Thursday, after the findings were made public.
The study found that Pratt employees who worked exclusively at the North Haven plant died of brain cancer at a rate 11 percent higher than would be expected in the broader population.
Gary Marsh, the University of Pittsburgh bio-statistician who led the study, said 25 percent was the threshold applied for statistical significance.
"Chance could still be an explanation," he said after presenting the findings to the press and a small group of worker representatives, including some family members, at a Rocky Hill hotel.
Of all the workers at all plants, 606 died of a central nervous system tumor, either malignant or benign, according to the study. This yielded a rate that was 15 percent lower than for the U.S. population and 16 percent lower than for the Connecticut population, researchers reported.
The studies were prompted in 2000 by a state Department of Public Health investigation of a suspected brain cancer cluster at the North Haven plant, which is now closed. The widows of two former North Haven workers who died of a rare form of brain cancer waged a passionate public campaign that led to the health department's investigation.
The study also found slightly higher rates of kidney cancer and non-cancerous respiratory disease that were statistically significant among Pratt employees who had worked exclusively at North Haven. And when workers at all eight Pratt plants were considered, researchers found elevated rates of bronchitis among hourly workers.
But the study reported that the elevated rates of kidney cancer, bronchitis and non-malignant respiratory disease could have been due to factors not related to work.
Researchers presented the findings to a small group of company, worker and state representatives Wednesday night and Pratt disclosed them to workers at its three remaining Connecticut facilities - in East Hartford, Middletown and Cheshire - midday Thursday. Researchers first disclosed the findings in public Thursday night.
Carol Shea, whose husband, John, died of a rare form of brain cancer in 2000 after working for Pratt for more than 30 years, said she found little satisfaction or comfort in the results.
"We're still trying to find out what happened to them," she said.
Researchers established causes of death for 65,272 former Pratt workers, or 95 percent of the 223,894 men and women who worked in one of eight Connecticut jet engine factories for at least one day between January 1952 and December 2001 and who had died by 2004. The factories are or were in East Hartford, Middletown, Cheshire, North Haven, Rocky Hill, Manchester and two in Southington.
The families of about 90 Pratt workers diagnosed with brain tumors, or workers themselves, have pending worker's compensation claims against the company with the state.