An 11-year study of the incidence of brain cancer at jet engine manufacturer Pratt & Whitney in the state ended Thursday with university researchers saying they found no statistically significant elevations in the rate of cancer among workers.
Researchers at the University of Pittsburgh and the University of Illinois at Chicago said they identified 723 workers diagnosed with tumors between 1976 and 2004 at the United Technologies Corp. subsidiary. The tumors were malignant, benign or unspecified and included 277 cases of brain cancer.
Researchers examined records such as work documents and cancer registries of 222,123 men and women who worked in one or more of eight Connecticut Pratt & Whitney plants between 1952 and 2001. They also reviewed 11 chemical or physical agents on the basis of known or suspected carcinogenic potential that could affect the central nervous system or other organs.
The $12 million study, commissioned by Pratt & Whitney, was overseen by the state Department of Public Health. William Gerrish, a spokesman for the state agency, called it a "comprehensive study that has met its goals," and the project's principal researcher said the results were positive.
"The news is good," said Gary Marsh, the University of Pittsburgh researcher who led the study.
Employees can be reassured that working at Pratt & Whitney before 2002, the start of the study period, "does not increase your risk of developing brain cancer and does not increase your risk of dying," Marsh said.
The son of a Pratt & Whitney worker who died at age 46 was not so certain, though.
"It leaves a lot of questions unanswered," said Todd Atcherson, whose father, Charles Atcherson, died in 1998 after working at Pratt & Whitney for about 25 years.
Workers and the union expressed concerns about several workers who died of brain cancer within a few years of each other and the study became too large, "losing sight" of individuals, he said.
Paul Dickes, chief health and safety representative at the Machinists union, which represents Pratt & Whitney workers, said he's reassured that the study determined it's safe to work at the two remaining Connecticut plants.
"It doesn't bring closure to people who had illnesses," he said. "I'm disappointed it doesn't resolve those issues."
Pratt & Whitney spokesman Ray Hernandez said: "We are pleased that employees have answers to their questions and there is no correlation between cancer and the workplace."
Comparisons among Pratt & Whitney plants showed a slightly higher incidence of tumors and cancer among workers at the North Haven plant, the researchers said. But further evaluation found no association with estimated workplace exposures.
The slightly elevated cancer rates at the North Haven plant may reflect external occupational factors that researchers did not measure such as other companies where employees worked or factors unique to North Haven, Marsh said.
The study is one of the largest and most comprehensive in an occupational setting, he said. It also is the first large-scale study of workers in the jet engine manufacturing industry.
The results echo what was released in the first stage of the three-stage study in 2008. The researchers said then they did not find statistically significant excesses in deaths from malignant brain tumors among North Haven workers.
Workers and their families, joined by the Machinists union, pushed for the study after widows and union officials said they were concerned with what appeared to be numerous and similar deaths at Pratt & Whitney plants.