ROCKY HILL, Conn. (AP) -- A study six years in the making of nearly 224,000 current and former workers shows that the rates of cancer deaths at jet engine manufacturer Pratt & Whitney is the same or lower than in Connecticut and the U.S., researchers said Thursday.

"We're encouraged by these findings," Pratt spokesman Jay DeFrank said. "There's no association between any health issues and our workplace."

University of Pittsburgh researchers released the results from the first phase of the massive three-phase study of former and current employees who worked at one of seven Pratt & Whitney sites in Connecticut between 1952 and 2001.

Principal researcher Gary Marsh called the first-stage findings "exploratory."

"We still are not at the point in the overall investigation to have definitive answers about health risks in these factories," he said.

Carol Shea, whose husband, John, died of brain cancer in 2000 at age 56, called the findings a start, but said she was disappointed with the study. John Shea worked at the North Haven plant for 35 years.

"I don't care what they say, I think it's significant that there are so many cases," she said.

The findings for kidney cancer, bronchitis and respiratory disease suggest a higher rate of deaths, but those deaths may have been due to causes not related to work or work outside of the company, researchers said.

The second stage of the study, commissioned by Pratt & Whitney at a cost of $12 million and overseen by the Connecticut Department of Public Health, will compare the incidence of brain cancer to types of work done by employees. The third phase will take a look at tissue samples from workers with brain cancer to compare genetic patterns with cancers in the general population. It also will compare work and non-work-related factors in brain cancer cases.

Pratt & Whitney, a subsidiary of Hartford-based United Technologies Corp., now employs about 12,000 workers in Cheshire, East Hartford and Middletown. The study has also looked at those who worked in former Pratt plants in North Haven, Rocky Hill, Southington and Manchester.

The study began in 2002 by the state Department of Health and Pratt after complaints from families of workers who had died from a form of brain cancer.

Concerns were first raised in 2000 by a health committee of representatives of Pratt and Whitney and the International Association of Machinists. The widows of two Pratt & Whitney workers were among the first to push for a comprehensive study.

An initial study by the state Health Department identified cases of the disease but reached no conclusion about a possible link between the cancer and workplace exposures to chemicals. Officials eventually said more than three dozen Pratt workers died of a rare form of brain cancer, glioblastoma multiforme.

Researchers added a genetic study, broadening the project's scope, as investigators waded through data on job applications, the race and sex of workers, work service cards, the location of jobs and job assignments.