The study, which examined 6,107 men first employed at the Rocketdyne plant before 1980, found that workers presumed to have a high exposure to hydrazine died from lung cancers and possibly cancers of the bladder, kidney, and blood and lymphatic system about twice as often as other Rocketdyne workers who were not exposed to the chemical.

No clear link with higher cancer deaths was found for workers who were less likely to have been exposed to hydrazine, although some elevation in cancer deaths was detected. Also, a companion study of about 4,000 different Rocketdyne workers who were exposed to asbestos at the sprawling field laboratory found no more lung cancer deaths than among unexposed co-workers.

The findings were released to workers and the community today during a series of public meetings organized by the California Department of Health Services, Occupational Health Branch.

Researchers cautioned that their findings have some limitations. Their analysis was done using surrogate measures of exposure, which had to be estimated because Rocketdyne -- like virtually all other companies -- did not monitor and record workers' exposures to toxic chemicals. In addition, workers were exposed to a number of chemicals, creating the possibility that something other than hydrazine is the cause of the increased cancer deaths.

"While we believe that something is going on with this group of workers, we don't know for certain what caused the excessive cancer deaths," said Beate Ritz, a UCLA epidemiologist and co-investigator of the study. "Our best information is that it was hydrazine, but it could be something else related to rocket-engine testing. We do know there is an excessive number of cancer deaths among workers in the high-exposure hydrazine group." The findings are from a federally funded UCLA study examining occupational exposures to low-level radiation and toxic chemicals at the Rocketdyne facility in Simi Valley. The radiation study, released in September 1997, found that workers exposed to low-level radiation over many years at the field laboratory have an increased risk of dying from several types of cancer.

The study of worker health at Rocketdyne began in the early 1990s at the urging of several state legislators. People working at and living near Rocketdyne in Simi Valley have expressed concern about potential health risks since 1980, when plant critics released a report detailing radiation-related accidents at the facility.

The 2,668-acre Rocketdyne field laboratory, located in the Santa Susana Mountains between Simi Valley and Canoga Park, opened in 1948 to design the nation's first rocket engines. Beginning in the early 1950s, one sector was used to develop prototype nuclear power reactors.

In the latest study, UCLA researchers analyzed company records for about 6,100 workers who were employed at the rocket engine testing areas of Rocketdyne for at least two years prior to 1980. Workers began wearing respirators when handling hydrazine beginning in the early 1980s.

Researchers determined that the workers in the rocket development areas were exposed to many chemicals in addition to hydrazine, including kerosene fuels, trichloroethylene and small amounts of asbestos. Unlike the earlier radiation study, where researchers could make use of worker-exposure monitoring information collected by the company, no detailed information about exposure to toxic chemicals was available.

Researchers estimated which workers were most likely exposed to hydrazine by conducting a detailed industrial hygiene review, which included visits to the facility and interviews with both managers and workers about past chemical handling practices. The only other substance for which researchers could estimate worker exposure was asbestos, which was used as an insulating material in the radiation areas of the facility. Too little information was available about the other chemicals to make meaningful estimates about worker exposure, researchers say.

Hydrazine compounds were used at Rocketdyne in large amounts from the middle 1950s to the early 1970s, as part of the facility's active role in the nation's space program. Hydrazine has been shown to be carcinogenic in animal studies and is classified as a possible human carcinogen.

UCLA researchers grouped workers into four categories of suspected hydrazine exposure (high, medium, low and no exposure) based on their job titles. The high-exposure workers included men employed as propulsion mechanics or propulsion technicians who were responsible for pumping hydrazine into test-stand rocket engines and fuel tanks -- operations that allegedly resulted in frequent leaks.

Researchers examined patterns of death due to cancer and found that workers who had high hydrazine exposures were about twice as likely to die from lung cancer. Excessive deaths from cancers of the bladder, kidney, and blood and lymphatic system were noted, although the association was most pronounced in lung cancer. The risk of dying from lung cancer increased the longer a worker had held one of the high-exposure jobs.

In addition, the risk of dying from one of the cancers was highest among those who worked in the high-exposure jobs during the 1960s, when Rocketdyne's use of hydrazine compounds was at its peak.

The strength of the findings are somewhat limited by the relatively small number of workers who died of cancer (404) and the imprecise way that the workplace exposures had to be estimated, according to researchers. But the hydrazine study did have a relatively long follow-up period -- an average of 29 years.

The Rocketdyne chemical study is one of the few ever done examining the possible health consequences of exposure to hydrazine in the workplace, one reason researchers say the effort should be continued to see whether the disease patterns change over time.

"Since less than one-quarter of the workers in our study died by the end of the follow-up period, we need to continue following these workers in the future," said Hal Morgenstern, a UCLA epidemiologist and principal investigator of the study. "It also would be useful to expand these future efforts to examine new cases of diagnosed cancers, rather than examining only cancer deaths."

The study does not assess the possible exposure of people in the surrounding community to toxic chemicals used at Rocketdyne. Researchers say it is not possible to extrapolate the worker findings to assess whether or not health effects among nearby residents have occurred.

Funding for the study was provided by the U.S. Department of Energy, working with the California Department of Health Services and the Public Health Institute. The project was advised by an independent Oversight Panel that included scientific, community, government and union representatives.

Other members of the research team were John Froines and Bambi Young, both of the UCLA School of Public Health.

Madeline Felkins ANTHOLOGY

Madeline Felkins Rocketdyne/Boeing HOTSHEETS Contamination News

Madeline L. Felkins: ANTHOLOGY *Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2003 Madeline Lucille Felkins All Rights Fruit of the Earth", Poisoning the Well", "Poverty Pig and Other Great Bores", Desert Song", Angel Baby", "Water Running", "Angel Baby Memorial", "Hotsheets", Madelinefelkins.com, Hotsheets.org



E-Mail Madeline Felkins Regarding Violin/Piano Instruction/Artist Development