Workers who helped assemble rockets at Rocketdyne's Santa Susana Field Laboratory died from lung cancer at twice the rate of other workers at the facility, researchers reported Friday.
After a six-year study, researchers at UCLA's School of Public Health released their second and final report examining the cancer risk to employees who worked at the laboratory between 1950 and 1994. The researchers linked the heightened rate of lung cancers to hydrazine compounds, toxic components used in rocket fuel, although other chemicals may also be involved, they said.
Bladder, kidney, and blood and lymphatic system cancers also claimed twice as many workers who handled a significant amount of hydrazine, the report concludes, although the authors expressed less confidence in those findings because they derive from just a handful of cases.
The researchers analyzed medical records of 6,107 Rocketdyne workers employed at the Ventura County lab since it opened in 1949. Over time, dozens of toxic chemicals were used, to test and develop rockets and MX nuclear missiles. During the period studied, about 2 million pounds of hydrazine was used at the lab and workers came into direct contact with it through mishaps and workaday exposure, according to the study.
"What you're seeing is the history of the Cold War and attention paid to production instead of health and safety in that period," said Dr. John Froines, UCLA epidemiologist and a member of the research team.
But Rocketdyne officials, flanked by company-hired experts at a news conference Friday in Simi Valley where the study results were announced, dismissed the findings as unreliable.
Steve Lafflam, division director for safety, health and environmental affairs at Rocketdyne, said the study's findings of elevated cancer risk are not supported by the data. He emphasized that the 500 workers at the lab today continue to deal with very small quantities of hydrazine and use protective equipment when dealing with hazardous chemicals.
"The findings are incomplete, inconclusive and need further work," said David M. Gute, professor of civil and environmental engineering at Tufts University in Massachusetts, one of seven experts Rocketdyne hired to review the report.
The study joins a growing body of evidence suggesting work at the lab endangered its employees and possibly the nearby community. Two years ago, the same UCLA team determined in an initial report that workers exposed to radiation during decades of nuclear testing at the lab have an increased risk of dying of cancer. The U.S. Department of Energy paid $1.6 million for the study and a panel to oversee work done by the UCLA scientists.
Preliminary findings from a 1997 California Cancer Registry report that surfaced Thursday showed lung cancers were 17% more common in Simi Valley neighborhoods around the lab than in the rest of Ventura, Santa Barbara and San Luis Obispo counties.
A similar cancer survey in 1991 showed increased cancer in San Fernando Valley neighborhoods east of the lab. Both those studies, however, appear to have serious flaws.
Community leaders and environmental activists say that taken together, those results provide ammunition to press for a more detailed survey to assess if pollution from the plant harmed people living nearby. Rocketdyne officials said that in the next 90 days they will consider undertaking such a study.
"The workers were the canary and the canary died. We need to know whether we're safe," said Marie Mason of Simi Valley, who lives below the hill where the lab is located.
The study released Friday showed that 44 of 1,053 workers at the lab who had heavy contact with hydrazine died of lung cancer. That rate is twice as high as the rate for the workers who had little or no contact with the substance, said Dr. Beate Ritz, a UCLA epidemiologist.
However, it is not certain all the cancer deaths can be directly ascribed to hydrazine compounds. Hundreds of chemicals were in use at the lab, many capable of causing cancer. The researchers focused on hydrazine because more complete records were available for workers who used it.
Also, the UCLA scientists lacked information showing precisely how much hydrazine each worker was exposed to and for how long. So they instead used job descriptions. Rocketdyne officials faulted the report for failing to identify the exact dosage of the hazardous chemicals to which workers were exposed.
"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," Ritz said. "Our best information is that it was hydrazine, but it could be something else related to rocket-engine testing."
The study may underestimate the true risk to workers at the plant, the UCLA scientists said. Their research did not include nonlethal cancer cases and did not attempt to examine other health problems associated with chemicals including neurological impairment or kidney damage, associated with toxic chemicals.
The California Cancer Registry report released Thursday did not identify the cause of the higher disease rates, and its author said that in addition to pollution at the Santa Susana Field Laboratory, factors ranging from smog to old age to smoking could explain the higher incidence of lung cancer in the community.
In the report by the Central Coast division of the California Cancer Registry, researchers found more incidents of lung cancer among 91,000 residents living within five miles of the lab.
Based on the average frequency of lung cancer in Ventura, Santa Barbara and San Luis Obispo counties, researchers expected to find 261 such cancers in the census tracts they examined, but instead found 306.
The report examined a dozen types of cancer reported in the study area between 1988 and 1995. Taken as a whole, cancer prevalence in those categories were within expected ranges. Some cancers, particularly those most often associated with exposure to radiation--a serious concern due to the presence of nuclear reactors and materials once used at the lab--were much lower than anticipated, said author and research epidemiologist Kiumarss Nasseri.
"My conclusion . . . is that residents of the study area seem to have cancer incidence risk which is similar to that of the other residents of the tri-counties region," except for lung cancer, Nasseri wrote in a September 1997 letter to the Ventura County health department.
Nasseri describes his work as a "preliminary, simple analysis." It has not been reviewed by independent scientists to check veracity nor has it been published in a scientific journal. He said he did the work at the request of Paul E. Lorenz, director of the Ventura County Public Health Services Department.