Chemical contamination from rocket engine testing at the site appears to have been much greater than previously suspected and continues to threaten soil and groundwater in the area around Rocketdyne's Santa Susana Field Laboratory, said the study published by the Los Angeles Times on Friday.

    The nuclear meltdown, which remained virtually unknown to the public until 1979, could have caused between 260 and 1,800 cases of cancer "over a period of many decades," the study concluded.

    The five-year study was conducted by an independent team of scientists and health experts.

    But the advisory panel that oversaw the study said it could not offer more specifics about potential exposure to carcinogens because the Department of Energy and Rocketdyne's owner, Boeing Co., did not provide key information, the paper said.

    "This lack of candor .. makes characterization of the potential health impacts of past accidents and releases extremely difficult," the panel concluded.

    Boeing officials vigorously disputed the findings, saying the study was based on miscalculations and faulty information.

    Phil Rutherford, a health, safety and radiation manager for the company, said overall cancer deaths among employees at the field lab and at surrounding facilities between 1949 and 1999 were lower than in the general population.

    He said this figure was provided by a Boeing-commissioned study which was released last year.

    The Boeing report contradicted findings from an earlier UCLA study that found elevated cancer deaths among workers exposed to high levels of radiation.

    Critics chided Boeing officials Thursday for failing to provide information for the new study.

    "The pattern of secrecy and misrepresentation that began at the time of the accident continues to this day, where sloppy practices are done under a cover of darkness," said Dan Hirsch, a physicist and co-chairman of the advisory panel.

    The lab was opened on a craggy plateau in easternmost Ventura County, Southern California in 1948. Originally operated by North American Rockwell, it conducted nuclear research for the federal government for more than four decades before ceasing those operations in the late 1980s. It has also been the site of more than 30,000 rocket engine tests, the thunderous explosions serving as a Cold War-era hallmark for nearby residents. Enditem