But highest incidence is among children of those with lowest levels of exposure, study says
A British study has found a higher-than-expected leukemia rate among the children of workers at plants similar to Colorado's Rocky Flats.
But the study also found the highest incidence of the disease among children whose parents received the lowest radiation doses, further clouding the murky picture of how a generation of Rocky Flats workers was affected by radiation..
"It's hard to see how you can explain this,'' said Dr. Gerald Draper of Oxford University's Childhood Cancer Research Group, who headed the study off 120,000 Britons who worked in nuclear power and weapons plants.
The report, released last month, comes as U.S. scientists try to determine the health risks faced by more than 500,000 Americans who participated in building nuclear weapons during the Cold War, including 24,000 at Rocky Flats.
Some studies have found hints that radiation even at levels previously deemed safe can affect health. But scientists are hampered by poor records of how much radiation workers absorbed, especially during the early years of the Cold War.
The issue is of interest beyond the mostly retired defense workers and their families.
Workers who dismantle the nation's highly contaminated nuclear weapons complex will face similar health threats. They will be tearing out pipes and ductwork laced with radioactive dust and bits of toxic materials, such as beryllium..
"You clearly have a concern there,'' University of Colorado Medical School epidemiologist Jim Ruttenber says of the workers who will be asked to clean up the mess at Rocky Flats.
Ruttenber worries that those doing the cleanup, who are working for several subcontractors, will not be monitored as closely for radiation exposure as the people who assembled the bombs.
Officials of Kaiser-Hill, the firm hired to close Rocky Flats, say they're being as cautious as possible as they try to meet the goal set by Energy Secretary Federico Peņa of completing the job by 2006.
Workers wear respirators and full body protection anytime they enter an area believed to contain even a hint of contamination.
But Kaiser-Hill is still investigating a 1996 incident in which two workers accidentally inhaled contaminated air but were not counseled about health effects for nearly 15 months, apparently because paperwork was misplaced.
Many studies have been conducted on Americans who worked on nuclear arms during the Cold War.
In addition to spotty records, the research is complicated by the fact that some workers smoked or handled chemicals that could account for their cancers.
The British study found more than twice the number of leukemia cases among children whose parents worked in nuclear power and weapons plants as in the general population -- about 11.9 cases of leukemia per 10,000 children of radiation workers, compared with a national rate for the disease of 5.4 cases per 10,000 children. But that's only about 65 additional cases for the 120,000 workers, a number the researchers consider small.
And no differences were found in the rates for other kinds of cancer.
The study looked mostly at the children of male workers. American scientists have long agreed that male reproductive organs are highly sensitive to radiation.
"It's not totally impossible it's radiation,'' Draper, the Oxford scientist, says of the cause of the higher incidence of leukemia cases. But he said that's unlikely, because the highest incidence was among children of workers who were least exposed.
British scientists have turned to other similarities among workers besides radiation doses to explain the leukemia rate. They suspect the answer lies in the mixture of people from different parts of Britain who worked together at nuclear plants.
When populations are mixed, they are more susceptible to infection, Draper says. Leukemia is not itself an infection, but an infection might put people at greater risk for leukemia.
Two U.S. studies suggest that radiation is harmful at levels previously believed safe. Neither study is conclusive because the data was incomplete and only small numbers of workers were involved, scientists say.
A study by scientists at the University of California at Los Angeles, released in September, found higher leukemia rates among atomic workers who were at the upper end of the safe exposure levels. The difference was slight but statistically significant, says UCLA Professor Hal Morgenstern, who headed the study.
But Morgenstern said he was hampered by a lack of data on radiation exposure that workers may have had on previous jobs. The federal government has sent the study to the National Institute for Occupational Safety and Health for review.
A 1987 study at Rocky Flats also found a faint pattern of higher-than-expected cancer rates among atomic workers. The head of that study, Gregg Wilkinson of the University of Buffalo, is conducting further research on Rocky Flats, to be released late next year at the earliest.
Morgenstern's and Wilkinson's studies have been criticized by Otto Raabe of the Institute of Toxicology and Environmental Health at the University of California at Davis. Raabe is president of the Health Physics Society, a national professional group that studies the effects of radiation.
Raabe says Morgenstern added several categories of cancer together to reach a number among the workers that is statistically significant. He calls the study "statistically flawed'' and "a fishing expedition in epidemiology.''
Raabe says safety limits on radiation exposure set by the federal government are adequate.
But the U.S. Department of Energy says its records aren't complete on how much radiation was absorbed by the last generation of atomic workers, the ones who assembled the bombs.
Ruttenber, the CU medical professor, says, "Hopefully, we kept track of the nuclear material better than we did the data for the workers.'' Reminded that a ton of plutonium is unaccounted for and presumed to be in the ductwork, Ruttenber says, "Maybe that is a good analogy.''
Ruttenber is trying to reconstruct the records of former Rocky Flats workers under a federal grant. In four years, he has compiled a roster of everyone who worked at the plant. The next step is to link them with archived data.
Ruttenber said he will attempt to reconstruct the exposure records of about 5,000 workers for further study.
He's not even close to completion.
"We're talking a couple more years, at least, of attacking the data,'' he says.
|
If you have come to this page from an outside location click here to get back to mindfully.org |