April 28, 2011 — On the 25th anniversary of the Chernobyl meltdown, with interest rekindled by the recent Japan nuclear disaster, the medical consequences from the fall out are once again under scrutiny.
Japan is still struggling to get the Fukushima incident under control, but radiation health experts are hopeful that it will provide new and more detailed data on health consequences, given Japan's superior scientific and political capacities.
In a commentary published online April 26 in the Lancet Oncology, Kirsten Moysich, PhD, and Philip McCarthy, MD, from the Roswell Park Cancer Institute in Buffalo, New York, and Per Hall, MD, from the Karolinska Institute in Stockholm, Sweden, note that the aftermath of the Fukushima incident might shed more light on the health outcomes of radiation exposure after a nuclear disaster than the 1986 Chernobyl meltdown.
Currently, little consensus has been reached over the estimated health effects of the Chernobyl accident, even though a large number of scientific papers have reported the cancer consequences of the event, the authors note. A number of challenges have hindered complete and accurate reporting of the incident; therefore, the true nature of the health impact has yet to be determined.
The Chernobyl reactor was not in a reinforced shell at the time of the accident, and the roof of the power plant essentially blew up. The explosion released anywhere from 8 to 180 metric tons of nuclear fuel, along with fission products (3 to 9 billion Ci), into the atmosphere, which the wind blew to the northwest, the authors write. But because of insufficient dosimetry calculations in the first several days after the accident, the exact quantities of the released products might never be known.
Cancer Consequences Unclear
A substantial amount of radiation was released from the reactor for about 3 weeks. In addition to several workers who were killed in the explosion, about 100 firefighters received extensive radiation exposure while battling the fire, and between 100 and 200 workers were diagnosed with acute radiation syndrome. Of this group, approximately 30 died early on; 14 more died during the subsequent 10 years.
But the longer-term development of cancer remains unclear. Dr. Moysich and colleagues state that the documented cancer consequences associated with Chernobyl were largely restricted to thyroid cancer in children, and were much less than initially anticipated. These researchers participated in the writing of the first major United Nations report concerning the effects of the accident and summarized the existing published work in 2002.
"We concluded that, with the exception of thyroid cancer in young people, there was no strong evidence to suggest that excess cancer incidence was substantial in the aftermath of the accident," the authors write, adding that several other investigators have shared this conclusion.
Children and Young Adults at Highest Risk
Although there have been reports of possible increases in childhood leukemia and breast cancer in some of the affected areas, the studies have a number of flaws. Data from the Japanese Life Span Study, which evaluated radiation-related risk factors after the atomic bombings during World War II, suggest that the highest excess risk for breast cancer was in women who were adolescents at the time.
"Another sensitive time point is lactation at the time of the accident, when the likelihood of radionuclide absorption to the mammary tissue is high," they write. The study suggesting an increased risk in breast cancer after Chernobyl should ideally be followed up "with an analytical epidemiological study focusing on women who were in puberty at the time of the accident," the authors add.
As for the current crisis in Japan, they point out that aggressive efforts are going to be needed to limit exposure to radioactive iodine and cesium and to isolate contaminated areas. Children and young adults are at highest risk; previous data have shown that exposure at young ages elevates the risk for adverse health effects, such as thyroid cancer.
Part of the problem in doing valid research after the Chernobyl disaster stemmed from the political instability after the collapse of the former Soviet Union in 1991 and the scarcity of funding available to the new independent nations that experienced the largest burden from the incident.
The situation in Japan is different, the authors note, and should allow for a more comprehensive examination of a major accident at a nuclear power plant. "Findings from such studies should be useful in informing the public about expectations of these health effects, and should guide public health officials in implementing an effective medical response," they conclude.
Health Risks Undermined
Physicians for Social Responsibility (PSR) and the Institute for Policy Studies recently held a joint press conference to discuss the impact of the Chernobyl nuclear disaster 25 years after it occurred and the continuing nuclear catastrophe in Japan.
"Unfortunately, the unknowns far exceed the knowns in these accidents," PSR past president Jeff Patterson, DO, told Medscape Medical News. "Japan may be a more open society than the former Soviet Union, but the government has not been completely forthcoming about the incident."
Reports of increased levels of radiation being released from the plant are different from what was originally reported by the government, explained Dr. Patterson, who is professor emeritus in the Department of Family Medicine at the University of Wisconsin School of Medicine and Public Health in Madison. "Workers have also complained that their radiation dosing levels are not being accurately recorded."
He pointed out that there are huge differences in the figures in studies and reports about the health effects of Chernobyl. "This is not unexpected, given the history of the nuclear industry," he said. "The hallmarks of the industry have been secrecy, cover-up, and minimization."
He also pointed out that the former Soviet Union was a secretive society, and unfortunately, many of the health records of the Chernobyl "liquidators" (people who were charged with cleaning up the disaster) have simply disappeared. "We have no way of following up these people, or knowing what happened to them."
That is why the public does not trust the government and the nuclear industry to tell them the truth, Dr. Patterson noted. "In the United States, we have seen the same indifference to public health when nuclear weapons were being tested. The Department of Defense didn't bother to alert the public."
The bottom line is that "we now know that these accidents happen, even though we were told they could never happen," he said. "And we can't make the nuclear reactors earthquake-proof or tsunami-proof."
With that in mind, one third of the population of the United States (more than 111 million people) currently reside within 50 miles of a nuclear reactor. Given the consequences of the Chernobyl and Fukushima disasters, he said, the PSR is calling for a major reassessment of contingency plans for nuclear accidents and a full and fair accounting of the data on the impact on public health and the environment.
Contingency plans for protecting the public from these reactor sites need to be reevaluated, he said. "We should have an immediate review of our sites and temporarily or permanently shut down those that are not safe."
International Support for Long-Term Research
A group of international experts is calling for a long-term research project to ensure that the health consequences of Chernobyl are fully assessed. Experts and advisors from the Agenda for Research on Chernobyl Health (ARCH) project, which includes individuals from Europe, the United States, and Japan, have reviewed current information about the health effects from the meltdown, and now recommend international support for the long-term funding of a Foundation — the Chernobyl Health Effects Research Foundation (CHERF).
CHERF is led by the International Agency for Research on Cancer (IARC), supported by the EU FP7 Euratom program and ARCH, and was initiated to develop a strategic research agenda for the health consequences of the Chernobyl accident.
"Our proposal with CHERF is to set up a mechanism to coordinate and fund studies that will enable assessment of the overall long-term health effects of the Chernobyl accident," said Ausrele Kesminiene, MD, deputy head of the IARC section of environment and radiation.
"A key to the success of the ARCH recommendations is the creation, maintenance, and follow-up of life-span cohorts," she said in a statement. "These will include already existing cohorts exposed to fallout as children in Belarus and Ukraine, with detailed thyroid dose measurements, as well as cohorts of liquidators."
The goals of CHERF are:
to initiate and support the conduct of comprehensive research on the health effects of the Chernobyl accident
to provide and disseminate an accurate unbiased assessment of the long-term consequences of the Chernobyl accident
to inform radiation protection organizations of the short- and long-term consequences of the Chernobyl accident relevant to radiation protection standards
to deepen scientific understanding of the interaction of radiation and tissue, with special attention to internal exposure
to provide public health organizations with the information needed to mitigate the consequences in the event of any similar exposure to radiation.
The authors have disclosed no relevant financial relationships.
Lancet Oncol. Published online April 26, 2011. Abstract
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