A report issued by a White House panel last week urging an examination of cancer threats posed by chemicals and other environmental hazards was cheered by scientist Maryanne Donovan for spotlighting concerns that she feels haven't gotten the attention they deserve.
"This report will give credibility to the idea that the environment is an exposure that needs to be reckoned with," said Donovan, who heads the University of Pittsburgh Cancer Institute's Center for Environmental Oncology. The molecular biologist said she sees the report as validation of work she has done on such issues for 30 years.
But the American Cancer Society, an organization seen by many Americans as leading the battle against cancer, greeted the report's May 6 release with two thumbs down, saying it overstates its case.
"[I]ts conclusion that 'the true burden of environmentally induced cancer has been grossly underestimated' does not represent scientific consensus," Michael Thun, the group's vice president emeritus, said in a statement. "Rather, it reflects one side of a scientific debate that has continued for almost 30 years."
At issue is the President's Cancer Panel report on the role played by environmental exposures in cancer risk. About 1.5 million Americans develop cancer each year and 560,000 die from it, the report says. About 41 percent of the population will develop cancer at some point in their lifetimes.
Thun said the report dismissed proven cancer-prevention efforts aimed at the major known causes of the diseases: smoking, obesity, alcohol, infections, hormones and ultraviolet solar rays. But Donovan said the group is doing Americans a disservice.
"When an organization like the American Cancer Society starts to say they don't think the [environmental] risk is high," she said, "it starts confusing people."
Margaret Kripke, an author of the White House report and an emeritus professor at the Texas MD Anderson Cancer Center in Houston, said the panel chooses a single issue for each report. It focused in 2007, for example, on lifestyle factors, half of which centered around tobacco exposure and the other half on obesity and exercise.
"We agree that tobacco is really the most preventable cause of cancer," Kripke said. "This [the role of environmental pollutants] is not a subject that's been addressed before by this panel and it is of great public interest, yet it seemed there was very little research being done in this area."
Studies of the causes of cancer shifted away from environmental factors in the early 1980s, Kripke said, because of a 1981 report finding that environmental contaminants were responsible for about 6 percent of all cancers.
"We debated a great deal about whether we should do this report," Kripke said of last week's document. The White House panel normally has three members, appointed by the president. There are currently two: Kripke and LaSalle Leffall Jr. of Howard University. Both were appointed by President George W. Bush.
Ultimately, she said, the panel decided to focus on this area because there is a scarcity of research and because of growing concerns of the increased prevalence of certain cancers for which there is no explanation.
Also, she said, the 1981 study failed to take into account multiple exposures to different substances over long periods of time, which ultimately led the panel to conclude that the 6 percent estimate is now "woefully out of date."
'It's very complicated'
Yet unraveling the relationship between environmental exposure and cancer remains complicated.
For example, the time of exposure to a chemical can matter as much as the type of chemical. And there is a chain of events that usually needs to happen for a cell to become cancerous; for most cancers, that sequence remains unknown.
Furthermore, exposures can have a synergistic effect and can have an impact that spans generations, the report says.
"It's very complicated," Kripke said. "I don't think anyone really knows how to investigate the contributions of environmental factors to the background of genetic risk. This kind of research is really in infancy and is just coming forward, so it's difficult to know how to interpret that.
"There are red flags suggesting that things are happening now that were not in previous years," Kripke added. "It really is difficult to say how many cancers are environmentally induced, but we really believe it's important to air on the side of being cautious."
For Richard Clapp, a professor of environmental health at Boston University's School of Public Health, last week's report signified a much-needed shift in the general research strategy for fighting cancer.
"There's a lot of momentum to accept these arguments in the report already," Clapp said. "A lot of groups have been working on this ... so this is already under way, and this report reinforces that. The fact that it came where it came from -- it's not fringe stuff."
Environmental and public health advocates heralded the panel's report as a major breakthrough in thinking about public health and cancer.
"Release of this report is a historic opportunity to change the course of the war on cancer so that, in the face of the large and growing body of scientific evidence linking cancer to environmental contaminants, we act now rather than wait for more evidence of harm," said Jeanne Rizzo, CEO of the Breast Cancer Fund.
The report, Rizzo said, highlighted the fact that "the government -- and institutions that advise the government -- have been locked in a cancer-fighting paradigm that has failed to look at the complexity of cancer causation and, in so doing, have missed the opportunity to create a national campaign for cancer prevention."
The American Chemistry Council said it supports research to address the relationship between chemicals and health but that it agrees with the American Cancer Society's concern that the report lacked balance.
"While we believe that the laws that regulate our industry have been protective of human health and the environment, we also strongly support improvements that reflect advances in science over the past few decades," the council said in a statement.
Call for federal reforms
The report is also being taken as a call to action by advocates for updating the federal law that regulates the 80,000 or so chemicals on the market.
On Capitol Hill, lawmakers have been debating how best to reform the Toxic Substances Control Act, or TSCA, to give U.S. EPA greater authority to collect information about chemicals before they come onto the market.
Rep. Bobby Rush (D-Ill.) and Energy and Commerce Chairman Henry Waxman (D-Calif.), along with Sen. Frank Lautenberg (D-N.J.) in April released legislative language that would revise the 1976 law for the first time.
Proponents of a major TSCA overhaul say the President's Cancer Panel report raises the issue's profile among the public and highlights the importance of enacting comprehensive TSCA reform.
"I'm hoping it [the report] is going to invigorate things like TSCA reform and give the government the ammunition it needs to make regulatory reforms," Donovan said. "When the biological effects of chemicals is known through laboratory research, I don't think we ought to wait another 30 or 40 years to take action."
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