An expert panel that advises the president on cancer said Thursday that Americans are facing "grievous harm" from chemicals in the air, food and water that have largely gone unregulated and ignored.
The President's Cancer Panel called for a new national strategy that focuses on such threats in the environment and workplaces.
Epidemiologists have long maintained that tobacco use, diet and other factors are responsible for most cancers, and that chemicals and pollutants cause only a small portion — perhaps 5 percent.
The presidential panel said that figure has been "grossly underestimated" but it did not provide a new estimate.
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"With the growing body of evidence linking environmental exposures to cancer, the public is becoming increasingly aware of the unacceptable burden of cancer resulting from environmental and occupational exposures that could have been prevented through appropriate national action," the panel wrote in a report released Thursday.
Federal chemical laws are weak, funding for research and enforcement is inadequate, and regulatory responsibilities are split among too many agencies, the panel found.
Children are particularly vulnerable because they are smaller and are developing faster than adults, the panel found.
The report noted unexplained rising rates of some cancers in children, and it referred to recent studies that have found industrial chemicals in umbilical-cord blood, which supplies nutrients to fetuses. "To a disturbing extent, babies are born 'pre-polluted,' " the panel wrote.
Health officials lack critical knowledge about the health impact of chemicals on fetuses and children, the report said.
In addition, the government's standards for safe chemical exposure in workplaces are outdated, it said.
In 2009, about 1.5 million American men, women and children had cancer diagnosed, and 562,000 people died from the disease.
"There are far too many known and suspected cancer-causing chemicals in products people, young and old, use every day of their lives," said Kenneth Cook, president and co-founder of Environmental Working Group, an environmental advocacy group. "Many of these chemicals are believed to be time bombs, altering the genetic-level switching mechanisms that lead to cancerous cellular growth in later life."
The panel said the country needs to overhaul existing chemical laws, a conclusion that has been supported by public health groups, environmental advocates, the Obama administration and even the chemical industry.
The current system places the burden on the government to prove that a chemical is unsafe before it can removed from the market.
The standards are so high, the government has been unable to ban chemicals such as asbestos, a widely recognized carcinogen that is prohibited in many other countries.
About 80,000 chemicals are in commercial use in the United States, but federal regulators have assessed only about 200 for safety.