The report recommends raising consumer awareness of the risks posed by chemicals in food, air, water and consumer products, bolstering research of the health effects and tightening regulation of chemicals that might cause cancer or other diseases.
They also urged doctors to use caution in prescribing CT scans and other medical imaging tests that expose patients to large amounts of radiation. In 2007, 69 million CT scans were performed, compared with 18 million in 1993. Patients who have a chest CT scan receive a dose of radiation in the same range as survivors of the Hiroshima atomic bomb attacks who were less than half a mile from ground zero, the report says.
The panel also criticized the U.S. military, saying that "it is a major source of toxic occupational and environmental exposures that can increase cancer risk." Examples cited include Camp Lejeune in North Carolina, where carcinogenic solvents contaminate drinking water, and Vietnam veterans with increased lymphomas, prostate cancer and other cancers from thier exposure to the herbicide Agent Orange.
Overall cancer rates and deaths have declined in the United States. Nevertheless, about 41 percent of all Americans still will be diagnosed with cancer during their lifetime, and about 21 percent will die from it, according to the National Cancer Institute's SEER Cancer Statistics Review. In 2009 alone, about 1.5 million new cases were diagnosed.
For the past 30 years, federal agencies and institutes have estimated that environmental pollutants cause about 2 percent of all cancers and that occupational exposures may cause 4 percent.
But the panel called those estimates "woefully out of date." The panel criticized regulators for using them to set environmental regulations and lambasted the chemical industry for using them "to justify its claims that specific products pose little or no cancer risk."
The report said the outdated estimates fail to take into account many newer discoveries about people's vulnerability to chemicals. Many chemicals interact with each other, intensifying the effect, and some people have a genetic makeup or early life exposure that makes them susceptible to environmental contaminants.
"It is not known exactly what percentage of all cancers either are initiated or promoted by an environmental trigger," the panel said in its report. "Some exposures to an environmental hazard occur as a single acute episode, but most often, individual or multiple harmful exposures take place over a period of weeks, months, year, or a lifetime."
Boston University's Clapp was one of the experts who spoke to the panel in 2008. "We know enough now to act in ways that we have not done...Act on what we know," he told them.
“There are lots of places where we can move forward here. Lots of things we can act on now," such as military base cleanups and reducing use of CT scans, Clapp said in an interview.
Dr. Ted Schettler, director of the Science and Environmental Health Network, called the report an “integrated and comprehensive critique.” He was glad that the panel underscored that regulatory agencies should reduce exposures even when absolute proof of harm was unavailable.
Also, "they recognized that exposures happen in mixtures, not in isolation" and that children are most vulnerable.
“Some people are disproportionately exposed and disproportionately vulnerable," said Schettler, whose group was founded by environmental groups to urge the use of science to address public health issues related to the environment.
Schettler said it "took courage" for the panel to warn physicians about the cancer risk posed by CT scans, particularly for young children.
“It’s almost become routine for kids with abdominal pain to get a CT scan" to check for appendicitis, he said. Although the scans may lead to fewer unnecessary surgeries, doctors should consider the high doses of radiation. “I'm very glad this panel took that on," Schettler said.