As many as 420 known or suspected carcinogens have been found in human populations through monitoring studies conducted across the globe, according to a first-of-its-kind literature review released today by the Environmental Working Group.

“The array of carcinogens detected in humans is alarming,” says the report by Curt DellaValle, a senior scientist with EWG, a Washington, D.C.-based advocacy group. “It underscores how much work is needed to reduce and eliminate toxic chemicals, particularly carcinogens, from our daily lives.”

Many studies have confirmed the presence of a harmful chemical or group of chemicals in human blood or urine. But the new report suggests that people may harbor traces of many carcinogens at a given time.

DellaValle, who holds a PhD. in environmental health from Yale University, reports that people who were not at risk for on-the-job exposure still had many cancer-causing chemicals in their blood or urine, confirming that humans are exposed to a wide range of carcinogens in their everyday lives, from things like pesticides, flame retardants and consumer products.

“This isn’t a problem that we can necessarily just shop our way out of.” Cancer-causing chemicals are “coming from a variety of sources that we may not even be aware of,” DellaValle said in an interview. Reducing the risk is “going to take a combination of both individual efforts of changing your habits as well as regulators stepping in and strengthening our environmental regulations.”

The report notes that banning lead in gasoline and PCBs—chemicals once widely used as cooling fluids—has reduced levels of those substances in people. “It shows that effective government regulation can make a big impact,” DellaValle said.

The report says that some hazardous substances found in people are naturally-occurring. And it stresses that the mere presence of carcinogens does not necessarily mean a person is in danger of getting cancer. It’s “hard to take a concentration of a chemical that’s measured and assign” the chance of getting cancer, DellaValle said.

But the report concludes that levels of nine carcinogens, including benzene and arsenic, are high enough “to pose non-trivial cancer risks” for many people. According to DellaValle, that means that concentrations are high enough to exceed what the Environmental Protection Agency considers an acceptable risk—typically, a one in one million to one in 10,000 chance of getting cancer.

Noting that it had not had a chance to review the EWG report, the American Chemistry Council, which represents the nation’s leading chemical manufacturers, said in a statement that “Although the data are helpful to assess risk from environmental substances, biomonitoring data is limited in the information it provides.”

Such data, the council said, does not show where exposures came from or offer “a complete exposure assessment. Studies of absorption, distribution, metabolism and excretion are needed to convert biomonitoring data into more useful information that in turn must be evaluated with toxicological data before they can be used to predict potential health risks.”

The EWG report comes one week after Congress sent President Obama legislation to overhaul the 40-year-old Toxic Substances Control Act. The legislation requires the Environmental Protection Agency to begin testing some 64,000 chemicals that have been unregulated.

The pace of the testing, however, would be slow. Under the bill, which the president is expected to sign, the EPA would have to test only about 20 chemicals at a time, and it could spend as long as seven years on each one.

This story was reported by FairWarning (, a nonprofit news organization based in Los Angeles that focuses on public health, safety and environmental issues.

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