The Chemicals That Stick Around in the Body
How the U.S. tracks the potentially harmful substances that build up in humans
Most Americans do carry traces of dozens—possibly hundreds—of potentially toxic chemicals in their bodies, according to the Centers for Disease Control and Prevention, which tests blood and urine samples in thousands of citizens as part of its continuing public-health surveys.
But just because a chemical is present doesn't mean it will cause health problems, the CDC says. In many cases, scientists don't know what level of exposure might pose harm or to what extent people's individual genes, age, weight and other factors vary the risk.
Many of the chemicals people are exposed to in food, air and water exit the body via waste or sweat within hours, experts say. Some of the most hazardous don't—and can't be removed with a detox diet, soaking in ionized water or purging the colon frequently.
"There is very little hard scientific data to support that these cleansing tools eliminate significant levels of these chemicals," says Linda Birnbaum, director of the National Institute of Environmental Health Studies, the federal agency that investigates environmental effects on health.
Some harmful chemicals that were banned years ago, like polychlorinated biphenyls, known as PCBs and linked to cancer in animals and humans, are still ubiquitous in the environment.
"We all carry traces of PCBs in our bodies because there are teeny little bits in the foods we eat and it takes 15 or 20 years to clear your system," Dr. Birnbaum says.
Levels of lead, which is known to damage many organs and interfere with children's neurological development, have declined dramatically in blood samples since the 1970s. But lead remains a major health concern, the CDC says.
The CDC tests for 212 of the more than 80,000 chemicals developed since the industrial revolution. Its latest full survey, released in 2009, listed many new ones, including Bisphenol A (BPA), a chemical used in polycarbonate plastics and epoxy; perchlorate, found in fireworks and explosives; perfluorinated chemicals, used in many nonstick coatings in cookware; and acrylamide, a chemical formed when carbohydrates are cooked at high temperatures (think french fries).
Virtually all the survey participants had measurable levels of those chemicals in their blood or urine, the CDC reported.
