Study Details Americans' Chemical Exposure
Many Exposures Down, but Health Effects Uncertain
The study also shows low but relatively widespread exposure to phthalates, a class of chemicals found in cosmetics, plastics, and many plastic-coated food packages. The chemicals are known to affect hormone-producing organs and can cause liver and testicular damage in lab animals.
They find that half of adolescents between 12 to 19 years old had phthalates measurable in their urine, though researchers said they still don't know what the health effects are. More research is needed.
The report states that there is very limited scientific information available on potential human health effects of phthalates.
"We have reason now to look further" at the possible health effects of Americans' exposure to the chemicals, Gerberding says.
Scientists pointed to an apparent overall drop in mercury exposure, though the toxin remains widely prevalent in the U.S. population. The metal is used in making electrical equipment (thermostats or switches). It is also combined with other substances in batteries, and while its use in pharmaceutical applications has been declining, it has been used as a preservative. It is also used in some countries outside of the U.S. in making cosmetic skin creams.
Yet most of the mercury in blood comes from the consumption of fish or shellfish.
The report shows no women of childbearing age approached levels known to affect newborns' nerve and brain development. Yet 6% of women had levels that were within a factor of 10 of those associated with harmful effects to the developing fetus.
Gerberding suggests that the figures would direct the CDC to encourage more research into defining safe levels of mercury in the blood.
The CDC also recorded falling levels of many pesticides, though levels of at least one industrial pesticide, DDE, were up since 2000 in all groups studied.
Meanwhile, an analysis released by the Pesticide Action Network of North America showed that 90% of people in the study harbored between five and 16 different pesticides in their bodies. On average, Americans show evidence of exposure to 10 to 11 different pesticides, according to the analysis.
"It just shows that we are carrying around a lot of pesticides and this is just the tip of the iceberg," Margaret Reeves, PhD, the group's senior scientist, tells WebMD.
Chemical manufacturers released a statement Thursday stressing that low levels of toxic exposure do not necessarily translate to increased disease risk.
"Just because people have an environmental chemical in their blood or urine does not mean that the chemical causes disease. Small amounts may be of no health consequence," a statement from the American Chemistry Council notes.