CDC finds 212 chemicals in human blood
CDC finds 212 chemicals in human blood

by Gayathri Vaidyanathan, E&E reporter

The U.S. Centers for Disease Control and Prevention have found 212 environmental chemicals in the blood, serum and urine of humans, 75 of which have never been tested for or found before in Americans.

The agency released its Fourth National "Report on Human Exposure to Environmental Chemicals <> " yesterday, in which it surveyed 2,500 people between 2003 and 2004.

Most of these chemicals do not have a maximum safety limit since there is not enough scientific research to say how much of a chemical can cause harm. Others, such as lead and mercury, are well-characterized. Some of the chemicals were tested for the first time by CDC.

CDC chose to look for these 212 chemicals because scientific data had already shown that they are prevalent in Americans, and some data has suggested that there could be potentially serious health effects. They are meant as a guide to doctors to monitor levels of these chemicals and give them an understanding of the routine limits of exposure. The testing is done by CDC every two years.

Among the new chemicals found was acrylamide, which forms when carbohydrates such as french fries are cooked at high temperatures. Most acrylamide is eliminated from the body quickly, but small quantities can bind to blood proteins. The survey found low levels of the molecule to be "extremely common" in the United States, presumably from diet and smoking. The finding may not necessarily point to health effects.

Mercury levels, also measured for the first time in its form methylmercury, which stays longer in the human body, was found to increase with age and was more common in black women than women of other races.

Other new chemicals were also found in trace amounts, including arsenic and perchlorate, which is known to affect thyroid function. Disinfection byproducts, formed in a chemical reaction between chlorine-based detergents and organic materials in water, were present in trace amounts. They can be inhaled through chlorinated waters in swimming pools and other sources.

Major culprits were industrial chemicals that have been embroiled in recent controversy. Three were found to be present in more than 90 percent of Americans surveyed.

Fire retardants -- called polybrominated diphenyl ethers, or PBDE -- were common. They are found in household items such as carpets, electronics and plastics and resemble naturally occuring body hormones. When they get into the body, PBDEs can integrate within fat tissue and bioaccumulate for a number of years. They were recently linked to altered thyroid hormone levels in pregnant women.

Bisphenol A, or BPA, was found in more than 90 percent of the people surveyed. The chemical, widely used in plastics and ubiquitous in the man-made environment, has been linked to reproductive toxicity. The limits of BPA exposure have not been characterized.

Perfluoro-octanoic acid, or PFOA, which is used in non-stick cookware and is a key polymer in Teflon, was found in most people in "measurable levels."

Pollutants commonly found in air were also tested to see if they have made their way into people. The report found that a "high percentage" of participants had trace amounts of a gasoline additive called methyl tert-butyl ether, or MTBE.

Some good news was also hidden in the report, with a 70 percent decrease in Americans exposed to tobacco smoke. Mercury levels in children has also decreased.

The presence of a chemical in the human body does not indicate a potential threat and the capacity of a chemical to cause harm depends on a variety of factors. Like poisons, the dosage and concentration of a chemical matters, as well as a person's sensitivity.

"Research studies, separate from the Report, are required for determining whether blood or urine levels are safe or are associated with disease or adverse effects," states the report.

Posted on 7/30/2010 (Archive on 8/20/2010)
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