Newswise — Levels of commercial flame retardants in human blood samples have risen sharply since the 1970s even as levels of dioxin and other "persistent organic pollutants" have decreased, reports a study in the March Journal of Occupational and Environmental Medicine, official publication of the American College of Occupational and Environmental Medicine (ACOEM).
Led by Dr. Arnold Schecter of University of Texas School of Public Health, Dallas, the researchers measured levels of polybrominated diphenyl ether (PBDE) flame retardants in U.S. blood samples obtained in 2003. They compared the results with measurements in stored (frozen) blood samples collected in 1973.
In the 1973 samples, overall blood levels of PBDEs were generally too low to measure. In contrast, nearly all of the 2003 samples had significant levels of PBDEs.
Total serum PBDE level in 2003 was 62 parts per billion—approximately 90 times higher than in 1973. The 2003 U.S. levels were the highest yet measured from any country.
The rise in PBDE levels was in direct contrast to levels of known hazardous persistent organic pollutants (POPs), such as dioxin and polychlorinated biphenyls (PCBs). Levels of the other POPs were significantly higher in 1973 than in 2003, reflecting bans on these substances enacted in the 1970s.
Levels of PBDEs were similar across age groups. Women had higher PBDE levels than men, although the difference was not statistically significant. Current samples of breast milk also showed rising levels of PBDEs.
PBDEs are synthetic flame retardants that are widely used in consumer products, such as Styrofoam, electronic equipment, and fabrics. More than 65,000 metric tons of PBDEs are manufactured each year worldwide, much of it used in North America.
With decreasing exposure to dioxin and PCBs, recent studies suggest that PBDEs are now the type of POP most commonly found in human blood samples. So far, no studies have been done to assess the possible health hazards of PBDE exposure in humans. Animal studies suggest a wide range of toxic effects.
Although exposure to other POPs comes almost exclusively through foods of animal origin, it's not even certain how PBDE flame retardants get into the human body. In Sweden, levels of PBDEs in breast milk have fallen since their use was banned. Because of the "ubiquitous, persistent, and toxic nature of these compounds," studies of the human health effects of PBDEs are "urgently indicated," Dr. Schecter and colleagues conclude.
ACOEM, an international society of 6,000 occupational physicians and other healthcare professionals, provides leadership to promote optimal health and safety of workers, workplaces, and environments.