(NaturalNews) Ubiquitous flame retardant chemicals appear to alter levels of thyroid hormones in the bodies of pregnant women, with potentially severe consequences for their infants, according to a study conducted by researchers from the University of California-Berkeley and published in the journal Environmental Health Perspectives.
"Normal maternal thyroid hormone levels are essential for normal fetal growth and brain development, so our findings could have significant public health implications," lead author Jonathan Chevrier said.
The chemicals in question, known as PBDEs, are widely used in everything from furniture to carpets to electronics and build up in the fatty tissues of humans and other animals. The two most common routes of human exposure are through household dust and through the consumption of fatty animal products. PBDEs have been found in the blood of 97 percent of all people tested.
Researchers tested the blood of 270 pregnant women in the Salinas Valley of California for levels of PBDEs and thyroid stimulating hormone (TSH). Levels of the TSH dropped 16.8 percent with every tenfold increase in PBDE concentration, suggesting an overproduction of thyroid hormone. Each tenfold increase also doubled the risk of subclinical hyperthyroidism.
Although none of the women in the study suffered from clinical hyperthyroidism, their PBDE levels were only half the California average.
The findings "raise concerns about women exposed to higher levels of PBDEs, which could be made clinically hyperthyroid," Chevrier said.
Clinical hyperthyroidism can produce miscarriages, premature births, reduced fetal growth and infant brain damage.
Two previously common PBDE formulas have been banned in the United States, where bodily levels of the hormones are 20 times higher than in other countries. Yet there is no sign that body burden of the chemicals is declining yet, said Linda Birnbaum of the National Institute of Health Sciences.
"It's too soon," she said.
Birnbaum also expressed concern that new formulations continue to be introduced without proper safety testing.
"We kind of jump from the proverbial frying pan into the fire," Birnbaum said.