Our daily dose of PBDEs may be enough to keep our children from learning at their potential. Studies in laboratory animals have found that PBDEs profoundly and permanently affect the developing brain at levels frighteningly close to those in today’s most exposed women. In a series of studies on rodents, rats and mice exposed to a single dose of PBDEs 10 days after birth had difficulty adjusting to new environments and negotiating mazes, indicating effects on learning, behavior, and memory (Ericksson 2001). A 2003 study found similar effects in mice exposed to Deca (Viberg 2003).

While long-term studies on PBDEs’ effects in humans have not been conducted, animal studies suggest their effects are eerily similar to those of PCBs, their close chemical cousins. Long-term studies of children exposed to PCBs show that early exposure leads to deficits in learning (Schantz 2003).  

PBDE exposure may also affect thyroid hormone, which is essential for proper brain development in the fetus. In animal studies, both penta and octa have been shown to reduce levels of thyroid hormone (Zhou 2002, Zhou 2001) and liver toxicity (Darnerud 2001). They’ve also been shown to cause bone malformations and reduced weight gain as a result of prenatal exposure (Darnerud 2003). 

Scientists are beginning to study the effects of PBDEs on wildlife. Recent research by the National Marine Fisheries Service has found that PBDEs alter fish thyroid hormone levels, delay hatching, and retard growth (Lema 2006). Scientists have expressed concern that PBDEs may threaten the health of orca whales, particularly when combined with effects from PCBs (Ross 2006).

Many of these toxicity studies have been conducted on the phased-out PBDE formulations. But researchers have produced considerable evidence that, once in the environment, the still widely used deca formulation gets broken down into chemicals that, like those in penta and octa, accumulate in human and animal tissue. Four studies, examining the breakdown of deca by sunlight and by living organisms, found that deca degrades into some of the PBDEs found in the penta and octa formulations (Söderstrom 2004, Bezares-Cruz 2004). A study of the degradation of deca in house dust found rapid breakdown and concluded that 83% of the deca converted to other PBDEs, some of which are more persistent and toxic than deca itself (Stapleton 2005). Use of deca continues at very high levels, and recent testing has typically detected more deca than the other formulations in the indoor and outdoor environment (Sharp 2004, Song 2004).