The polybrominated diphenylethers (
PBDEs) are a class of chemicals widely used as
flame retardants. Concentrations of
PBDEs in some human and marine mammal populations are increasing. The toxicological endpoints of concern for environmental levels of
PBDEs are likely to be
thyroid hormone disruption, neurodevelopmental deficits and
cancer. Unfortunately, the available toxicological evidence for these endpoints is surprisingly limited, given their widespread use, bioaccumulative potential, and structural similarity to
thyroid hormones and
polychlorinated biphenyls (
PCBs). Available evidence suggests that the
PBDE congeners likely to bioaccumulate (i.e., those observed in human tissues and other biota) have the propensity to disrupt
thyroid hormones, cause neurobehavioral deficits and possibly cause
cancer in laboratory animals. It is unclear whether current concentrations of
PBDEs in human tissues would be expected to adversely impact human health. Since nearly all individuals are exposed to low levels of
PBDEs, the potential health impacts also should include assessment at the population level. This paper summarizes the available toxicological evidence for
PBDE-induced
thyroid hormone disruption, neurodevelopmental deficits, and, for some congeners,
cancer, and provides a perspective on the potential risks of the
PBDEs for human health.