Polybrominated diphenyl ethers, a group of brominated flame retardants, can interact with polychlorinated biphenyls in enhancing developmental neurobehavioral defects.

The present study shows that polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) can interact and enhance developmental neurobehavioral defects when the exposure occurs during a critical stage of neonatal brain development. PBDEs are used in large quantities as flame-retardant additives in polymers, especially in the manufacture of a great variety of electrical appliances, and textiles. In contrast to the well-known persistent compounds PCBs and DDT, the PBDEs have been found to increase in the environment and in human mother's milk. We have previously shown that low-dose exposure to environmental toxic agents such as PCB can cause developmental neurotoxic effects when present during a critical stage of neonatal brain development. Epidemiological studies indicate the adverse neurobehavioral impact of PCBs. Recently, we reported that neonatal exposure to PBDEs causes developmental neurotoxic effects. In the present study, 10-day-old Naval Medical Research Institute male mice were given one single oral dose of PCB 52 (1.4 micromol/kg body weight [bw]) + PBDE 99 (1.4 micromol), PCB 52 (1.4 micromol or 14 micromol), or PBDE 99 (1.4 micromol or 14 micromol). Controls received a vehicle (20% fat emulsion). Animals exposed to the combined dose of PCB 52 (1.4 micromol) + PBDE 99 (1.4 micromol) and the high dose of PCB 52 (14 micromol) or PBDE 99 (14 micromol) showed significantly impaired spontaneous motor behavior and habituation capability at the age of 4 and 6 months. The neurobehavioral defects were also seen to worsen with age in mice neonatally exposed to PCB 52 + PBDE 99.