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PERINATAL EXPOSURE TO A POLYBROMINATED DIPHENYL ETHER MIXTURE (DE-71) DISRUPTS THYROID HORMONES BUT NOT NEUROBEHAVIORAL DEVELOPMENT.
Citation:
Taylor, M. M., J M. Hedge, M J. DeVito, AND K M. Crofton. PERINATAL EXPOSURE TO A POLYBROMINATED DIPHENYL ETHER MIXTURE (DE-71) DISRUPTS THYROID HORMONES BUT NOT NEUROBEHAVIORAL DEVELOPMENT. Presented at Society of Toxicology, Nashville, TN, March 17-21, 2002.
Description:
Polybrominated diphenyl ethers (PBDEs), produced commercially as mixtures, are used as flame-retardants for numerous consumer products. Because of their lipophilicity and persistence, PBDEs have become ubiquitous environmental contaminants. Previous work in our lab has demonstrated that short-term (4 day) in vivo exposure to DE-71 in young rats (a commercial polybrominated diphenyl ether mixture containing mostly tetra- and penta-bromodiphenyl ethers) induces hypothyroxinemia. In this study, motor and auditory function were measured in offspring following perinatal maternal exposure to DE-71. Primiparous rats were orally administered DE-71 (0, 1, 10 and 30mg/kg/day) in corn oil from gestation day 6 (GD6) to postnatal day 21 (PND21). Offspring were evaluated at various ages for body weight, thyroid hormones, hepatic enzymes, eye opening, survival, motor activity development, and auditory startle response. There was no effect of DE-71 on body weight gain or survival in either the dams or offspring. There were dose-dependent decreases in thyroxine (maximal decrease of 55% on PND14), and increases in hepatic glucuronidation (3-fold). Both endpoints return to control levels by PND36. There were normal age-dependent changes in motor and sensory behaviors, but no effects of treatment. Benchmark dose (BMD) modeling resulted in BMDs of 2.3 and 5.5 mg/kg/day, and BMDLs (lower bound) of 0.9 and 3.4 mg/kg/day, for serum T4 and hepatic glucuronidation, respectively. These data suggest that DE-71 alters thyroid homeostasis during development, but does not seem to alter sensory or motor development as determined by these endpoints. This abstract does not necessarily reflect US EPA policy.