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DEVELOPMENTAL EXPOSURES TO POLYBROMINATED DIPHENYLETHERS: DISRUPTION OF THYROID HORMONES, HEPATIC METABOLISM AND NEUROBEHAVIORAL DEVELOPMENT.
Citation:
Crofton, K M., M. M. Taylor, J M. Hedge, M. E. Gilbert, AND M J. DeVito. DEVELOPMENTAL EXPOSURES TO POLYBROMINATED DIPHENYLETHERS: DISRUPTION OF THYROID HORMONES, HEPATIC METABOLISM AND NEUROBEHAVIORAL DEVELOPMENT. Presented at International Neurotoxicology Association, Dresden, Germany, 6/23-27/03.
Description:
Polybrominated diphenyl ethers (PBDEs), produced commercially as mixtures, are used as flame-retardants in numerous consumer products. Previous work has demonstrated that the DE-71 induces hypothyroxinemia in various animal models. In a series of studies, primiparous dams were exposed to the commercial PBDE, DE-71 (1 - 100mg/kg/day) in 1.0 ml/kg corn oil from gestation day 6 (GD6) to postnatal day 21 (PND21). Offspring were evaluated at various ages for survival, body weight, serum thyroid hormones, hepatic enzyme activity (EROD, PROD, UDPGT), age of eye opening, motor activity development, auditory startle, auditory thresholds, and fear conditioning. 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 during the early postnatal period that recovered in adults. There were no effects on T3 or TSH. DE-71 caused increases in hepatic EROD, PROD and UDPGT activity in both offspring and dams. Motor activity and startle were unaffected by treatment. Tests of fear conditioning revealed a dose-dependent decrease in cue- but not context-based performance in male offspring tested as adults. There was no effect on fear conditioning performance in offspring tested as weanlings. Auditory thresholds were slightly elevated (~15 dB) at 1 kHz. These data suggest that developmental exposure to DE-71 induces hypothyroxinemia via up-regulation of hepatic enzymes in both dams and offspring, and alters some aspects of offspring neurobehavioral development. This is an abstract of a proposed presentation and does not necessarily reflect U.S.EPA policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.