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MARGINAL IODINE DEFICIENCY EXACERBATES PERCHLORATE THYROID TOXICITY.
Das, P. C., J M. Hedge, D C. Wolf, AND K M. Crofton. MARGINAL IODINE DEFICIENCY EXACERBATES PERCHLORATE THYROID TOXICITY. Presented at Society of Toxicology, Baltimore, MD, March 21-25, 2004.
The environmental contaminant perchlorate disrupts thyroid homeostasis via inhibition of iodine uptake into the thyroid. This work tested whether iodine deficiency exacerbates the effects of perchlorate. Female 27 day-old LE rats were fed a custom iodine deficient diet with 0, 50, or 75% iodine deficiency for 28 days. After 14 days on the diet 0, 31, or 250 mg/L perchlorate were provided in drinking water for 14 days. Serum total T4, T3, and TSH were assayed by RIA, and standard histopathology was performed on thyroid. Neither the 50% deficient diet nor 31 mg/L perchlorate produced effects when given alone, but together reduced T4 ~35%, and elevated TSH ~5- fold. A 75% deficient diet plus 250 mg/L perchlorate also caused additive effects on T4 and T3. TSH was induced ~14-fold. Follicular cell hypertrophy was present in all treated rats, but was more severe with both treatments than either alone. Colloid depletion was present only after perchlorate treatment but not iodine deficiency. The marginal iodine deficient rat could represent a model for a sensitive sub-population for studying disruptions in thyroid homeostasis. This is an abstract of a proposed presentation and does not necessarily reflect U.S.EPA policy.
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY
NEUROBEHAVIORAL TOXICOLOGY BRANCH