Antithyroid and Goitrogenic Effects of Coal-Water Extracts from Iodine-Sufficient Goiter Areas

Goiter in iodine-sufficient areas has been linked to water-borne goitrogens in watersheds and aquifers rich in coal and shale. In the present study, the potential antithyroid and goitrogenic effects of coal-water extracts (CWE) were investigated in vivo in rats after chronic and acute oral administration of CWE, and in vitro by a thyroid peroxidase (TPO) enzyme system. CWE was prepared by continuous extraction of ground (40 mesh) Appalachian coal with goitrogen-free water (GFW). Female Buffalo rats fed on Purina iodine-rich diet (12 μg I-/day/rat), were given ad lib CWE (50 mg/ml; ~ 20 mL/day/rat) or GFW (controls) for 2 months. At the end of the experiment, 125I 1 μCi, was injected i.p. and 4 h later the thyroid glands were removed, weighed, and analyzed histologically and for total 125I and 125I-labeled compounds. Rats on CWE had larger thyroid glands [7.2 ± 0.3 mg/100 g (mean ± SE) vs 5.0 ± 0.5 controls; p < 0.005] with distinct histological changes of smaller thyroid follicles, some with columnar epit...