Freudenthal R I, Kerchner G, Persing R, Baron R L
J Environ Pathol Toxicol. 1978 Sep-Oct;1(1):147-61.
Ethylene thiourea (ETU) was fed to groups of rats at 0, 1, 5, 125 or 625 ppm for up to 90 days. Other groups of rats received either propylthiouracil (PTU; 125 ppm) or amitrole (50 ppm) in their diets as positive controls. Only those rats which received ETU at 125 or 625 ppm and those ingesting PTU or amitrole demonstrated a measurable toxic response. This toxicity was reflected as an alteration in thyroid function and a significant change in thyroid morphology. Ingestion of 625 ppm ETU or 125 ppm PTU resulted in very substantial decrease in serum triiodothyronine (T-3) and thyroxine (T-4). Marked increases in serum thyroid stimulating hormone (TSH) levels were found in the 625 and 125 ppm ETU rats, the 125 PTU rats, and the rats receiving amitrole, each time this hormone was measured. Rats which ingested 625 ppm ETU also exhibited a decrease in iodide uptake by the thyroid. While a statistically significant increase in serum T-4 and degree of thyroid hyperplasia was observed for rats ingesting 25 ppm ETU for 60 days, normal thyroid hormone levels and thyroid morphology was found in rats on 25 ppm ETU for either 30 or 90 days. Based on diochemical and microscopic changes examined, the no-effect level for dietary ETU in this 90-day study is considered to be 25 ppm.
将乙烯硫脲（ETU）以0、1、5、125或625 ppm的剂量喂给几组大鼠，持续90天。其他几组大鼠在饮食中分别接受丙硫氧嘧啶（PTU；125 ppm）或杀草强（50 ppm）作为阳性对照。只有那些接受125或625 ppm ETU的大鼠以及摄入PTU或杀草强的大鼠表现出可测量的毒性反应。这种毒性表现为甲状腺功能改变和甲状腺形态的显著变化。摄入625 ppm ETU或125 ppm PTU导致血清三碘甲状腺原氨酸（T-3）和甲状腺素（T-4）大幅下降。在每次测量时，发现625和125 ppm ETU组的大鼠、125 ppm PTU组的大鼠以及接受杀草强的大鼠血清促甲状腺激素（TSH）水平显著升高。摄入625 ppm ETU的大鼠甲状腺对碘的摄取也减少。虽然摄入25 ppm ETU 60天的大鼠血清T-4和甲状腺增生程度有统计学意义的增加，但摄入25 ppm ETU 30天或90天的大鼠甲状腺激素水平和甲状腺形态正常。根据所检查的生化和微观变化，在这项90天的研究中，饮食中ETU的无作用水平被认为是25 ppm。
