Record Display for the EPA National Library Catalog


Main Title Dietary Subacute Toxicity of Ethylene Thiourea in the Laboratory Rat.
Author Freudenthal, Ralph I. ; Kerchner, Gail ; Persing, Ronald ; Baron, Ronald L. ;
CORP Author Health Effects Research Lab., Research Triangle Park, NC. Environmental Toxicology Div.
Year Published 1977
Report Number EPA-600/J-77-168;
Stock Number PB80-129927
Additional Subjects Toxicology ; Thyroid gland ; Ingestion(Biology) ; Rats ; Laboratory animals ; Thyroid hormones ; Diets ; Responses ; Morphology ; Physiological effects ; Reprints ; Thiouvacil/propyl ; Toxic substances ; Histopathology
Library Call Number Additional Info Location Last
NTIS  PB80-129927 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 17p
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 decreases 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 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 biochemical and microscopic changes examined, the no-effect level for dietary ETU in this 90-day study is considered to be 25 ppm.