skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Possible effects of fluorides on the thyroid

Abstract

A review of the literature on the relationship of fluorides and the thyroid gland reveals that the fluoride concentration within the thyroid gland on a wet basis is frequently at levels approximating, or above, those of blood and also, frequently, above those of other tissues including the kidneys. According to some investigators the fluoride concentration in the thyroid decreases at a slower rate than in other organs once animals are removed from fluoride intake. Fluoride appears to be actively concentrated by some of the thyroid cells and metabolized into such a form that it is not lost as readily as it is from other tissues when blood levels decrease. Fluorides at sufficient concentration produce profound morphological changes in the thyroid. The lower level of fluoride intake at which this may occur is open to discussion. Functional changes, however, may be seen frequently at daily intakes of 5 mg. Changes in activity of adenyl-cyclase concentrations are frequently encountered in thyroid glands at current levels of fluoride pollution. To date, analytical methods have not permitted these changes to be shown in vivo.

Authors:
Publication Date:
OSTI Identifier:
5117956
Resource Type:
Journal Article
Resource Relation:
Journal Name: Fluoride; (United States); Journal Volume: 9:2
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; CYCLASES; ENZYME ACTIVITY; FLUORIDES; BIOLOGICAL EFFECTS; TISSUE DISTRIBUTION; THYROID; MORPHOLOGICAL CHANGES; BLOOD; METABOLISM; BIOLOGICAL MATERIALS; BODY; BODY FLUIDS; DISTRIBUTION; ENDOCRINE GLANDS; ENZYMES; FLUORINE COMPOUNDS; GLANDS; HALIDES; HALOGEN COMPOUNDS; LYASES; MATERIALS; ORGANS 560305* -- Chemicals Metabolism & Toxicology-- Vertebrates-- (-1987)

Citation Formats

McLaren, J.R.. Possible effects of fluorides on the thyroid. United States: N. p., 1976. Web.
McLaren, J.R.. Possible effects of fluorides on the thyroid. United States.
McLaren, J.R.. 1976. "Possible effects of fluorides on the thyroid". United States. doi:.
@article{osti_5117956,
title = {Possible effects of fluorides on the thyroid},
author = {McLaren, J.R.},
abstractNote = {A review of the literature on the relationship of fluorides and the thyroid gland reveals that the fluoride concentration within the thyroid gland on a wet basis is frequently at levels approximating, or above, those of blood and also, frequently, above those of other tissues including the kidneys. According to some investigators the fluoride concentration in the thyroid decreases at a slower rate than in other organs once animals are removed from fluoride intake. Fluoride appears to be actively concentrated by some of the thyroid cells and metabolized into such a form that it is not lost as readily as it is from other tissues when blood levels decrease. Fluorides at sufficient concentration produce profound morphological changes in the thyroid. The lower level of fluoride intake at which this may occur is open to discussion. Functional changes, however, may be seen frequently at daily intakes of 5 mg. Changes in activity of adenyl-cyclase concentrations are frequently encountered in thyroid glands at current levels of fluoride pollution. To date, analytical methods have not permitted these changes to be shown in vivo.},
doi = {},
journal = {Fluoride; (United States)},
number = ,
volume = 9:2,
place = {United States},
year = 1976,
month = 4
}
  • Thirty-two holstein-friesian heifers, divided into groups and fed 10, 25, 50, and 100 ppm sodium fluoride for approximately 7 1/2 years, were studied to determine the effect of fluoride on the hematopoietic system, liver, and thyroid gland. The composite and individual results of numerous detailed blood studies, identical to those used in evaluating the hematopoietic system in man, established that fluoride, fed daily in concentrations up to 100 ppm for more than seven years, (1) does not show gross, histological or functional effects on the thyroid gland or liver and does not produce significant changes in the serum albumen phosphorusmore » or numerous other blood chemistries studied; (3) had a minimal blood effect in the form of a slightly higher total eosinophil count and a lower level of serum folic acid activity in the 100 ppm group; (4) does not produce anemia or detectable abnormalities of the bone marrow or otherwise affect the hematopoietic system.« less
  • The risk of developing thyroid cancer and other thyroid neoplasms after radiation exposure is well known, but specific modifiers of the dose-response relationship are not. The authors have identified 4,296 subjects who received treatment before their sixteenth birthday with orthovoltage radiation for benign conditions in the head and neck area. Individual thyroid dose estimates were calculated for 3,843 subjects. Of the 2,634 subjects who have been found, 1,043 have developed thyroid nodules of all types, and 309 have developed thyroid cancer. The radiation dose-response relationship was consistent with a linear excess relative risk model for thyroid cancer and thyroid nodulesmore » within the range of observed doses. Women developed thyroid cancer and thyroid nodules at a higher rate, but the slopes of the dose-response curves were the same for men and women. Age at radiation exposure was a significant factor of the risk, with a lower age at exposure associated with a higher risk. To determine the effect of the wide publicity and the screening program, which began in 1974, the authors compared the dose-response relationship for cases diagnosed before and after 1974. The overall rates increased dramatically after 1974, but the estimates of the slopes of the dose-response curves were not statistically different. The slope of the dose-response curve for thyroid neoplasms appears to have reached a maximum 25-29 yr after radiation exposure, but the dose response continued to be elevated at the end of follow-up. These data are consistent with the tumorigenic effects of radiation lasting at least 40 yr.« less
  • Reports of thyroid cancer as a consequence of head and neck irradiation during infancy are discussed. It is pointed out that physicians have overlooked the use of radiotherapy for pertussis during 1920 to 1940. Hazards of thyroid neoplasia in adults as a result of radiotherapy for whooping cough are emphasized. (HLW)
  • It has been shown previously that the thioureylene antithyroid drugs 6-propyl-2-thiouracil (PTU) and 1-methyl-2-mercaptoimidazole (MMI) can inactivate thyroid peroxidase (TPO) in a model iodination system containing relatively high concentrations of iodide. The purpose of the present study was to determine whether these drugs may also inactivate TPO in vivo in rats. Assays for total TPO activity after injection of PTU or MMI did not prove to be a valid approach. As TPO inactivation might be expected to result in a relatively prolonged inhibition of enzyme activity, most of our experiments involved measurement of the duration of the inhibitory effect ofmore » a single injection of drug. Young rats were injected with low doses of PTU or MMI, and the effect on thyroidal organic iodine formation was determined at intervals after injection, either by 1-h pulse labeling with /sup 131/I- in vivo or by incubation of excised thyroid lobes in a medium containing /sup 131/I-. Results of both types of experiment demonstrated that the inhibitory effect of a small dose of PTU (1 mumol/100 g BW) was still very marked 17-18 h after injection. Moreover, an inhibitory effect of this small dose of PTU on the metabolism of (/sup 35/S)MMI could also be demonstrated. Administration of MMI to rats, on the other hand, did not show the prolonged inhibitory effect observed with PTU. This is most likely attributable to the much lower thyroidal uptake of MMI than of PTU in rats. Intrathyroidal metabolism of (/sup 35/S)PTU and (/sup 35/S)MMI was also investigated. In contrast to the rapid disappearance of /sup 35/S from plasma, both drugs showed accumulation and retention of /sup 35/S in the thyroid. However, we obtained no evidence that thyroidal accumulation of PTU or one of its metabolites could explain the prolonged inhibitory effect of this drug. It seemed more likely that this was attributable to TPO inactivation.« less