Acute and Chronic Fluoride Toxicity

Compared with the latter half of the 19th century and the first half of the 20th century, the frequency of fatalities stemming from the ingestion of fluoride compounds has declined dramatically. Since 1978, there have been four fatalities caused by the ingestion of fluoride, all in dental products. The numbers of exposures to fluoride doses that cause concern, however, has increased, as judged by the annual reports of the American Association of Poison Control Centers. The number of reports made to poison control centers has increased from approximately 7700 in 1984 to 10,700 in 1989. Over 3700 persons have been treated in health care facilities for exposure to fluoride during this period, and there have been 133 cases for which the medical outcomes were classified as moderate or major. The sources of fluoride have been limited almost exclusively to fluoride-containing vitamins and dental products. Based on a review of the doses involved in the four fatalities, three of which involved young children, the “probably toxic dose” of fluoride has been set at 5 mg F/kg body weight. For children who are 6 years of age or less, the PTD can be found in single containers of several kinds of dental products. Recommendations that should reduce the frequency of over-exposures to fluoride are described. Regarding adverse effects due to the chronic intake of fluoride (excluding dental fluorosis), there is no evidence for risk in the US up to the level of intake that is associated with drinking water containing 4 ppm. This statement is based on 1990 or 1991 reports by the NY State Department of Health, the USPHS, and the National Cancer Institute. Two new reports, however, have implicated chronic fluoride intake at relatively low levels in a higher incidence of bone fractures. This relationship requires further study.