Fluorine

Executive Summary

Abstract

The Food Safety Commission of Japan (FSCJ) was asked by the Ministry of Health, Labour and Welfare to assess the risks of chemical substances related to the revision of the standards and criteria for ‘beverages.’ Since fluorine is one of the substances, the risk assessment on fluorine and fluoride was conducted. The data used in the assessment include those from: acute toxicity tests in mice and rats, subacute toxicity tests in mice, rats, rabbits, dogs and pigs, chronic toxicity and carcinogenicity tests in mice, rats and rabbits, neurotoxicity tests in mice and rats, immunotoxicity tests in mice, rats and rabbits, reproductive and developmental toxicity tests in mice and rats, genotoxicity tests, and epidemiological studies and others. Although fluorine has been considered to be an essential element, clear evidence has not been presented. Moreover, its daily minimum requirement has not been established. Epidemiological studies to examine the carcinogenicity of fluoride in drinking water have been conducted, but failed to provide clear evidence of carcinogenicity in humans. Carcinogenicity has not been clearly shown in laboratory animals, either. Fluoride has been reported to be weakly genotoxic in in vitro studies using cultured mammalian cells. It is, however, reported that in vivo DNA damage tests have not indicated genotoxicity. Taken together, it was considered that fluorine has no genotoxicity relevant to human health. Hence, it was concluded that it is appropriate to specify a tolerable daily intake (TDI) of fluorine in terms of non-carcinogenic toxicity. Based on an epidemiological study of 5,800 children from 12 to 14 years old in the United States, a concentration of 1.0 ppm at which effect was not observed, was taken as a base. Given that the body weight of a child is 20 kg and the amount of water that a child drinks per day is 1 L, no-observed-adverse-effect-level (NOAEL) was calculated to be 0.05 mg/kg body weight per day. Since this value was that obtained from the study of susceptible population, it was considered that this value could be taken as TDI without applying uncertainty factors. As a conclusion, FSCJ specified the TDI of fluorine to be 0.05 mg/kg body weight per day.