Abstract
In India, there has been a change from the situation present in the 1930s–1970s, when fluoride toxicity was seen to involve just the hard tissues of teeth and bones, to the situation in the 2000s–2010s when recognition was given to the occurrence of non-skeletal symptoms and that these were a key to a new approach to the prevention and treatment of fluorosis by dietary editing and dietary counselling. In New Zealand, a lack of recognition of non-skeletal fluorosis, similar to that present in India in the 1930s–1970s, was present in 1957, when a Commission of Inquiry on the Fluoridation of Public Water Supplies gave the opinion that the individual signs and symptoms of the alleged “Spira-Waldbott Syndrome” syndrome may be due to any number of unrecognised causes. A similar conclusion was reached in a 2014 New Zealand report, Health effects of water fluoridation: a review of the scientific evidence, which noted that “The only side effect of fluoridation at the levels used in NZ (0.7–1.0 mg/L) is minimal fluorosis, and this is not of major cosmetic significance. … In particular, no effects on brain development, cancer risk or cardiovascular or metabolic risk have been substantiated, and the safety margins are such that no subset of the population is at risk because of fluoridation.” Currently, an international difference is present between India and New Zealand in the recognition of non-skeletal fluorosis. In India, recognition of this syndrome has been seen to be the key to the prevention and treatment of fluorosis while in New Zealand an authoritative panel has found that non-skeletal fluorosis is not a cause for concern. However, taking account of the recent papers by Bashash et al. (2017) and Thomas et al. (2018), a safe daily intake of F for pregnant women and children of all ages to give protection from F-induced neurotoxicity can been estimated to be approximately 0.04 mg F/day (0.0006 mg F/kg bw/day for a 70 kg woman) and 0.15 mg F/day (0.003 mg F/kg bw/day for a 45 kg child, the 90th percentile children’s body mass at 8–13 yr), respectively, which would be contained in only 72 and 214 mL, respectively, of water fluoridated at 0.7 mg/L. A consequence of this is that in order to prevent F-induced IQ loss in children, pregnant women and children, up to the age of 7 yr, should avoid the use of fluoridated community water supplies. In conclusion, the Indian view that non-skeletal fluorosis is a real problem and that for drinking water the “lesser the fluoride the better, as fluoride is injurious to health” is more consistent with the current scientific knowledge than the New Zealand view that the existence of a condition of non-skeletal fluorosis is not supported by an evidence base and that the use of drinking water fluoridated at 0.7 mg/L has no effects on brain development.