Fluoride intake of infants in New Zealand

Abstract

A study was designed to determine current levels of fluoride ingestion from all sources by infants aged 11-13 months, resident in fluoridated and non-fluoridated areas in New Zealand. The quantity, nature, and form of all food and drinks ingested by 60 infants over a period of 3 days were duplicated and analysed for fluoride. The HMDS-HCl diffusion technique was used to isolate the fluoride content in unashed liquid homogenates of the diet, and the isolated fluoride was then measured by the fluoride electrode. Ionic fluoride content of breast milk was analysed by the direct method. Other sources of fluoride intake in this age group of infants were identified to be fluoridated toothpastes and fluoride supplements, and the fluoride intake from these sources was estimated. In this study, the daily dietary fluoride intake ranged from 0.009-0.056 and 0.004 - 0.038 mg F/kg of body weight for infants resident in fluoridated and non-fluoridated areas respectively. The mean dietary fluoride intake of infants in the non-fluoridated areas was one third that of the fluoride intake of their counterparts in the fluoridated areas, and was nearly five to seven times less than the recommended "optimal" levels of intake. In the fluoridated area, the mean fluoride intake of infants was about half the recommended "optimal" level of intake. The use of fluoride supplements (0.25 mg F/day) in the non-fluoridated area raised the total fluoride intake, but it was still below the recommended "optimal" levels of intake. The use and ingestion of fluoridated toothpastes increased the total fluoride intake of infants in the non-fluoridated areas to near "optimal" levels, but it caused total fluoride intake of some infants in the fluoridated areas to exceed the "optimal" levels. It was calculated that, if a child on soy-formula in the non-fluoridated areas was to ingest fluoride supplements and large amounts of toothpaste as well, then the total fluoride intake of this infant could exceed "optimal" levels of intake. This observation stresses the need to identify higher sources of fluoride intake in a child's diet before any form of fluoride supplementation is recommended. The study also demonstrated the need for determining the relationship between dietary fluoride intake, plasma fluoride level, dental caries and enamel fluorosis in order to establish optimal levels of fluoride intake.