Fluoride intake of Japanese infants from infant milk formula

This study aimed to measure the fluoride (F) content of all infant milk formulas (IMF) available for purchase in Japan and estimate the F exposure of infants whose primary source of nutrition is IMF when reconstituted with different F concentrations of water. Twenty-two commercially available IMFs were purchased from 6 manufacturers in Japan. These IMFs included 21 milk-based products and 1 soy-based product. Each IMF was reconstituted using distilled water and 0.13 μg F/ml fluoridated water according to the manufacturers' instructions. The F concentrations in each sample were measured using the hexamethyldisiloxane diffusion technique and an F ion-selective electrode. The mean F concentration of all products was 0.41 (range 0.15-1.24) μg/g. There were no statistically significant differences among mean F concentrations of newborn milks, follow-on milks and other milks or among manufacturers. The mean F concentration of all products, when reconstituted with distilled water and 0.13 μg F/ml water, was 0.09 and 0.18 μg/ml, respectively. The mean F intake from IMF ranged from 0.039 to 0.134 mg/day with distilled water and from 0.078 to 0.258 mg/day with 0.13 μg/ml fluoridated water, respectively. These results suggested that F intake of infants from IMFs depended on the F concentration of added water, and therefore the risk of dental fluorosis for most Japanese infants would be small since most Japanese municipal water supplies are low in F. However, there was a possibility to exceed the tolerable upper intake level, even under the limit of the law, especially for infants within the first 5 months of life.