A laboratory study of fluoride concentration in infant formulas marketed in Malaysia and estimation of daily intake

The window of maximum susceptibility for the development of dental fluorosis for anterior teeth is during the first two to three years of life. The primary source of fluoride intake for infants at this age is mainly from the diet including infant formula. Thus, the present work aimed to investigate the fluoride concentration in commercially available Malaysian infant formulas that required reconstitution before consumption. A total of 29 infant formulas available in the Malaysian market were reconstituted with deionised water, fluoridated tap water, and filtered tap water. The fluoride concentration of the infant formulas was analysed directly using a fluoride ion selective electrode. The daily fluoride intake estimation from the infant formulas was calculated using the median infant body weight and recommended volumes for formula consumption from newborn to > 12 months of age. Results showed that the fluoride concentration of the infant formulas when reconstituted with deionised water ranged between 0.009 to 0.197 mg/L that contributed to the estimated daily fluoride intake ranging from 0.005 to 0.100 mg (total intake per day) or 0.001 to 0.025 mg/kg (total intake per body weight/day). The fluoride concentration in the selected infant formulas was low, but after reconstitution with fluoridated tap water, the overall fluoride concentration in infant formulas sample significantly increased (p < 0.001). Nevertheless, the estimated daily fluoride intake from infant formulas alone did not exceed the lowest-observed-adverse-effect level (LOAEL) of fluoride at 0.10 mg/kg/day.