Potential for Manganese-Induced Neurologic Harm to Formula-Fed Infants: A Risk Assessment of Total Oral Exposure.

BACKGROUND

High oral exposure and biological vulnerabilities may put formula-fed infants at risk for manganese-induced neurotoxicity.

OBJECTIVES

We sought to characterize manganese concentrations in public drinking water and prepared infant formulas commonly purchased in the United States, integrate information from these sources into a health risk assessment specific to formula-fed infants, and examine whether households that receive water with elevated manganese concentrations avoid or treat the water, which has implications for formula preparation.

METHODS

Manganese was measured in 27 infant formulas and nearly all Minnesota community public water systems (CPWS). The risk assessment produced central tendency and upper-end exposure estimates that were compared to a neonatal animal-based health reference dose (RfD) and considered possible differences in bioavailability. A survey study assessed esthetic concerns, treatment, and use of water in a Twin Cities community with various levels of manganese in drinking water.

RESULTS

Ten percent of CPWSs were estimated to exceed the EPA health advisory level of . Manganese concentrations in formula ranged from 69.8 to , with amino formula concentrations. Central tendency estimates of soy and amino acid formula reconstituted with water at the CPWS 95th percentile manganese concentration exceeded the neonatal-based RfD. Upper-end estimates of manganese intake from formula alone, independent of any water contribution, equaled or exceeded the neonatal-based RfD. In the survey study, we observed increased awareness of esthetic issues and water avoidance at higher manganese concentrations, but these concentrations were not a reliable consumption deterrent, as the majority of households with inside tap drinking water results above reported drinking the water.

DISCUSSION

Excessive exposure to manganese early in life can have long-lasting neurological impacts. This assessment underscores the potential for manganese overexposure in formula-fed infants. U.S. agencies that regulate formula and drinking water must work collaboratively to assess and mitigate potential risks. https://doi.org/10.1289/EHP7901.