CEHN Articles of the Month, June 2015 Issue
Estimated Exposure to Arsenic in Breastfed and Formula-Fed Infants in a United States Cohort
Authors: Courtney C. Carignan, Kathryn L. Cottingham, Brian P. Jackson, Shohreh F. Farzan, A. Jay Gandolfi, Tracy Punshon, Carol L. Folt, and Margaret R. Karagas
Arsenic is a naturally occurring element found in bedrock and is a common global contaminant of well water. It is also a known human carcinogen that is associated with skin, lung, bladder, kidney, and liver cancer, and can affect neurological, respiratory, cardiovascular, immunological, and endocrine systems. Infants and children are especially vulnerable to arsenic exposure in utero and during early life. They can experience higher total contaminant levels of arsenic in their bodies because their intakes adjusted for body mass are high, and their diet diversity is low. Arsenic exposure in early development is associated with increased fetal mortality, decreased birth weight, increased and more severe infections, and diminished cognitive function. Effects of chronic early life exposure to arsenic can continue into adulthood.
The U.S. Environmental Protection Agency (EPA) has set a maximum contaminant level of arsenic for public drinking water at .010 parts per million, but private well water is not subject to these regulations. Wells are a primary source of water for many rural parts of the United States (U.S.), and serve approximately 40% of the population in New Hampshire (where this study was conducted). Recent studies now show that formula powder can also contain low concentrations of arsenic. This suggests that both components of formula (powder and the water with which it is mixed) can be sources of arsenic for formula-fed infants who rely on well water. Breast milk, conversely, has been shown to have relatively low concentrations of arsenic, even in women with high exposure to arsenic from drinking water.
The objective of this study was to estimate the relative contributions of breast milk and formula to arsenic exposure during early infancy in the U.S. population.
To test the hypothesis that breastfed infants in New Hampshire have lower exposure to arsenic compared with formula-fed infants, arsenic in home tap water, arsenic in breast milk, and urinary arsenic concentrations were measured in a subset of infants enrolled in the New Hampshire Birth Cohort Study. A 3-day food diary for infants, where mothers/caretakers recorded the time, type of food or drink item, amount consumed, amount of water combined with formula (if any), and the source of the water was also used to estimate daily arsenic intake from breast milk and formula. These samples and the food diaries were then analyzed to predict the daily levels of the infant’s exposure to arsenic from breast milk and formula.
Urinary arsenic concentrations were lowest in infants that were exclusively fed with breastmilk, and 7.5 times higher in exclusively formula fed in-fants. Infants fed with both formula and breast milk had intermediate concentrations. The median estimated daily arsenic intake by infants was 5.5 times higher for formula fed infants than for breastfed infants. Among formula fed infants, formula powder was estimated to account for about 70% of the median exposure.
Infants fed only with breast milk had lower exposures to arsenic than those fed with only formula or with a mix of formula and breast milk. Both for-mula and drinking water can be sources of exposure to arsenic for U.S. infants.
As this study and others have shown, breastfeeding has important health benefits, such as reducing infant exposure to arsenic from formula and from arsenic found in well water. State and local health departments should continue to educate on the benefits of breastfeeding, and states and local councils should create safe spaces in the workplace and other environments outside the home for breastfeeding. In addition, supported education and outreach programs offering free or low-cost private well water testing in rural areas should be implemented. The U.S. Food and Drug Administration (FDA) recently tested levels of arsenic in rice and rice products, including in infant and toddler products. Rice cereal is a common first solid food for infants in the U.S., and some infant formula powders contain rice products. Results from this testing are being used to inform a draft risk assessment to determine any necessary further action. Considering vulnerable populations’ potential for cumulative exposure to arsenic from multiple sources, including drinking water, and contaminated air from the burning of arsenic-containing fossil fuels and pesticide manufacturing facilities, the regulation of food and food products for arsenic by FDA may be an important step in the protection of public health.