Studies find arsenic in food adds up
By Angela Spivey
Three studies published in the last two months by grantees of the NIEHS Superfund Research Program (SRP) and NIEHS/EPA Centers for Children’s Environmental Health and Disease Prevention Research add to the growing body of evidence for proposals that arsenic levels in food require regulation.
The studies show that, in some cases, the amount of total arsenic being consumed in certain common foods is as much or more than the acceptable limits set for drinking water by the U.S. Environmental Protection Agency (EPA). In all three studies, the authors conclude that the results point to a need to set regulatory limits for arsenic in food.
“It’s possible that for a large number of individuals, their main exposure route to arsenic is food, not water. But we don’t have guidelines on what the acceptable levels are for arsenic in food,” said Brian Jackson, Ph.D., director of the Trace Element Analysis Core Facility at Dartmouth College, a member of the SRP, and the lead author of two of the studies.
Popular foods may be sources of arsenic
The research findings, published in December 2011 and January and February 2012, show that in addition to plain rice, foods that may be sources of arsenic exposure include toddler formula, baby foods, cereal bars, and energy gels used by athletes.
“From all these food products, the exposure is cumulative,” Jackson said. One food alone would not be cause for concern, but eating a diet made up exclusively of rice-based foods may expose people to arsenic levels comparable to the current drinking water limits. “Groups at potentially greatest risk are toddlers who are fed a rice syrup-based toddler formula, and potentially people who are following a gluten-free diet,” Jackson explained. Many gluten-free products substitute rice for wheat.
The most recent of the three studies, published Feb. 16 in Environmental Health Perspectives, found that organic brown rice syrup, which is used in organic food products as an alternative to high fructose corn syrup, can contain significant concentrations of inorganic arsenic, the form classified as a human carcinogen. Toddler formula, cereal bars, and energy foods aimed at athletes that contained organic brown rice syrup had higher total arsenic concentrations than similar products that didn’t contain the syrup. One toddler formula that listed organic brown rice syrup as the main ingredient had inorganic arsenic concentrations that were up to 2.5 times the EPA safe drinking water limit.
Infants of special concern
Jackson’s January 2012 study, published in Pure and Applied Chemistry, showed that infant formula and jarred baby foods are a significant source of arsenic exposure. Though many of the formulas and foods tested had relatively low levels of arsenic, 1-23 nanograms per gram of food, the levels were of concern because the arsenic was mostly of the toxic inorganic form and because infants are so small.
“Especially for some of the second- and third-stage foods, infants could be getting a high rate of exposure to arsenic based on their body weight,” Jackson said. These exposures do not include any additional exposure from water or from rice-based cereals. “However, comparing levels in food to safe drinking water limits is not ideal. Drinking water limits are based on lifetime exposure and can’t be translated to any single food item. This further highlights the need for guidelines or regulations specifically for food," cautions Kathryn Cottingham, Ph.D., who leads the Children’s Center study investigating dietary sources of arsenic among infants.
An earlier study showed that in pregnant women, rice consumption was associated with increased urinary levels of arsenic. Women who had eaten rice in the previous two days had urinary arsenic concentrations of 5.27 micrograms per liter, compared to 3.38 micrograms per liter for those who hadn’t eaten rice, a statistically significant difference. The study was published December 2011 in the Proceedings of the National Academy of Sciences. Margaret Karagas, Ph.D., was the senior author of this study and principal investigator of the cohort.
Gilbert-Diamond D, Cottingham KL, Gruber JF, Punshon T, Sayarath V, Gandolfi AJ, Baker ER, Jackson BP, Folt CL, Karagas MR. 2011. Rice consumption contributes to arsenic exposure in U.S. women. Proc Natl Acad Sci U S A. 108(51):20656-20660.
Jackson BP, Taylor VF, Punshon T, Cottingham KL. 2012. Arsenic concentration and speciation in infant formulas and first foods. Pure Appl Chem 84(2): 215-223.
Jackson BP, Taylor VF, Karagas MR, Punshon T, Cottingham KL. 2012. Arsenic, Organic Foods, and Brown Rice Syrup. Environ Health Perspect; doi: 10.1289/ehp.1104619 [Online 16 February 2012].
(Angela Spivey is a contract science writer for the NIEHS Superfund Research Program.)