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Risks of Naturally Occurring Arsenic in Rice in Infant Cereals—Commentary

Commentary
06/06/16 Gerald F. O’Malley, DO, Grand Strand Regional Medical Center|Sidney Kimmel School of Medicine, Thomas Jefferson University Hospital;

A recent epidemiological study examined the association between rice product consumption and arsenic exposure during the first year of life. The researchers recorded modestly elevated levels of arsenic in the urine of a small number of children who ate rice-based products compared to those whose diets did not include rice or fish. The authors recommend limiting the amount of arsenic that children are exposed to.

Arsenic in rice food products is not a new concern, and the US FDA recently devoted attention to the potential adverse health effects of early life exposure to arsenic and proposed an “action limit” of 100 parts per billion (ppb) for inorganic arsenic in infant rice cereal.

Why is there arsenic in rice?

Arsenic is a naturally occurring element in soil and groundwater that is incorporated into foods during growth; hence, there are small amounts of arsenic in rice, broccoli, carrots, and many other plant foods. Rice, because it grows in water, may contain more arsenic than other plants. Arsenic in rice products is not a contaminant or byproduct of production. Several different types of arsenic exist; rice products contain inorganic and organic species of arsenic.

The amount of arsenic in rice cereal is an important issue for several reasons. Beginning at 6 months of age, infant iron stores diminish, and fortified rice cereals are a good source of iron. In addition, single-grain infant rice cereal is recommended as one of the first solid foods because it is the least likely grain to induce allergies. Finally, in developing countries, rice foods comprise a large percentage of the infant diet. Infants typically consume significant amounts of rice relative to their body weight during their first year of life and thus may be exposed to higher amounts of arsenic than at any other time.

What are the toxicities of arsenic, particularly at levels found in this study?

Both organic and inorganic arsenic are potentially toxic, but inorganic arsenic has a greater potential for toxicity. Exposure to relatively high levels of inorganic arsenic in utero may result in decreased performance on certain developmental tests that measure learning in childhood. An analysis by the US FDA in 2013 estimated that exposure to inorganic arsenic in rice and rice products caused a very small (less than 1%) increase in the number of cases of lung and bladder cancer over a lifetime.

The levels of total urinary arsenic (all species) in the recent study was 5.83 mcg/L. This level is consistent with total urinary arsenic concentrations associated with rice food consumption described in previous studies of American children from the National Health and Nutrition Examination Survey (8.9 mcg/L ) and an order of magnitude less than that found in a Bangladeshi population of rice eaters (37 mcg/L). The Bangladeshi study must be considered in the context of the median concentration of arsenic in the water (80 mcg/L), which is much higher than the US Environmental Protection Agency standard of 10 mcg/L. However, even though rice foods comprise a large percentage of the infant diet in developing countries, evidence of severe or widespread neurodevelopmental effects or cancers is lacking. The US FDA and the American Academy of Pediatrics (AAP) have published brief statements emphasizing that arsenic intake at the levels found in rice is not expected to pose any acute or immediate health risks. 

What steps can be taken?

There is no way to completely remove arsenic from rice, but cooking rice in excess water (from 6 to 10 parts water to one part rice instead of the more typical 2:1 ratio), and draining the excess water, reduces 40 to 60 percent of the inorganic arsenic content, depending on the type of rice. However, this method may also remove nutrients from the rice. There is no similar home method to remove arsenic from processed rice products (eg, rice cereal). The US FDA has requested manufacturers of rice-based foods to reduce the arsenic exposure to meet actionable threshold guidelines, since almost half the rice products tested by the Agency exceed the recommended concentration of arsenic.

What’s the bottom line for our patients?

Current evidence (and statements from the FDA and AAP) does not suggest need for alarm. But, given the availability of alternatives to rice-based infant cereals and the advisability of limiting arsenic exposure to the developing human, it seems reasonable for families to reduce feeding of rice-based food products, including rice milk, and to substitute a variety of iron-fortified cereals made from oats and barley. However, if such products are not tolerated, parents should not be worried about giving rice-based cereal.  

References

Karagas MR, Punshon T, Sayarath V, et.al. Association of rice and rice-product consumption with arsenic exposure early in life. JAMA Pediatr. Published online April 25, 2016. doi: 10.1001/jamapediatrics.2016.0120 

Carignan C, Punshon T, Karagas MR, Cottingham KL. Potential exposure to arsenic from infant rice cereal. Ann Global Health. Published online March 4, 2016. doi.org/10.1016/j.aogh.2016.01.020

Lai PY, Cottingham KL, Steinmaus C, et.al. Arsenic and rice: Translating research to address health care providers' needs. J Pediatr 167(4):797803, 2015.

Zhu YG, Williams PN, Meharg AA. Exposure to inorganic arsenic from rice: A global health issue? Enviro Pollut 154:169–171, 2008.

Tolins M, Ruchirawat, Landrigan P. The developmental neurotoxicity of arsenic: Cognitive and behavioral consequences of early life exposure. Ann Global Health 80(4):303-314, 2014. doi: 10.1016/j.aogh.2014.09.005

Melkonian S, Argos M, Hall MN, Chen Y, Parvez F, Pierce B, et al. Urinary and dietary analysis of 18,470 Bangladeshis reveal a correlation of rice consumption with arsenic exposure and toxicity. PLoS ONE 8(11): e80691, 2013. doi:10.1371/journal.pone.0080691

See Dr. O'Malley's discussion of Poisoning in The Manual.