Arsenic in rice: big trouble for little infants?

Arsenic is a naturally occurring element found in soil and water, as it is present in the Earth’s crust as a constituent of over 200 different minerals. Natural processes like dust storms and volcanic eruptions, as well as human application, such as through pesticides, herbicides, wood preservation, production of electronics, paints, and other industries, contribute to the accumulation of arsenic in the environment. Arsenic is found both in inorganic and organic forms, which are compared in Figure 1. The inorganic kind is generally recognized as the more toxic form. Organic arsenic is found primarily in seafood like fish, shellfish, and seaweed.

Figure 1: Inorganic versus organic arsenic

Inorganic arsenic is a known carcinogen that can cause cancers of the lung, bladder, skin, kidney, and liver. Infants are particularly vulnerable to toxicants, and data from both observational studies and animal models suggest^[1] that arsenic exposure during early life increases the risk of respiratory diseases, impaired lung function, cancer, and cardiovascular disease. By contrast, organic arsenic^[2] exposure has little to no association with toxicity in humans.

Infant rice cereal is a common first food during the transition away from breast milk or formula, but intake of rice during infancy is not well characterized in the U.S. There has been a growing concern over levels of inorganic arsenic in rice and rice-based products because some rice crops may be cultivated with contaminated^[3] groundwater. This is amplified by the use flooded fields^[4] for growing rice crops, as increased exposure of the soil to water increases the amount of arsenic released into water for absorption by the rice. This explains why arsenic contamination in rice is particularly concerning when compared^[5], for example, to wheat and barley.

On April 1, 2016, the U.S. Food and Drug Administration (FDA) proposed setting an upper limit of 100 parts per billion for arsenic concentrations in infant rice cereal. This parallels current regulations in the European Union. Given the vulnerability of infants to arsenic exposure, the study under review investigated rice-based food sources of arsenic exposure among infants during their first year of life.

Inorganic arsenic is a contaminant that accumulates in rice. Since rice cereal is a common transitional food for infants, the current study examined food sources for arsenic exposure among infants during their first year of life.