Arsenic, Organic Foods, and Brown Rice Syrup

Article excerpt

BACKGROUND: Rice can be a major source of inorganic arsenic ([As.sub.i]) for many subpopulations. Rice products are also used as ingredients in prepared foods, some of which may not be obviously rice based. Organic brown rice syrup (OBRS) is used as a sweetener in organic food products as an alternative to high-fructose corn syrup. We hypothesized that OBRS introduces As into these products.

OBJECTIVE: We determined the concentration and speciation of As in commercially available brown rice syrups and in products containing OBRS, including toddler formula, cereal/energy bars, and high-energy foods used by endurance athletes.

METHODS: We used inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography coupled to ICP-MS to determine total As ([As.sub.total]) concentrations and As speciation in products purchased via the Internet or in stores in the Hanover, New Hampshire, area.

DISCUSSION: We found that OBRS can contain high concentrations of As; and dimethylarsenate (DMA). An "organic" toddler milk formula containing OBRS as the primary ingredient had [As.sub.total] concentrations up to six times the U.S. Environmental Protection Agency safe drinking water limit. Cereal bars and high-energy foods containing OBRS also had higher As concentrations than equivalent products that did not contain OBRS. [As.sub.i] was the main As species in most food products tested in this study.

CONCLUSIONS: There are currently no U.S. regulations applicable to As in food, but our findings suggest that the OBRS products we evaluated may introduce significant concentrations of [As.sub.i] into an individual's diet. Thus, we conclude that there is an urgent need for regulatory limits on As in food.

KEY WORDS: arsenic, baby formula, brown rice syrup, cereal bars, energy bars, organic foods, speciation. Environ Health Perspect 120:623-626 (2012). http://dx.doi.org/10.1289/ehp.1104619 [Online 16 February 2012]

Arsenic (As) is an established carcinogen based on studies of populations consuming contaminated drinking water (Smith et al. 2002). Recently, attention has focused on As exposure from food, in particular fruit juices (Rock 2012) and rice (Stone 2008). Rice may contain As in total concentrations up to 100-400 ng/g, including both inorganic As ([As.sub.i]) and the organic species dimethylarsenate (DMA) (Williams et al. 2005), with much lower concentrations (relative to DMA) of monomethylarsenate (MMA) also occasionally detected. Total As ([As.sub.total]) in rice and relative proportions of DMA and As; differ both geographically (Meharg et al. 2009) and as a function of genetic and environmental controls (Norton et al. 2009).

[As.sub.i] is more toxic than DMA or MMA (Le et al. 2000), and food regulatory limits, where they exist, are based on [As.sub.i]. Infants fed rice cereal at least once daily may exceed the daily As exposure limit of 0.17 [micro]g/kg body weight per day based on drinking water standards (Meharg et al. 2008b). Rice products such as cereals and crackers (Sun et al. 2009) and rice drinks (Meharg et al. 2008a) are potentially significant dietary sources of As. Infants and young children are especially vulnerable because their dietary As exposure per kilogram of body weight is 2-3 times higher than that of adults [European Food Safety Authority (EFSA) 2009].

DMA is a metabolite of [As.sub.i]. Although considered less toxic than [As.sub.i], its toxicological potential has not been studied extensively. The presence of DMA in rice is likely due to natural soil microbial processes; however, DMA was used as a pesticide before being banned by the U.S. Environmental Protection Agency (EPA) in 2009 (U.S. EPA 2009). Organic food consumers may therefore object to its presence in organic foods even in the absence of direct evidence of human health effects of DMA.

In the United States, organic brown rice syrup (OBRS) is used as a sweetener as a healthier alternative to high-fructose corn syrup in products aimed at the "organic foods" market. …