Arsenic, Organic Foods, and Brown Rice Syrup

Trace Element Analysis Core Laboratory, Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA.
Environmental Health Perspectives (Impact Factor: 7.98). 02/2012; 120(5):623-6. DOI: 10.1289/ehp.1104619
Source: PubMed


Rice can be a major source of inorganic arsenic (Asi) for many sub-populations. 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.
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.
We used inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography coupled to ICP-MS to determine total As (Astotal) 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 Asi and dimethyl-arsenate (DMA). An "organic" toddler milk formula containing OBRS as the primary ingredient had Astotal 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. Asi was the main As species in most food products tested in this study.
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 Asi into an individual's diet. Thus, we conclude that there is an urgent need for regulatory limits on As in food.

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    • "Fish contain high amounts of organic arsenic compounds, predominantly arsenobetaine (Molin et al. 2015; Tao and Bolger 1999). In contrast, rice contains predominantly inorganic arsenic (Jackson et al. 2012). The relative contribution of the diet as a source of arsenic exposure may be substantial, particularly when drinking water arsenic levels are low. "
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    ABSTRACT: Background: Exposure to inorganic and organic arsenic compounds is a major public health problem that affects hundreds of millions of people worldwide. Exposure to arsenic is associated with cancer and non-cancer effects in nearly every organ in the body, and evidence is mounting for health effects at lower levels of arsenic exposure than previously thought. Building from a tremendous knowledge base with more than 1,000 scientific papers published annually with "arsenic" in the title, the question becomes, what questions would best drive future research directions? Objectives: The objective is to discuss emerging issues in arsenic research and identify data gaps across disciplines. Methods: The National Institutes of Health's National Institute of Environmental Health Sciences Superfund Research Program convened a workshop to identify emerging issues and research needs to address the multi-faceted challenges related to arsenic and environmental health. This review summarizes information captured during the workshop. Discussion: More information about aggregate exposure to arsenic is needed, including the amount and forms of arsenic found in foods. New strategies for mitigating arsenic exposures and related health effects range from engineered filtering systems to phytogenetics and nutritional interventions. Furthermore, integration of 'omics data with mechanistic and epidemiological data is a key step towards the goal of linking biomarkers of exposure and susceptibility to disease mechanisms and outcomes. Conclusions: Promising research strategies and technologies for arsenic exposure and adverse health effect mitigation are being pursued, and future research is moving toward deeper collaborations and integration of information across disciplines to address data gaps.
    Full-text · Article · Nov 2015 · Environmental Health Perspectives
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    • "arsenate, As V , and arsenite, As III ) are among the most toxic forms, generally organoarsenic compounds are less toxic, and the organoarsenical arsenobetaine (AB) is completely non-toxic. Recent interest has focussed on traces of arsenic found in food sources like cereal bars and baby formulae, [1] [2] but food sources from aquatic environments have long been known to contain arsenic. As a general observation, marine organisms such as fish, mammals and crustaceans contain mainly AB. [3] However this is only true for noncontaminated waters where the average arsenic concentration is generally between 1 and 4 mg L À1 . "
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    ABSTRACT: Freshwater phytoplankton (Chlamydomonas) and zooplankton (Daphnia pulex) were exposed to arsenic to trace the arsenic transformations and the formation of organoarsenic compounds at the base of the freshwater food chain. Plankton were cultured in artificial lake water, and exposed to arsenic through several pathways, hypothesised to be the main exposure sources: through water, food and contaminated sediments. High performance liquid chromatography–inductively coupled plasma–mass spectrometry and X-ray absorption spectroscopy were used to determine arsenic speciation in the studied organisms, and X-ray fluorescence mapping was used to locate the arsenic in a single Daphnia specimen. The results show that the formation of methylated arsenic compounds and arsenosugars by the zooplankton organisms was independent of the exposure route, but instead dependent on arsenic concentration in the environment. Specifically, organoarsenic compounds were dominant in extracts of Daphnia organisms exposed to low arsenic concentrations through water at 10 µg L–1 (67 %), and through contaminated food (75 %), but inorganic arsenic was dominant in Daphnia exposed to high arsenic concentrations, including contaminated sediments. Phytoplankton cultures contained variable amounts of arsenosugars, but on average the dominant compound in phytoplankton was inorganic arsenic. The main implications of the present study for understanding arsenic cycling in the freshwater plankton community are that arsenosugars are formed at possibly both the phytoplankton and zooplankton trophic levels; and that higher arsenic loads in plankton correspond to higher inorganic arsenic concentrations, which could indicate a saturation of the arsenic methylation process by plankton organisms.
    Full-text · Article · Oct 2014 · Environmental Chemistry
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    • "Arsenic is a naturally occuring metalloid that finds its way into the food chain through water, plants, and animals. In many parts of the world, arsenic is a major health hazard [1-3]. Chronic arsenic exposure has been associated with cancer, heart disease, neuropathies, and with deficits in intelligence in children [4,5]. "
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    ABSTRACT: Background Arsenic is a major environmental toxin that is detoxified in the liver by biochemical mechanisms that are still under study. In the traditional metabolic pathway, arsenic undergoes two methylation reactions, each followed by a reduction, after which it is exported and released in the urine. Recent experiments show that glutathione plays an important role in arsenic detoxification and an alternative biochemical pathway has been proposed in which arsenic is first conjugated by glutathione after which the conjugates are methylated. In addition, in rats arsenic-glutathione conjugates can be exported into the plasma and removed by the liver in the bile. Methods We have developed a mathematical model for arsenic biochemistry that includes three mechanisms by which glutathione affects arsenic methylation: glutathione increases the speed of the reduction steps; glutathione affects the activity of arsenic methyltranferase; glutathione sequesters inorganic arsenic and its methylated downstream products. The model is based as much as possible on the known biochemistry of arsenic methylation derived from cellular and experimental studies. Results We show that the model predicts and helps explain recent experimental data on the effects of glutathione on arsenic methylation. We explain why the experimental data imply that monomethyl arsonic acid inhibits the second methylation step. The model predicts time course data from recent experimental studies. We explain why increasing glutathione when it is low increases arsenic methylation and that at very high concentrations increasing glutathione decreases methylation. We explain why the possible temporal variation of the glutathione concentration affects the interpretation of experimental studies that last hours. Conclusions The mathematical model aids in the interpretation of data from recent experimental studies and shows that the Challenger pathway of arsenic methylation, supplemented by the glutathione effects described above, is sufficient to understand and predict recent experimental data. More experimental studies are needed to explicate the detailed mechanisms of action of glutathione on arsenic methylation. Recent experimental work on the effects of glutathione on arsenic methylation and our modeling study suggest that supplements that increase hepatic glutathione production should be considered as strategies to reduce adverse health effects in affected populations.
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