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The Federal Drug Administration is investigating research that has found some rice contains inorganic arsenic levels being characterized as "worrisome." Their review of the research may result in their finally setting a maximum limit of inorganic arsenic in our foods.
While this should be good news to consumers, the media's coverage seems to be missing some crucial information. Like where the arsenic comes from and how we can avoid it.
The FDA's data found inorganic arsenic levels between 3.5 and 6.7 micrograms per serving in their sampling. And a recent Consumer Reports study found similar levels. But this really is not news.
Numerous studies have been published over the past decade documenting arsenic content in rice grown from around the world. Dr. Andrew Meharg, a professor of biogeochemistry at the University of Aberdeen, has led or been part of the research teams in many of these studies.
In 2007, Dr. Meharg led a study that measured arsenic levels among rice grown throughout the U.S. He and his team analyzed 107 samples of rice grown in Louisiana, Mississippi, Texas, Missouri, and Florida, and 27 samples of rice grown in California.
Meharg and his team found that the 107 southern US and central US rice samples averaged .30 micrograms per gram of arsenic (equivalent to 4.4 micrograms per serving), and the California rice samples averaged 0.17 micrograms/gram (ppm) (about 2.5 mcg per serving).
However, <em>Organic brown rice grown in California had the lowest levels of all 134 samples, with 0.10 micrograms/gram.</em> This is equivalent to about 1.5 micrograms per serving - far less than the "worrisome" levels found in the FDA and Consumer Reports data. This indicates that organic rice will most likely be significantly lower in arsenic.
It should also be noted that these findings were on total arsenic content. Organic arsenic is a natural component of soils and is considered a trace mineral necessary for health. Inorganic arsenic is another creature altogether.
Inorganic arsenic has been found to be carcinogenic.
Dr. John Duxbury of Cornell University studied U.S. rice samples from different regions and found the total arsenic content averaged only 22% inorganic, while Dr. Meharg's findings showed that the percentage of inorganic arsenic to total arsenic content averaged 42%. This is explained by the fact that different soils have different levels of chemical contamination.
Organic arsenic in its unoxidized form is not necessarily harmful to the body in trace amounts. The body utilizes and metabolizes this form. The inorganic forms – oxidized versions such as arsenic oxides or arsenic trioxide, are produced with synthetic chemicals. These are the forms that have been found to be the most carcinogenic, although large amounts of organic arsenic are considered harmful and possibly even carcinogenic.
In other words, organic arsenic is readily present in natural soils, while inorganic arsenic is found in soils that have been sprayed with arsenic-based chemical pesticides, or watered with water containing chemicals high in arsenic. And since the plants will readily retain and store both forms, foods grown in soils that undergo chemical spraying - or have in the past - will contain higher levels of inorganic arsenic.
For example, cotton has been known to contain some of the highest levels of arsenic among U.S. crops. This is because cotton crops have historically been sprayed heavily with arsenic-based pesticides to control boll weevils.
Accordingly, Louisiana rice – where a fair amount of rice is grown in soils previously farmed in cotton – had the highest levels of arsenic in Dr. Meharg's research. Louisiana rice had 0.66 micrograms/gram of arsenic. This means that the arsenic levels of the organic rice were 15% of the arsenic levels of the Louisiana conventional (non-organic) rice.
In addition to cotton, fruit trees were sprayed with lead hydrogen arsenate for many decades. Now, conventional fruit trees are often sprayed with disodium methyl arsenate (DSMA) or monosodium methyl arsenates. These yield oxidized arsenic, but without the lead. Oxidized arsenic is also used in wood preservatives, antifungals and many other chemicals.
While there is no arsenic standard in food, there is an arsenic standard for drinking water, set by the U.S. Environmental Protection Agency. Using the average arsenic levels found in Dr. Meharg's research, one would have to consume over 115 grams of rice to exceed the EPA's standard of 10 micrograms/liter, equivalent to 10 parts per billion (ppb). The average American consumes only about 12 grams of rice per day. Asian Americans, however, average more than 115 grams of rice in a day.
A more recent Meharg study from Spain showed that most rice-based infant formulas - which used conventionally grown rice from around the world - also contained high arsenic content.
Other studies by Dr. Meharg found that arsenic levels in rice milk often exceed the U.S. as well as E.U. arsenic drinking water limits. Dr. Meharg and his team found that 80% of rice milk samples tested from supermarkets in 2008 exceeded the 10 microgram/liter limit. Rice cakes and crackers also contained higher levels of arsenic according to another study.
Dr. Meharg's research also found that cooking rice in good water lowered inorganic arsenic content.
Research has illustrated that rice from Bangladesh has some of the highest arsenic levels in the world. This is not surprising, since Bangladesh has been faced with an arsenic catastrophe stemming from contaminated groundwater sources.
Dr. Duxbury's research found that using less water to grow rice will dramatically reduce the arsenic content in the harvested rice.
Dr. Meharg and his associates also studied arsenic levels in China's rice. They found that most of the varieties contained less than .15 micrograms/gram, but rice grown in regions that were near or on previous mining sites had as much as .64 micrograms/gram.
Dr. Meharg's research also discovered that some of the lowest arsenic levels among foreign rice are found in basmati rice from India and Pakistan and jasmine rice from Thailand.
How to lower exposure to inorganic arsenic
The research clearly indicates that eating organic rice will dramatically lower one's total arsenic exposure. Organic rice will lower one's exposure to inorganic arsenic to an even greater degree because these fields are not sprayed with arsenic oxide-rich chemicals. Organic rice may also contain traces of inorganic arsenic due to the fact that inorganic arsenic is floating in our atmosphere from pollution, and some of our polluted waterways contain chemicals. Soils used for non-organic farming in the past may also contain arsenic. But conventional rice contains these and more, caused by a constant barrage of arsenic-loaded chemicals being sprayed on the crops.
Choosing organic rice grown in farming regions that have been farmed organically or lay fallow prior to being farmed will assure an even lower arsenic content in the rice. One of these growers is Lundberg Farms, a long-time California family farm that has been growing organic rice for decades (the author and website have no affiliation with Lundberg).
The Lundberg Farms' organic rice is also grown with less water. As Dr. Duxbury's studies showed, this decreases the uptake of arsenic in the rice.
If foreign rice is preferred, basmati rice imported from India or jasmine rice imported from Thailand are better bets, especially if these rices are also certified organic.
An antioxidant-rich diet will also help reduce oxidized arsenic levels within the body.
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- Carbonell-Barrachina AA, Wu X, Ramírez-Gandolfo A, Norton GJ, Burló F, Deacon C, Meharg AA. Inorganic arsenic contents in rice-based infant foods from Spain, UK, China and USA. Environ Pollut. 2012 Apr;163:77-83.
- Carey AM, Lombi E, Donner E, de Jonge MD, Punshon T, Jackson BP, Guerinot ML, Price AH, Meharg AA. A review of recent developments in the speciation and location of arsenic and selenium in rice grain. Anal Bioanal Chem. 2011 Dec 8.
- Abedin MJ, Cresser MS, Meharg AA, Feldmann J, Cotter-Howells J. Arsenic accumulation and metabolism in rice (Oryza sativa L.). Environ Sci Technol. 2002 Mar 1;36(5):962-8.
- Meharg AA, Rahman MM. Arsenic contamination of Bangladesh paddy field soils: implications for rice contribution to arsenic consumption. Environ Sci Technol. 2003 Jan 15;37(2):229-34.
- Williams PN, Price AH, Raab A, Hossain SA, Feldmann J, Meharg AA. Variation in arsenic speciation and concentration in paddy rice related to dietary exposure. Environ Sci Technol. 2005 Aug 1;39(15):5531
- Williams PN, Islam MR, Adomako EE, Raab A, Hossain SA, Zhu YG, Feldmann J, Meharg AA. Increase in rice grain arsenic for regions of Bangladesh irrigating paddies with elevated arsenic in groundwaters. Environ Sci Technol. 2006 Aug 15;40(16):4903-8.
- Williams PN, Raab A, Feldmann J, Meharg AA. Market basket survey shows elevated levels of As in South Central U.S. processed rice compared to California: consequences for human dietary exposure. Environ Sci Technol. 2007 Apr 1;41(7):2178-83.
- Meharg AA, Deacon C, Campbell RC, Carey AM, Williams PN, Feldmann J, Raab A. Inorganic arsenic levels in rice milk exceed EU and US drinking water standards. J Environ Monit. 2008 Apr;10(4):428-31.
- Zhu YG, Sun GX, Lei M, Teng M, Liu YX, Chen NC, Wang LH, Carey AM, Deacon C, Raab A, Meharg AA, Williams PN. High percentage inorganic arsenic content of mining impacted and nonimpacted Chinese rice. Environ Sci Technol. 2008 Jul 1;42(13):5008-13.
- Sun GX, Williams PN, Zhu YG, Deacon C, Carey AM, Raab A, Feldmann J, Meharg AA. Survey of arsenic and its speciation in rice products such as breakfast cereals, rice crackers and Japanese rice condiments. Environ Int. 2009 Apr;35(3):473-5.
- Raab A, Baskaran C, Feldmann J, Meharg AA. Cooking rice in a high water to rice ratio reduces inorganic arsenic content. J Environ Monit. 2009 Jan;11(1):41-4. Epub 2008 Nov 20.