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Arsenic and Rice


If you think arsenic poisoning is something relegated to the pages of mystery novels, think again. Arsenic may be in foods you routinely eat—but it's undetectable by taste or smell. How much arsenic in your diet is safe?

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Number 33 on the periodic table, arsenic is a naturally-occurring heavy metal—and a much-used poison throughout history. Because it appears in the soil, arsenic may be lingering in foods you and your family frequently eat. Recent research raises questions about arsenic levels in rice products, apple juices, and pear juices. Image source: Wikipedia.
When I spotted a headline in my Facebook stream a few weeks ago that warned of arsenic in food products made with rice, or sweetened with brown rice syrup, I was curious. The NPR headline wasn't alarmist. It was, instead, middle of the road: "Yes, There's Arsenic In Your Rice. But Is That Bad?"

I didn't know it then, but apparently I had missed out on public alarm over similar headline news (and FDA response) last year about arsenic levels in apple juice. The idiom "what you don't know can't hurt you, right?" comes to mind as particularly foolhardy when it comes to health consciousness, and catching wind of potentially dangerous levels of 'poison' in my rice wasn't a comfortable thought. From the indulgence of a comfort food like rice pudding to my favorite short-grain brown rice, good with just about everything (including milk and sugar), to a frequent menu of ethnic foods, often accompanied by rice, the grain has earned 'staple' classification in my vegetarian diet. And, while my kids haven't wholeheartedly jumped on the bean and spinach train of my healthy eating, "rice" is something they've grudgingly adopted as a frequent side dish and part of my attempt to incorporate more whole grains in their diets.

My health-consciousness hackles already raised, as I read the initial report, I got even more icky feeling when I saw that the levels of arsenic in brown rice are reportedly higher, on average, than in the ostensibly less-good-for-you white counterpart. Great, I thought. Here's another instance where many of us have made lifestyle eating changes in the name of whole grain and better health, and suddenly we find out that what we did with the best of intentions can actually be causing unexpected (and unseen) harm.

Further reading told me that while the FDA has established guidelines for the acceptable threshold of arsenic in bottled drinking water, there are no regulations in place for food products—or beverages other than water. I'd read enough. In what has become my typical modus operandi since I began working at Science Buddies, I fired off an email to our Lead Scientist. In part, I wanted to know what a student could do to explore this issue. In part, I wanted her opinion of the issue and the potential health risk.

It was from her response that I realized I'd somehow overlooked the rampant apple juice reports last year. Her response clued me in to the larger spiral of arsenic concern but also gave me the kind of "slow down, be objective, and understand the facts" counsel which you might expect from a scientist. In other words, she put the 'headline' in perspective: Arsenic is in our food chain.


A Dark History

Mystery reader or not, most of us are familiar with the classic whodunit plot that involves poisoning by arsenic. Agatha Christie favored arsenic in her mysteries, along with a host of other poisons, strychnine being the most common, but "Arsenic and Old Lace" may be one of the most famous of arsenic-laden storylines. At the heart of the tale are "two spinster aunts who have taken to murdering lonely old men by poisoning them with a glass of home-made elderberry wine laced with arsenic, strychnine, and 'just a pinch' of cyanide" (Wikipedia).

With arsenic having a prominent and deadly role in such stories, I started looking at arsenic more broadly, trying to make sense of the fact that a known poison was also part of last night's dinner, which I cooked for myself. As I started down the research path before me, a path scattered with arsenic-laced grains of brown rice, I quickly realized that arsenic has a fascinating history, one that gets increasingly insidious, dark, and creepy the farther you look, from its use as a rat poison to its, ostensibly well-earned, nickname, "the inheritance powder."

Digging into the history of arsenic as a choice for mystery writers leads to interesting facts about the availability and early uses of arsenic, and a scan of a list of historical poisonings (alleged and confirmed) shows arsenic popping up a fair number of times. Perusing the Wikipedia entry on arsenic poisoning brings other well-known historical figures to the forefront as possible victims of the secret poison, including Napoleon Bonaparte.

And then, of course, there was Mary Ann Cotton, convicted in 1873 of murdering more than 20 people, including her children, with arsenic. Though not a household name in the way other serial killers have occupied public consciousness, Cotton's tale is frightening and might make you think twice about accepting a drink (or a rice ball) from a friend! One of the most unexpected finds in my jaunt through the history of arsenic poisoning was an article from November 2011 covering a current mystery writer's speculation that Jane Austen, whose cause of death at age 41 remains the subject of much conjecture, may have died of arsenic poisoning.


Hidden Ingredients

Given the history of arsenic and its association with "secret" poisoning, it's certainly discomfiting to realize that arsenic isn't something confined to the intrigues of centuries gone by or the dark and dusty upper recesses of a mystery book protagonist's kitchen cabinets. Instead, arsenic, in trace amounts, may well be sitting on the shelves of many of our cabinets and most of our grocery stores.

In reality, arsenic is a naturally-occurring element in the Earth's crust, number 33 (Arsenum) on the periodic table. From arsenic released by volcanoes to arsenic produced as a byproduct of burning fossil fuels, arsenic, in both its organic and inorganic forms, appears worldwide. Studies have shown that animals even need a trace amount of arsenic in their diets. Whether humans also need a bit of arsenic—and how much—has yet to be conclusively determined.


Why Rice?

Part of the problem is that the soil rice is grown in may contain arsenic, both natural and residual, and rice may absorb arsenic more easily than other foods. As for the difference in arsenic levels between brown and white rice, a report in the MinnNews suggests that processing rice may remove some of the inherent arsenic: "The arsenic accumulates in the rice's outer hull and stays there unless the hull is removed (as it is during the processing of white rice)."

While studies are relating the amount of arsenic detected in brown-rice syrup to the limits of arsenic allowed by the FDA in drinking water, whether or not the same thresholds can be considered safe in food has not been determined. Reports, however, like this one in USA Today from December 2011, suggest that even 1/2 a cup of rice a day, may provide too much arsenic for health safety.

So arsenic surrounds us. It is, as I was warned, a part of our food chain. Even so, arsenic in certain levels is toxic—and arsenic is a known, but undetectable to the consumer, factor in certain foods. In other words, you don't have to be someone's victim to be ingesting a known poison. Think about how many foods are rice-based. Cereals, salads, puddings, and even snacks may be made from rice or contain brown-rice syrup, commonly used as a sweetener. Rice cake anyone? Energy bar? If rice contains arsenic, and it doesn't have to be monitored or regulated, it seems to me we have a problem. Checking ingredients labels won't help. "Arsenic" hasn't been "added." Complicating matters is the fact that not all brown rice or brown rice syrup contain the same levels of arsenic, a reality that seems to beg the question: why isn't it being regulated?


Making Connections

Unfortunately, arsenic detection isn't something students can tackle at home or in a kitchen-based lab. But students can look at the larger picture and take into account that arsenic is a heavy metal, a class that also contains silver, copper, mercury, nickel, cadmium, and chromium, all of which can be toxic in certain environments. The Heavy Metals and Aquatic Environments project lets students investigate the impact of the heavy metal copper (Cu) on an aquatic environment containing snails and plants.

While students can't evaluate the relationship of arsenic and rice—or the impact of arsenic on human biology—as easily, a firsthand investigation of heavy metals and the consequences of increased levels, and of buildup, can help students better understand the unfolding news and research related to arsenic.

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