In recent years, close examination of rice and rice products has exposed a dark side of this healthy grain. Most rice contains significant levels of arsenic, a toxic poison. This may sound shocking but arsenic is a natural part of our planet Earth, being present in the soil and water as well as in plants and animals. The problem is that humans have added more arsenic to the environment through the rampant use of arsenic-containing pesticides and fertilizers and preventative treatments of poultry.
Arsenic can exist in two forms: organic and inorganic. Organic arsenic, the type commonly found in plants and animals, exists in combination with carbon and hydrogen. Inorganic arsenic occurs in combination with other elements such as oxygen, chlorine and sulfur. Inorganic arsenic is the type found in soil, rocks and water and in fertilizers and pesticides (1). Both are a concern for health but inorganic arsenic is much more toxic than the organic type. Organic arsenic and most inorganic arsenic can be expelled from the human body in a few days through elimination in the urine. However, some of the inorganic type remains in human tissues for months and even years (1).
Arsenic has no smell or taste. It has been known for centuries that an amount of inorganic arsenic the size of a pea can be fatal (1). Smaller doses cause stomach aches, headaches, drowsiness, diarrhea and confusion and, in more extreme cases, numbness and tingling, muscle cramping and death (3). Long-term exposure is linked to lesions of the skin, dementia, Type-2 diabetes (6), high blood pressure, heart disease (7), neurological problems and cancers of the skin, lung, bladder, liver and kidney (4,5).
The threat of arsenic to our health is not a straightforward one. Scientists currently do not agree about whether arsenic is a non-threshold carcinogen, meaning that any dose no matter how small carries some risk, or if arsenic has a threshold dose below which it will not cause cancer (20). Also there are many variables that can affect the extent of health damage from eating arsenic-contaminated foods such as rice. Those who eat rice more frequently are at higher risk. Children and infants, because of their smaller body size, are more susceptible to harm from arsenic in rice. Adding to the confusion is that not all rice contains high arsenic levels and it is difficult to determine the actual arsenic content without measuring it in a lab. Some countries whose wells are contaminated with arsenic and who also eat large amounts of rice have not been shown to exhibit elevated rates of bladder and lung cancer in spite of the known association of these cancers to high arsenic levels (21). Rice itself contains some nutrients, B vitamins and selenium for example, that protect against the toxic effects of arsenic (22,23). Even the simple act of eating a healthy balanced diet reduces the potential risk of arsenic ingestion. However, in spite of all these perplexing variables, it is prudent to take as many precautions as possible to limit exposure to arsenic in rice.
HUMAN SOURCES OF ARSENIC
Human activities involving the use of arsenic in pesticides, fertilizers and poultry medications have contaminated the soil and ground water. Years of repeated applications have resulted in inordinately high levels of inorganic arsenic that cycles through the soil, water and food. Regrettably inorganic arsenic can remain in the soil almost indefinitely. Arsenic-containing chemicals are banned in Europe and more recently, many of them have also been prohibited in North America (15) but past farming activities can cast a long shadow over our food supply.
One of the consequences of past arsenic use is its presence in a variety of foods, the predominant ones being seafood, rice, mushrooms and poultry (1). In Europe it has been estimated that 95% of the average human arsenic intake comes from food, with half of that from rice and rice products (19). Much of the arsenic present in seafood is of the organic type that is less harmful. However, the inorganic arsenic level in poultry, mushrooms and rice can be quite high (16). The process of producing poultry has traditionally involved the feeding of arsenic-containing drugs to prevent parasites and help the birds grow faster. Unfortunately this means that there is arsenic present in the resulting chicken meat (11,13). In 2014, removal of the arsenic-containing drug Roxarsone from chicken feed was initiated in North America, but the process will be a slow and ongoing one. In addition, poultry litter is fed to other livestock such as beef and also heavily used as fertilizer, both practices that only increase the presence of arsenic in our environment and our food (14). Mushrooms suffer from the past practice of growing them in poultry manure although this custom seems to be declining. A good sign is that the level of arsenic in mushrooms has decreased over the last ten years (12,13).
Rice in North America is often grown on soil that has been the recipient of arsenic-containing fertilizers and pesticides over many decades. For example, lead-arsenate insecticides were used by farmers to control pests for many years. These particular chemicals are doubly dangerous because they contained not only arsenic but also lead. They were banned in the 1980s but much of the arsenic left behind is still in the soil. The worst offenders were cotton farms in the US south that relied heavily on chemicals to produce a bountiful crop. Consequently rice grown on fields previously used for growing cotton is very high in arsenic.
Unfortunately the rice plant is highly efficient at taking up arsenic from soil, absorbing up to ten times more arsenic than other grains (18). Additionally the best growing conditions for rice require flooded land and, if the water used is also contaminated with arsenic, the problem is multiplied. In 2012 Consumer Reports tested 223 samples of rice products and found that almost all of them contained significant amounts of arsenic. The samples encompassed rice from all regions of the world and included white, brown, parboiled, jasmine, basmati and other types of rice (8). Arsenic tends to collect in the outer hull of a rice kernel and so brown rice can contain up to 80% more arsenic than white rice (although arsenic is easier to remove from whole grain rice than from white rice). Even rice grown organically is impacted. Although fewer pesticides are used in its production, it soaks up arsenic from soil contaminated from past practices. Wild rice can be much lower in this element but only if the water used during its growth is low in arsenic.
Besides food, other sources of arsenic for humans are the soil and water, especially in areas with exceedingly high arsenic levels due to the presence of natural arsenic or to extreme use of arsenic-containing pesticides and fertilizers. In fact, drinking water in such areas can be the principal contributor to the daily arsenic intake (2,19).
HOW TO CHOOSE RICE LOWER IN ARSENIC
Rice produced in California, India, Thailand or Pakistan contains only about one-third of the inorganic arsenic found in rice grown elsewhere. Rice grown in Arkansas, Texas, Louisiana and most other US states contains the highest levels of arsenic (8).
REMOVING ARSENIC FROM RICE
The good news is that arsenic is water soluble so it can be at least partially washed off of rice. Cooking rice in excess water (ten to twelve parts water to one part rice) and then draining the excess water left after cooking can remove 40 to 60% of its inorganic arsenic content (17).
A 2015 study found that cooking rice in a filter coffee maker could reduce the arsenic level by an even larger percentage. Whole grain rice starts out with a higher arsenic content than white rice but arsenic can be more efficiently removed from whole grain rice, resulting in removal of up to 80% of the original amount of arsenic present in the uncooked rice (9). The key to this process is to constantly pass hot water through the rice as it cooks and then discard most of the water.
With white rice, the downside of this excessive use of water for rinsing and cooking is that 50 to 70% of its healthy nutrients such as folate, iron, niacin and thiamin can be removed (10). This is not so in brown rice, whose vitamins and minerals are protected inside its outer hull resulting in much less loss (17).
SOME PRACTICAL WAYS TO LOWER ARSENIC IN RICE
Cook rice in copious amounts of water. For best results, use between ten and twelve parts of water to one part of rice. When the rice is cooked, discard the excess water.
For even better arsenic removal, rinse rice thoroughly and then soak it in water for 48 hours before cooking. Every 8 to 12 hours, pour the water off, rinse and replace with new water. Cook the rice in ten to twelve parts of water to one part of rice. When the rice is done, drain off the excess water.
To make use of a filter coffee maker, line the machine’s filter holder with a paper filter and add the rice. Fill the machine with water and turn it on, allowing the water to run through with the coffee pot underneath to catch the water. Cooking time depends on the kind and amount of rice used. For whole grain rice, researchers used three cycles of water, taking thirty minutes and 6 liters of water for the process (9).
EATING GRAINS IS IMPORTANT FOR HEALTH
Studies involving more than 100,000 women and men over a period of about twenty-five years have shown that for every single serving of whole grains (28 gm) eaten per day, overall death risk drops by 5% and risk of death from cardiovascular disease drops by 9%. It is clear that increasing whole grain consumption has benefits in both primary and secondary prevention of chronic disease and is associated with extended life expectancy (24). Consequently if concerns about arsenic result in lower intake of rice, other grains should be eaten in its place. Tests show that most grains besides rice contain negligible amounts of arsenic. There are many to choose from – whole wheat and wheat berries, quinoa, oatmeal, barley, bulgar, millet and buckwheat are the more commonly known grains. Be adventurous too and delve into more unusual grains such as farro, teff and amaranth. You might even discover a new favourite.
BOTTOM LINE – DON’T GIVE UP RICE ALTOGETHER
Professor Andy Meharg of Queen’s University in Belfast has been studying arsenic for decades. He points out that the more rice you eat, the higher your cancer risk due to arsenic. However, it is not necessary to stop eating rice altogether. Stick to the following simple guidelines to continue to enjoy the bountiful health benefits of rice (9).
Choose a whole grain rice, a wonderful source of fiber, to provide the most health benefits.
Wild rice is a healthy choice with less potential for high arsenic content.
Choose rice grown in areas known to contain less arsenic – California, India, Thailand and Pakistan.
Aim to eat rice up to twice a week at the most.
Cook rice with lots of water; ten to twelve parts of water to one part rice is optimal.
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