Ask SciMoms: Is arsenic in rice harmful?

In my family, as in most Iranian families, rice is a staple and an art form. Making rice fluffy and beautiful is a skill that I have yet to master. Given the amount of rice my family eats, we all worry about the safety of rice, particularly when it comes to arsenic. There are a lot of scary articles online about the amount of arsenic in rice, but are they true? In this post, we’ll explore: Why is there arsenic in rice? How can we decrease the amount of arsenic in rice? Is rice safe to eat? Is rice cereal safe for children?

What is arsenic?

Arsenic is an element of the periodic table (abbreviated as “As”). It’s naturally occurring and found in our environment in two forms:

  • Organic arsenic: In this form, arsenic is attached to a carbon atom that may be part of a compound such as sugar molecule. Note that the term “organic” here doesn’t refer to a farming method, but to the carbon atoms in the molecule. Organic arsenic compounds are “not known to be toxic to humans”.
  • Inorganic arsenic: In this form, arsenic is found as a pure element or in non-carbon-based compounds. This form of arsenic is highly toxic, and was even used historically as a poison.  

Inorganic arsenic is all around us in varying quantities. In addition, arsenic has many industrial applications, some of which have been phased out. These include:

  • Pharmaceutical to treat cancer and in antibiotics (phased out in the 1970s)
  • Antifungal compound in pressure treated wood (voluntary ban in 2003 in North America)
  • Alloy manufacturing
  • Processing of glass
  • Pigment manufacturing and leather preservatives
  • Agriculture, including its use as a pesticide (inorganic arsenic has not been used as a pesticide since 1993, and organic arsenic pesticides were phased out by the EPA by 2013)

How are we exposed to arsenic?

Arsenic is found in very small amounts in soil and in varying amounts in water. In many regions of the world, groundwater has naturally elevated levels of arsenic. The World Health Organization lists “Argentina, Bangladesh, Chile, China, India, Mexico, and the United States of America” as regions of the world with elevated levels of arsenic in water. The American Cancer Society clarifies that “most US areas with higher levels of arsenic in drinking water are rural communities. Albuquerque, New Mexico, is the only urban area in the US with substantial natural arsenic levels in drinking water.” However, the EPA now regulates the amount of arsenic in water, using expert guidance provided by several institutions, including the National Academy of Sciences.

Individuals who work in industries that handle arsenic tend to have greater levels of exposure. In the United States, the Occupational Safety and Health Administration published guidelines for working with inorganic arsenic to reduce exposures.

The greatest source of exposure to arsenic, at least for most non-smokers, is through our diet. The Institute of Medicine states that the largest source of organic arsenic in North American diets is seafood, as well as rice, flour, grape juice, and cooked spinach are all dietary sources of inorganic arsenic. For smokers, cigarettes are the largest source of arsenic, which is one of the many compounds that make cigarettes carcinogenic. This is yet another reason why they should consider quitting.

Baghali Polo is a Persian rice dish that Layla’s family makes at family reunions, made with dill and fava beans. Persian rice is traditionally soaked, boiled, and strained. (Image from Wikimedia Commons)

Does arsenic cause cancer?

The International Agency for Research on Cancer (IARC) has done a hazard assessment on arsenic. It has found that arsenic and inorganic arsenic compounds are known carcinogens meaning that there’s sufficient evidence that arsenic can cause cancer in humans. Exposure to high levels of arsenic can cause cancer and many other symptoms including gangrene, stomachaches, nausea, vomiting, and much more.

Studies examining the incidence of cancer in people who have been exposed to a lot of arsenic, such as people working in mines and smelters, have found a higher incidence of cancer associated with these greater exposures.

Studies have also looked at the incidence of cancer in people who live in areas where the groundwater is contaminated with arsenic. These show an increased incidence of cancer. Consequently, the International Agency for Research on Cancer (IARC) “has also stated that arsenic in drinking-water is carcinogenic to humans.” It is this source of arsenic that is the primary focus of the World Health Organization: the agency aims to ensure that people living in areas with high-arsenic in groundwater have a safe source of drinking water.

On the other hand, studies examining a relationship between arsenic in drinking water and cancer in the US have not found a strong relationship. The American Cancer Society states that “[t]his is largely because for most Americans who are on public water systems, drinking water is not a major source of arsenic.”

When it comes to arsenic in food, the Institute of Medicine states: “There is no evidence linking organic arsenic in food to any adverse effect, including cancer.” Additionally, we metabolize and excrete the arsenic from our diet, and there’s little evidence that it builds up in our bodies. But if that’s the case, why is there so much concern over arsenic in dietary staples, particularly rice? In other words, we know that inorganic arsenic is a hazard, but is the amount present in our diets a risk?

Five Colors of glutinous rice
All rice, including this five color glutinous rice from Vietnam, has arsenic. The amount of arsenic depends on a variety of factors including weather, soil, water, and pesticides/fertilizers used (Image from Wikimedia).

Is arsenic in rice safe?

Inorganic arsenic in rice is of particular concern because:

  • Rice tends to absorb arsenic more than other crops from the water and soil where they are grown. This is partly due to the increased arsenic naturally present in many areas where rice is grown. If the soil had previously been treated with pesticides or fertilizers that contained arsenic, then the rice might absorb additional arsenic. The FDA highlights that arsenic is present in all rice-based products, whether they are grown organically or conventionally.
  • Many products for infants are rice-based. Taking into account their bodyweight, infants can end up having 2 to 3 times more dietary exposure to inorganic arsenic than adults.

In 2012 and in 2014, Consumer Reports examined the amount of arsenic present in rice-based products and found “worrisome levels” of arsenic. Academic studies found that infant rice cereal had significantly more inorganic arsenic than formula or breastmilk. When the FDA conducted a risk assessment on inorganic arsenic in infant rice products, it concluded that “infants and children may be particularly susceptible to adverse neurodevelopmental effects of exposure to inorganic arsenic”. This is supported by very recent evidence gathered from experiments in pregnant rats showing that arsenic in drinking water can impact the development of pups.

As a result, the FDA proposed a limit for the amount of arsenic present in infant rice cereal (100 parts per billion), which is the same limit that the European Union has adopted. This limit was welcomed by the American Academy of Pediatrics. It is important to note studies conducted by the FDA had shown that most infant formulas (78%) were already at or below 110 parts per billion.

It must also be noted that studies examining whether people who ate a lot of rice over long periods of time were at greater risk of developing cancer failed to find any association. However, these studies did not examine the amount of rice consumed as infants.

We’d also like to stress that the FDA’s measures are being adopted out of caution. The FDA is currently establishing an expert panel to review the evidence supporting whether dietary arsenic in infancy causes developmental delays. When reading studies on the topic of arsenic and developmental delays, the evidence was quite mixed. Studies highlighted that not only is the amount of arsenic important, but also the amount of time that an infant or child is exposed to arsenic important, and collecting such data in humans is challenging. Consequently, the FDA’s panel and the animal studies they’re conducting are important steps to determining if dietary arsenic is a risk to infants and if we need different regulatory limits for infant products.

How can we reduce our exposure to arsenic in rice?

Eating a varied diet is the best way to reduce dietary exposure to arsenic. As pointed out previously, not only is the amount of a hazard we’re exposed to of importance, but also the frequency we’re exposed to it. By adding variety to our diets, we reduce the frequency of our exposure. This recommendation comes not only from the FDA, but also from institutions in Europe as well as the American Academy of Pediatrics. For infants adding variety to their diets means varying the grain in their cereal to include barley, oat, or multigrain cereal. There is no guidance on avoiding infant rice cereal altogether.

The British Nutrition Foundation advises avoiding rice drinks for children under the age of 4.5. Choose formula, breastmilk, or cow’s milk instead.

The American Academy of Pediatrics suggests avoiding products with rice sweetener. Rice-based sweeteners are often used instead of sugar in products labeled as “no sugar added”, but contain the same amount of calories.

But what if your family’s culture is one where rice is present at every meal? In such cases, the FDA and European institutions both recommend pre-rinsing the rice. This decreases the amount of inorganic arsenic by ~10% in basmati rice.  More importantly, studies show that cooking the rice in excess water (6:1 water:rice) and then straining it, similar to how pasta is prepared, will get rid of 40-60% of inorganic arsenic. The drawback is that many nutritionally important minerals, such as iron and folate, are also lost when it is prepared in this fashion. If you’re not familiar with this method of preparing rice, you can check out this recipe on how to prepare Persian rice, or my step-by-step tweets.

The FDA states that there many different factors that determine the amount of arsenic in rice: the weather, the soil, the type of rice, and others. As such, it’s not really possible to state that rice from a particular global region should be avoided.

(Post continues after infographic)

SciMoms infographic on arsenic. Arsenic is a naturally occurring element found in varying amounts in water and soil. Many forms of arsenic are known carcinogens. Many items in our diet, including rice, spinach, juice, and meat, have arsenic. These are not known to cause cancer, but there is concern that dietary arsenic might impact the development of children. Because of this, much focus has been given to rice-based infant products. You can decrease your exposure to dietary arsenic by 1) boiling rice in excess water, 2) avoiding rice-based drinks, 3) adding variety to your family's diet, including your infant's cereal. Use rice cereal as well as barley or multigrain.
SciMoms infographic on Arsenic

Conclusion

There are legitimate concerns regarding arsenic, however, the greatest risks are to those who live in areas where their drinking water might be contaminated and those who are exposed in their workplace. In the United States, the amount of inorganic arsenic present in public drinking water is regulated. It is important that our regulatory agencies uphold safety standards surrounding drinking water.
The recommendations that our scientific and medical institutions provide on reducing our exposure to inorganic arsenic in rice are suggestions that we should be following anyway: having a diet that is varied in grains and oats, reducing our intake of sugar including those that are rice-based, and giving our children breastmilk, formula, or cow’s milk.

And for my family that’s reading this: we don’t need to panic. We are already pre-rinsing and straining the rice. And as painful as it may be, we might be better off if we sometimes varied our diet: maybe potatoes or quinoa?