November 30, 2016
Arsenic, a chemical element with the symbol As, atomic number 33 and a metalloid, is usually a name synonymous with poison or malicious intent. Discovered approximately in the 1250s, this tasteless, inert element that is readily water-soluble was probably why it was the preferred poison for the Italian family of Borgias who used it as a tool for political assassinations. It was also the conspiracy theory behind Napoleon’s death in exile. Once mentioned by the ancient Egyptians, studied by Greek philosophers and known by the Chinese for uses as pesticides, arsenic was recently in the spotlight following publication of an article analyzing arsenic findings from fruit juices and rice products in the U.S. diet. This has sparked considerable public interest. Concerns rise about how arsenic got into our foods and whether consumer exposure to arsenic are below levels of toxicological significance.
Arsenic is a natural element of the earth’s crust and is widely distributed throughout the environment’s air, water and land. Most arsenic compounds have no smell or taste, so it is hard to tell if you are ingesting any.
Long-term exposure to arsenic can cause cancer and skin lesions. It has also been associated with developmental effects, cardiovascular disease, neurotoxicity and diabetes.
Arsenic occurs as organic and inorganic forms.
Inorganic arsenic has been employed in certain industries. It has been used as a preservative in pressure-treated lumber and animal hides, in pesticides, glass manufacturing, semiconductors and even as an additive in lead-acid batteries.
Inorganic arsenic, such as those found in industry practices and arsenic-contaminated water, tends to be more toxic and has been linked to cancer.
Organic arsenic is much less toxic than the inorganic arsenic compounds. They are not thought to be linked to cancer. These compounds are found in some foods, such as fish and shellfish. It is excreted in urine within 48 hours of ingestion.
Since arsenic occurs naturally in the environment, we normally take in small amounts in the air we breathe, the water we drink, and the food we eat. People can also be exposed to higher levels of arsenic through certain occupations such as jobs in the industries mentioned above. However, such exposures are now rare due to stringent laws imposed on industry practices protecting workers’ welfare.
Safe drinking water is a major concern in a number of countries like Bangladesh, China, India, Mexico, Taiwan and in some rural communities in the United States. Arsenic levels tend to be higher in water from ground sources, such as wells. In fact, international health experts are battling with arsenic poisoning from well water in Bangladesh, where inorganic arsenic are naturally present in high levels. Meals prepared with contaminated water and crops irrigated with such adds to other sources of exposure, especially for people living near current or former industrial or agricultural sources of arsenic.
Arsenic in food
Since arsenic is a natural occurrence in the environment, it is not unforeseen for it to get into our foods. According to the FDA, arsenic may be found in grains, fruits and vegetables.
Arsenic dissolves easily in water, it is easily mistaken as nutrients by plants because of its chemical structure which absorbs it readily from the soil. “All plants pick up arsenic,” according to John M. Duxbury, PhD, a professor of soil science and international agriculture at Cornell University in Ithaca, N.Y. He said: “Concentrations in leaves of plants are much higher than in grains of plants. Thus, leafy vegetables can contain higher levels of arsenic than rice, especially when they are grown on arsenic-contaminated soils.”
According to Consumer Reports citing a study from 2010, vegetables account for the biggest dietary exposure to arsenic, accounting for 24 percent of intake. It is followed by fruits and fruit juices with 18 percent, and then rice with 17 percent.
Seafood also has high levels of arsenic, though most experts believe the form of arsenic in seafood to be nontoxic (organic arsenic). Calcium supplements made from seafood may therefore also contain high amounts of arsenic. It might be better to choose an organic plant-based calcium supplement instead.
Rice and Arsenic
Rice stands out among the other grains not only because it is a major part of the Asian diet. Since it is grown in paddies which are flooded with water, it is particularly susceptible to arsenic contamination than those crops grown in drier soil. Rice is also a dominant component of cereals eaten by infants and young children. Young children are especially vulnerable to arsenic exposure because of their small body size. Of additional concern is brown rice syrup, a rice-derived sweetener that may be high in arsenic.
Nearly all rice products have been found to contain at least some arsenic, although the levels can vary widely.
The highest levels of arsenic in U.S.-grown rice were detected from the southern states possibly because they are grown on what used to be cotton fields. Cotton farmers were known to use pesticides to eradicate bugs like the boll weevils. Since arsenic can remain in the soil for many years, it is readily integrated into the rice crops. The lowest arsenic levels were detected in rice grown in California. Notwithstanding, Scottish researchers have found higher levels of arsenic in rice grown in the U.S. than in basmati or jasmine rice from Thailand or India.
A research assistant professor at Dartmouth College in Hanover, Tracy Punshon PhD, X-rayed rice grains to see where they store arsenic. She found that arsenic concentrates in the part of the grain called the germ, which is removed to make white rice. That means brown rice has higher concentrations of arsenic that white rice. If you eat large amounts of rice, the white variety may be a better choice especially the aromatic ones like basmati or jasmine. Furthermore, rice from the Himalayan region, including North India, North Pakistan and Nepal may contain lower amounts of arsenic.
Below illustrates the comparison of arsenic content among the different grains:
Is organic food any better, in terms of arsenic risk?
According to experts, organically grown produce isn’t any safer than conventionally grown food since arsenic persists in the soil for years.
How to Reduce Arsenic in Rice
Even when it’s safe to consume rice imported into Singapore, it is still prudent to reduce the arsenic content of rice. This may be achieved by washing and cooking the rice with clean water. It is effective for both white and brown rice, potentially reducing the arsenic content by up to 61%. Although important nutrients may also leech away with rinsing and cooking with excess water, harmful arsenic content is markedly reduced.
Below is a table from the FDA, displaying the percentage reduction of inorganic arsenic with rinsing and cooking in excess water. The data reveal rinsing and using plenty of water when cooking significantly reduces the content of inorganic arsenic by 9-61%. Rinsing polished rice has the most noticeable reduction in inorganic arsenic content (16%). In addition, cooking rice in excess water considerably reduce (by 43-61%) inorganic arsenic content for all three types of rice (brown, polished and parboiled).
Percent reduction with rinsing
Percent reduction with cooking in excess water (averaged 6:1 and 10:1 ratios)
Courtesy of: http://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm319948