Decreasing Arsenic Uptake in Organic Rice Systems
The Organic Center is collaborating with the U.S. Department of Agriculture’s (USDA’s) Agricultural Research Service (ARS) to conduct targeted research on the factors affecting the presence of arsenic in organically grown rice.
This project examines methods for reducing arsenic levels in organic rice. Arsenic uptake in rice occurs naturally, but the levels are typically very low. In fact, they are well below the internationally-recognized safety limits set by the Codex Alimentarius, a commission established by the United Nations Food and Agriculture Organization (FAO) and World Health Organization (WHO). That said, consumer safety is one of the organic industry’s top priorities, so the Center proactively investigated ways to decrease these already low levels of arsenic in rice. The aim of the research was to ensure that organic rice is as healthy as it can possibly be by providing growers science-based steps to prevent their rice from accumulating excess arsenic.
Arsenic in rice: Where does it come from?
Arsenic is a naturally occurring metalloid in the soil, but its presence in some areas has risen due to human activity such as the past use of arsenic-based pesticides in conventional agriculture. There are two types of arsenic compounds: organic arsenic and inorganic arsenic. Only the inorganic form of arsenic is known to have high toxicity. Although arsenic is not used by rice, it can be present in the plants because of the chemical’s similarity to silicon, which the plant uses to strengthen its stems and husks. Rice is grown in flooded fields. These wet conditions can increase arsenic’s ability to fit into the crop’s silicon transporters, and the rice then takes in more arsenic. As the plant produces rice grains, the arsenic can be integrated into the grains rather than silicon.
Why organic is important
Our research found there is no difference in the amount of inorganic arsenic taken up by organic versus conventional rice. However, organic rice production has a lot of advantages over conventional. Conventional rice production is a heavy user of pesticides, using over 40 different pesticides to control weeds and insects—pesticides that contain such toxic chemicals as piperonyl butoxide, malathion, and carbaryl. Organic rice paddies use environmentally friendly soil amendments such as compost, which helps increase soil health and decrease nutrient run-off. Lastly, organic growers are banned from using arsenic-based drugs and pesticides in production, among other regulations, which help cut the number of ways that arsenic can enter our food supply and environment.
Rice: The bottom line
Several studies have shown health benefits from consuming whole grains such as brown rice, and organizations like the American Heart Association and the National Institutes of Health and the U.S. Dietary Guidelines recommend that we eat more of these whole grains. Additionally, while the benefits of whole grains have been scientifically proven, there is no evidence that people who eat large quantities of rice have higher rates of cancer than people who avoid rice. However, several studies have found that exposure to pesticides can have an impact on human health and the environment, so it’s important to choose organic when making decisions about rice. The bottom line is that organic rice can be a wholesome part of our diet, while minimizing our exposure to pesticides and promoting the health of our environment.
The Organic Center is collaborating with the U.S. Department of Agriculture’s (USDA’s) Agricultural Research Service (ARS) to conduct targeted research on the factors affecting the presence of arsenic in organically grown rice. ARS scientists are testing samples of organic rice grown under controlled organic conditions at USDA research facilities, and examining the factors that directly impact the rate of arsenic accumulation in rice grown organically—varietal selection, flooding and organic compliant fertilizers. The goal is to offer future strategies to the organic sector to minimize such accumulation.
Dr. Anna McClung, USDA ARS
The Organic Center
The Organic Farming Research Foundation