One of the most poisonous substances discovered by man is arsenic; hence, it was a public health concern when a team of scientists from Dartmouth published about potentially consuming toxic levels of the element from eating rice. This is because Americans tend to consume one half cup of rice in a day, based on the data from the Department of Agriculture, but this amount increases two to three times in some groups such as the Asian-American population.

According to the study published in the PNAS or Proceedings of the National Academy of Sciences, the element is naturally occurring in the environment and commonly found in groundwater. But because of the harmful effects of arsenic to health in higher concentrations, the levels of arsenic in water cleaned for drinking is limited to 10 micrograms per liter, as set by the World Health Organization.

However, the results of the Dartmouth study showed that consuming rice can expose humans to harmful concentrations of arsenic because the plant can extract it from the environment. People familiar with planting rice are aware that for the crop to grow, it needs to be exposed to constant influx of water specifically well or ground water.

The threat of arsenic to the health is very serious, as further explained by Margaret Karagas who is a professor from Dartmouth Medical School, since it can cause damaging effects to the fetus when pregnant women are exposed to it. Other noted effects of arsenic include low birth weight, high death rates among infants, suppressed function of the immune system, and increased chances of dying from lung cancer or other types of malignancies in later life.

Diane Gilbert-Diamond, a co-author of the research study together with Karagas, discussed how the study was conducted. She said that 229 pregnant women from New Hampshire were chosen as the subjects of the study and were divided - those who ate rice for the past two days and those who do not have rice intake. The arsenic concentration in their bodies was tested with a urine sample, and the tap water from their residences was also collected and tested for concentration of the same element. The latter step was done in order to clearly show that arsenic can indeed be transferred from the water to the cooked rice.

The results of the study show that among the 73 participants who ate rice, the median arsenic concentration in urine was 5.27 micrograms every liter, while a lower median of 3.38 micrograms was found in participants who did not eat rice. There was indeed a significant difference between the concentrations of arsenic between these two groups.

The study was funded by the National Institute for Environmental Health Sciences (NIEHS) and the Environmental Protection Agency (EPA), but the researchers emphasized that despite the well accepted result of their study, the actual effects of eating rice from arsenic contaminated water in humans should still be studied further, and they also reminded readers that eating rice should not be totally banned since rice remains a good source of nutrients.


Source: Joann Gruber, Emily Baker MD, Vicki Sayarath. Dartmouth College. 6 December, 2011.