Approximately 115 grams of rice contaminated with arsenic can affect a person, said Clemence Rupert, laboratory coordinator for the Instituto Regional de Estudios en Sustancias Tóxicas at Universidad Nacional in Heredia.
Costa Ricans eat approximately 56 kilos of rice per person a year, an equivalent to approximately a daily 150 grams, said Diego Jiménez Prendas, agricultural engineer for Conarroz, a government organization that maintains a market for rice and promoted its development. Americans consume an average of half-a-cup of rice per day, approximately 113 grams, according to the U.S. Department of Agriculture.
“In Costa Rica no one has taken a look at arsenic in rice, we’re focused on other issues, such as pesticides and conservation of land . . . In the cases of metals, it’s very weak here,” said Rupert. “But in the case of Costa Rica, it’s important to investigate.”
A recent study, published by Dartmouth University researchers, showed that arsenic in urine increased with rice consumption in a group of pregnant women. The study was a sample of 229 pregnant women who were split into two groups, based on whether they had eaten rice in the past two days. The women who didn’t eat rice showed a significantly lower amount of arsenic in their urine. The 73 women who ate rice showed an average 5.27 micrograms per liter, and the 156 who hadn’t eaten rice showed an average of 3.38 micrograms per liter.
Another finding of the study was that 10 percent of the women drank well water contaminated with arsenic above the World Health Organization standards. All the test subjects were from the U.S. state of New Hampshire. The authors of the test also concluded that private water is a potential source for arsenic exposure.
Exposure to high levels of arsenic can be related to the cause of infant mortality, reduced birth rate, dysfunctional immune system, and death. Rupert said arsenic is a complicated substance with serious effects if taken in harmful amounts.
Costa Rica doesn’t have a specific law that states the highest limit of arsenic in products. But the country does follow the international rule of 10 micrograms per liter, a World Health Organization guideline, for arsenic level in drinking water. Although there isn’t a precise law in Costa Rica for arsenic in rice, the spokesperson for the Ministerio de Salud said the agency follows the international Codex Alimentarius 195, Standards for Rice that state under part 4 “Contaminants” section 4.1 “Heavy Metals,” the product “standard shall be free from heavy metals in amounts which may represent a hazard to human health.” The codex doesn’t provide a numerical value for harmful amounts of arsenic in products.
The Dartmouth researchers pointed out that China already has statutory limits on arsenic content in rice (0.15 micrograms of inorganic arsenic per kilogram of food) but the United States and the European Union do not.
If there is no testing or sampling for arsenic in rice produced in Costa Rica, then there is no way of knowing what the heavy metal content might be.
There are two different ways rice is exposed to arsenic. Rice can absorb arsenic through water when it is in the field. The application of pesticides to rice also can contaminate the food with arsenic.
Jiménez of Conarroz said that rice is important in the country and as an export. The majority of the country’s rice comes from local growers, but a portion is still based on import from El Salvador and other countries, including the United States. The areas of Chorotega and Brunca produce 73 percent of the rice in the country.
That would be the north and south Pacific coast areas.
Earlier this year, Costa Rica returned rice to El Salvador because tests showed that aflatoxins was present. Aflatoxin is a form of fungus. All international food imports into the country are tested for toxins, but not the local crop.
U.S. imports also have been embargoed because of aflatoxins. The fungus can cause cancer, but the levels are reduced in the milling process.
Dartmouth researchers are calling for the U.S. government to monitor arsenic levels in food.
The team at Dartmouth Medical School studied pregnant women because scientists believe arsenic may be linked to premature births and low birth-weights.
“Developing fetuses may be more vulnerable to environmental agents,” said Margaret Karagas, senior author of the Dartmouth study, which appeared in the Dec. 6 edition of Proceedings of the National Academy of Sciences. She was quoted in a university release.
Ms. Karagas said pregnant women should not avoid rice, as it contains important nutritional elements, according to the university. Instead, she said her team wants food “to be monitored for the presence of arsenic and regulated to keep it below certain levels.”
Ms. Karagas is a professor of community and family medicine and director of the Children’s Environmental Health and Disease Prevention Center at Dartmouth Medical School.