Arsenic health risk in food adds up
Professor Partha Basu.
Aaron Barchowsky, a University of Pittsburgh Graduate School of Public Health professor.
Duquesne University professor Partha Basu, left, who has studied arsenic contamination in food, observes grad student John Thomas prepare compounds to be analyzed.
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To eat or not to eat rice, that is the dietary question.
Two local professors knowledgeable about arsenic -- levels in food, impacts on health and pervasiveness in the environment -- are weighing in on whether people should eat rice and rice products now that it has been reported that rice contains elevated levels of toxic arsenic.
One is more cautious than the other, but neither recommends removing it from the diet.
"It's complicated, but I don't agree with what Consumers Union says -- that we should avoid rice," said Aaron Barchowsky, a professor in the department of environmental and occupational health at the University of Pittsburgh's Graduate School of Public Health. "I agree with the FDA and its ongoing study on rice content. Eat a balanced diet and don't focus on one food group. That's always good advice."
Brown rice and wheat germ contain compounds including vitamin B3, niacin and folates that help eliminate arsenic from the body. "When you focus on arsenic and not all the compounds in rice, it gives you a distorted picture of the real risk," he said. "We get more benefit than risks from eating rice."
Partha Basu, a professor in Duquesne University's department of chemistry and biochemistry, said the danger lies with chronic exposure to elevated arsenic levels in the diet. His research focused on high arsenic levels in a now-banned pesticide and its impact on the environment and potential impacts on human health. He recommends rinsing rice before cooking it, then draining the water and rinsing it again after it's cooked to reduce arsenic levels. "We do that in our house," he said.
Elevated arsenic levels in rice and other foods aren't a new issue in nutritional science.
"But now it's a big issue and millions are at risk," Mr. Basu said.
Consumer Reports, whose own study found elevated arsenic levels in rice and rice products, recommended last month that people refrain from eating those foods. The U.S. Food and Drug Administration got similar results in preliminary results and plans to have its full study completed by year's end.
Elevated levels of arsenic were found in rice grown in Arkansas, Louisiana, Missouri and Texas -- levels higher than rice grown in India, Taiwan and California. But arsenic levels in rice generally are elevated worldwide due to growing practices, water sources, natural arsenic levels in soil and the plant's ready uptake of Earth's 21st most abundant element into stalks, leaves and grain. No regulatory standard exists for arsenic in food. Nor is it easy to determine where store-bought rice is grown.
Hitting a new record, 512 million tons of rice were produced internationally in 2010, according to data collected by the Food and Agriculture Organization of the United Nations.
Noting public concern, the FDA said it hopes to determine the health risks of arsenic in rice and offer ways to minimize them. "Based on data and scientific literature available now, FDA is not recommending that consumers change the consumption of rice and rice products at this time, but that people eat a balanced diet containing a wide variety of grains," its news release states.
Arsenic not only causes bladder, lung and squamous-cell skin cancers but also Mr. Barchowsky said there's good evidence that it causes cardiovascular disease, hypertension, lung disease and, possibly, neurological deficits and diabetes.
He said daily arsenic intake shouldn't exceed 30 micrograms with the possible start of health effects above 50 micrograms. In preliminary findings, the FDA found 6.7 micrograms of arsenic in a cup of cooked rice other than basmati rice, with rice cakes having 5.4, rice beverages with 3.8, and rice cereals and basmati rice with 3.5 micrograms.
Arsenic levels in organic rice are lower but still worrisome, Consumer Reports said.
Two types of arsenic compounds -- organic and inorganic -- are found in water, food, air and soil. Total arsenic is the measure of both forms. But inorganic arsenic, the metalloid that has metallic properties but isn't a metal even though it often is described inaccurately as a heavy metal, is found in rock and soil. "It is the amount of inorganic arsenic that we are concerned with in food and water since this is the form that enters the body and impacts health," Mr. Barchowsky said.
With a doctorate in pharmacology and toxicology, he and his Pitt colleague Felicia Wu, who has a doctorate in engineering and public policy, are calculating global levels of disease caused by arsenic in food and water for the World Health Organization, with an emphasis on the increased number of annual cancers it causes.
The daily 30-microgram limit for arsenic intake was established for a 220-pound adult, with a sliding scale downward for those weighing less. For a 50-pound child, the daily limit would be 14 micrograms of arsenic.
"Generally it is thought that children should be exposed to less since they are smaller and their metabolism might be different," he said. "Another way to look at it, though, is that a 50-pound child may not consume as much food as a 220-pound adult, so the amount of arsenic consumed would tend to be proportional."
Drinking water can contain more arsenic than foods, especially well or spring water that, unlike public water systems, isn't regulated by the U.S. Drinking Water Standards that sets a 10-parts-per-billion limit on arsenic. Most public water has about 4 ppb of arsenic. But wells and springs can exceed 200 ppb. At 100 ppb, cancer rates begin rising with one or two additional cancers per 100,000 people, Mr. Barchowsky said. Cancer rates greatly increase with arsenic levels in water containing 500 ppb. These cancer rates are based on the assumption that individuals consume 2 liters of water containing these amounts of arsenic, which means these individuals would have a daily consumption of more than 200 micrograms of arsenic before the amount in food is added.
Fish have high quantities of total arsenic but it is mostly organic arsenic, which is not toxic to humans, Mr. Barchowsky said. Seaweed, particularly hijiki seaweed, and edible algae do contain high rates of dangerous arsenic. Meats generally don't contain worrisome levels. As happens in the human body, inorganic arsenic is quickly metabolized in livestock and not stored in tissue or fat, he said.
Industrial processes -- including mining, gas drilling, industrial waste disposal and past use of pesticides in agriculture -- have raised environmental levels of arsenic. It's not clear what role those sources play in arsenic levels in food and water. But Mr. Barchowsky warned that mining and hydraulic fracturing used to produce natural gas are "mobilizing arsenic from the earth."
Mr. Basu published research in 2008 about the feed additive, roxarsone, which was first approved by the FDA in 1944 and fed to chickens as a treatment for intestinal parasites. But Mr. Basu's study also revealed that the arsenic compound formed more blood vessels in chickens, which also is the process that occurs in many diseases and cancers.
In June 2011, the FDA announced it had completed a study that showed the less-toxic organic arsenic in roxarsone could transform into inorganic arsenic, the known carcinogen. The drug manufacturer voluntarily suspended sales of the feed additive.
In the decades of its use, chicken litter containing high concentrations of arsenic from roxarsone was spread on fields and used in commercial fertilizers. The annual amount of chicken litter generated in the years when the drug was used would cover 2,000 square miles at a half inch thick. That equals the size of Delaware.
But Mr. Basu said no study has been done to show whether arsenic from roxarsone has increased water or food levels, but in 2008 he described the results as "a significant finding as it relates to potential human health effects."
In his current research, he's measuring how far the arsenic can migrate from the farmland.
First Published October 8, 2012 12:00 am