Let’s see what’s on this week’s dinner menu.
Monday: pasta and cheese sauce with broccoli
Tuesday: salmon burgers and asparagus over a bed of rice and arsenic
Wednesday—Wait a minute. Arsenic?
I was disturbed to read a Consumer Reports study about the prevalence of arsenic in rice, which is one of my favorite menu staples. According to an article in the November 2012 issue of the magazine, most of the 223 samples of rice products it analyzed—from baby cereal to basmati—contained detectable amounts of the toxic metal. In addition, arsenic levels were found to be higher in brown rice than in white rice.
Further analysis by Consumer Reports showed that rice eaters had 44 percent higher levels of arsenic in their urine than those with rice-free diets.
Those findings come as no surprise to Barry Rosen, a molecular biologist at Florida International University who’s been studying arsenic, a human carcinogen, for more than 30 years. Rosen and his collaborators are working to reduce arsenic levels by genetically engineering rice grains that will vaporize the toxin.
“Rice is what is called a natural arsenic accumulator,” explains Rosen, the associate dean for Basic Research and Graduate studies at FIU’s Herbert Wertheim College of Medicine. “Most plants don’t accumulate large amounts of arsenic, but a few accumulate high levels, and rice is one of them. Wheat does not. It’s partly genetic. This is a property of rice. And it’s partially the fact that water in rice paddies has arsenic in it.”
What’s troubling about arsenic, he explains, is its potential to cause cancer “way down the road.” It’s ranked number one on the Environmental Protection Agency’s list of hazardous chemicals.
In 2006, working with an international research team, Rosen isolated a gene from the soil bacterium Rhodopseudomonas palustris that causes it to convert arsenic into a harmless gas. They introduced it to rice.
Thinking it would be better to introduce a plant gene to a plant, they searched for one that accomplished the same function. Higher plants don’t have the ability to volatize arsenic, but it’s present in Cyanidioschyson merolae, a type of alga that thrives in the hot springs of Yellowstone National Park. “Yellowstone is a volcanic area with some of the highest concentrations of arsenic in the world,” Rosen says. “This alga lives in concentrations of arsenic that would kill us, but it has mechanisms to deal with it that are highly evolved.”
In 2009, Rosen and a team of researchers cloned genes from Cyanidioschyzon. But rice can’t grow in the temperatures where this type of alga is found. More recently, the scientists have taken what they learned from the Yellowstone alga to identify “essentially the same gene” in closely related algae that grow in ponds at normal temperatures. “The next step is to introduce one of those genes into rice, but it will take three to five years before we’ll know if it works.”
Rosen’s discoveries could one day lead to new methods of environmental cleanup as well as safer rice on the supermarket shelves.
In the meantime, he says, he wouldn’t change his diet based on the Consumer Reports findings. But rice-eaters might want to follow some of CR’s recommendations for managing their risk, such as washing rice before cooking it or boiling it in extra water. “And not all rice has arsenic in it, he says. “So if you vary the rice you buy, you might be better off that way, too.”