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White wine, beer and Brussels sprouts can be major sources of the toxic metal arsenic in people's diets, according to a new study.
Researchers analyzed the diets of 852 people in New Hampshire, and the levels of arsenic in their toenails, which show long-term exposure to the chemical.
Of the 120 foods the researchers looked at, four turned out to significantly raise people's arsenic levels: beer, white wine (and to a lesser extent, red wine), Brussels sprouts and dark-meat fish such as salmon, tuna and sardines, according to the study, published last week (Nov. 16) in the Nutrition Journal.
The most significant source of arsenic in most people's diets is drinking water. The new study is the first to take into account the levels of arsenic in the participants' household water when looking at the amount of arsenic coming from foods.
The results suggest that diet can be an important source of people's arsenic exposure over the long term, regardless of arsenic concentrations in their drinking water, the researchers said.
The element arsenic occurs naturally in the environment. Long-term exposure to arsenic, even at low levels, has been linked to increased risks of bladder, lung and skin cancer, as well as type 2 diabetes and cardiovascular disease. The Environmental Protection Agency (EPA) limits the arsenic in drinking water to 10 micrograms per litter for drinking water, but there are few limits set for foods. [5 Things You Should Know About Arsenic]
In the study, the arsenic levels in the participants' household tap water were well below the EPA limit, at 0.30 micrograms per liter, on average. However, 52 participants had tap water arsenic levels higher than the EPA's limits.
The arsenic levels in participants' toenails were 0.12 micrograms per gram, on average. However, it is unclear what level of concentration found in toenail samples might signal an unsafe level of arsenic exposure, said study author Kathryn Cottingham, researcher at Dartmouth College in New Hampshire.
The toenail measurements in the study served only as a way to compare levels among people, the researchers said.
People who reported drinking on average two and half beers or a glass of white wine every day had arsenic levels 20 to 30 percent higher than those of people who didn't drink.
The study wasn't designed to find why higher consumption of beer and wine was linked to higher arsenic levels, but a few scenarios are possible, Cottingham said. [7 Ways Alcohol Affects Your Health]
One possibility is that the ingredients in beer and wine are high in arsenic. It is also possible that arsenic is added during the filtration process that gives beer and wine their sparkly, clear looks, as one recent study suggested, Cottingham said.
And lastly, alcohol itself may be to blame for the higher arsenic levels, by impairing the body's ability to detoxify arsenic.
"The mechanisms that our bodies use to try to get rid of the stuff that is not good for us can be impaired by alcohol consumption," Cottingham said.
The researchers didn't find a link between arsenic levels and intake of rice, which is thought to be relatively high in arsenic. But in line with previous studies, they found that the more dark-meat fish people ate, the higher were their arsenic levels.
People who ate dark-meat fish once a week had about a 7 percent higher arsenic concentration in their toenails compared with people who consumed these fish less than once a month.
Although some foods are high in arsenic, people don't need to avoid them entirely, Cottingham said. "Probably the best way to avoid exposure from diet is to mix it up in the foods, and not eat the same thing every day."
It's also important to keep water sources safe, she said. "If someone is drinking water from a private well, they should get it tested. Water is something we are drinking and using every day," Cottingham said. "So knowing what your water exposure is, I think, is a big piece of the puzzle."