A new study by Consumer Reports found arsenic levels that exceed federal drinking water standards in 10 percent of the apple and grape juices tested. The group also found excessive levels of lead in 25 percent of grape and apple juices. Arsenic and lead are both poisonous and can cause health problems, especially in pregnant women, infants, and young children. Kids drink a lot of juice—more than one-third drink more than recommended by pediatricians. Although there is no technical limit for these chemicals in most juices and foods, these levels found in five brands exceed the 10 parts per billion allowed in drinking water for arsenic and the 5 ppb allowed for lead (find detailed information about individual brands tested here in a PDF). Consumer Union, Consumer Reports’ advocacy arm, called for the Food and Drug Administration to establish maximal safe levels for these contaminants in juices. Several studies suggests that chronic exposure to arsenic and lead—even at levels below water standards—can result in serious health problems, the group said.
NASA’s big astrobiology news last week had nothing to do with E.T., of course—the team behind a study in Science announced the find of a kind of bacteria that appear to thrive in arsenic and can even use it in place of phosphorus in the backbone of its DNA double helix. But after the big announcement finally happened and squelched the more imaginative rumors, scientists started asking some hard questions about the study online.
Over at Slate, DISCOVER blogger Carl Zimmer rounded up expert critiques from biologists, and many didn’t hold back.
Almost unanimously, they think the NASA scientists have failed to make their case. “It would be really cool if such a bug existed,” said San Diego State University’s Forest Rohwer, a microbiologist who looks for new species of bacteria and viruses in coral reefs. But, he added, “none of the arguments are very convincing on their own.” That was about as positive as the critics could get. “This paper should not have been published,” said Shelley Copley of the University of Colorado. [Slate]
The science world is abuzz with news of a strange new life form found in California’s Mono Lake: Researchers report that they’ve discovered a bacterium that can not only thrive in an arsenic-rich environment, it can actually use that arsenic to build its DNA. If the researchers, who published their findings in Science, are correct, then they’ve found a form of life unlike anything we’ve ever seen before.
As you might expect, DISCOVER’s blogs offered plenty of coverage of this exciting news.
At The Loom, Carl Zimmer writes: “Scientists have found a form of life that they claim bends the rules for life as we know it. But they didn’t need to go to another planet to find it. They just had to go to California.”
At Bad Astronomy, Phil Plait explains exactly how the bacteria can make use of arsenic to build their DNA. A few days ago, Phil also took NASA to task for its press release promising news of “an astrobiology finding that will impact the search for evidence of extraterrestrial life,” which fueled wild speculation on whether NASA had found little green men in the solar system.
At Not Exactly Rocket Science, Ed Yong debunks a few of the more breathless accounts. The bacteria do not “belong to a second branch of life on Earth…. They aren’t a parallel branch of life; they’re very much part of the same tree that the rest of us belong to. That doesn’t, however, make them any less extraordinary.”
80beats: Life Found in the Deepest, Unexplored Layer of the Earth’s Crust
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80beats: Arsenic-Eating Bacteria May Resemble Early Life on Primordial Earth
DISCOVER: Renewed Hope for Life on the Red Planet
It was a twisted cycle: In the 1970s, Bangladeshis used surface ponds or rivers to collect rainwater for drinking. But thanks to garbage dumping and sewage, that water became a breeding ground for disease. So UNICEF sought to fix the problem—the agency helped residents drill simple wells that drew water from a shallow aquifer. But this remedy became a tragedy. Bangladesh’s groundwater was laced with arsenic. Now, in a study in Nature Geoscience, a team from MIT has answered one of the outstanding pieces of the Bangladesh puzzle: Just how all that arsenic got into the water in the first place.
Bangladesh occupies the flood-prone delta of the river Ganges [New Scientist], and that river brought the arsenic to the region’s sediments. But why doesn’t it just stay in the sediments once it’s there? Back in 2002, another MIT team began to answer the question by showing that microbes digest organic carbon in the soil in such a way that frees up the arsenic, but they couldn’t say where that carbon itself came from until Rebecca Neumann and colleagues figured it out this year: man-made ponds left behind by excavations.
A new study has shown that people with small amounts of arsenic in their urine are more likely to suffer from diabetes, and raises the possibility that drinking tap water contaminated with trace amounts of arsenic may be a risk factor for the disease. The [diabetes] risk was apparent at levels generally considered harmless and grew with increasing exposure [Bloomberg].
“It seems there is may be no safe level of arsenic,” [lead researcher Ana] Navas-Acien said in a telephone interview. “Worldwide it’s a huge problem” [Reuters]. Previous epidemiological studies in Bangladesh, Mexico, and Taiwan have shown that drinking water with high levels of arsenic in linked to high rates of diabetes. While safety standards for drinking water are much stricter in the United States, researchers say that 13 million Americans may be drinking water with arsenic levels that exceed federal guidelines. People in rural areas who drink well water may be particularly at risk, researchers say.