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In the water: Arsenic’s tumor-triggering mechanism discovered

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arsenic drinking water cancer signaling hedgehogArsenic exposure has long been linked to cancer, but just how the toxic element triggers tumor growth has been unknown.

A new study, published online February 23 in the journal Cancer Research, describes for the first time the impact of arsenic on crucial signals among the body’s cells—a potentially potent discovery for the 100 million people worldwide whose drinking water exceeds arsenic levels recommended by the World Health Organization.

The researchers, led by Dennis Liang Fei of the Department of Pharmacology and Toxicology at Dartmouth Medical School in Hanover, N.H., were tipped off by recent work that had shown that the Hedgehog protein signaling pathway (which plays a role in embryo development and likely some cancers) was often overactive in many of the same cancers to which arsenic has been tied—in particular bladder cancer.

Through study of cell cultures, tumors in mice and tumors from 265 bladder cancer patients, the team established that "arsenic is able to activate Hedgehog signaling," they noted in the paper describing the research. And "chronic activation of Hedgehog signaling by arsenic might contribute to the development of a subset of these tumors," they argued. 

They found that both acute and chronic low-levels of arsenic exposures led to the overactive signaling. And in studying the bladder cancer patients, the researchers discovered that "high levels of arsenic exposure are associated with high levels of Hedgehog activity."

This new knowledge will add "insight into the etiology of arsenic-induced human carcinogenesis," the researchers wrote. And though more questions remain, the findings might eventually be "relevant to millions of people exposed to high levels of arsenic."

Image courtesy of Wikimedia Commons

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  1. 1. Adam MacCannell 2:40 pm 02/23/2010

    Should North Americans continue to allow imports of food from regions with high arsenic counts in their soil and water? Local agriculture subjected to mining and or geologic contamination should be considered as well.

    Regardless of what levels are considered to be safe, food safety should be paramount! High level sources that skate below safety maximums provide the ability to concentrate in the consuming public.

    With the lack of disclosure as of present, there is nothing to allow the consumer to evaluate risk. Take dill pickles grown in Bangledash for example. Does high arsenic soil amount to high absorbtion/concentration rates in the cucumber? Does the higher priced product of Canada/US mean that the cucumbers weren’t just packaged and marketed here?

    Governments must choose between policies of disclosure, prevention or treatment.

    It’s no big surprise that toxins make us sick! So what now, that we know?

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  2. 2. JamesDavis 7:42 am 02/24/2010

    I’ll tell you what they are going to do Adam MacCannell… Until they stop using and extracting fossil fuel…nothing. SciAm had an article lately about a powder they called White Powder that cleans all these deadly chemicals, caused by fossil fuel extraction, out of the water, but they will never use it because it cuts into their profit and they will wait for the federal government to bail them out after four or five hundred thousand, of a couple of million, of us are killed by the chemicals. The toxins in West Virginia are so strong and plentiful that they are killing fish all the way down in Virginia bay and the government just shake their heads and say, "Oh, well! What kin a person do?"

    In West Virginia where these fossil fuel extraction companies put billions of tons of toxins into our water, air, and land, they do nothing to clean up after themselves and it caused numerous health problems and deaths. Their reason for not cleaning up their deadly chemicals is, "It will cost too many jobs and we will have to raise taxes to pay for it and no body wants their tax to go up". Until the EPA force these people to clean up their toxins, with billion dollar fines and law suits, we are going to loose lives…that is a given fact.

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  3. 3. Ray Van Ostran 11:52 am 02/24/2010

    Nothing will change until big business is no longer in control and we have the best politicians that money can buy.

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  4. 4. gothceltgirl 2:23 pm 02/24/2010

    You’re absolutely right JamesDavis. I grew up in WV & its a very toxic place. I had to go to NYC to get fresh air. How about that?!

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