Not everyone who is exposed to an infectious disease, even the widely-feared new “swine” flu (H1N1), gets sick. And many people who do come down with the flu or another illness get over it without much trouble. While a lot of factors can be at work, from good nutrition to physical fitness, a new study suggests an all-too-common toxin in the water you drink could play a role in whether an H1N1 infection makes you seriously ill.
According to scientists at the Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts, and Dartmouth Medical School, the ability to mount an immune response to H1NI infection, a form of influenza A, can be significantly compromised by even low levels of arsenic exposure that commonly occur through drinking contaminated well water.
Respiratory infections with influenza A virus are a worldwide health problem and kill about 36,000 people each year according to the CDC. The recent outbreak of a type of influenza A known as H1N1, or “swine flu”, has killed over 70 Mexicans so far and at least six Americans. The fact that Mexico has large areas of very high arsenic in well water — and these include the locations where H1N1 first appeared — intrigued the MBL and Dartmouth research team.
“One thing that did strike us, when we heard about the recent H1N1 outbreak, is [that] Mexico has large areas of very high arsenic in their well water, including the areas where the flu first cropped up. We don’t know that the Mexicans who got the flu were drinking high levels of arsenic, but it’s an intriguing notion that this may have contributed,” Joshua Hamilton, the MBL’s Chief Academic and Scientific Officer and a senior scientist in the MBL’s Bay Paul Center, said in a statement to the media.
Immune response seriously hampered by arsenic exposure
In a study just published in the journal Environmental Health Perspectives, Hamilton and his colleagues reported on their study of mice that ingested 100 ppb (parts per billion) of arsenic in their drinking water for five weeks and then were exposed to H1N1.
“When a normal person or mouse is infected with the flu, they immediately develop an immune response in which immune cells rush to the lungs and produce chemicals that help fight the infection,” Hamilton stated in a press release. But in the lab animals exposed to arsenic in their water, something was clearly amiss. The researchers found that the animals’ immune response to H1N1 infection was initially very weak. But, several days later, the rodents’ immune systems produced a reaction that was too strong and too late.
“There was a massive infiltration of immune cells to the lungs and a massive inflammatory response, which led to bleeding and damage in the lung,” Hamilton said in the media statement. He also noted that morbidity from the influenza infection was found to be significantly higher for the arsenic-exposed mice than the control animals who had not consumed arsenic-tainted water.
Hamilton and his research staff have been studying the effects of arsenic for years. They’ve found that arsenic exposure not only disrupts the immune system but also disrupts the endocrine system, causing unusually broad hormonal upheavals.
“Most chemicals that disrupt hormone pathways target just one, such as the estrogen pathway,” Hamilton explained in the media statement. “But arsenic disrupts the pathways of all five steroid hormone receptors (estrogen, testosterone, progesterone, glucocorticoids, and mineralocorticoids), as well as several other hormone pathways. You can imagine that just this one effect could play a role in cancer, diabetes, heart disease, reproductive and developmental disorders — all the diseases that have a strong hormonal component.”
“We don’t yet know how arsenic disrupts either system at the molecular level. But once we know how it affects one system, we will have a pretty good idea of how it affects the other systems as well,” he added. Currently, Hamilton’s lab is working on understanding the unusual dual effect arsenic has on the endocrine system. Very low amounts of arsenic stimulate or enhance hormone responses but at doses just slightly higher, like those found in drinking water, it appears to suppress those hormone responses. “Our principal focus is to figure out this switch. We think that will help us understand why arsenic does what it does in the body,” Hamilton stated.
He explained that for arsenic to have health consequences, it requires exposure day after day, year after year, such as through drinking water — and that’s exactly the kind of exposure far too many Americans have to the toxin. The U.S. Environmental Protection Agency (EPA) claims 10 parts per billion (ppb) of arsenic in drinking water is “safe”. However, according to Hamilton, concentrations of 100 ppb and higher are commonly found in well water in many regions of the country including Massachusetts, New Hampshire, Maine, Florida, and large parts of the upper Midwest, the Southwest, and the Rocky Mountains.
As reported (Arsenic in Water at EPA Approved Standards Linked to Heart Disease), research suggests the EPA’s supposedly “safe” level of arsenic allowed in water supplies for public consumption isn’t safe at all and could be causing a host of health problems, including high blood pressure and artery-clogging atherosclerosis. What’s more, when the non-profit Natural Resources Defense Council (NRDC) analyzed data compiled by the EPA, the group’s most conservative estimates based on the data indicated that more than 34 million Americans were drinking tap water supplied by systems containing average levels of arsenic that posed unacceptable cancer risks. Now it appears another serious health problem — a higher susceptibility to a serious case of “swine flu” — can be added to that list of arsenic-in-drinking-water linked worries.
S. L. Baker
Kozul, C.D., Ely, K.H., Enelow, R.I., and Hamilton, J.W. (2009) Low dose arsenic compromises the immune response to influenza infection in vivo. Environmental Health Perspectives, doi:10.1289/ehp.0900911