Contaminant Example 1: Arsenic in Groundwater

RICHARD WILSON: Arsenic has been known to be acutely toxic for millennia. If you take it at 700 parts per million in the water, then it will certainly kill you moderately quickly. But what was not known until fairly recently is continuous use in fairly low doses can be very bad. And that means continuously daily ingestion.

Arsenic is a very common element in the Earth's crust. It's number 20 or something like that. And the question is, how do you get it inside? And it's coming mostly through water.

BEN BOSTICK: The reason that's important, for example, in New England is maybe one-quarter of all the peoples' wells in New England have levels of arsenic that we might think of as not being safe.

JANE DOWNING: We have estimated that about 2.3 million people in New England use private wells as their source of drinking water. And in some states like Maine and New Hampshire, that's about 40% of the population.

BERNIE LUCEY: New Hampshire law does not require water testing at private homes, nor quantity requirements at private wells.

ANGELINE ANDREW: Low-dose arsenic exposure has been associated with skin cancer, bladder cancer, particularly in smokers, and possibly lung cancer.

JANE DOWNING: That's why it's particularly important for private homeowners with wells to test their wells periodically and to take action to protect their family. In 2001, EPA revised their drinking water standard for arsenic to 10 parts per billion. And that was done after many months and years of extensive testing and research.

JOSHUA HAMILTON: The drinking water standard in the United States for the levels that we used to think were safe was 50 parts per billion, which sounds like a really tiny number, and it is. It's 50 micrograms, which is a millionth of a gram for every liter of water. So it's a really, really tiny amount. And yet, we now know from epidemiology studies that that level is not safe. That if you drink that level for a lifetime, your disease risk is pretty substantial.

COURTNEY KOZUL: With the previous arsenic drinking water standard of 50 parts per billion, it was thought that the cancer risk was as high as 1 in 100, meaning 1 in 100 people drinking arsenic at 50 parts per billion would develop cancer.

BERNIE LUCEY: Normally for man-made contaminants, the acceptable risk rate for pesticides, herbicides, fuels, industrial solvents is one in a million.

JOSHUA HAMILTON: We now have laboratory studies and some emerging epidemiology studies that suggest 10 is not safe either. That we're seeing health effects at as low as 10 parts per billion.

COURTNEY KOZUL: So we're really interested in looking at these low levels and what's happening, so sort of asking the question of, how low is low enough for an appropriate drinking water standard?

JOE AYOTTE: Overwhelmingly, the evidence that we have suggests that the arsenic we see in groundwater originates from natural sources in the minerals in the rocks of the region. Apparently, there's two main factors that control whether arsenic ends up in your groundwater.

And that's having some arsenic in the rocks as a source, but also having the right geochemical conditions. And in New Hampshire, that equates to having water that's relatively high pH and water with relatively little dissolved oxygen. Those two factors together result in higher arsenic concentrations in water.

PRESENTER: In the world today, in Asia alone, about 100 to 120 million people suffer from arsenic-related illnesses.

PRESENTER: How arsenic causes disease is the big $64,000 question. Nobody really knows the answer to this. What we do know is that arsenic doesn't behave like any other chemical that we know.

COURTNEY KOZUL: My research focuses on the effects of low-dose arsenic exposure on the immune system, particularly the immune system within the lung. What we've done is developed a mouse model in which we exposed mice to arsenic in their drinking water at 100 parts per billion for five weeks.

100 parts per billion is not an uncommon level of arsenic to find in areas of New England, such as New Hampshire and Maine. Following that exposure, we infected the mice with a sub-lethal dose of influenza A, an H1N1 strain of flu.

And what we found was that the mice exposed to arsenic had an increased susceptibility to infection, and they also had an increased severity of infection, resulting in a severe morbidity observed in those arsenic-exposed mice.

In theory, there would be a dose threshold in which we would expect no effects for arsenic exposure. The problem is that we don't really understand what that dose would be. We've certainly seen effects following arsenic exposure at 10 ppb or even lower.

JOSHUA HAMILTON: In my laboratory, we've seen effects on endocrine disruption and some other endpoints that we measure at below one part per billion. So now, we're talking about parts per trillion, which is a hard number to even think about.

COURTNEY KOZUL: The question remains as to whether or not these effects are biological effects or toxicological effects, meaning, do they have an adverse outcome on human health or not?

BERNIE LUCEY: And so the issue is one to educate the homeowner on, in terms of the importance of having a comprehensive water quality test.

SHARI YOUNG: I go to the state. I get a little decanter free. And the test costs $10 to $15.

BRIAN JACKSON: The liquid is sprayed into the instruments, and it goes into the inductively coupled plasma, which is a hot ionized gas. It's 7000 degrees, which is hotter than the surface of the sun. So the sample, basically, is desolvated. You lose all the water.

And the molecules are broken up into the chemical elements. And those elements are extracted into the mass spectrometer. And then the mass spectrometer basically counts the atoms of any particular element. So we determine the element by its unique mass. And we count the number of atoms in that sample, and that's how they determine concentration.

SHARI YOUNG: It takes maybe two weeks to get the results back. It's a pretty easy process-- in and out. There are various ways to remediate arsenic, and they're pretty inexpensive for a household like ours.

PRESENTER: There are two different sizes of water treatment devices. One is called whole house and would deal with approximately 200 gallons of water each day. The other is called point of use and would only deal with the water that one would consume each day.

COURTNEY KOZUL: It's not thought that dermal exposures, such as you would get in the shower, is such an immediate concern when compared to ingestion through the drinking water.

SHARI YOUNG: We actually got ours at Sears and had a plumber come and put it in underneath the sink. So I think you can put them in yourself, though.

JOE AYOTTE: At the USGS in New Hampshire, our primary responsibility is to provide impartial science information on the nation's water resources. We know from our studies that certain parts of the state have 30% of wells where we see arsenic concentrations exceeding 10. By zooming in and looking more closely at specific geology, we see some places where every other well has arsenic greater than 10.

BEN BOSTICK: If arsenic is in a city water supply, the city takes care of it, generally, and at least tells you if there's a problem. If you have your own water in your own well, the city doesn't have to do that. So, in fact, it's your own responsibility to take care and figure out what that arsenic concentration is.

JOSHUA HAMILTON: So, really, the bottom line is that everybody has to test their well. There's no predictive power. It doesn't matter whether your neighbor does or doesn't have arsenic. Each well is individual and has to be tested individually.