September 5, 2011

Toxic Taps Part 1: High amounts of arsenic in local wells

READFIELD — Marc Loiselle built his home to code.

His Cape on the outskirts of the village is well insulated, has proper wiring and an air-exchange system that keeps it cozy in winter, cool in summer.

“Then you drill a well, and surprise!” Loiselle said. “Most people assume it’s fresh, pure, natural water, and perfectly safe to drink.”

Eventually, Loiselle found out his wasn’t. After he built his Sturtevant Hill Road home in 1995, he had his well tested as part of a Columbia University study.

It showed arsenic in his drinking water at 30 parts per billion.

“At the time we drilled, I presumed the risk to be minimal,” said Loiselle, a retired hydrologist. “It was below the contaminated level, so we didn’t do anything.”

Then, in 2002, the U.S. Environmental Protection Agency strengthened the standard, moving it from 50 parts per billion to 10 parts per billion.

Loiselle’s is hardly the only home in Maine with toxic levels of arsenic in its well water.

Using data from more than 11,000 wells in 530 Maine municipalities, a landmark U.S. Geological Survey study released in 2010 showed, for the first time, three high-arsenic clusters: the southern coast, Down East and Greater Augusta.

Columbia University followed up those results and estimated 31 percent of private wells in Greater Augusta contain arsenic above the federal standard. Arsenic found in some private wells sampled by Columbia researchers exceeded the standard by 10 to more than 100 times.

Using various analytical methods, Columbia researchers say 12,293 to 15,561 Kennebec County residents are drinking from private wells that have toxic levels of arsenic, which has been linked to increased risk of skin, lung and bladder cancer; developmental problems in children; diabetes; and undesirable effects on the immune system.

The problem — naturally occurring from underlying rock — is particularly prevalent in Readfield and Manchester, and in a band along the western edge of the county from Winthrop and Monmouth south through Hallowell and Litchfield.

The solution is fairly simple: a water test for $15 to $25 and, if deemed toxic, a filtration system that can cost as little as a few hundred dollars.

But many are still in the dark about the problem. Standards continue to evolve. And Maine does not require any testing of private wells, on which 74 percent of Kennebec County homes rely for potable water, according to U.S. Census data.

It’s in the rocks

Loiselle, 61, was at least prepared to deal with the results of his water test: He’d dealt with enough water supplies during his career as a Maine Geological Survey hydrogeologist to know the risks of arsenic.

He said he knew arsenic is a part of the earth’s crust and occurs naturally in central Maine’s soil and rocks.
The Columbia study found arsenic correlates with certain types of bedrock, in particular: Silurian meta-sedimentary, Devonian granite and Ordovician-Cambrian volcanic rocks.

State Geologist Robert Marvinney said arsenic is absorbed into ground water as it flows through fractured bedrock.
Development and blasting may change the way fractures are connected, allowing water with more arsenic to reach a well it once didn’t. Such situations are rare, he said. 

Arsenic compounds also were widely used as pesticides and herbicides in the 20th century. Such use has been discontinued, but Marvinney said it’s possible some arsenic found in Maine’s ground water may be from such sources.

“Arsenic is common in many minerals found in Maine and other parts of the country, particularly . . . compounds with sulfur,” Marvinney said. “Sulfide minerals can be found throughout the metamorphic rocks that underlie much of central and southern Maine. Arsenic is also fairly mobile within a few hundred feet of the surface, meaning conditions can cause it to be leached from the minerals into water fairly readily.”

(Continued on page 2)

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Additional Photos

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Symptoms of acute arsenic poisoning include patches of darkened skin, as with this Bangledeshi woman.

Photo contributed by Yan Zheng/Columbia University

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Charles W. Culbertson, a scientist with the US Geological Survey-Maine Water Science Center, poses in Litchfield with some of the equipment that uses to test well water.

Staff photo by Joe Phelan

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Andrew E. Smith State Toxicologist and Manager Environmental and Occupational Health Program

Staff photo by Joe Phelan

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Andrews Tolman

Staff photo by Joe Phelan

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