August 16, 1999

Expert estimates that one in 10 drilled wells has high arsenic levels

By Charlie Pomerleau
Staff Writer

Reprint from
Lewiston Sun Journal

You can’t see, smell or taste arsenic in water, but if you use a drilled well there’s a good chance it could be contaminated by the cancer-causing metal.

“Arsenic is becoming Maine’s new radon problem,” said Dr. Andrew Smith, toxicologist with the Maine Bureau of Health.

He estimates that one in 10 private drilled wells have arsenic at levels high enough to greatly increase the risk of lung or bladder cancer.

It also may cause liver and kidney cancers, but evidence is not as strong there, he said.

Public water systems pose no added risk because most use open-surface supplies such as lakes and are already filtered and frequently tested, Smith said.

Arsenic in private wells is another matter, though, and it can be deadly.

“The current estimate of cancer risk from arsenic exposure ranges from one in 100 to one in 1,000,” Smith said, citing a National Research Council report issued this spring that looked at areas other than just Maine.

The usual federal standards for allowable lifetime cancer risk range from one in 100,000 to one in 1 million, he said, so “these are clearly more dangerous levels of contamination than permissible.”

The Bureau of Health says anyone with a drilled well should have it tested for arsenic. The tests can be done by private water labs for $12 to $15 or by the Maine Health and Environmental Testing Laboratory, Smith said.

If a test finds high concentrations, several treatment options are available. Boiling the water isn’t one of them, as it only increases the concentration, he said.

“First we recommend the household use bottled water for drinking and cooking as an inexpensive way to reduce their exposure,” Smith said. “Then, they’ll have time to study their needs to determine what kind of treatment system will work best for them.”

Air & Water Quality of Windham is a private company that has installed dozens of treatment systems, according to Mike Gelberg, co-owner. He recommends a process called reverse osmosis as the simplest and most effective, a choice Smith supported.

The system forces water through a special membrane that captures the arsenic and other contaminants, flushing them away while pure water is stored in a tank connected to a separate faucet at the sink. It’s a slow process with the output greatly determined by water pressure and temperature, so a system may produce only three to six gallons a day, Gelberg said.

“That means you’re only going to use it for drinking and cooking,” Gelberg said. “You won’t be flushing the toilet or watering the lawn with this water.”

The basic point of use system can cost from $1,000 to $1,200, he said. Larger systems to treat all the water used can cost a minimum of $4,000 and easily up to $7,000.

Long-term exposure

When you stop drinking tainted water, Smith said, the arsenic leaves your body fairly quickly. The problems come with continued long-term exposure, he said.
The state first became aware of the problem when a well for a new school in Buxton was found to have high levels of arsenic. Smith said nearby homes were tested, then the probe widened to include more than 1,000 wells in the Buxton-Hollis area and eventually 5,000 more statewide.

“We saw a fairly consistent picture that one in 10 wells had levels higher than the current federal maximum of 0.05 milligrams per liter,” Smith said. Half the wells checked had some measurable level of arsenic.

Arsenic occurs naturally in soil and rocks, so some wells may have tapped pockets rich with the metal. Other contamination may be from human uses, because arsenic was heavily used as a pesticide on apples, blueberries and potatoes in the first half of this century, Smith said.

“We don’t know how much has leached into the ground down to the bedrock and is there when a well is drilled through it,” he said.