Arsenic, radon in Maine groundwater

    Every now and then Mother Nature throws us a curve ball. We work like crazy to keep gasoline, antifreeze, septic system effluent and other potentially harmful materials out of our groundwater in the hope of preserving it for drinking, bathing and other domestic uses. But even with all our hard work and best intentions, Mother Nature has whipped two nasty curve balls by us for two strikes: arsenic and radon.
    When we hear “radon” most of us think of air quality. Arsenic probably conjures up visions of cold-hearted killers and scary novels. The truth is less exciting, but much more serious for Maine citizens and the public health officials working to protect them. Arsenic and radon can be present, sometimes in very high concentrations, in Maine groundwater.
    Long-term exposure to both contaminants can potentially cause cancer and short-term exposure to high levels of arsenic can result in stomach irritation, fatigue, a pins and needles sensation in hands and feet or skin irritation.
    Where is all this arsenic and radon coming from? Both are found in the minerals that make up different types of Maine bedrock. When in contact with water, one of the most effective solvents in nature, minerals dissolve and are carried away. For example, iron and manganese are two elements common in Maine bedrock that are abundant in groundwater because of this process. It’s these dissolved minerals that give our drinking water its flavor (mineral water!!). Unfortunately, arsenic and radon enter our water the same way.
    To make matters worse, both arsenic and radon have no color, taste or odor in water, even at very high levels. The only way to find out if your well water contains either of these naturally occurring elements is to have it analyzed by a laboratory. The phone book lists private laboratories, or you may contact the State of Maine Health and Environmental Testing Laboratory in Augusta for a test kit. (207) 287-2727.
    Test results for radon will be measured in pico curies per liter (pCi/l). Maine’s health standard for radon in drinking water is 4,000 pCi/l. The federal Environmental Protection Agency is currently proposing a much lower standard for public water supplies.
    Arsenic results will be reported in milligrams per liter (mg/l). The new standard for arsenic in drinking water is .01 mg/l, or 10 parts per billion (ppb), down from 50 ppb. The old 50 ppb standard was set by EPA in 1975 and has been recently changed based on new health studies.
    If you test your water and find either radon or arsenic you don’t need to panic. Both can be removed very effectively. Aerating your water and exhausting the gas to the outside of your home can remove radon. Arsenic can be removed by using a reverse osmosis system, which utilizes membrane filtration.
    Don’t let Mother Nature throw you that third strike. Test your well water for both arsenic and radon. For more information visit the Division of Environmental Health’s home page on the Internet at http://www.maine.gov/dhhs/eng/water/ or call them at 207-287-2070.
    This column was submitted by David Braley, a geologist with the Maine Dept. of Health and Human Services, Division of Environmental Health. In Our Back Yard is a weekly column of the Maine Department of Environmental Protection. E-mail your environmental questions to infodep@maine.gov or send them to In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333.