EPA to re-examine chemical Mass. already limits in drinking water

Three years ago, the Massachusetts Department of Environmental Protection put in place the nation’s toughest standard for perchlorate, a chemical used in explosives that was found in some public water sources.

Some fireworks can contain perchlorate (Dina Rudick/Globe photo)

Now in what has to deeply satisfy state environmental officials, the U.S. Environmental Protection Agency has announced it will re-evaluate the chemical. That reverses an October 2008 preliminary decision not to regulate it – and gives the EPA the opportunity to perhaps come to the same conclusions that Massachusetts did after four years of research: Better to protect vulnerable populations than to be sorry later.

Perchlorate can affect normal function of the thyroid gland, and interfere with metabolism and growth and development. For several years, Massachusetts officials said that could pose a particular risk to children. Now, the new EPA analysis will focus on the impact of perchlorate on infants and young children to take into account that infants and children consume more water per body weight than adults.

Widely used on military bases since the 1940s, environmentalists had previously charged the federal government with delaying or proposing lax standards because much of the contamination is on military bases.

Massachusetts began looking at the chemical in depth in 2001 when perchlorate was found in the groundwater at the Massachusetts Military Reservation at levels of 600 parts per billion.

By 2004, it had been found in 10 state drinking water supplies, with one reading at 1300 parts per billion.

Nationally, there was conflicting data on how dangerous it was. One National Academy of Sciences report suggested that limits could be set higher than 20 parts per billion and EPA originally proposed a 24.5 parts per billion threshold. But last year, the agency said no standard was needed.

By that time, however, Massachusetts had set a standard at 2 parts per billion. California’s drinking water standards is 6 parts per billion.

Massachusetts just may be a guide to the EPA for a more protective threshold.