Ground-water samples taken by the Army near Aberdeen's drinking-water wells contain a chemical linked to thyroid cancer, and a top environmental officer at Aberdeen Proving Ground says that discovery makes the area a "high priority" for investigation and treatment.
The Army and Environmental Protection Agency stressed that no traces of the chemical, perchlorate, were found in the drinking water or in the 11 wells along the APG boundary.
"It's not in city wells, but it's close -- too close for comfort," said University of Maryland toxicologist Cal Baier-Anderson, who works closely with the post on environmental issues.
"This is a high priority," said Ken Stachiw, chief of the proving ground's environmental restoration program. "Something else will have to go because this is close to people's drinking water."
He is rearranging projects to put this at the top of his list of cleanup priorities.
Perchlorate was discovered within 300 feet of the city wells, said Stachiw. The toxic chemical was discovered in the area in March of last year, prompting the further tests, which were completed several weeks ago.
Aberdeen City Manager Peter Dacey said the proving ground shared the findings with the city about three weeks ago. "We're extremely concerned," he said.
Dacey played down the fact that neither the city nor APG made the findings public immediately.
"First of all, we need to do proper testing and then we need to go to the next step," he said. "We're not going to take an alarmist position till we have all the facts."
No public mention of the perchlorate findings was made Thursday night at a meeting of a committee of environmental officials and Harford residents who meet regularly to discuss cleanup issues at APG.
Several of the wells are close to Camp Stanton, a training area in the northern corner of the proving ground, where soldiers use smoke bombs and other obscurants in exercises.
Perchlorate is a key component in such explosives, said Baier-Anderson. "We speculate that the perchlorate may be related to training at Camp Stanton," she said.
"The aquifer the city of Aberdeen is drawing from is so shallow and unprotected," she added. "There's no continuous layer of clay over the aquifer to provide a barrier to contaminants."
The aquifer is 27 to 80 feet underground, she said.
Perchlorate, which does not break down easily in water, can persist for decades, Baier-Anderson said. Although toxicological evidence shows the chemical can cause thyroid cancer, she said, experts disagree about what level of exposure poses a risk.
Perchlorate suppresses thyroid function and is used as a treatment for thyroid disorders, she said, adding that altered growth and development could result from perchlorate exposure.
"The thyroid is a very complex organ because it integrates so many body functions," she said. "When you start messing with these very complex body systems, we start to worry. There could be long-term implications that are hard to study."
At 59 sample locations along the city's northern boundary with the post, 47 detected no perchlorate, but 12 had readings of the chemical that ranged from 5 parts per billion to 23 parts per billion, Stachiw said. In the area within 300 feet of the wells, Stachiw said, the readings were in the 7 to 8 parts per billion range.
The EPA added perchlorate to its list of contaminants to consider regulating in 1998, an agency spokesman said yesterday. No acceptable limits for perchlorate in drinking water have been established, but maximums being considered range from 2 parts per billion to 18 parts per billion.
"It didn't hit the radar screen until about five years ago," said Bruce Beach, an EPA remedial project manager, who oversees cleanup at the Naval Surface Warfare Center in Montgomery County.
Extensive explosives research was conducted at the center before it closed in the mid-1990s, and perchlorate levels as high as 150 parts per billion have been discovered on the installation -- but none in drinking water, he said.
About a year ago, the Maryland Department of the Environment told Aberdeen to test its finished water for perchlorate, said Dacey, the city manager. The city complied, but never asked the department why it wanted the test done.
"I'm not sure what prompted MDE to test that," he said.
Now the city is testing its raw and finished water, he said, and no traces of perchlorate have turned up. He said that although he was unaware of the perchlorate problem until a few weeks ago, other contaminants have been found in the vicinity of the city's wells.
"This reinforces why we've been pursuing alternative water supply sources," he said.
The contamination is in the 10-year capture zone for the wells, Baier-Anderson said, meaning that the natural draw could pull the contaminants closer to the water supply over time.
Ammonium perchlorate is a key component in all explosives, from fireworks to rocket fuel. The compound provides the oxygen so the fuel can burn, said Chris Adams, spokeswoman for Indian Head Surface Warfare Center, where explosives are tested. Information on testing for perchlorate in ground water at the installation was not immediately available, she said. Ammonium breaks down quickly, unlike perchlorate.
Any military installation or commercial manufacturing business that handles rocket fuel, fireworks or other explosives faces a problem with perchlorate, Beach said.