Low levels of mercury have been found in fish taken from two northern Carroll County ponds near Keystone landfill, but biologists who tested the animals say the levels are not considered dangerous.
Environmental Protection Agency officials who are overseeing cleanup of the closed Pennsylvania landfill, a Superfund site, say the tests are encouraging because the levels weren't any higher. But some area residents are skeptical.
A more definite answer to what the results mean to the health of humans, farm animals and crops will have to await analysis by biologists and a broader ecological assessment of the area, said Christopher J. Corbett, EPA's site manager for Keystone landfill. He added that the EPA does not have clearly defined standards for levels of contaminants in fish or wildlife.
"I would like to give you a quick answer. It's not that simple, I'm afraid," he said.
Keystone, a privately owned landfill in Adams County, Pa., across the border from Carroll County, was placed on EPA's Superfund cleanup list in 1987. Citizens groups in Maryland and Pennsylvania have been monitoring the cleanup effort through a task force that includes EPA representatives and elected officials from Carroll County and Pennsylvania's Union Township.
Technicians took 40 bluegills and bass for laboratory analysis from two farm ponds on the Maryland side of the border in June. The laboratory technicians created composites from the small fish to form eight large sample fish for the tests.
The lab found six with mercury levels Corbett called "very low." One bass contained 502 nanograms per gram, nearly three times the level of mercury in the least-contaminated fish, which had 175 nanograms per gram. A nanogram is one billionth part of a gram.
One bass contained 1,370 nanograms per gram, identified by EPA as a level of "concern" but not dangerous. That fish came from the pond closest to the landfill, "which I think is significant," Corbett said.
Various contaminants have turned up in wells beyond the landfill in recent years, but attorneys for Keystone Sanitation Corp. have argued that the contamination may come from a source other than the landfill.
In March, three homeowners' wells near the landfill -- two in Carroll County and one in Pennsylvania -- showed dangerous lead levels. The test results came seven months after four Adams County, Pa., wells revealed high levels of thallium, once used in rat poison.
Susan Hardinger, president of People Against Contamination of the Environment, a Silver Run area citizens group, called the results "of grave concern. It's something we all knew. We expected this, but it's documented now that the fish were affected."
Marcia Brown, co-owner of one of the ponds that was sampled, said the presence of contaminated fish in her pond fits her theory that contaminants emerge sporadically from the landfill. She said that she and her husband have not eaten fish from the pond or allowed friends who fish there to eat their catch for many years.
The pond suffered a fish kill in late August, which a tenant worker on the farm didn't discover until the fish had decomposed too badly to be analyzed. Brown said the kill probably occurred the weekend of Aug. 24.
"We don't know [why], bottom line," she said. "I don't think mercury would have acted that fast; I agree with [EPA officials] on that. But from the questions I've asked, I don't think there's anything we did, such as spraying, that would have caused it." She said recent tests showed adequate oxygen in the pond for fish.
Corbett said that although he considered the test results "very positive," he could understand residents' concerns. He said a draft remedial investigation of the site, scheduled for release in December, will evaluate the health of ponds, sediments, plants and farm operations near the landfill.
The fish test was one of several recommended by the Atlanta-based Agency for Toxic Substances and Disease Registry, which was hired by the EPA to assess agricultural use in the Keystone area earlier this year. The agency recommended monitoring water sources for livestock raised on farms near the landfill "to ensure that contaminants that can be harmful to the animals and to people consuming the animal products are not present."
Corbett said he was unsure about monitoring water sources for livestock, but EPA plans to sample plants to see if they have absorbed contaminants.
Pub Date: 9/13/96