Small DDT levels found in Ravalli Co. building
HAMILTON, Mont. - The Montana Department of Agriculture has released results of samples it took in the Ravalli County Administration Building to determine if DDT was present.
The samples were taken in January, after bats were found to have high levels of the banned pesticide.
The sick and dying bats were were found in the building's fourth floor attic last summer.
They were said to have had "exceedingly high levels" of DDT in their system and on their wings.
Ravalli County commissioner Jeff Burrows said the latest tests found there were small levels of DDT found on the walls of the fourth floor.
But he said those levels were highest where the bats were roosting and grew fainter to non-detectable as you moved farther away from the roost.
He said there are indications the bats brought the pesticide into the attic from an outside source.
"It's still inconclusive as to where the origination of the DDT was," he said. "Based on those levels we don't think the DDT originated in the upstairs in the building. But we are still unsure at this point where the source of the DDT is."
Burrows said "it is unlikely that the source is upstairs because the concentrations aren't high enough to support it being up there. It's like the bats brought the DDT in on their wings and exterior of their bodies."
He said the fourth floor is not open to public access. But he said it never has been.
The Environmental Protection Agency banned DDT more than 40 years ago.
A National Pesticide Information Center document said the once common pesticide is slightly to moderately toxic to mammals, including people if it is eaten.