It shoulders a huge and complex responsibility to assess the health risks at Superfund cleanup sites and other hazardous waste locations.
But it is hindered by a lack of broad expertise in scientific fields like veterinary medicine and meteorology, by staff reductions - from 500 a few years ago to about 300 today - and by the simple fact of scientific uncertainty, Frumkin said.
"While communities expect us to provide definitive answers about the links between exposures and illnesses, even the best science sometimes does not permit firm conclusions," he said.
"The communities we serve feel distressed and disappointed and so do we."
However, the committee chairman, Representative Brad Miller, Democrat of North Carolina, accused Frumkin's agency of poor science, and "a keenness to please industries and government agencies that prefer to minimize public health consequences of environmental exposures."
Scientists and residents of chemical-plagued communities across the country described what they said were the health agency's failings in addressing asbestos contamination and deformed animals, and in pursuing hazardous waste documentation and a test for exposure to depleted uranium.
The toxic substances agengy, a branch of the Health and Human Services Department, avoids "the most obvious toxic culprits" that threaten communities, and delays, minimizes or ignores legitimate health concerns, a subcommittee report said.
Frumkin defended his agency's science but also acknowledged a possibility of some instances where it fell down on the use of data or best monitoring techniques.
If those occur, he said, "Shame on us and we should do better."
He promised in response to Representative Steven Rothman, Democrat of New Jersey, to take a fresh look at toxic exposure on the Puerto Rican island of Vieques where years of live bombing practice by the US Navy left uranium and other toxins in the sea and land.
Miller's panel viewed a video of deformed horses and dogs in Midlothian, Texas, a center for cement manufacturing and chemical emissions.
Sal Mier, a former federal health official who lives in Midlothian, presented statements from several scientists attacking the agency's findings to date that the human health hazard there was "indeterminate."
Frumkin said the agency does not have the capacity to evaluate animal illnesses.
"To maintain the status quo will only continue risking the public health of many US communities," said Mier.
At Illinois Beach State Park on Lake Michigan, ATSDR says levels of asbestos are not high enough to harm people's health. Jeffery Camplin, an environmental consultant and critic of government actions there, said the agency produced "outdated, inferior work products."
