The Air Force has decided it will have to evacuate and decontaminate more than 200 houses found to be contaminated with the pesticide chlordane, a top Air Force health official said yesterday.
And a spokesman said the General Accounting Office had found that similar contamination problems may affect as many as 10 million houses across America.
The statements were triggered by National Public Radio news broadcasts Tuesday and Wednesday, in which it was charged that hundreds of thousands of houses across the country may be contaminated with the pesticide.
Chlordane, and several other related pesticides such as dieldrin and aldrin, are used to kill termites by spraying heavy doses, up to 20 pounds of the material, under house foundations where the insects live.
Chlordane was banned for all use except termite control in 1975, chiefly because it was found to cause cancer and nervous disorders in animals. The effects on humans at low doses are not known with certainty, but some reported effects include tremors and seizures.
The Air Force is just completing a three-year survey of its housing to discover how many of its dwellings have dangerously high levels of chlordane, Dr. Victor Furtado, chief of environmental affairs in the Air Force surgeon general's office, said in a telephone interview. Of 4,000 houses tested, he said he expects about 220 to be in need of decontamination, with chlordane levels above the recommended limit of 5 micrograms per cubic meter.
GAO, a congressional watchdog, asked the Environmental Protection Agency two years ago to consider banning the pesticide, and to determine how many civilian houses in America might be affected.
An EPA spokesman said yesterday that report will probably be out in October, and that the study's project officer has found that, with the exception of the Air Force housing, "there isn't any evidence of problems in homes . . . unless the pesticide was misapplied."
Furtado said he could not see why the problems found on bases wouldn't exist in other housing because construction and termite treatment methods are essentially the same.
According to Furtado, the Air Force has found that three types of housing construction made it possible for the chlordane to seep up into a house: two involve where heating ducts were placed within or under a foundation's concrete slab or where there is a "crawl space" between the ground and the floor of the house.
Though the Air Force has been sued by some families who have lived in chlordane-contaminated housing, Furtado said the service believes that no direct health hazard was caused by the substance. What the Air Force is worried about, he said, is that over many years, exposure to chlordane may cause cancer.
Furtado said that a little less than 1 percent of the houses with slab foundations that were treated with chlordane while the house was under construction were found to have high levels of chlordane.
Of the houses that were treated after construction, 4 to 5 percent had very high levels of chlordane, as much as 10 times the limit recommended by the National Academy of Science.
Of the homes with crawl spaces instead of slab foundations, the rate of contamination varied from 1 percent to 25 percent of the houses at a base in Wichita, Kan.