A Fairfax County jury found yesterday that an Alexandria firm was not negligent when it treated a Mount Vernon couple's house for termites, rejecting claims that the couple was permanently driven out of the house by improper pesticide use.

George Callaghan said the verdict vindicated his company, Callaghan's Exterminating Corp. He said the firm's "spotless reputation for 24 years" had been damaged by the suit and the publicity it brought.

"We never did anything wrong in the first place," Callaghan said. "I've had long-term customers call me and say, 'George I can't use you anymore.' I know accusations are one thing, but this hurt a small, family business."

Callaghan's had been accused of negligence when it treated the house owned by Blanche Weaver, 60, and Ward Weaver, 64, for termites in November 1984 with chlordane, a termite-killing chemical.

The Weavers, who have been living in a trailer in their back yard since 1988, claimed in Circuit Court that they had been poisoned by chlordane and that their house in the 4200 block of Colonial Avenue is contaminated.

Blanche Weaver testified that the chlordane caused burning eyes, sore throats and respiratory problems. In 1985, she committed herself to a psychiatric unit at Mount Vernon Hospital, where she was found to be psychotic and stayed for 30 days. Her psychiatrist testified that chlordane may have contributed to her mental illness.

Callaghan's attorney, P. Clark Kattenburg, argued during the six-day trial that Blanche Weaver's medical problems were not caused by chlordane but came as a result of a family history of mental illness and several medications she was taking for illnesses, including high blood pressure.

Juror William Harris cited the medical evidence as the reason the jury voted in favor of Callaghan's. The jury deliberated about two hours.

Kattenburg told the jury during closing arguments, "Mrs. Weaver is by no means faking any of her symptoms. If you have a mental disorder, the brain, the mind creates these symptoms and they are always there."

David L. Hilton, an attorney for the Weavers, told the jury that chlordane caused Blanche Weaver's symptoms. "It's curious she took {blood pressure medication} for 12 years and had no problem. Chlordane is known to have a propensity to cause those symptoms."

Chlordane was canceled by the Environmental Protection Agency in the late 1970s for any use other than termite control after laboratory tests found that chlordane may cause cancer.

In 1987, Velsicol Chemical Co., which manufactured chlordane, voluntarily pulled the chemical after the EPA raised questions about possible air contamination. Chlordane was then banned from sale, distribution or commercial use after April 15, 1988.