For Judy Washington, an empty gas tank means trouble.

When she stops at a gas station to fill up her car, the fumes make her dizzy and nauseous, sometimes even incoherent, she says. When she smells a strong bleach, her throat swells and she has trouble breathing and breaks out in hives. Washington is also having trouble with her memory: She says she often can't remember the contents of a book she just read or a phone conversation she just had.

"I get so scared," said the 35-year-old mother of four. "I sit there and think, 'Am I going crazy? Is this really happening to me?' "

For two years, Washington helped produce computer circuit chips for one of the fastest-growing semiconductor companies in Silicon Valley. That work has permanently damaged her health, she claims in a suit she filed against her former employer, Advanced Micro Devices Corp., based in Sunnyvale.

AMD is contesting her claims. "We do everything we can to have the safest environment people can be in," said Elliott Sopkin, vice president of communications for AMD.

The idea of Silicon Valley as a possibly dangerous place to work doesn't square with the popular perception of the high-tech electronics industry as "clean" and "light." Few outsiders, however, are aware it uses hundreds of toxic chemicals -- some of them suspected carcinogens and reproductive hazards -- as essential parts of the manufacturing process.

"The 'clean' image is an illusion," said Pat Lamborn, program director of the Santa Clara Center for Occupational Health and Safety, a private information and advocacy center for workers with health and safety concerns. "The cleanliness is to protect the chip from contamination, not the workers. They're working with some very dangerous things in that industry, and people are suffering the effects."

The health and safety of workers is a highly sensitive issue for the 500 or so electronics companies in Silicon Valley. But the question is particularly touchy for the semiconductor industry, which produces the integrated circuit chips -- and uses the greatest volume of chemicals.

The controversy over potential health hazards began in the late 1970s. In 1979, five employes at Signetics Corp., a semiconductor company, filed workers' compensation claims against their firm, contending that exposure to chemical fumes had left them with a hypersensitivity to everyday chemicals.

Other chemical exposures soon came to light, including a May 1979 acid explosion at Fairchild Camera and Instrument Corp., a major chip manufacturer, which resulted in the hospitalization of three employes and caused the company to send 14 workers home after they inhaled acid fumes.

In 1981, the state dropped a bombshell on the industry when it published statistics showing an extremely high incidence of job-related illness in the semiconductor industry -- more than three times that of manufacturing in general. According to the survey, semiconductor companies had a 1980 occupational illness rate of 1.3 per 100 full-time workers, compared with manufacturing's rate of 0.4 per 100 workers. The electronics industry as a whole had an illness rate of 0.9 per 100.

The semiconductor industry promptly compiled a study of its own, which said that the high incidence of illness resulted from companies reporting minor chemical burns and inhalation cases as illnesses. Both should have been reported as injuries, the industry study said.

The 1980 illness survey was the last published by the state. California officials have declined to make public the illness statistics compiled by semiconductor companies in 1981 and 1982 because of uncertainty about the methodology of the statistics.

Curious about a "sudden dramatic drop" in the number of illnesses reported for those two years, California's Department of Industrial Relations investigated the medical records of several Silicon Valley firms to determine if they were underreporting, department spokesman Richard Stephens said.

The state determined that the industry had been recording some illnesses as injuries, and ordered it to change its record-keeping methods. The companies contended that the state's reporting guidelines were unclear. The issue still is not resolved.

Industry officials say that elaborate precautions are taken to protect employes from hazardous chemicals. "Our record is extremely good in this area," said Sheila Sandow, manager of communications for the Semiconductor Industry Association, the industry's trade group. "It's a newer industry, and so we've been able to learn from the errors of some of the older industries, especially the problems they've had in occupational health."

The U.S. Bureau of Labor Statistics in May 1984 ranked the semiconductor industry as third best on health and safety among durable goods manufacturers, based on 1982 data.

"We are constantly looking into new methodology, the technology to increase safety," Sopkin of AMD said. "We know we can't make it as safe as somebody's bed, but we try to be as close to that as possible."

AMD has been the subject of an investigation by the National Institute for Occupational Safety and Health (NIOSH), acting at the request of a group of AMD employes who complained of a variety of ailments ranging from fatigue to reproductive problems.

In an interim report issued this fall, NIOSH said it had examined company medical records for 58 employes and found 13 cases of chemical exposure requiring medical attention.

Although most of the exposures "did not result in lost work time, the long-term health effects from repeated short-term exposures are not known," the NIOSH report said. "Further evaluation is requested to determine the extent of any occupational health problem from these incidents. . . . "

Adding to concerns about workers' health in the industry is the fact that relatively little research has been done on the effects of human exposure to hundreds of the chemicals used by the industry.

In addition, according to occupational health experts, virtually no information and research is available on the effects of low-level exposure to chemicals over long periods of time. Likewise, there is little knowledge of the effects of exposure to combinations of gases -- a pertinent point for semiconductor workers because the industry often uses complex mixtures of chemicals.

Dr. Joseph LaDou, chief of the division of occupational and environmental medicine at the University of California School of Medicine in San Francisco, is one expert who has become increasingly worried about health threats posed by chemicals in the semiconductor industry.

"These companies use such a broad spectrum of chemicals that a person could have simultaneous exposure to carcinogens and other hazards, like reproductive hazards," he said.

"What makes it worse, the technology advances so rapidly that you hardly get a handle on what people are using before there's a whole new set of circumstances."

According to LaDou, the vast array of chemicals used by semiconductor companies present "an almost infinite number of possibilities for trouble" -- depending on the frequency and level of exposures.

The effect of chemicals on semiconductor workers is "a totally neglected field of research," adds Dr. Jeanne Stellman, executive director of the Women's Occupational Health Resource Center and associate professor at Columbia University's School of Public Health.

During Judy Washington's two years at Advanced Micro Devices, she says she was exposed to many acids, solvents and gases, including boron and phosphine. Experienced in wafer production, she was hired by AMD in 1979 as a process control technician, assigned to monitor one fabrication (production) area. It is in these "fab areas" that electronic circuitry is etched onto silicon chips with the aid of chemicals.

After she worked there for almost a year, she says, she developed a persistent cough and sore throat. She adds that she had trouble breathing and was constantly nauseated and light-headed.

Doctors, however, were unable to find anything wrong with her. Finally, she went to a lung specialist, who told her to stay home for six weeks. Shortly after she returned to work, she collapsed when the ventilation system failed temporarily and she was exposed to chemical fumes. The company nurse told her she probably had a virus and sent her back to work, Washington says.

Although her symptoms continued, she stayed at work for several more months, until her doctor ordered her to leave her job. When she took her doctor's letter to AMD's personnel office and asked for a transfer, she says, she was told to go home and wait until the company found her a job fitting her qualifications and pay.

That was in March 1981. She still has no job.

Washington has filed a claim for workers' compensation, in addition to suing AMD for wrongful discharge. She also has filed a suit against the companies that produced the chemicals to which she was exposed.

According to her attorney, Amanda Hawes, an AMD doctor wrote to company officials on April 15, 1981, saying: "The patient at this time has pulmonary hypersensitivity due to the chemical environment of the plant. This sensitivity most likely will be long-standing. Recommendation that she find a new job in a nonchemical environment, probably outside the semiconductor industry, or be transferred within the company to a clerical position or one totally removed from the chemical environment."

Sopkin of AMD declined to comment on the Washington case because it is in litigation. But in a general comment on workers' suits, he said, "It's not mathematically impossible we'd get a malingerer. There are a lot of us who would love to retire and have somebody support us for the rest of our lives."

Susan Tanenbaum, AMD's director of employe relations, added: "We don't deny liability in workers' compensation cases where there is clear evidence that an illness has been caused by work. But in cases where medical evidence is less than convincing -- that's where we litigate the case."

The stakes are high for the industry, says Hawes, who is handling about 50 such workers' compensation suits.

There is, she says, an "expanding recognition that this is a chemical-handling industry and that the materials that assemblers and production workers are working with are hazardous to human health."