The Public Citizen Health Research Group yesterday disclosed the names of 249 work places in 42 states where the government has identified -- but never notified -- some 250,000 workers who face an increased risk of cancer, heart disease and other illnesses because of their working conditions.

Federal health officials have been debating whether the government is obligated to notify workers who may be in danger of contracting diseases from substances in work places studied by the National Institute for Occupational Safety and Health (NIOSH) over the past 15 years. The consumer group obtained the data through a Freedom of Information Act request.

"We have more than 200,000 workers at severely increased risk, and the government does not want to notify them," said Dr. Sidney M. Wolfe, director of the group, which was founded by Ralph Nader. "And so the chemical companies win out over the people they employ . . . . The government is nodding to the industry, and ignoring the public."

The Health and Human Services Department rejected a $4 million budget request from NIOSH to begin a "worker notification" program in the current fiscal year, citing the substantial cost, the confusion in some industries about whether the medical evidence justifies a government warning, and the fear that notification will unduly alarm communities.

"There has been a lot of discussion and a lot of agonizing over how to do it, and how to do it right," said Shirley Barth, an HHS spokesman. "We are still trying to determine how to proceed and how to tell somebody . . . without panicking somebody who is not in danger."

The NIOSH list released yesterday includes major corporations in the oil, chemical, metal, asbestos and pharmaceutical industries whose production of hazardous substances has been well-publicized, such as Allied Chemical Corp.'s handling of the pesticide Kepone in the 1970s in Hopewell, Va., and Baltimore. The list also includes scores of lesser-known employers from New England to California where many current and former employes are unaware of their exposure, Wolfe said.

In addition to the two Allied sites, the other sites in Maryland and Virginia that were listed were: Young-Aniline Co. in Baltimore, where benzidine was used; Chesapeake Instrument Corp. of Shadyside, Md., where unspecified carcinogens were used; R.H. Bogle Co. of Alexandria, where arsenic and mercury were used; and an unnamed facility in Fredericktown, Md., where workers were exposed to silica dust and diesel fumes.

The Bogle and Chesapeake Instrument plants have closed since the NIOSH studies, and Young-Aniline officials were unavailable for comment. An Allied Chemical spokesman said he was not familiar with the NIOSH study but said, "Our policy is to make a full disclosure to employes when hazards are determined."

Since the early 1970s, NIOSH has conducted 66 "mortality studies" and other medical tests to determine the dangers of substances and help set standards to regulate them. NIOSH often told the results to companies, unions and medical and trade associations, but not workers, especially in studies that used death records and involved little direct contact with employes.

The Centers for Disease Control, which includes NIOSH, asked its own ethics advisory panel to review the issue in 1983. It concluded that although the government did not have a legal obligation to inform workers, "NIOSH does have an ethical obligation" to do so. NIOSH also has determined that 40 percent of the 250,000 workers it has identified could benefit from early detection of treatable illnesses.

The HHS has never approved money for the program, which is expected to cost between $150 and $300 per worker.

In 1981, NIOSH conducted one "pilot" notification program at an Augusta, Ga., chemical plant where as many as 1,100 workers were exposed to the carcinogen beta-naphthyalamine.

Using Social Security Administration and Internal Revenue Service records, NIOSH located most of the workers and found bladder cancer rates ranging from five to 110 times the normal rate among longtime workers.

NIOSH, according to published results of the Augusta program, also found that nearly 75 percent of the employes were unaware of the danger.

The notification sparked lawsuits against the company totaling more than $330 million.