More than 200,000 of the 9 million surviving workers who have been exposed to asbestos during the past 40 years will die of asbestos-associated cancer by the end of the century, an internal Department of Labor report concludes.

Thousands of more cancer deaths will occur among the workers' family members as well as among consumers who use asbestos products and former members of the Armed Forces who were exposed to the cancer-causing mineral, the report concludes. The 650-page report, which is expected to be released by the Labor Department early next year, was obtained by the Washington Insurance Newsletter.

Even before its release, a number of insurance companies were criticizing the report, which was prepared by Dr. Irving J. Selikoff, a specialist in occupational disease, especially asbestos-associated cancer.

If its findings are accepted by the Department of Labor, the report could lead to significant changes in policy. For one thing, it could lead to tighter standards for asbestos exposure in the work place. The Occupational Health and Safety Administration is scheduled to review the current rule next year.

The report also could lead to changes in worker compensation programs and product liability laws. The report concludes that as the number of deaths increase and as the public becomes more aware of their cause, so many additional worker disability claims and damage suits will be filed that the existing compensation and legal systems will not be able to handle them.

The increase in litigation also could hurt the financial stability of many insurance companies that end up paying the monetary damages, the report notes.

Among its specific findings:

Approximately 8,500 asbestos-related cancer deaths are occurring annually among workers who were exposed to asbestos since 1940. This total will rise to about 10,000 by the year 1990.

There was no minimum exposure level at which workers are safe. Less than one month of work was sufficient to increase the risk of death significantly.

Even consumers who use asbestos products and employes who are not exposed directly to asbestos where it is used face risks. "We may have to include risk to the garage supervisor or owner in addition to the brake-repair mechanic, to the supervising architect as well as the carpenter, the naval draftsman as well as the shipyard welder, and to the plant guard at the asbestos factory," the report says.

Exposure to asbestos increased the risk of lung cancer about four or five times. The risk is even higher to exposed workers who also smoke-- 50 times as great as that of a nonsmoker not exposed to asbestos and five times greater than other smokers.

The number of lawsuits against manufacturers of asbestos products has increased dramatically.

In the fiscal year that ended March 1, 1976, 124 suits were pending against Johns-Manville Corp., the nation's largest asbestos company. In 1978 that number grew to 623, and from 1980 to 1981 the number rose from 2,857 to 5,800, according to a Johns-Manville spokesman.