Cuts in federal spending for highway safety mean that the nation's highways "face the possibility of a return to the mayhem of the 1960s," according to a recent study of factors contributing to highway fatalities.

The study, which was produced and funded by Potters Industries Inc., says that spending for construction under the Highway Safety Act of 1973 prevented some 7,000 deaths and more than 40,000 severe injuries in 1979. These programs are slated to be cut by more than two-thirds next year, according to the Reagan administration budget.

But the Reagan administration says that federal highway safety spending is an insignificant portion of the total, and it cites a study by the General Accounting Office in its claim that the programs weren't that effective anyway.

The backers of the new study have an interest in highway safety that reaches deep into the pocketbook. Potters makes tiny glass beads that are blended into paint to reflect the headlights of night drivers. Millions of pounds of Potters beads have been painted onto American highways to make those ubiquitous center stripes.

The 1973 measure was passed just after traffic deaths reached their peak of more than 56,000 in 1972. It authorized a range of construction programs to improve safety on rural roads. Intersections were modified to improve visibility, improved markings were painted on highway sufaces, and shaky bridges were rebuilt.

The 1973 act and the 1966 Highway Safety Act, which get their money from the federal gasoline taxes that flow into the Highway Trust Fund, are victims of shifting priorities. The new budget figures are down significantly from the $670 million the program receives for the year ending this September.

The researchers say they tried to screen out the effects of other possible downward pressures on the highway death rate such as the oil shortage, the 55-mile-an-hour speed limit and changes in traveling patterns to isolate the impact of the 1973 act's safety construction programs. They projected that, had the act not been passed, there would have been 58,900 traffic fatalities in 1979 instead of 51,900.

But Lorenzo Casanova, associate administrator for safety at the Federal Highway Administration, defended the cuts. "It's a task that can be absorbd by the states," he said of the safety programs. "We've carried them for many years, and it's time for them to take the responsibility." Casanova said the administrationhs approach is to redirect revenues for the Highway Trust Fund back to state governments, which then can decide whether to use the revenues for safety programs.

A study by the General Accounting Office last October only partly confirms the Potters report, and many of the GAO's conclusions run directly counter to Potters.' For one thing, the GAO points out that general trends toward reduced highway death were apparent before the 1973 act was approved. And since 1976, "annual deaths have climbed despite a dramatic increase in federal funding," says the GAO report.

The Potters study makes the casse that highway safety is a cost-effective proposition. Summing up the payments that had to be made as a result of traffic collisions, deaths and injuries, the report comes up with a figure of $21.7 billion for 1978.These include property damage, medical expenses and insurance payments, withdrawals from savings by affected families and losses by employers.