Development of the country's oil shale reserves, a cornerstone of President Carter's energy program, could yield cancer-causing waste materials, according to an Environmental Protection Agency Official.

EPA, the Department of Energy and the American Petroleum Institute are currently studying the oil-extraction process and its wastes to determine possible carcinogenic effects, said Terry Thoem, director of EPA's Energy Policy Coordination Office here, the only one of its kind.

Thoem said benzo-a-pyrene (BAP), a "known carcinogen," has been found on processed shale, but it has not been determined how much of the substance would appear in waste materials of a commercially operating plant. No oil shale processing plant has yet begun to operate on a commercial basis. The first is scheduled to be completed in Colorado within five years.

Under President Carter's energy plan, 2.5 million barrels of synthetic fuel, including 400,000 barrels of oil from shale, would be produced daily by 1990. Colorado has about 85 percent of the nation's oil shale, buried in the Green River Formation, which extends into Utah and Wyoming.

It is estimated that each of the eight oil shale plants now planned for Colorado would produce about 50,000 barrels daily.

With that, "you'll have 60,000 tons of material to be disposed of each day. If you don't do it right, there is a potential for water getting into it, and leaching out toxic materials. If it gets into streams or ground water, it has the potential for contamination," Thoem said.

His remarks followed a visit to Denver last week by Charles Duncan, Carter's energy secretary-designate. Duncan reassured the governors of Colorado and other western states rich in energy resources that synthetic fuels would be developed on a phased basis, although he said he did not plan to alter the president's timetable.

"It is known that there are quantities (of BAP) that do exist on this processed shale. The question is, at what levels, in what concentration?" Thoem said.

Rat-mice studies of BAP are being conducted at EPA's Health Effects Laboratory in North Carolina, and other tests are under way at the Oak Ridge National Laboratory for DOE and by the petroleum institute. A labscale version of the shale extraction process has been constructed, but it may not exactly duplicate commercial conditions.

While carcinogens may occur in quantities too small to be harmful, the EPA is examing proposals to protect supplies by isolating any contaminated water. The water would be sealed in gulches and canyons using an "impermeable material" on the reservoir floor. The water would be allowed to evaporate, and the residue probably be covered again with a material such as a strong plastic or clay. As this stop-and-go process continued, eventually the contaminated residue would be sealed in the earth in layers.

Development Engineering Inc. of Grand Junction, Colo., proposed a water-holding plan for Standard Oil of Ohio, which wants to extract oil from shale in Colorado. The proposal would use processed shale itself, in compacted form, as an impermeable water-holding material. Industry representatives called the method tested and effective, Thoem said. But government workers conducted their own tests and found it 99 percent ineffective, he said.

"It's questions like that that leave us concerned," the EPA official said.

Thoem believes, however, that the technology exists to solve possible health-related problems, and that such concerns will not impede the development of oil shale plants.