DENVER (AP) _ A cargo of mildly radioactive material has been sitting in a truck in a parking lot since 1983, and the shipping company and the state can't get rid of it.

American Shippers, a trucking company, was hired to haul nine cartons of smoke detector parts containing tiny amounts of a radioactive isotope, americium 241, to Los Angeles for eventual shipment to a company in Taiwan.

The deal fell through and the cartons were returned to Denver and American Shippers, which agreed to keep the material because the export broker didn't have space. The broker eventually went out of business.

Robert Fawcett, an owner of American Shippers, says he has run into nothing but problems trying to get rid of the cartons.

``Everybody has really treated this stuff like it's the plague,'' he said. ``We're trying to be good citizens, but no one will help us.''

The cargo is ``extremely low-level material,'' said Chuck Mattson of the state Department of Public Health and Environment's radiation control division.

``There is no radiation exposure outside the truck, and right now it poses no health risk,'' he said. ``But we really do want to take care of it for once and for all.''

Fawcett called the U.S. Environmental Protection Agency, which said the boxes were the responsibility of the Colorado Health Department.

The health department found it would cost as much as $40,000 to dispose of the radioactive parts, but neither it nor American Shippers was willing to pay.

In 1993, Gov. Roy Romer asked the U.S. Department of Energy for help.

``This material ultimately needs to be disposed of safely,'' Romer wrote.

Last February, the Energy Department said it couldn't help.

Romer then contacted the Nuclear Regulatory Commission, which this month sent him right back where American Shippers started.

``If the state believes the situation with American Shippers is a radiological emergency, we suggest you recommend to the state that they contact EPA for assistance,'' wrote Richard Bangart of the NRC.

American Shippers is still trying.

``We want to do the right thing,'' Fawcett said, ``but this stuff is just not going to go away on its own.''