The shutdown of a nuclear waste dump in Nevada this week threatens to halt much of the nation's cancer research.

"Every large university hospital doing cancer research now faces a decision to close down," Philip Lorio, chief radiation safety officer at Columbia University, said by telephone yesterday from New York. "In our own case, we have two weeks of storage space left for our radioactive waste, and we have a lot more storage space than most of the other large medical research centers in the country."

The sudden crisis in radioactive garbage was triggered by Nevada Gov. Robert List Monday night when he closed the low-level dump at Beatty because technicians had found five barrels of waste buried outside the fence.

Less than three weeks earlier, Gov. Dixy Lee Ray of Washington closed a similar waste dump at Hanford after technicians discovered the packing stripped from a shipment of irradicated steel and radioactive pharmaceuticals leaking from a shipment of discarded containers.

The Nevada and Washington dumps were the last ones open to liquid radioactive chemicals -- the type used in U.S. cancer research.

Last spring South Carolina halted shipments of liquid wastes to its dump in Barnwell on grounds that the chemicals carrying the radioactive material -- as distinct from the radioactive material itself -- were a threat to the environment.

"The chemicals used as the carriers for radioactive tracers are toluene and xylene," Columbia's Lorio said. "South Carolina banned the burial of these two chemicals, which in effect was a ban on all of our radioactive waste, which meant we had to ship our wastes to Hanford and then to Beatty."

The liquid wastes that will now be piling up in the nation's medical centers are known as tracers. These are isotopes put into organic chemicals so that cancer researchers can locate the chemicals inside test animals. This way scientists can tell if, for instance, a drug concentrates in tumors or spreads through healthy tissues. The method is a major tool in cancer research.

With the closing of Hanford and Beatty, Lorio said, the more than 300 laboratories at Columbia using radioactive tracers in everything from nutrition to cancer research must now store their own waste. Lorio said Columbia generates about 24 drums of liquid medical waste a week. It has room to store about twice that much but no more.

"That gives us two weeks of storage time," Lorio said. "At the end of that time, I might have to tell the researchers using these radidoactive chemicals to stop their research."

Many major cancer research laboratories are in straits just as dire. Duke University says it has three weeks of storage space for its radioactive medical waste. Harvard University has no more than 10 days storage space left. Memorial Sloan-Kettering Cancer Center in New York could store waste for a couple of months at most, according to radiation safety officer Jean St. Germain.

Columbia's Lorio said one way to get around the closing of the western dumps would be to incinerate the wastes locally, but the city of New York refuses to give Columbia permission to do so. Nor can Harvard persuade Cambridge, Mass., to allow it to burn wastes.

"There's no other way of doing this kind of work," Lorio said. "If we don't get a solution to this problem, this kind of research is going to stop."

The Nuclear Regulatory Commission's William Dircks, who heads the division that licenses the burial of low-level wastes, agrees that the situation is "alarming." Dircks adds: "We're dealing with three sites in only three states and there's absolutely no political gain in having a burial site in your state."

One reason South Carolina, Nevada and Washington have moved is that their governors do not want their states to be nuclear dumping grounds for the nation.

As long as everybody can ship it off to South Carolina and forget about it," Gov. Dick Riley said when he ordered the ban on liquid radioactive medical waste, "then everybody is going to regard low-level waste as a South Carolina problem"

Not every medical research center will be hurt by the closing of the dumps. Yale University stores its medical waste in an unused building that once house a cyclotron. The National Institutes of Health has a more ingenious solution. It annually sends 70 million vials of liquid waste to a Texas coast. The vials and their dried-out contents are crushed and shipped to Barnwell, S.C., which accepts the solid waste.