A team of U.S. scientists today began testing the use and possible harmful consequences of a chemical tracking agent allegedly found on U.S. Embassy property.

Dr. Ernest McConnell, the toxicologist from the National Institutes of Health who heads the four-member team, said he had "a blank check" to investigate the possibly cancer-causing powder that the United States has accused the Soviet Union of using to keep track of the movements of U.S. diplomats.

"They are giving this high priority, not just lip service," McConnell said, referring to the U.S. government, in a briefing this morning for Americans in Moscow who do not work at the embassy. "They take this very seriously."

He said the team would stay in Moscow 10 days to two weeks and perhaps find some answers to the medical questions posed by NPPD, or nitro phenyl pentadiene aldehyde, within 30 to 60 days.

U.S. officials said at briefings last week that NPPD, a synthetic chemical largely unknown in the United States, had been discovered last year to be a mutagen, meaning it may cause cancer. Protests about use of the chemical were lodged against the Soviet government last week.

The team, which arrived here last night and briefed U.S. Embassy personnel today, came equipped with 500 vials to collect samples from doorknobs, steering wheels and other surfaces that might have been sprinkled with the chemical dust. The samples will be tested in the United States.

One of the team's first tasks is to find out how widely NPPD has been used and whether other members of the American community have been exposed to it. It is estimated that 500 Americans live here.

At today's briefing, Richard E. Combs Jr., charge d'affaires at the U.S. Embassy, said it was still not known what the KGB, the Soviet security agency, used to detect the powder. "We have shined every damned kind of light on it and detected nothing," he said.