Short Supplies May Be Diluting Street Cocaine : Drug War: Some officials speculate enforcement efforts are driving prices up, forcing a ‘cut’ product.

The average purity of cocaine sold in the United States declined significantly in the first four months of this year, possibly indicating that shortages have forced traffickers to dilute their product, according to data collected by the Drug Enforcement Administration.

The statistics, compiled at the request of The Times, show that cocaine marketed in one-gram quantities across the country is now about one-fifth less pure than that purchased by federal agents last year.

At the same time, the cost of the drug appears to have increased at wholesale levels while prices on the street remain unchanged. The drop-off in quality suggests that dealers may have chosen dilution as an alternative to price hikes.

“There definitely is a change,” says Charles P. Gutensohn, the DEA’s top cocaine expert. “This indicates that the trafficker may not have as much cocaine available but wants to get the same amount of money as he used to.”

The new federal data--substantiated by separate reports from local authorities--gives national scope to a phenomenon first reported this month in Southern California, where law enforcement officials say the quality of cocaine has declined even more precipitously.

“It’s a real dramatic drop,” said Dawn Speier, a police department chemist in Minneapolis, where cocaine that until late last year was 80% pure has suddenly plunged to purity levels of less than 50%. “I really don’t know why this is happening, unless we’re winning the war.”

Some federal and local officials cautioned that the less-pure cocaine might simply demonstrate that dealers have eliminated local competition and can peddle lower-quality cocaine to a captive and addicted market.

But most drug experts, including those who had expressed skepticism about the effect of an anti-drug crackdown, said the trend made them more inclined to believe that some shortages were developing.

“There has been a big increase in law enforcement at all levels,” said Mark A. R. Kleiman, a professor at Harvard University’s Kennedy School of Government. “Maybe now it’s beginning to take its toll.”

There have been record seizures of cocaine in the United States and abroad in the past six months, while U.S. authorities have increased pressure on street level dealers.

The new indicators were collected as part of a DEA intelligence-gathering system that is used to assess annual trends in the drug market. High-ranking agency officials said in interviews last week that they were aware of no sharp decline in cocaine purity, but agreed to compile the year-to-date figures for The Times.

The figures, based on undercover buys made by federal agents and analyzed at a DEA laboratory, show that the average purity of a street-bought gram of cocaine in the United States has dropped from 66% in 1989 to just 55% in the first four months of 1990.

At the wholesale level, the average purity of a one-ounce cocaine purchase dropped from 75% in 1989 to 62% this year.

And while the street price for small quantities of cocaine remained constant, the new data found that the going price for an ounce of the drug jumped 16% in the first four months of 1990. Separately, the DEA’s Gutensohn said the agency has noted a similarly sharp jump in the price for even larger quantities of cocaine. One-kilogram bricks that last summer sold for $15,000 “are now tough to find for anything less than $20,000.”

“This seems like a reasonable indicator that something has happened out there,” said Peter Reuter, a Rand Corp. economist who is a leading authority on the economics of the drug trade. “It appears to be getting harder and more expensive to get good-quality drugs.”

With the number of American cocaine users believed to be dropping, the drug experts said they saw no evidence of a growing demand for the drug--a factor which might otherwise have explained the price increase and quality decline.

To the contrary, the experts noted that a sharp decline in cocaine-related deaths and emergency-room admissions in late 1989 suggested that cocaine use was likely diminishing even among heavy users.

Some hospital officials have suggested that last year’s decline in medical emergencies was related to the diminishing potency of cocaine, but the new data suggests that dilution of the drug did not begin in earnest until the early months of this year.

The DEA figures, part of the agency’s system to retain information from drug evidence, show that purity of an average gram of cocaine had dropped from 72% in 1988 to 66% in 1989 before falling to 55% in the first part of this year.

Wholesale cocaine tends to remain purer than the retail product because it has passed through fewer hands in which each dealer “cuts” the drug to boost profits.

DEA officials cautioned that the agency statistics give disproportionate weight to large cities in which federal activities are the most intensive, and may not be representative of the nation.

But the indication of a decline in cocaine quality is consistent with reports last week from Southern California, where Orange County officials said average purity had declined from about 80% to 18%, and with the accounts of other local officials.

In Seattle, for example, chemists in the Washington State Patrol Crime Lab said that 1 of 4 samples of cocaine being seized today is too impure for chemical analysis--more than double the occurrence last year.

And in Washington, D.C., police department narcotics officers said they have noted a drop in cocaine purity of 5 to 6 percentage points in the past six months.

But officials in Chicago said they were not aware of any such decline, and in New York, police chemists expressed skepticism about DEA statistics.

In a separate development, federal officials said they had been mistaken in releasing statistics that suggested that the number of cocaine-related deaths dropped in the United States by 26% between 1988 and 1989, as reported in Monday’s edition of The Times.

That apparent decline was artificially magnified by the fact that Los Angeles has not yet submitted its 1989 data to the federal government, the officials said. Allowing for the omission, the correct estimate for the annual decline is 15%.

Times staff writer Shawn Pogatchnik contributed to this story.

DECLINING PURITY

Purity of cocaine bought by undercover agents in amounts of 1 ounce (about 28 grams) and 1 gram. The drug is typically diluted as dealers divide large quantities into smaller ones for resale. 1 OUNCE 1988: 79% 1989: 75% 1990: 62% 1 GRAM 1988: 72% 1989: 66% 1990: 55% Source: Drug Enforcement Agency