Cocaine Use Down 45%, U.S. Says; Doubt Voiced : Drugs: Bush hails results of survey. The findings are sharply disputed by Sen. Joseph Biden and L.A. Police Dept.

Current cocaine use by Americans plunged 45% from 1988 levels and 72% from five years ago, according to the government’s most comprehensive drug survey, which President Bush immediately hailed Wednesday as “the most compelling evidence that drug use is declining significantly.”

The cocaine results, along with other signs of marked improvement reported by the National Institute of Drug Abuse, were sharply disputed by Sen. Joseph R. Biden Jr. (D-Del.).

The Administration’s study “actually misses more addicts than it counts,” said Biden, chairman of the Senate Judiciary Committee. A study done by the Democratic staff of his committee found that the household survey “grossly underestimated the number of hard-core cocaine addicts and weekly heroin users.”

The Los Angeles Police Department also took issue with the survey’s upbeat findings. “The numbers we see do not suggest any drop as dramatic as that,” said Lt. Fred Nixon, a department spokesman. But he added: “I can’t give you any number.”

Bush said the results suggest “that our hard work is paying off and that our national strategy is having an effect,” but he cautioned that “a declaration of victory would be premature.” He pledged that there will be no cutback in the stepped-up federal effort against illicit drugs.

The survey, conducted from March through June, included these highlights in comparison with the last survey, which was done in 1988.

* The number of adolescents using any drug dropped to 1.6 million from 1.8 million. The number of adolescents using cocaine fell 47%, to 119,000 from 225,000.

* The number of crack users stayed stable, with 494,000 among the 1.6 million current cocaine users. Individuals are counted as current users if they admit using the substance at least once in the last month.

* Those using any illicit drug at least once in the last month fell to 12.9 million from 14.5 million.

* Daily cocaine users ran counter to the downward trend, increasing to 336,000 from 292,000. Those using cocaine once a week or more dropped to 662,000 from 862,000.

But some critics called the 662,000 figure virtually meaningless because the homeless, those in jail and others living in institutions are not counted in the survey, and 18% of all those approached refused to participate. Officials acknowledged that that group is most likely to contain illegal drug users.

* Although those engaged in any current illicit drug use declined to 6.4% of the population, some demographic subgroups had markedly higher rates. Among 18- to 25-year-olds, 14.9% used drugs; among the unemployed, 14%; among blacks, 8.6%; among those living in large metropolitan areas, 7.3%; and among residents of the West, 7.3%.

* Marijuana remains the most commonly used illegal drug in the country, with 66.5 million Americans, or 33.1% of the population, having tried it at least once in their lifetimes and 20.5 million having used it at least once in the last year.

* Alcohol and cigarette use continued to decline, as it did from 1985 to 1988. The latest total of 102.9 million current drinkers of alcoholic beverages was down almost 3 million from the 1988 figure. Cigarette smokers dropped to 53.6 million from 57.1 million.

The survey involved interviews in 9,250 randomly chosen homes.

Health and Human Services Secretary Louis W. Sullivan, joining Bush in announcing the results, spoke of “marked progress (in) changing attitudes and behaviors as more and more of our neighbors and co-workers have turned away from illegal drugs.”

Sullivan cited favorable results from a survey of cocaine-related cases reaching hospital emergency rooms. Such cases dropped by 9.5%, from 8,323 cases in the first quarter of 1990 to 7,532 cases in the second quarter.

The emergency room statistics are among the most important indicators of hard-core drug abuse, because they monitor the overdoses and drug-related violence that are among the most tangible consequences of chronic cocaine addiction.

Biden was joined in questioning the household survey by Rep. Charles B. Rangel (D-N.Y.), chairman of the House Select Committee on Narcotics.