Critics say transplanted foreign programs won't work in New York because the addict population is different.

The 900 drug users in the clean-needle program represent less than 10 percent of the local addict population.

In Edinburgh, which has a large addict population, for instance, the clean-needle program is open one afternoon a week and handles 70 addicts.

For one thing, the federal government's National Drug Control Strategy for 1996 says that the addict population is basically stable.

Rates are still much lower among addicts in other cities, and it may be among these addict populations that the epidemic has greatest potential for growth.

New York has the nation's largest addict population, yet state and city officials lack the resolve even to test a needle exchange program.

Private treatment centers are, on average, only 55 percent full and can accommodate a good portion of the largest addict population: employed 18- to 40-year-olds.

The effects of drug education programs in schools may not be felt for years; much of the addict population doesn't go to school.

Social scientists and drug-treatment experts say they, too, are seeing an aging of the addict population.

Moreover, he said, four-fifths of the slots were geared to heroin addicts, who account for less than half the addict population.