LA PAZ, BOLIVIA -- South Americans used to view cocaine as a North American problem. Now, many on the continent have come to see it as a drug that is poisoning their own societies.

The sharp change in attitude comes as Colombia, Ecuador, Peru and Bolivia, which produce virtually all of the world's cocaine and have long profited from meeting the huge demand for the drug in the United States, are discovering that tens of thousands of youths have become hooked on highly addictive and dangerous cocaine paste. "We used to think that cocaine was good because it creates a lot of jobs and brings in a lot of dollars," said Mario Mercado, president of one of Bolivia's biggest private mining companies. "But now it's corrupting our youth; we're all afraid our kids will become drug addicts."

In each of the Andean countries, cocaine paste addiction has spread from low-income groups into middle-class and professional circles in the past two years. Usage has increased even though governments in all four countries are waging antidrug campaigns.

In Colombia, cigarettes made of cocaine paste, called bazuco, cost about 50 , and are peddled on street corners throughout the country. Colombia's Health Ministry estimated that 300,000 to 500,000 of the country's 28 million residents smoke bazuco regularly.

In Lima, Peru, the cream-colored paste is sold in thumb-sized packets called quetes. Police have identified at least 500 locations in the Peruvian capital where the drug is sold regularly.

In Bolivia's second-biggest city, Santa Cruz, teen-agers and young professionals smoke the cocaine paste cigarettes, known as pitillos, in dozens of so-called smoking houses that some compare to opium dens of 19th century China.

"I know of many patients who, after two or three days there, ran out of money and were kicked out into the street," said Dr. Nils Noya, one of the few doctors treating drug addicts.

In Cochabamba, Bolivia's third-largest city, dozens of homeless boys, some as young as 8, smoke pitillos in parks at night. On a recent evening, when a social worker tried to help three teen-aged boys to their feet in a downtown park, they collapsed.

Even those who profit most from drug consumption have become addicts. Noya said he has treated more than 10 known drug traffickers and their relatives for cocaine addiction.

As usage has spread throughout the Andean cocaine-producing nations, doctors and government health officials have warned that cocaine paste's highly impure state can cause permanent brain, liver and lung damage.