Cocaine seizures and major drug raids in Argentina and Brazil have surged in the past two years. The influx of raw cocaine paste used to make crack, from both Bolivia and Peru, has been particularly acute. In Brazil, such seizures by the federal police nearly quadrupled from 2006 to 2007, to 2,700 pounds from about 710 pounds, according to the police.

Image An addict holding paco, a cocaine residue that is smoked. Credit... Joao Pina for The New York Times

In Argentina, the deep financial crisis of late 2001 turned places like Ciudad Oculta into what are known here as villas miserias, or towns of misery, easily exploitable markets of impoverished people looking for escape.

“Cocaine is no longer the drug only of the elite, of high society,” said Luiz Carlos Magno, a Brazilian narcotics officer in the São Paulo State Police Department. “Today kids buy three lines of cocaine for 10 reals,” or about $6. For about $1 in Brazil and about $1.50 in Argentina, users can buy enough of the cocaine for a 15-minute high.

Paco is highly addictive because its high lasts just a few minutes  and is so intense that many users smoke 20 to 50 paco cigarettes a day to try to make its effects linger. Paco is even more toxic than crack cocaine because it is made mostly of solvents and chemicals like kerosene, with just a dab of cocaine, Argentine and Brazilian drug enforcement officials said. The surge in lower-quality cocaine hitting the streets has resulted from a crackdown by both countries on the chemicals needed to transform cocaine paste, or pasta base, as it is called, into powder form.

Tougher customs rules to track the flow of the chemicals, manufactured in large quantities in both countries, have limited access for Bolivian traffickers seeking to refine the base cocaine into higher-value powder, said Gen. Roberto Uchõa, Brazil’s national drug secretary.

As the quality of Bolivian cocaine has fallen off, the European market, in particular, has rejected it, the general said. So more of it has gone to Argentina and Brazil. In São Paulo, the police say the cocaine on the streets is less than 30 percent pure. “Every year they are producing more, and that is driving down prices,” said Mr. Magno, with the state police.