A drug trafficker shows a rock of crack in the old center of Salvador da Bahia March 19, 2012. Many Brazilian cities now have their own "cracklands," areas of the city where swarms of crack users have converted entire neighborhoods into nocturnal encampments doubling as open-air crack markets. At nightfall throngs of stupefied buyers crowd around dealers before skulking away behind the telltale glow of cigarette lighters. Sociologists, health experts, and law enforcement officials all agree that crack use is a rapidly growing problem that puts Brazil squarely in the center of the international drug trade, just a few years ahead of the 2014 World Cup and 2016 Olympic Games. Picture taken March 19, 2012. To match Feature BRAZIL-CRACK/ REUTERS/Lunae Parracho (BRAZIL - Tags: DRUGS SOCIETY POLITICS CIVIL UNREST CRIME LAW) ATTENTION EDITORS - PICTURE 3 OF 24 FOR PACKAGE '24-SEVEN - CRACK IN BRAZIL'