Opium production fell in the Golden Triangle last year as Thailand and Laos slashed the amount of land being cultivated for the raw ingredient of heroin, the United Nations said. Myanmar, also in the area, remains a risk. Southeast Asia accounted for 424 metric tons of opium, or about 5 percent of the world’s total production, down from 33 percent in 1998 and more than 50 percent in 1990, the UN Office of Drugs and Crime said in a report yesterday. Myanmar produced most of the drug as Thailand and Laos became almost opium-free.