There is evidence that some heroin also enters China from Laos and Vietnam and that smaller amounts enter from Southwest Asia. Preliminary figures suggest that heroin seizures in China declined significantly in 1999 from 1998's record level. Since narcotics interdiction remains one of China's primary law-enforcement priorities, it is likely that this decline was due, at least in part, to a decline in production in Burma. There are 596,000 registered heroin addicts in China, but the government recognizes that the actual number of users is far higher. Seizures of ATS more than doubled in 1999, with the largest seizure in excess of one metric ton.
China is a major producer of precursor chemicals.
The ephedra plant, from which the precursor of methamphetamine is made, grows wild in northern China. China monitors all 22 of the chemicals on the 1988 UN Drug Convention watch list. Yunnan, the province most directly affected by China's drug problem, goes further by monitoring exports of 28 chemicals. Under Chinese law, laundering the proceeds from narcotics trafficking is a crime, but the legal system and the banking system have not kept pace with China's rapid internationalization. Consequently, China is vulnerable to financial exploitation by drug traffickers.