11.   They are responsible for smuggling in precursor chemicals for methamphetamine production and starting up laboratories in California to produce and distribute the drug, he said.

12.   They have also set up mini-cartels dedicating to smuggling precursor chemicals, Merchan said.

13.   Tons of precursor chemicals also enter Colombia as contraband from neighboring Venezuela, Brazil and Ecuador.

14.   Yang said China was ready to work with the United States to solve drug cases and control precursor chemicals and to exchange samples from seized drugs.

15.   Other issues include the use of precursor chemicals, which are diverted from legitimate commerce to process cocaine and heroin, and to manufacture synthetic drugs.

16.   But the U.N. commission is still concerned about the vast quantities of VX precursor chemicals that are unaccounted for, he said.

17.   He also suggested illnesses may be due to the unsanitary conditions that coca growers live in and their exposure to toxic precursor chemicals.

18.   Investigators said a chemist who lives in Europe helped arrange shipment of the precursor chemicals.

19.   Land, air and river patrols can prevent precursor chemicals -- essential to turning coca into cocaine -- from entering the region and cocaine from leaving.

20.   U.S. officials have cited a soil sample taking from the grounds of the complex which they say contained EMPTA, a precursor chemical for the deadly nerve agent VX.