A new study suggests restrictions put into place by the U.S. government on a chemical needed to produce cocaine have led to a reduced use of the drug in the past decade.
Mexican police action against a company importing pseudoephedrine, which is used to make meth, also contributed to the decline.
The U.S. government cracked down on the availability of the chemical used in making cocaine, sodium permanganate, in 2006, UPI reports.
Since then, the number of people using cocaine in the past year decreased by 1.9 million people, or 32 percent.
After the Mexican government closed down a company accused of importing more than 60 tons of pseudoephedrine, the supply of meth was reduced significantly, researchers report in the journal Addiction.
The researchers reported a 35 percent decrease in past-year use of meth after that action.