Over 12 years, there was a decrease in about 1.9 million past-year cocaine users.
Back in December of 2006, the US Drug Enforcement Association (DEA) implemented federal restrictions on access to sodium permanganate — one of the essential chemicals required to manufacture cocaine.
Additionally, Mexico — the primary source of methamphetamine in the US — closed down a chemical company accused of illegally importing over 60+ tons of pseudoephedrine (a methamphetamine precursor chemical).
"Cocaine and methamphetamine production for international markets requires access to massive amounts of legally manufactured chemicals," James Cunningham, a social epidemiologist at the University of Arizona College of Medicine - Tucson, said in a press statement. "Disrupting that access can be expected to disrupt the drugs' availability and use."
During the early 2000s, cocaine use in the US stayed pretty consistent, but following the sodium permanganate regulation in 2006, cocaine use began to drop.
The University of Arizona team measured the number of past-year and past-month cocaine users from the period of 2002 to 2014, and linked the regulation to an estimated decrease of about 1.9 million past-year cocaine users, as well as 0.7 million past-month cocaine users — a reduction of 32 percent and 29 percent, respectively.
Further, between 2006 and 2014, the researchers found that there was little to no rebound in number of cocaine users.
Similar to the downward shift seen with cocaine, methamphetamine use also dropped following the 2007 chemical company closure. There was an estimated decrease of about half a million past-year meth users and more than a quarter-million past-month meth users — 35 and 45 percent decreases, respectively.
"Strategies directed toward individual users--information campaigns and direct medical care, for example--have not yet fully addressed the public health problem of cocaine and methamphetamine misuse," Dr. Cunningham said.
“Chemical controls are relatively inexpensive. And there's room to improve them through better international cooperation,” he concluded.
The research has been published in the journal Addiction.