Super-strength methamphetamine from Mexican super labs is flooding streets in the United States.

And no, this isn’t an episode of “Breaking Bad.”

Local and federal authorities in San Diego are reporting methamphetamine imported from Mexico at dangerous new levels of purity.

The average gram of meth a decade ago was 39 percent pure.

Today, it could be close to 100 percent, reports the San Diego Tribune.

The potency of the drug, like so many others streaming into the United States right now, including opioids like fentanyl, is just simple economics.

“When you are wholesaling drugs like the Mexican drug traffickers do, their product is going to be a lot stronger. It’s going to come across the border pure. Then, as it travels, it will get cut and cut and cut,” said Amy Roderick, spokeswoman for the U.S. Drug Enforcement Administration (DEA) in San Diego.

But, she explains, meth has an interesting history in the United States, and tracking its purity levels can be tricky.

“Meth is a hard one to read because our meth production used to be domestic. Fifteen years ago, the meth production was all done here in the United States,” Roderick told Healthline.

“Now the Mexican cartels have taken over all the meth production, so their meth seems to be purer than what we were seeing 10 to 15 years ago,” she added.

Cracking down on chemicals

The shift toward imported methamphetamine and the demise of domestic production has occurred over the past decade.

During that time, federal authorities began enforcing stricter regulations over pseudoephedrine, a precursor in the production of methamphetamine.

Pseudoephedrine is commonly found in a wide array of cold medicines because of its effects as a nasal decongestant.

In 2005, the government enacted the Combat Methamphetamine Epidemic Act, which, among other things, made it more difficult to purchase large amounts of products containing pseudoephedrine.

Prior to that, says Roderick, smaller domestic meth labs would often rely on individuals to go from pharmacy to pharmacy buying up boxes and boxes of cold medicine to cook meth.

“Now when you go to CVS and say ‘I want some Sudafed,’ you go to the counter, provide your driver’s license, and you are allowed to purchase two boxes,” says Roderick. “That really cut down on the meth production here domestically.”

While methamphetamine doesn’t receive nearly as much attention as opioids, Roderick warns that the drug has not gone away.

It still remains an addictive and problematic part of the U.S. drug epidemic.

Prohibition makes it stronger

Dr. Daniel Ciccarone at the University of California San Francisco School of Medicine, explains that the kind of high-potency drugs available today are part of a historical trend.

“The prohibition of drugs and alcohol leads to increasing potency as volume is reduced to enhance smuggling (reduced detection). This is known as the Iron Law of Prohibition and the best evidence is for alcohol during U.S. prohibition,” he told Healthline.

The “Iron Law of Prohibition,” was first coined in 1986 by Richard Cowan, a former director of the National Organization for the Reform of Marijuana Laws (NORML).

The name refers to alcohol prohibition in the United States during the 1920s and early 1930s.

During that time, there was a shift from low-alcohol content drinks, such as beer, to increasingly strong spirits.

Both sellers and purchasers wanted the “biggest bang for their buck.”

Among members of the public health community, including Ciccarone, the Iron Law is a succinct explanation for the current deluge of super-strength drugs in the United States.

An article published this year in the International Journal of Drug Policy argues that the current state of drugs in America appears to be the latest iteration of the Iron Law.

Perhaps the scariest part of their conclusion is that drugs may continue to get stronger.

“Without serious, sustained efforts to address the direct and root causes of nonmedical opioid use, intensive supply suppression efforts that brought us fentanyl will continue to push the market towards deadlier alternatives,” the study authors wrote.