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The CDC Says Synthetic Weed May Be Contaminated With Rat Poison

They found that, of the 202 reported cases of unexplained bleeding nationwide, 95 patients tested positive for brodifacoum, a chemical used as rat poison.
Spencer Platt/Getty Images

The Centers for Disease Control and Prevention is warning the public that synthetic marijuana could be contaminated with rat poison, after state health departments have reported more than 200 cases of poisoning with unexplained bleeding, including five deaths.

The outbreak began in early March, with the Illinois Department of Public Health reporting unexplained bleeding among people who had used synthetic cannabinoids—also known as K2 or spice. These products are marketed as a cheaper alternative to produce “high” effects similar to tetrahydrocannabinol (THC), the main active ingredient in marijuana, by activating the same receptors that THC does.


These synthetics can contain a variety of chemicals, and produce unpredictable results when consumed, including hallucinations and agitation. The chemicals can be sprayed on plant matter then smoked, or inhaled through e-cigarettes or added to tea or food. And despite concerns about safety, they’re widely available, even sold in convenience stores as legal marijuana alternatives. (Though it’s banned in the state of Illinois, K2 still makes its way onto shelves).

In the Illinois cases, investigators found the products contained brodifacoum, a chemical used as a rat poison. Brodifacoum is an anticoagulant, which can cause bleeding disorders in healthy people who don’t need blood thinners. It produces a wide variety of awful blood-related issues, including bruising, nosebleeds, gum and mouth bleeding, urinating or vomiting blood, an excessively heavy menstrual bleeding—basically, anything you don’t want your blood to be doing.

The working theory now is that rat poison was added to synthetic cannabinoids, with most of the cases (164 so far) appearing in Illinois. But they haven’t been confined to the Prairie State: Maryland has had 20 reported poisonings, while Florida, Indiana, Kentucky, Missouri, Pennsylvania, Virginia, and Wisconsin have all had six or fewer cases. The CDC says that 95 people in the 202 cases reported nationwide (or 47 percent) have tested positive for brodifacoum.

In April, Chicago police busted a convenience store selling K2—a variety of synthetic marketed under brand names such as "Crazy Monkey," "Blue Giant," and "Matrix"—that tested positive for brodifacoum. The store owner was arrested, but it’s not clear yet whether authorities have discovered the main source of the contaminated products. New York City has also been dealing with a rising number of K2 overdoses this month—there were 14 as of May 20th, a number that skyrocketed to more than 100 at press time. Some people who overdosed spit up blood. While authorities there have also made arrests, it’s unclear whether a common supplier is involved.

Investigators are still working to identify the source of the contaminants, and in the meantime the CDC is reminding the public that synthetic cannabinoids are not safe—and never have been. It’s almost impossible for people to know what they’re ingesting. Anyone who has recently used these products and is concerned about their health, the agency says, should immediately consult their healthcare provider, especially if they have any unusual bleeding or bruising.

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