Proving synthetic drug use is the cause of traffic accidents can be difficult, experts tell The Seattle Times. Prosecutors in some cases involving traffic fatalities have ended up charging drivers with less serious crimes.

Because recreational marijuana is legal in Washington state, use of synthetic cannabinoids is not a big problem there overall, according to Dr. Alexander Garrard, clinical managing director of the Washington Poison Center.

People whose jobs require regular drug testing are an exception, he says. While marijuana shows up on drug screening, synthetic marijuana, known as Spice or K2, often does not. These synthetic drugs are easily available to teens in convenience stores and online.

“Synthetic marijuana” is a misleading term, say experts, who prefer the term “synthetic cannabinoids.” The drugs may affect the brain more powerfully than marijuana and their effects can be extremely unpredictable.

“We see a lot of cases around military bases, in Tacoma, Olympia and Spokane,” Garrand said. Some people who use commercial driver’s licenses and professional athletes also use synthetic drugs to avoid detection, the article notes.

The drugs are very dangerous, says Garrand. “We don’t know what’s in them, they’re not tested for safety or efficacy, and the effects are entirely unpredictable. Of all the abused drugs out on the market, synthetic marijuana scares me the most.”

According to Brianna Peterson, who manages the Washington State Toxicology lab, private lab tests confirmed the presence of synthetic cannabinoids in 53 driving incidents in which the drug was suspected. An equal number of suspected cases came back negative, she said.

“Now that marijuana is legal, people think the synthetic version is safe; they take it,” said Dr. Nephi Stella, Professor of Pharmacology at the University of Washington. “We’re just starting to have a little understanding that the psychotropic molecule is very potent. It’s stronger and more potent than THC. And some individuals might also react very strongly.”