A decade after first appearing in the United States, synthetic marijuana is a growing health danger, experts say.

Some marijuana smokers turn to it because it is relatively cheap and not detected in routine drug testing. Dozens of people in New Haven, Connecticut, were taken to hospitals last week after overdosing on a batch of synthetic pot.

While states have moved to legalize traditional marijuana, synthetic marijuana is unregulated. According to the Centers for Disease Control and Prevention, research shows that synthetic pot affects the brain much more powerfully than marijuana, "creating unpredictable and, in some cases, life-threatening effects, including nausea, anxiety, paranoia, brain swelling, seizures, hallucinations, aggression, heart palpitations and chest pains."

It is linked to violent behavior and suicidal thoughts, and can also cause kidney damage severe enough to put users on dialysis.

Synthetic pot is made by taking plant material and spraying it with chemicals that can mimic the high from marijuana. It is sold under names like K2, AK47, Spice, Kush, Kronic, and Scooby Snax. It is a Schedule 1 drug, joining cocaine and heroin as a drug with high abuse potential.

The chemicals also can also be mixed into a liquid and vaped, and mixed into tea or food. The substances can produce some effects similar to traditional marijuana, including relaxation, elevated mood and altered perception.

Authorities have detected scores of chemicals in synthetic marijuana, and say chemical composition can vary not only from product to product but also from batch to batch. Some ingredients are banned by federal or state law. Drug dealers peddle synthetic marijuana, and police say people have been able to buy it online or in convenience stores and gas stations.

As an unregulated product, synthetic marijuana is not tested for safety. Earlier this year, more than 160 people in Illinois were sickened and at least four died after using synthetic marijuana tainted with rat poison.

Health officials track reports of illnesses related to synthetic marijuana through hospital emergency department visits or poison center calls. Poison centers report thousands of cases each year, including nearly 8,000 in 2015. This year, as of last month, poison control centers handled about 1,300 calls for synthetic marijuana illnesses.