After the city experienced its first incident regarding synthetic marijuana in more than a year Wednesday, Madison police are warning downtown residents about the increased use of the substance in the upper State Street area.

Ald. Mike Verveer, District 4, who sat in on a meeting with police concerning the issue said though some types of synthetic marijuana are legal, police are more concerned about the effects of it on users, especially given the most recent incident.

A Madison Police Department report released Thursday said police arrested two individuals Wednesday in connection with dealing or using synthetic marijuana, or “hazardous substances.” The statement said the individuals were smoking a “cigarette” they admitted contained such a substance when police approached them.

Verveer said police concern on the issue is not new, though this is the first incident he has heard of involving synthetic marijuana in more than a year.

“This isn’t really new,” Verveer explained. “The police departments locally and around the county have been dealing with synthetic forms of marijuana for a long time. In fact, the government keeps chasing what the latest development is in that field by passing laws defining what is legal and what’s illegal.”

Verveer said some downtown businesses do sell the legal forms of synthetic marijuana, though police have conducted raids on these establishments in search of illegal types.

The statement added that police have seen very concerning behavior from users of synthetic marijuana, including violent behavior and a heart attack in one case.

Verveer said this behavior is likely what has police so concerned.

“I think what the police also might be saying is that even if some varieties of synthetic marijuana are legal, they are still causing problems that are alarming the cops,” he said.

According to the statement, synthetic marijuana can cause a stronger high in users when smoked. The manufactured chemicals that are often sprayed on synthetic marijuana can also cause hallucinations, psychological problems and even seizures or convulsions, the statement said.

The police report also detailed one arrestee said though he is aware of the risks associated with synthetic marijuana, he has formed an addiction “similar to crack cocaine.”

Police warned products are often sold as “herbal incenses” and their packages often say the product is “not for human consumption.”