Massachusetts and New Hampshire authorities are working to seize the production and sales of synthetic marijuana that has been linked to several cases of overdoses.

The legislature of Massachusetts has already passed a ban on synthetic cannabinoids which have the street name "spice." Most of the products are listed as ingredients for incense and potpourri, but according to the police, synthetic marijuana can also be included in tea.

Dr. Jose Montero, New Hampshire's public health director, said when compared to real marijuana, the synthetic version can be more dangerous because its effects are more difficult to predict.

"They keep changing it all the time, playing this game with the federal government to see what's illegal and what isn't," Montero told the Boston Globe. "These are just psychotropic drugs."

New Hampshire Governor Maggie Hassan also declared a public health emergency to support efforts in getting the drug banned. Reuters reported that the drugs with synthetic marijuana have resulted to overdoses primarily in Manchester. The police in New Hampshire seized some samples of the drug which goes by the street names "Bubblegum" and "Smacked!"

The U.S. Drug Enforcement Administration named the active ingredients found in synthetic cannabinoids in 2011. This year, the agency has been investigating the presence of synthetic cannabinoids in other products, including MDMA ("Molly") and bath salts.

The challenge of the crackdown, according to the authorities, lies with the producers' speed in changing the formulation of the substances. This allows them to dodge laws and policies governing the use of synthetic marijuana.

 "These products pose a serious threat to public health, especially to young people, and it is our responsibility to do whatever we can to combat the recent rash of overdoses," Hassan said in a statement.