In March, the Drug Enforcement Administration imposed an emergency ban on five of chemicals that have shown up in some products, but there are hundreds more, and chemists can easily and quickly change the formula to escape a ban.
The chemicals are also manufactured in laboratories in Russia, India, and even Cameroon, making it difficult for the Drug Enforcement Agency to cut them off at the source.
"The web site may be located in one particular country or somewhere within the United States, but the actual product is being manufactured someplace else through an intermediary," said DEA Special Agent Gary Boggs.
"You really don't know exactly what the source of these products are," Boggs said, adding that there is no way to tell if there is any quality control at the labs.
"You don't know what conditions they were manufactured under. You don't know what kind of training the individuals had that are manufacturing these particular products."
Boggs said that greed is the driving force behind the making of these dangerous chemicals.
"Despite the fact that these products cause harm, many of these businesses are distributing these products solely for the profit that they can generate," he said.