NEW YORK (CBSNewYork) – Sen. Charles Schumer wants the federal government to do more to stop the flow of synthetic marijuana, also known as K2.

Synthetic marijuana can be purchased online with a credit card, WCBS 880’s Jim Smith reported.

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“These drugs are more dangerous and can have worse side effects than marijuana,” Schumer said.

Schumer says websites from China selling the dangerous substance are still easily accessible, Smith reported.

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Schumer wants the Drug Enforcement Agency to set up a separate unit to identify the sites and then ban credit card companies from doing business with them.

“By simply telling the credit card companies not to deal with these sites, we can shut them down,” Schumer said.

“When you buy a synthetic drug, you give a credit card number. You can go on your iPhone right now and pull up some of these websites. They say ‘We take Visa,'” Schumer told 1010 WINS. “Visa would no longer take them. None of the credit card companies would take them. We could strangle them.”

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Schumer’s call comes as the NYPD is in the midst of a crackdown on K2.