drugs has been traced back to countries in the Middle East and elsewhere, he said.

He declined to link the synthetic drugs to anti-American extremists in the Middle East but said they had relied on sales of illicit drugs as a source of funds in the past.

Designer synthetic drugs are often marketed as herbal incense, bath salts, jewelry cleaner or plant food. They are made up of plant material that has been infused with psychoactive compounds that mimic THC, the active ingredient of marijuana, the DEA said.

Abuse of the drugs can lead to seizures, vomiting, loss of consciousness and overdose deaths, the DEA said in a statement. The number of emergency room visits associated with the drugs reached 28,531 in 2011, more than twice the number the year before,General Motors' all-electric Chevrolet Bolt compact car will be able to go 238 miles on a single charge, the automaker announced Tuesday.

That's enough to drive from New York City to Washington DC or nearly enough to make a round trip between Los Angeles and San Diego.

Perhaps more importantly to GM, it beats the 215 miles Tesla has promised for its upcoming Model 3, a similarly-priced electric car that's expected to go on sale next year.

"Chevrolet showed the world the production version Bolt EV earlier this year and in a few short months we've moved from that vision to a reality," said GM North America President Alan Batey.

Sales of the Chevrolet Bolt are scheduled to begin before the end of this year.

While the Bolt's name is very similar to