U.S. safety officials have recalled about 4.2 million Chinese-made Aqua Dots bead toys that contain a chemical that has caused some children to vomit and become comatose after swallowing them.

Bindeez, which were named Australia's toy of the year, contain a chemical that converts into a "date rape" drug.

Scientists have found the popular toy's coating contains a chemical that, once metabolized, converts into the toxic "date rape" drug GHB, or gamma-hydroxy butyrate, U.S. Consumer Product Safety Commission spokesman Scott Wolfson told CNN.

"GHB is this drug that in low doses actually causes euphoria," said Dr. Sanjay Gupta, CNN's chief medical correspondent. "In higher doses, it can cause people to go into a coma. It can cause seizures. It can cause something known as hypotonia, where all your muscles just become very flaccid.

"And it can cause people to become amnestic, meaning they forget everything that's about to happen to them, which is why it became a date-rape drug," Gupta said.