NEW YORK (CNN) -- 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, ... which is why it became a date-rape drug," Gupta said.

"So this is nasty stuff, and it appears that the chemical is actually converting into it in the body."

The arts and craft beads, aimed at children 4 years and older, have been selling since April at major U.S. retail stores as "Aqua Dots" and in Australia under the name "Bindeez Beads."

CPSC spokeswoman Julie Vallese said anyone with Aqua Dots at home should immediately take the toy away from children and contact distributor Spin Master Ltd. to return for free replacement beads or a toy of equal value.

For additional information, contact Spin Master at 1-800-622-8339 between 9 a.m. and 6 p.m. ET, Monday through Friday.

The toy was named toy of the year in Australia and recently made Wal-Mart Stores Inc.'s list of top 12 Christmas toys.

Wal-Mart on Thursday listed Aqua Dots on its Web site as "out of stock online" and had removed them from its top toy list.

Toronto-based Spin Master stopped shipping Aqua Dots and asked retailers to pull them off their shelves, where they had sold for $17 to $30. Watch what's known about the beads »

Melbourne-based Moose Enterprise Pty. Ltd. recalled Bindeez Beads on Tuesday after three children in Australia swallowed large quantities of the beads and were hospitalized.

"I was so frightened because I thought she wasn't going to make it," Heather Lehane told CNN affiliate Network 7 of her 10-year-old daughter, Charlotte, who was sickened by the beads.

In the United States, the Washington-based safety commission said it has received two reports detailing the severe effects of the digested beads.

The CPSC said a boy nearly 2 years old "swallowed several dozen beads. He became dizzy and vomited several times before slipping into a comatose state." The toddler was hospitalized and has since fully recovered, the commission added.

In the second incident, a child vomited, fell into a coma and was hospitalized for five days. It was not immediately clear whether the child had made a full recovery.

The recall is the latest to target Chinese-made toys. See if your child has any recalled toys »

Last month, U.S. government safety officials and retailers recalled at least 69,000 Chinese-made toys over concerns of excessive amounts of lead paint, which can cause lead poisoning. E-mail to a friend

CNN's Janine Brady, Jason Carroll, Laura Dolan, Julie O'Neill and Leslie Wiggins contributed to this report.