Which chemical made Aqua Dots toys dangerous when swallowed, prompting a 2007 recall?

The chemical that made Aqua Dots toys dangerous when swallowed was 1,4-butanediol.

Aqua Dots were craft beads that children arranged and fused with water. The beads contained a chemical coating that could metabolize into the sedative gamma-hydroxybutyrate, commonly called GHB. Children who swallowed the beads reportedly became unconscious or suffered seizures.

The 2007 recall covered millions of sets sold internationally. The product was manufactured in China and distributed by Spin Master. The recall is sometimes confused with toy recalls involving lead paint, but Aqua Dots involved a chemical substitution in the adhesive coating rather than paint contamination.

The incident helped focus attention on chemical testing of imported toys and on the dangers of products that resemble candy. It also illustrated why ingestion hazards can be serious even when a toy appears intact and functions normally.