U.S. Customs and Border Protection officers in Southern California have seized nearly 36,000 Chinese rubber ducks that contain levels of a chemical that may be unhealthful for children.

The ducks decorated as Santas, Snowmen and other holiday figures were seized Dec. 4 by officers and import specialists at the ports of Los Angeles and Long Beach.

The customs agency said Friday that it worked with the U.S. Consumer Products Safety Commission in determining that the ducks contain an excessive level of a regulated phthalate, a chemical used to make vinyl and plastics soft and flexible.

The rubber ducks were valued at more than $18,000.