DENVER -- A company is recalling 500,000 liquid-filled baby teethers due to a possible bacterial contamination that could cause serious illness.

The teethers come in six different styles and are manufactured by The First Years Co.

Some teethers feature Disney and Sesame Street characters. The others feature fish and animal graphics. The teethers have been on store shelves since July of last year.

The liquid inside the teethers may contain pseudomonas aeruginosa and pseudomonas putida, which can cause serious illness in children if the teether is punctured and the liquid from the teether is ingested, the company said.

No illnesses have been reported to date in connection with the problem but the company decided to voluntarily recall the product.

Consumers should place the recalled teether in its current condition in a sealed plastic bag and send it to:

Parent Service Center, RC2/The First Years
100 Technology Center Dr.
Stoughton, MA 02072

Consumers should include their mailing address in the envelope to receive a replacement teether and free gift.

To learn more about the recall, call the company at (866) 725-4407 or visit www.thefirstyears.com or FDA.gov.