OAKLAND (CBS 5) – A cancer-causing chemical banned more than three decades ago is turning up in baby products found nationwide.

The Center for Environmental Health in Oakland went shopping at baby product stores and found nap mats, changing pads, crib mattress pads and other foam products with high levels of the cancer causing flame retardant Tris (full product list).

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The CEH said the products contain levels of the flame retardant chemical in excess of California safety standards.

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Tris , a chemical once widely used in children’s pajamas, was banned in 1977 when it was linked to genetic mutations. Last year, California added Tris to the state’s list of chemicals known to cause cancer.

But CEH said manufacturers continue to use the flame retardant chemical in foam products often used in children’s products. The group calls such products a “ticking time bomb.’

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The CEH found the baby products at Walmart, Target and Babies-R-Us. They sent the products to an independent lab for testing and identified 16 products with the cancer causing chemical.

On Thursday, the group sued the retailers and manufactures for violating California state law for selling products containing Tris.

The American Chemistry Council, which represents manufacturers of flame retardants, said the products are “well studied and provide important safety benefits.”

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