Tests on several plastic baby bottles have found they emit "very significant" levels of a chemical linked to deadly illnesses in laboratory animals. That is according to a new report released by American and Canadian environmental health groups. Advocates are demanding immediate action, as VOA's Robert Raffaele explains.

The study found 95 percent of all baby bottles on the market are made with bisphenol A, or BPA, a synthetic sex hormone used in making hard, polycarbonate plastic.

Low levels of BPA have been linked to diseases in laboratory animals, including cancer.

Researchers found that after heating four brands of baby bottles (Avent, Evenflo, Dr. Brown's and Disney/First Years) , they emitted between five and eight parts per billion of BPA.

Health advocate Mike Schade from The Center for Health, Environment and Justice explains, "When bottles are used extensively over time and when they're heated, higher levels of this chemical leaches, exposing young infants to elevated levels of this unnecessary toxic chemical."

Canada's federal health department, Health Canada, says it is conducting a "high priority" review of bishpenol A, with a report due in May.

The U.S. Food and Drug Administration says BPA's adverse effects occur in animals only when they are exposed to "far higher levels" of the chemical than possible from a baby bottle. That agency is also reviewing BPA's potential risks.

"We know the animal studies raise concerns but there aren't human studies showing effects yet, so when we don't have the evidence, then what we recommend that parents do is actually err on the side of caution," says, Dr. Maida Galvez of New York's Mount Sinai Hospital.

Environmental groups are calling for a ban on all uses of BPA in plastic containers.

In the United States, nine states have introduced legislation that would restrict its use in children's products, including baby bottles.