OTTAWA  The Canadian government moved Friday to ban polycarbonate infant bottles, the most popular variety on the market, after it officially declared one of their chemical ingredients toxic.

The action, by the departments of health and environment, is the first taken by any government against bisphenol-a, or BPA, a widely used chemical that mimics a human hormone. It has induced long-term changes in animals exposed to it through tests.

Also on Friday, Senator Charles E. Schumer, Democrat of New York, said he intended to introduce on Monday a bill that would ban many uses of BPA-related plastics. It would prohibit them in all children’s products, including nonfood items they may put in their mouths, as well as in any product used to contain food or beverages.

The toxic designation will allow Canada eventually to ban the manufacture, import or sale of baby bottles made with polycarbonate. Polycarbonate, which dominates the North American baby bottle market, mimics glass but is lighter and shatter-resistant.