Children are at risk for swallowing button batteries they may mistake for candy, but Canadian researchers say anyone with poor vision is also at risk. Small disc-shaped button batteries found in many products -- including remote controls, musical greeting cards, watches, calculators, flashing jewelry and shoes, key fobs, books and other small electronic devices -- could block an airway or cause serious internal chemical burns if swallowed, Health Canada officials said. Due to the hazards they pose to young children and seniors, new or used button batteries should be stored in a location where they cannot be unintentionally found or swallowed. Children should never play with button batteries or remove the button batteries themselves, officials said. Health Canada officials recommend consumers only buy household products with secure battery compartments that cannot be easily opened by children and supervise children when they use products containing button batteries. The officials say children should not be permitted to play with button batteries or remove them from household products. Consumers should store button batteries away from food and medicine, and out of reach of children, and check floors, tables and counters for loose button batteries. Also, Health Canada recommends disposing of batteries so children cannot gain access to them, and taking care when changing button batteries in a product that they do not get mixed in with any pills, medicine or food. If you think someone has swallowed a button battery, seek immediate medical attention, officials advise.