Maryland’s senators approved a bill that would ban polystyrene foam food containers and cups starting next year.If the bill eventually becomes law, Maryland would be the first state to enact a ban on the products. Some local governments in Maryland — most recently Anne Arundel County — have banned them. The Senate vote of 34-13 came after days of off-and-on debate, with many Republicans raising concerns that the ban would cause difficulty or increased expenses for farmers, small businesses and nonprofit organizations.They also questioned how much the ban would do to reduce litter and improve the health of the Chesapeake Bay. Sen. Adelaide Eckardt said she lives at the headwaters of a creek in Cambridge and regularly picks up litter, but rarely finds foam cups or containers.