“Could a vintage, dog-eared copy of ‘The Cat in the Hat’ or ‘Where the Wild Things Are’ be hazardous to your children? Probably not, according to the nation’s premier medical sleuths, the Centers for Disease Control and Prevention. But a new federal law banning more than minute levels of lead in most products intended for children 12 or younger — and a federal agency’s interpretation of the law — prompted at least two libraries last month to pull children’s books printed before 1986 from their shelves.”