“Look, Ma! No cavities!” Toothpaste makers have patted themselves on the back for keeping kids cavity free for decades, but adding fluoride to public drinking water for dental purposes, which began in 1945, has also played a big role in oral health. The practice has had plenty of detractors, and the latest research may have consumers rethinking their brushing and drinking habits. A new study suggests that prenatal exposure to this chemical may affect cognitive abilities and that...