From the international association FIFA on down, the governors of the world's most popular sport expose players to needless injuries by letting them return to play after concussions, failing to monitor their conditions and allowing head-on-ball contact by even the youngest players, the suit said. "There is an epidemic of concussion injuries in soccer at all levels around the world, including in the United States, from elite players to children playing for the first time, women and men, girls and boys," plaintiffs' lawyers said in U.S.