In the early 20th century many states allowed the sale of raw milk that was certified by a "medical milk commission", effectively allowing an alternative of extra inspection for pasteurization. Now most states impose restrictions on raw milk suppliers due to concerns about safety. Forty-three U.S. states allow sales of raw milk. Cow shares can be found, and raw milk purchased for animal consumption in many states where retail for human consumption is prohibited. The sale of raw milk cheese is permitted as long as the cheese has been aged for 60 days or more.