California Code, Food and Agricultural Code (Formerly Agricultural Code) - FAC § 34803

Milk, cream, or any product of milk or cream shall not be transported in connection with, or close to, any other commodity from which it may absorb any foreign flavor or which may contaminate it. Milk, cream, or any empty container which is used for milk or cream shall not be hauled in any vehicle which is used for hauling manure or garbage or in any other unclean conveyance.