Final answer:
The French ban on substitute milk, particularly in powdered form for vending machines and airports, was primarily based on concerns over the additives present in the powdered version.
Step-by-step explanation:
The French ban on the sale of substitute milk, particularly in powdered form for vending machines and airports, was primarily based on concerns over the additives present in the powdered version. These additives were not present in regular milk, and the ban aimed to protect consumer health and safety. The ban did not focus on prohibiting the sale of substitute milk in certain geographical regions, but rather on restricting its use in specific contexts where the powdered versions were available.