Pasteurization switched from the old to new method [0]; the health issue with milk is not just the condition when it was produced, but the growth of pathogens afterwards, during the supply-chain:
* From c. 1910-end 1960’s, milk was treated by batch pasteurization at 63°C/145°F for 30 mins (pathogenic bacteria killed off as measured by 1960s technology, but flavor barely affected)
* Since then industry switched to HTST pasteurization at 72°C/162°F for 15 seconds (kills more pathogens; 120 times faster but affects flavor)
* Even higher-temperature methods are HHST and UHT [1]
US milk producers also refused to pasteurize for decades after some European countries started, only because it would slightly decrease their profits. So they put formaldehyde and other stuff in it instead.
* From c. 1910-end 1960’s, milk was treated by batch pasteurization at 63°C/145°F for 30 mins (pathogenic bacteria killed off as measured by 1960s technology, but flavor barely affected)
* Since then industry switched to HTST pasteurization at 72°C/162°F for 15 seconds (kills more pathogens; 120 times faster but affects flavor)
* Even higher-temperature methods are HHST and UHT [1]
[0]: https://en.wikipedia.org/wiki/Pasteurization#Efficacy_agains...
[1]: https://www.idfa.org/pasteurization
(PS: By a twist of history, Al Capone was also responsible for expiration dates on US milk bottles)