Although I do enjoy very much watching chicks doing Ass-To-Mouth action or Ass-To-Pussy, I wonder if these aren´t dangerous for them, I hope they check themselves regularly. Oh, what the hell... I hope they never cease of doing it.
ATM isn't that huge of a health risk as ASS-To-PUSSY. The asshole carries both good bacteria's that maintain the proper PH balance preventing irritations and infections as well as bacteria that isn't necessarily hygenic. But the bacterias in the asshole vs the pussy are not compatible. Even the good bacteria's because the PH balance is different than the pussy. Therefore you are more than likely to have some irritation. Although some may never have a problem after practicing ATP. Depending on the persons bodily chemistry.
Which is why most companies are rather cautious when it comes to ass fucking and going back to pussy fucking. People try to cut to clean up a bit and then presume. I know it breaks the moment but some refuse to do anything else.