To be clear: I'm not saying that the FDA process isn't broken. I agree the US is behind but that's not what this discussion is about. I'm purely trying to learn more about a specific regulatory question that I haven't seen a satisfying answer to.
As i'm sure everyone on this sub already knows: the US treats sunscreens as OTC drugs, so only monograph-approved filters can be active ingredients. The US has only 16 filters approved, while other countries have moved far ahead (EU has 28, Japan has 34, etc.).
But the restriction is only on actives. Sunscreens are full of inactive ingredients, and common cosmetic ingredients like niacinamide and ferulic acid already have UV-absorbing properties with zero regulatory issue. Cosmetic ingredients don't need FDA pre-approval, even the ones that have known UV-absorbing properties.
So, why is it not possible to include a filter like Tinosorb S as an inactive, no active listing, no SPF claims about it? I assume the FDA doesn't maintain a banned list of UV-absorbing substances. Also, from what I've found online, SPF is measured empirically, so the filters will still be reflected in the actual rating. Sure, including unapproved filters as inactives would inflate the measured SPF beyond what the listed actives produce, but that seems like a non-issue.
People like EU/Asian sunscreens because of the nicer product formulations while maintaining good SPF/PA rating. Those benefits apply just the same even if the filters aren't officially listed as actives.
That's actually what makes me think that there must be some reason they can't do this. EU/Asia sunscreen brands go so far as to reformulate their products for the US market with approved filters, and I'm sure they'd much rather keep their products the same if such a simple loophole were available to them.
Is there some regulation I'm missing, or is there some other reason that companies don't go this route?