They are basically a lottery ticket for cancer. They don’t accumulate, just the more you are exposed to, the worse your risk. The ideal amount of times you want to risk cancer is zero, realistically that’s impossible, but less is always better.

It’s not like something like salt where some amount is fine or even good but too much could cause issues.

This sounds like bullshit to me, it's mass accumulation resulting in inflammation. Below a given threshold inflammation does not occur at all.

If they don’t accumulate, then why is more exposure worse than less exposure? There must be some type of compounding factor at play.

Above a certain amount you get inflammation, that's it. Small amounts are dealt with by the slime covering all your internals.