Do note that hearing damage, tinnitus, hyperacusis etc. are extremely underresearched and underprioritized by the medical and public communities as of the year 2008, regarding causes, treatments and the nature of the injuries. I'd go with safe rather than sorry.
These things aren't showered with money for research, unlike cancer. Don't put your child at risk for developing tinnitus and/or hyperacusis, especially the latter, which is very uncommon but pure hell to live with.
It is one of the most disabling and at the same time least ostensively displayed afflictions. It is about as understood and tolerated today as homosexuality was in the year 1400. You can hardly do anything that involves other people. There is no treatment. No one believes you have a real problem. You're an outcast, like a lone virus trapped in a struggle against the immune system that is society, constantly guilty, constantly suffering. Everyday happenings such as a pot dropping to the floor, someone yelling or screaming nearby, a tire going flat become fist punches to the face from nowhere. Anyone who is aware of your condition becomes equipped with a tool of torture that is both invisible to others and not recognized by the law. Sounds that are already loud to others are something from beyond any nightmares you've ever had.
I guess you can tell I'm speaking from personal experience.
I say don't shoot unless you're the only shooter nearby, you're outside and using a suppressed .22. It's just not worth the risk. The doctors don't know and don't care enough to know whether it's safe or not. The unborn baby of another poster here on The High Road violently reacted to the mother shooting a .22. That's far beyond necessary evidence, if such is desired and required at all.
?? NAH!
