What is the legal age for a child to be on a ATV (4 wheeler) in PA?

[g35girll]

At what age is it legal to have a child ride on your lap while on an ATV?
My stepson is 2 years old and has been on them with his mother for like 6 months now. He's always coming over all scraped up and cut up and I'm genuinely concerned for his safety. I already have pictures of her taking him out on them that we are giving to the lawyer. I'm just looking to see if anyone has knowledge on this. Thanks

[atctim]

there is no law for this in PA - only common sense - which eludes many people these days!

What's a lawyer gonna do about it? be a real parent and do the right thing (BTW - that does not mean lawsuit)