I wouldn't have any problem giving my son a printed toy made out of either PLA or ABS. I'm not sure where any lead would come from but even if it was present, you'd likely have to eat a whole spool of filament before you'd get any traceable amount. Lead poisoning was an issue when I was growing up because a kid might eat paint chips that flaked off of a dilapidated wall. Now paint does not have lead in it. I suppose my print head leaches off a miniscule bit of metal with each print, but it's not made of lead and to I'd have to eat the part, not just suck on it, to ingest any of this miniscule amount. But now that I think of it, I'm probably ingesting some metal every time I use a fork or spoon. I'm going to have to switch to plastic. But wait, that seems to be contaminated too, so I'll use my hands. But they have touched dirty things so I'll have to wash them first, but the water might be contaminated so I may not be able to eat at all. Fortunately I can take some pills that have all of the minerals I need, like iron. But if I need all of these minerals in my body maybe I should just forgo the expensive vitamins and eat a few printed toys.
I recommend that you give you 9 month old a toy that you created and not worry about it. Please do make sure the toy is big enough that he can't swallow it or break off a piece that can be swallowed.
Chris