the neonates thing threw me. I'd say medication taken by Mom either during pregnancy or during breastfeeding. The lead/cleaner stuff I'd toss out just 'cuz neonates can't crawl to where it would be.
Mmmm.. how about OD on OTC cold medications? I have met too many parents who think "well, it's a BAAAAAAAAAD runny nose, so I bet if 1 tsp is good, 10 tsp would be better!" No kidding. Also throw in there the ones that think if the med doesn't work on 10 minutes they must need to give the poor kiddo more.