When I first opened this toy for my son I noticed it was really light weight. It feels like hallow plastic. After about a week I noticed the paint chipping on some of the peices, under the paint was not wood at all but particle board.Here is what wikipedia has to say about particle board:"...concern is with the release of formaldehyde... a small amount of emission occurs dueto decomposition of the resin."My son is 2 and still puts toys in his mouth. I hate the thought of him chewing on particle board made with formaldehyde.Also the toys are flat and light weight, hard to stand up and fall over easily. My son would try and play with them like a normal toy, but the peices would just fall over like a domino affect.