I figured they are made of wood, so they've got to be better for him to chew on than plastic (with who knows what kinds of chemicals in it). (crunchydomesticgoddess.com)
Books printed in the 19th and 20th centuries use different kinds of chemicals during the printing cycle. (goodereader.com)
What kind of chemical bond is intrinsic moral value stored in, anyway? (mommyish.com)