Would you put something with harmful chemicals in your mouth and start chewing, licking and biting it? Would you let your children? No, we didn't think so. Unfortunately, many of the common vinyl, plastic, synthetic plush and rubber dog toys on the market are exactly that. But in their quest to find toys that stand up to a dog's heavy chewing, dog owners often overlook this danger. Yes, some may last for ages, but have you thought about what goes into them to make them so darn tough? Lots of chemical processes - some that are even carcinogenic. It's just not natural.