Toys made from plastic are more dangerous and harmful to dogs as well as humans. This PVC contains, DINP, a chemical used to make hard plastic soft and pliable; this chemical can cause cancer.
Toys made in China may contain lead, chromium, and cadmium. If ingested by a dog this may lead to lead poisoning. Rawhide chews are pieces of cow skin which have been chemically treated, stretched, and then dried into a variety of shapes (e.g. Knots, sticks, rings) which can be dangerous and may cause injuries.
They can be broken off into sharp fragments which may lead to partial intestinal obstruction. If this is not diagnosed at early phase it may also be fatal. Pigs' ears and trotters can cause an upset stomach if overeaten by a dog.
Wood and plastic can cause damage and injuries and infections. Stuffed toys are fun but can be harmful. A dog can easily choke on them. Tennis balls and racquet balls are small in size which can be easily swallowed that may also lead to choking.
If you give rope toys for dogs they may ingest the strings of rope, causing digestive and gastrointestinal problems so these must be given under observation. So, these are some reasons why dog toys may be unsafe for the dog.