Most of those contain chemicals and inks and glues/binding agents...definitely not environmentally friendly to burn. Even burning regular dried wood can pollute the environment and cause poor air quality when there are too many people in an area relying on wood burning heat. Where I live, they have burn ban days and not only in the summers...depends on the air quality and even then burning is only allowed in super efficient wood stoves that burn as much of the "residue" as possible.