In my opinion it is as newspaper is 100% biodegradable and most of the ink is soy based and red worms love it, but other posts on the web dissagree with this. I made a video a while back using newspaper for a worm bin and it works well, but some debate about the ink. http://www.youtube.com/watch?v=-DTsex06ppE&playnext=1&list=PL749F33993FED29DA&feature=results_video