Kys...I don't really know the answer to your question. I would think the top soil would be safe but you never know. I know that cedar mulch is advertised as repelling bugs but I don't know if anything has been added. I know if I was going to buy mulch I would certainly read the bag and ask the person at the nursery for any information on what's inside. Before even taking their word, though, I would probably try and see what the manufacturer says, either via an e-mail or just jotting off a letter. Can't take chances with our furkids!