We use an EPA approved water based solution that contains the synthetic version of Pyrethrum (an organic compound known as pyrethroids) which is derived from the flower heads of Chrysanthemums (The African Daisy). Pyrethroids are used in lice shampoos for children as well as flea shampoos for dogs. We do recommend staying out of the treated area until it dries, which in most cases is 30 minutes. A risk/benefit balancing analysis conducted by the EPA saw the benefits of permethrin dramatically outweighing the risks. In a comparative test with DEET, when put directly on the skin, typically less than 1% of the active Permethrin ingredient is absorbed into the body; DEET can be absorbed at over 20 times that rate.