Pyrethrum is considered nontoxic to mammals when used in accordance with the label instructions. Pyrethrum has been used in agricultural and equine applications for a quarter of a century with no known harmful effects. Commonly Pyrethrum is a component on many flea dip applications. A word of caution, pyrethrum may be toxic to some species of fish. As with anything common sense plays a factor. Do not place food or water bowls directly under a spray nozzle.