It explodes. It kills on contact with the skin. It kills via air, food, or water. It is odorless and colorless. There is no antidote. Even minor exposure will result in permanent damage to brain cells.
University of Arizona atmospheric scientist Eric Betterton was one of the first to expose the hazards of this unregulated material in 2000. The author J. A. Jance used it as the poison of choice in her book 'Partners in Crime'.