Phosphldes are particularly dangerous because they tend to decompose to the very toxic phosphine upon contact with moisture or acids. Dangerous fire hazard by chemical reaction, particularly with moisture. Moderate explosion hazard. They react with water, steam, acid, or acid fumes to produce toxic and flammable phosphine gas. Can react vigorously with oxidizing materials. Dangerous; when heated to decomposition they may emit highly toxic fumes of POx. See also PHOSPHINE