Phosphorus is widely used in the manufacture of matches, fireworks, firecrackers, signal flares, some synthetic dyes, artificial phosphate fertilizers, pesticides, rodenticides and medical drugs. Old-style match powder contains yellow phosphorus, which is highly toxic. The daily match powder currently produced does not contain phosphorus, but the side powder of some matchboxes contains about 40% red phosphorus. The head powder of phosphorus sulfide matches that can be lit anywhere contains about 10% tetraphosphorus trisulfide (P4S3), which is toxic. It is mostly caused by accidentally taking phosphorus-containing rodenticides such as zinc phosphide, and occasionally by swallowing match heads containing yellow phosphorus; if you chew the side of a matchbox containing phosphide or red phosphorus many times, you may also experience poisoning symptoms. Red phosphorus generally contains 0.6% to 1% yellow phosphorus. Few people are poisoned by inhaling yellow phosphorus fumes or phosphine.