The bacterium Clostridium botulinum produces a poison called botulinum toxin that can prevent the release of acetylcholine from motor neuron axons at neuromuscular junctions, causing botulism, a very serious form of food poisoning. This condition is most likely the result of eating home-processed food that has not been heated enough to kill the bacteria in it or to deactivate the toxin. The endospores of this bacterium are very heat resistant and can withstand several hours of boiling at 212°F (100°C) and ten minutes at 248°F (120°C). Botulinum toxin blocks stimulation of muscle fibers, paralyzing muscles, including those responsible for breathing. Without prompt medical treatment, the fatality rate for botulism is very high.