[H2S poisoning and nervous system damage].

H2S (hydrogen sulfide) is a very toxic gas. Even brief exposure to high concentrations may be fatal. Unconsciousness may occur without warning. Those who try to help are often poisoned too. In Norway, most poisonings have been described in connection with the herring oil and fish meal industry, farmers handling manure, and sewage work. The risk of hypoxic damage to the nervous system is considerable. The clinical picture varies, and the connection between the patients' symptoms and the poisoning is easily overlooked, especially with delayed sequelae, which may occur several weeks after the acute poisoning. The risk of damage depends on both the exposure time and the concentration of H2S, and a thorough anamnesis, noting the course of events, is important in order to achieve a correct diagnosis.