THE TOXICITY OF HYDROGEN SULPHIDE AND OTHER SULPHIDES

Abstract

1. Hydrogen sulphide inhaled, or sulphide or H 2 S injected in solution into the circulation, is carried for a time in the plasma in the form of an equilibrium mixture of sulphide and H 2 S. It only slowly penetrates into the red cells, where it is destroyed in reactions in which oxyhaemoglobin is reduced. The lethal dose of H 2 S will therefore vary according to the rate and site of its administration. 2. The physiological effects of hydrogen sulphide and other sulphides are similar to those of hydrocyanic acid, probably for the reason that both fix the iron in cytochrome A 3 , so reducing the oxygen intake of cells, and especially of nerve cells. 3. The most conspicuous actions of sulphides are on the nerve centres, which are first stimulated and then paralysed. The actions are reversible. 4. Because of the slow penetration of the red cells by H 2 S, or by the HS ion, the removal of sulphides from the plasma and their subsequent destruction is relatively slow, so that injections into the blood stream at sites from which the nerve centres are soon reached are more potent than those made at more remote places. 5. The reduction of oxyhaemoglobin resulting from the action of sulphides is reversible, and this is probably true also for the cytochrome A 3 . The action is therefore reversible, and the main treatment indicated is the application of artificial respiration.