The Prevention of Pneumoconiosis Among Coal Miners in Great Britain

tion of the nasal septum and other effects follow ; but if a dithiol successfully competes with the enzyme for arsenic, such events do not occur and arsenic appears in the urine. Further, if the dithiol be liberated in the body within one or two hours of the invasion by arsenic, it will snatch the arsenic from the very mouth of the enzyme by its sulphur prongs ; the monothiols are merely elevator tools and are not so effective. The eventual choice was 2 : 3 dimercaptopropanol (BAL). This has also been found to be effective in poisoning by certain other metals, although it appears to add to the toxicity of lead. Some nonmetallic poisons, such as methyl iodide, are also said to be rendered innocuous. So, in therapeutics, as in so many other fields of human endeavour, belatedly perhaps, empiricism yields to science. Some substances, like sulphanilamide, compete with a substrate such as />-aminobenzoic acid, for an enzyme in the bacterial cell, the key to the cure of many diseases. Other substances, like BAL, actually compete with the enzyme itself for a substrate such as arsenic. Such knowledge should deflect many research projects from their all too frequent ignominious course, " the long way to the sink." More importantly, it should speed the discovery of more potent therapeutic weapons and so increase our understanding of toxicology that we can plan our preventive measures with greater certainty.