CHANGE IN CEMENT MANUFACTURING PROCESS, A CAUSE FOR DECLINE IN CHROMATE ALLERGY

Hexavalent chromate in cement is the commonest cause of allergic conta ct dermatitis, especially among construction workers. Over the past de cades, there has been a general decline in the prevalence of chromate allergy among construction workers. We suspect that a change in the co nstituents of cement, resulting in the lowering of hexavalent chromate , contributed to the decline. Slag (free from hexavalent chromate) fro m the iron-quenched, blast furnace process has been used as a substitu te for clinker (which contains high hexavalent chromate) in manufactur ing cement. As a result, the slag has diluted the hexavalent chromate content of cement. Our analytical study showed that slag is free from hexavalent chromate and that the hexavalent chromate of clinker ranged from 6-17 mu g/g. Substituting slag for clinker resulted in dilution of hexavalent chromate in the cement. The hexavalent chromate content of cement declines proportionately with increasing proportion of slag, e.g., a cement containing 5% slag has a total hexavalent chromate con centration of 17.5 mu g/g, whereas increasing the proportion of slag t o 60% reduced the hexavalent chromate content to 7.1 mu g/gm in the sa me cement. (C) Munksgaard, 1996.