Toxicity of chromic acid in the chromium plating industry(2)

Abstract

A population of chromium platers in the West Riding of Yorkshire, defined as described in a previous paper, together with a closely matched control group of manual workers in the same area, were subjected to morbidity screening for respiratory symptoms; the “plater” population was also screened for the ulcerative and dermatitic lesions commonly seen in chromate handlers. A standard questionnaire was used, but no physical examinations or physiological tests were performed; questionnaires relating to 997 platers and 1117 controls were successfully completed. In general, respiratory symptoms were experienced to a greater extent by the plater population. A higher proportion of platers had worked in dusty jobs, however, and, when the populations were divided into “dust-exposed” and “not-dust-exposed” groups, the disparity in symptomatology was seen to be more marked in the (larger) group of dust-exposed subjects. An exception appeared in the case of effort dyspnoea which, in its most severe form, affected practically the same proportion of each population. The prevalence of bronchial asthma was high in both platers (13.1%) and controls (9.8%), this increase being much more marked in the dust-exposed group. In the case of seasonal hay fever, 3.9% of platers and 5.5% of controls were affected. The risk of skin and intranasal ulceration is shown to increase progressively, the longer the period of chromic acid exposure, whereas allergic contact dermatitis occurs equally in platers with short and in those with longer exposure. An industrial hygiene survey, including air and dust analyses for chromic acid content, was carried out in 42 of the 54 plating plants from which the plater population was derived. In only two cases was the Threshold Limit Value (TLV) for atmospheric chromic acid exceeded. Analyses of many dust scrapings showed chromic acid content of from 0 to 298 mg/g. No comparison figures are available, but it is thought that these were high, and that the dislodgement of such dust could form an intermittent inhalant hazard in chromium plating.