The effect of the use of calcined alumina in china biscuit placing on the health of the workman.

The serious morbidity and mortality from silicosis among china biscuit-ware placers and oddmen and china biscuit warehouse workers, when flint was the placing medium for the biscuit firing, have been fully recorded by Arlidge (1892), Sutherland and Bryson (1926), Middleton (1936), and Meiklejohn (1947 and 1949). So alarming was the hazard that ceramic chemists and practical potters urgently strove to discover a safe placing medium, which could be used as a substitute for flint. About 1929 (Plant, 1939) laboratory researches and practical trials proved that calcined alumina (corundum) could be used satisfactorily in the manufacture of fine china. Later, following a carefully planned survey (Industrial Pulmonary Diseases Committee, 1936) among a group of furnacemen engaged in the manufacture of alumina, Sutherland, Meiklejohn, and Price (1937) concluded that " there was no evidence of pneumoconiosis or of any other form of pulmonary disease arising from the considerable dust to which these workmen were exposed ". Assured by the practical and medical evidence, china manufacturers in increasing numbers adopted alumina as a medium for biscuit placing. Meiklejohn and Jones (1948) carried out a survey among china biscuit ware workers in North Staffordshire and reviewed the furnacemen who had been examined in the inquiry 10 years previously. They reaffirmed that alumina (corundum) as used in the pottery industry had no adverse effect on the health of workmen. Finality was reached when, under the Pottery (Health) Special Regulations, 1947, the Minister of Labour and National Service prohibited the use of powdered flint or quartz with or without the addition of other materials in the placing of ware for the biscuit fire. These regulations became effective on January 7, 1948. Between 1952 and 1954 the Mass Radiography Service at Stoke-onTrent radiographed (35 mm. film) 248 out of approximately 280 china biscuit placers and oddmen. The results accorded with previous reports: all cases of pneumoconiosis which were detected had worked in flint for varying periods or had been exposed to other forms of siliceous dust. Then in 1955 King, Harrison, Mohanty, and Nagelschmidt reported the results of laboratory experiments, which they had conducted on the effect of alumina, aluminium phosphate, and corundum stack fume on the lungs of rats. They concluded that certain forms of alumina, particularly hydrated alumina, can produce fibrosis of the lungs nearly as severe as can be produced by quartz. They emphasized, however, that the doses of dust used in these animal experiments vastly exceeded those used in the prophylaxis of human silicosis. Commenting on these findings Middleton (1955) wrote: " the results of the present experiments are disturbing and a reassessment of the dust exposure and control in the china branch of the pottery industry appears to be indicated."