In order to investigate loss of work from rheumatic diseases in the metal trades, employees in 10 foundries were questioned.
Of 325 foundry workers aged 35 to 74 years, who had worked for at least 10 years on the foundry floor, 299 were examined clinically and radiologically for evidence of rheumatic disease. Radiographs of the hands, knees, and dorsal and lumbar spine were taken as a routine, and the pelvis was included in those aged 45 and over. A comparison was made with a control series of radiographs, from men, matched for age, in a random population sample examined earlier in the town of Leigh.
Rheumatic complaints in general were less frequent in the foundry workers than in the random sample, and the foundry workers less often gave a history of prolonged incapacity (three months or more) due to this cause.
Radiological evidence of disc degeneration in the lumbar spine, however, was more frequent in the foundry workers than in the controls and was of greater severity. Further, the foundry workers more commonly had symptoms and signs of lumbar disc prolapse. On the other hand, the controls had more osteo-arthrosis of the hips and knees and lost more work from pain at these sites. This was associated with a difference of body habitus, obesity being less frequent in the foundry workers.
Foundry workers directly exposed to hot conditions did not have less back or leg pain than those not so exposed despite a greater prevalence of disc degeneration.
Measurements of air temperature, humidity, and radiant heat were made in a foundry while pouring was in progress. The air temperature rose from 18°C. to 26°C. and the humidity ranged from 70% to 54%. The mean intensity of radiation incident on the clothed surface of a foundry worker was 0·12 watt/cm.2. This was compared with conditions during therapeutic exposure to radiant heat. The radiant heat under conditions of `heat therapy' varied between 0·16 and 0·37 watt/cm.2. The possible influence of radiant heat on the prevalence of rheumatic complaints is discussed.