Decompression sickness: a review.
Work in compressed air is a dangerous activity, whether it is carried on under water in a conventional diving suit, in self-contained breathing apparatus or in a diving bell, or in relatively dry conditions in a caisson or an underwater tunnel. Surprisingly large numbers of men have worked at one time or another in compressed air in tunnels or caissons and it is the dangers which arise to the health of these men that are considered here. When a tunnel is driven through water-logged strata or through porous ground under a river, the open end of the tunnel must be sealed off and air pumped in to balance the hydrostatic pressure, should there be any danger of water flooding in and bringing with it unmanageable quantities of silt or sand. A pier of a bridge may be constructed in deep water by means of a caisson (Fr. caisse, a box), which is a compressed air chamber in which a gang of men excavate foundations. In both tunnels and caissons men come and go through an air lock and must be compressed on entering and decompressed at the end of the work period. Although working conditions in these circumstances have much improved over the last 6o years, our understanding of the reactions of the human body to atmospheric pressures greater than the normal and of the pathogenesis of decompression sickness is still insufficient to prevent illness completely. In engineering practice it is customary for working pressure to be expressed as gauge pressure in pounds per square inch (p.s.i.g.) which is the pressure over and above the normal atmospheric pressure of I4-7 p.S.i. (I 03 kg./cm.2). For certain calculations absolute pressure (gauge pressure plus atmospheric pressure) is used, and for clarity it must always be stated whether gauge or absolute pressure is referred to. In naval practice it is usual to think in terms of feet of sea water, each 33 feet of depth corresponding to about one atmosphere or approximately I5 p.s.i. Sometimes the unit of pressure used is the atmosphere (atm.). On the
The Newcastle Papers in Industrial Medicine over the Last 21 Years
The Chair of Industrial Health in Newcastle upon Tyne was first filled in March, 1946. For about the first 12 years diseases of coalminers posed the main clinical and research problems. They stimulated surveys of pneumoconiosis in the Durham and Northumberland coalfields and led to studies of ϰ-ray viewing techniques and of the relationship of radiological appearance to symptoms in dust disease of the chest. A section of medical statistics, now headed by a professor, was one of the earliest elements of the department to be inaugurated, and this was followed by a section of pulmonary physiology. The emphasis on industrial pulmonary disease, on which 14 papers have been published, has gradually widened and become transferred from coal to beryllium, asbestos, and antimony. Coalminers with nystagmus were shown to be socially similar to miners without the disease but psychologically less stable. They also suffered from a breakdown of their binocular vision. A darkness-induced nystagmus was experimentally produced in kittens, with increasing difficulty as they became older. Decompression sickness has become an important interest. In the build-up of the department demands for occupational hygiene soon led to the formation of a section which started work on the decalcification of teeth by organic acids in a fruit salt factory. Lead poisoning in shipbreakers and smelters, and vanadium poisoning in fitters and gasmakers were studied jointly with clinicians. The thermal decomposition of protective coatings and welding rods has also attracted research, as also have the noise levels in a glassblowing school and in several power stations. All medical, engineering, and public health undergraduates are taught by the department, and also the honours chemists. All medical undergraduates and honours engineers are examined in industrial health. The departmental budget (including the field service) is about £54,000, and the department inhabits 12,660 sq. ft. of space.
Carcinoma of the Lung in Workmen in the Chromates-producing Industry in Great Britain*
The chromates-producing industry provides the basic chromates, sodium and potassium dichromate or monochromate, from which metallic chromium and the chromium compounds used in industry are obtained. The process involves extraction of chromium from the ferrous ore known as chromite or chrome ironstone, FeO.Cr,O, which contains 40 to 50% chromium and small amounts of alumina and silica. The ore is dried, crushed, mixed with limestone and the carbonate either of sodium or potassium and heated in a rotary furnace to convert the insoluble oxide to soluble monochromate. The monochromate is extracted from the furnace roast by repeated washing with water and treated with sulphuric acid to form dichromate, with sodium sulphate as a by-product. Carcinoma of the lung in employees in the chromates-producing industry has been investigated and recognized as an occupational hazard in Germany (Pfeil, 1935; Alwens, Bauke, and Jonas, 1936; Teleky, 1936; Gross and K6lsch, 1943) and more recently in the United States of America (Machle and Gregorius, 1948; Baetjer, 1950a, b; Mancuso and Hueper, 1951; Gafafer, 1952). An investigation has been in progress in the industry in Great Britain since 1948 and the results are reported in this paper. One of us has previously published the results of a clinical and radiographic investigation of men employed in the chromates-producing industry in Great Britain (Bidstrup, 1951). Seven hundred and twenty-four workmen were interviewed and radiographed and among these one was found to have carcinoma of the lung, from which he died during the survey. It was obviously not possible to