Silicosis in West Country Granite Workers by L
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Brit. J. industr. Med., 1963, 20, 218. SILICOSIS IN WEST COUNTRY GRANITE WORKERS BY L. W. HALE and G. SHEERS From the West Cornwall Hospitals Group and the Mass Radiography Service of the South Western Regional Hospital Board (RECEIVED FOR PUBLICATION MAY 8, 1962) The granite industry in Cornwall and Devon is briefly described, especially the production of dust in dressing the stone. In 1951, 210 granite masons were examined (about 84% of the total at that time) and 37 (17 6%) showed silicosis. These men were followed up for 10 years. No silicosis was seen in men with less than 15 years' exposure, but after this time the risk increased to 11 out of 14 in those with over 35 years' exposure. Nine deaths occurred, two of which were due to silicosis. Radiological pro- gression was observed in 13 of the 28 survivors. It was not necessarily associated with additional exposure but was related to age. More young men progressed. In 1961, 132 of the granite masons (about 93% of the total at that time) were re-examined and nine new cases of silicosis were found to have developed during the 10-year interval. The exposure in the 1961 cases was comparable with that of similar cases in 1951. Thus, the risk has not been much reduced over this period. Pulmonary tuberculosis occurred in eight of the 37 cases of silicosis in 1951, and between 1951 and 1961 a further five cases were diagnosed, four being from one locality. This was by far the most frequent and disabling complication. Only one case of progressive massive fibrosis was seen. More extensive use of protective antituberculous chemotherapy is advocated, and also better dust control. Description of the Industry In 1900 the granite industry in Cornwall and Devon employed about 10,000 men; at present the Cornwall and Devon form the south-western labour force is in the region of 600. There are three extremity of the granite ridge which extends north- main areas: (a) the Kerrier Highlands, south of east through England into Scotland. The granite in Penryn; (b) St. Breward and thereabouts, north of these areas is an acid rock, occurring by volcanic Bodmin; and (c) the western fringe of Dartmoor, intrusion of the molten magma into the surface slaty east and west of Tavistock. There are a few large material. It is coarse-grained, and consists mainly of works, employing up to 80 men, but many are small felspars, micas, tourmaline, and quartz. The quartz concerns of the "family" type and may not employ crystallized latest in time and "binds" the rock and more than three or four. gives it its hardness. The quartz content of this The works consist of quarries, concerned with granite varies from place to place, between 30 % and rock-getting, and yards, where the blocks of granite 40 % free silica being usual, though figures well above are shaped, smoothed, scribed, and polished. 50 % free silica are quoted, especially near metallic Quarrying involves the selection of blocks of rock lodes. to be got from the quarry face; drilling of shot-holes The getting and dressing of the granite has been a patterned to secure suitable blocks without excessive considerable industry in the area for many centuries. shattering; shot-firing, using gelignite, to dislodge Rising costs and the development ofcheaper building the block required; and subsequent further drilling materials have greatly limited the demand for pre- ofrows ofholes in the block, into which pegs are then pared granite for building and paving, and the driven to fracture the rock along its natural lines of industry has in recent years been largely focused on cleavage, so achieving the initial crude shaping of the monumental work. block, ready for transport to the yard. The drilling 218 SILICOSIS IN WEST COUNTRY GRANITE WORKERS 219 is done with pneumatically-operated percussion pushed back in fine weather. Thus the ventilation is drills, with no water-feed, and no dust-prevention very free, and conditions approximate to those of measures are used. There is no tunnelling for the working in the open air. The banker is set so that the granite and all the quarrying is in open-air condi- mason has its upper surface at a convenient height to tions. Quarry work is unskilled or semi-skilled. work on it in a standing stooped position, his face The "yards" vary from a quite small clearing on the being about 1 ft. (0 304 m.) above the surface on exposed moorland to the type of yard illustrated which he is working. (Fig. 1), where 20 or 30 sheds are in use. In the The granite mason nowadays uses hand-operated yards large blocks are reduced to a smaller size by and pneumatically-operated tools about equally, though there may in a few cases be a tendency for a man to specialize to some extent. In general, the smoothing of medium degree may be done by hand, while the finishing of the surface may be done with a small pneumatic chisel, about 1 ft. (0 304 m.) long and held rather like a large fountain-pen. Scribing and lettering is almost always done with mechanical tools today. Pneumatic work on the banker produces a cloud of visible dust about 6 in. (15 24 cm.) in range from the point of the tool, often less. Hand working produces a small spurt of dust of about the same height at each stroke of the hammer (Fig. 2). Much FIG. 1-Stall, % ith roof pushed back, and masons working on banker. sawing with a mechanical saw which works in a spray of water directed on the block. No dust is visible in the process. Blocks of granite may first be surfaced with the "dunter", a type of heavy mechanical hammer whose striking-face is equipped with rows of chisel-like points. As the striking-face moves to and fro on the surface of the block it removes gross irregularities by fracture. The dunter is the most obvious producer of dust in the processes, but it is used intermittently and is idle for considerable periods, often weeks at a time. The smaller yard may not possess one, all the FIG. 2.-Smoothing by hand, showing puff of dust. smoothing being done by hand. The skilled work of final smoothing, shaping, and of the dust found on rafters and shelves in the stalls scribing is done by tradesmen, known as dressers or is obviously coarse and of large particle size; eye banker-masons, the "banker" being the granite slab injuries due to flying chips are fairly common. mounted on wooden joists in the shed where the Not infrequently masons experience numbness and tradesman works. Banker-masons serve a five-year tingling in the fingers, and occasionally they have apprenticeship and, being skilled tradesmen, tend to "white fingers" due to the use of vibrating tools. We remain lifelong in the industry. have not met any case showing necrosis of the skin. The sheds, or in a large yard, stalls, are in general Men who use mechanical tools much usually have a of similar pattern and set in a row; the floor dimen- "gall" (a cushionlike soft tissue thickening, painless, sions are about 10 x 12 ft. (3-2 x 3 8 m.); the sheds not callous, and not oedematous) up to the size of are entirely open-fronted with side walls usually half a walnut on the finger, usually the right ring- about 1 ft. (0 304 m.) short of the roof, cubicle finger, which they hook round the barrel of the tool fashion, the rear walls having a flap-type window when using it. about 4 x 3 ft. (1-37 x 1 07 m.). The roof has its The finished piece of granite may or may not be front half designed like a car sunshine roof, and is polished, according to requirement. Most polishing 220220BRITISH JOURNAL OF INDUSTRIAL MEDICINE is done mechanically by rubbing the surface with an workman's way, and up to the present it has not been abrasive disc under a water-spray, but occasionally completely successful (Fig. 3). dry polishing is seen. Finally, in some of the larger yards there is a build- Methods and Materials ing which houses a crusher of the type commonly found in quarries, which produces ballast, chips, With the co-operation of the Cornish and Devon gravel, etc. as a by-product from the waste granite. Granite Masters' Association and the Associated Union of This machine produces much visible air-floated dust, Building Trade Workers, 406 workers in the industry with were brought to three centres for clinical and radiographic and the rafters in the building are heavily coated examination. These were at Longdowns, near Penryn, at it. Many works do not include a crusher, and the De Lank Quarry, near Bodmin, and at Tavistock. workers with the crusher are unskilled and tend to These surveys were carried out between November, move more from job to job, within or out of the 1951, and November, 1952. The total of406 examinations industry, than do the masons. represents a response of approximately 67% from all classes of worker in the industry, but the main purpose of the surveys was to examine as many as possible of the Dust-prevention Measures granite masons. Of these, there were 250 in the industry in 1951, and 210 were examined, a response of 84%. Studies of dust concentration or of ventilation Having regard to the number of small, independent firms, have not, as far as we know, been made in the totalling approximately 90, many of which were isolated environmental conditions obtaining in this country.