Document x1Z5dKMzkyJj7w70583exOKDy

British Journal ofIndustrial Medicine, 1979, 36, 98-112 A she. data in th Asbestosis: a study of dose-response relationships relev in Et in an asbestos textile factory basa! have who G. BERRY1, J. C. GILSON1, S. HOLMES2, H. C. LEWINSOHN2-4, AND S. A. ROACH2 had by E cism From the 1MRC Pneumoconiosis Unit, Llandough Hospital, Penarth, South Glamorgan, CF6 1XW, befoi 2TBA Industrial Products Limited, Rochdale, Lancashire, OL12 7EQ, and ^Imperial Chemical Industries time: Limited, Wilmslow, Cheshire, SK9 1QB thee thosi In abstract A group of 379 men who had worked at an asbestos textile factory for at least 10 years stud, has been followed up. The prevalence of crepitations, `possible asbestosis', certified asbestosis, small prev opacities in the chest radiograph and values of lung function have been related to dust levels. The 1968 type of asbestos processed was predominantly chrysotile although a substantial amount of crocidolite had also been used in the past. There was a higher prevalence of crepitations than had been observed previously at the same factory. The presence of crepitations is not a specific effect of asbestos exposure and `possible asbestosis', a combined judgement of two physicians on whether a man had developed signs which mightbe attributable to early asbestosis, was preferred. Fifty per cent ofmen with a diagnosis of possible asbestosis were certified as suffering from asbestosis by the Pneumoconiosis infoi Firsl mad of nr syste syste lung Medical Panel within 3-5 yr. The most reliable data relate to men first employed after 1950 ; 6-6% ches of men in this group had possible asbestosis after an average length of follow-up of 16 yr and an ings average exposure to 5 fibre/cm3 where the dust levels were determined by static area samplers. The natii forced expiratory volume and forced vital capacity declined significantly with exposure, after Thit allowing for age and height, but there was no decline in the total lung capacity. The transfer factor fact< also declined with exposure, but not to a statistically significant extent. The non-smokers and light smokers as a group had less crepitations, asbestosis and small opacities on the chest radiograph graf pro\ t: than heavier smokers with similar exposure. Combining dust concentrations to form the cumulative pur] dose may not be completely satisfactory, and a family of measures was investigated which allows for < for elimination of dust from the lungs and includes the cumulative dose as a special case. Because 1961 the rate of elimination of dust from the lungs is unknown, and cannot be estimated from the data, pres this approach leads to a wide range of possible interpretations of the data; for example the con witt centration such that possible asbestosis occurs in no more than 1 % of men after 40 years' exposure could be as high as IT fibres/cm3 or may have to be as low as 0-3 fibres/cm3. This range is wide because the data relate to higher dust levels, and a shorter period of follow-up. Until data are avail able on groups exposed to lower levels it will not be possible to assess the effects of the current standard with any certainty. However, the results of this study show that it is important to continue to reduce dust levels to values as low as possible. T met dusi ship thin rela for lem In 1968 the British Occupational Hygiene Society (BOHS) published hygiene standards for chrysotile asbestos dust (British Occupational Hygiene Society, 1968). One of the features was that risk was related to accumulated exposure, that is the sum of con- `Present address: Raybestos Manhattan Corporate HQ, 100 Oakview Drive, Trumbull, Connecticut 06611, USA Received for publication 13 March 1978 Accepted for publication 6 July 1978 centration x period of exposure to that concentration over the whole period of exposure. With an accumulated exposure of 100 fibre/years/cm3 it was concluded that it was probable that the risk of contrading asbestosis would be less than 1 %, where asbestosis was defined as the earliest demonstrable effect on the" lung attributable to asbestos and this effect was the presence of persistent basal rales. The recommendations were made with two main notes of caution. First, it was pointed out that few i i ; ?- Met THl The at t witl whe 196 incl SCF-FA-7306