Document gEbmO7QvMb9qxkDDVMwpOK6n3

Jc : K .0.:., b.-M: Uth May, 1060 Dr* King, Di rector, Taberc ;losis Cont r*o J 17 Murray street, PKr'rH Branch, Periodical chest x-ray examination of workers in the Asbestos industry during 1959 disclosed no new cases of' AsbestoGis, althou ;h there arc sever*! men whose x-rays toast be considered susp ect* Those whose x-rays are considered suspicious of Asbestosis will he. examined a Min in I960. The length 02 exposure or workers contracting Asbentosis or Silicon! is much shorten than comparably employed men in the gold-mining industry ind the extent of disease is greater. The smal 1 ru*nh r or workers and the extrcnely hi;*h labour turnover -.ike thi 9 3e: -: obyious. -There art? V h'u.mh';r- 'of .puzzling and: disquieting features. In sevrr.il inst.c cer A&bestoft'is- has- been d iagnosed in Underground workers although the disease'had been considered peculiar to the. 'ill. One member o; the tr .in crew underground, not usually at. gre^t dust risk, h-s what .appears to be a mixture of silicosis, Ashestosis urifl possibly Tuberculosis. Another underground worker has wh.it j rc-A'T rudiologically to be pure silicosis, but his eput contains asbestos bodies. The lAines Dop~rt~ent h.*a permitted me to inspect the result;-; of their periodi- xl dust counts. It is obvious that the new .4111 is u great improvement on the old Will and that oonditior underground huve also improved. It in too early to tell whether t new .ill will he responsible for fresh cases of industrial chest dist.ar-s or not. The disqui- ing features about the dust counts are two 3 1) The rock mined is apparently highly ailicious and therefore particularly dangerous. The dust counts are on a par with figures for the old mines. .4 higher standard should be 8 in view of the high silica content and the additional Ashe tools risk. 2) "he- dust counts arc oi particles only, the suae instrument is ised for detectin'; silica particles and asbestos fibres ;,^>vrc a j ' ..J . ''is n R i i I i; "1 ' Memorandum; ^Dr. King, y~\ ifth :&*y, I960. The dangerous particle size in Silicosis is less than 5 microns, in Asbestosis the dangerous fibre length is between 20 and io microns. The dust counts are therefore of little value unless they show the number of fibres per cc within that range. The Konimeter in use in this State is not regarded as an effective instrument for dust counting in the Asbestos industry in Canada. A tfidget--Xmpinger ie used. It is stressed that fibres over 10 microns in length are of particular importance and whilst the total dust concentratioi should be below 10 million particles per cubic foot of air. The maximum fibre count (ie over 10 microns in length) per mitted, is 1 million fibres per cubic foot of air. Many workers remain at Wittenoom for less than one year and less than 5095 of the work force, at any one time, have been continuously employed for more than four years, A very rough estimate of the percentage of workers, with over 4 years exposure and suffering from industrial chest disease is. 12$ (estimated by expressing the number of workers, detailed below, as a percentage of the number of workers examined in 1959 whose initial mining certificate was issued prior to 1955*) In. receht years it would .b.e -unusual to diagnose Silicosis in a gold miner 'with .less th.in 10 years exposure. E,g,`in 1958,' there were no new cases of Silicosis in the 0-10 year group, 20 cas in the *0-20 ye<ur group and 29 cases in the 20-30 year group. Expressed as a percentage of the total number of mine workers this gives an annual incidence of Silicosis of approximately 1$, These percentage incidences are not very accurate and are not really com parable, but they do illustrate the grave hazard which existed at Wittenoom compared with the general .lining industry. The following are the particulars of cases of industrial disease detected at Wittenoom since 1958* The list is con^lete as far ar oar records go, but there may be a few cases diagnosed else where who were not examined under either of the relevant Mining Act and therefore not brought to our notice. Some newly diagnosed cases of Silicosis are not included because of previous lengthy gold-mining history which could reason ably be held responsible. There have also been a few cases of workers developing pulmonary tuberculosis without Silicosis or Asbestosis, but their number does not suggest any particular hazard at Wittenoom, other than that associated with mining in general. Five Mill workers have been diagnosed as ^bestoeiB Brnce 1958 -na one under-round worker. Their average ~ Ai ( exposure. to asbestos dust us four yeur-c. __ Three workers with a ..ixed gold ui.d usbestos lining history have developed silicosis and ushestosis. Four workers with a simil. njr.i history havv. Developed pare silicosis. Of these seven workers the average exposure to dust including all mining was 12 -- years a*d excluding previous aining (which in not entirely justl- iiahlr) *a 7 years. Conclusion: The percentages quoted above (i.e. *2% of asheBtoo workerr> ! __ saffi ring fro.: industrial chest disease with over h years exposure ! .compared with 1% of gold miners with oyer 10 years exposure) are } :J crude and probably paint too black a picture of the conditions which existed, ffith a shifting working population It is almost \ ~ impossible to work-out accurate incidences. However, the very high labour turnover at Wittenoom is necessarily associated with a short average exposure per worker and many workers at risk were protected ri tply because their exposure time was too short. At lejst one of these short-term workers has been diagnosed as suffer ing Asbostosis iary years after he left the* industry. The proble : is essential *jy one of ventilation conducted with j proper ipprdc:'at Ion -of :.the rel itdve. iuportaned .'and. medical significance *of the ashortos fibre as dietiqct from the silica particle, . wispite the ;r ny marked improvements which have been effected at the Mine and Mill, Ian not satisfied that the risk of industrial chest disease h*s been eradicated or even brought to paj with the risk of Silicosis in the gold-mining industry. The prevention of industrial chest disease is a medico-engineering problem and requires close liuson between the Mines Department, wh< are responsible for ventil tion and dust counts, and -,the medical officers, who are responsible for r.he periodical clinical and ches* x-r^y exj-Minatioris. CHEW PHYSICIAN AND M.t NTS SniC/J, OFFICER. ?--