Tubercle, Lond., (1964), 45, 379

T U B E R C U L I N S E N S I T I V I T Y IN C O A L M I N E R S W I T H P N E U M O C O N I O S I S

By CH. A. M. HENDRIKS and M. A. BLEIKER

fi'om lnstitltUt voor Longonder:oek voor de Steenkolemnijnindustrie, Treebeek, Nederland; and Gezondheidsorganisatie T.N.O., Den Haag, Nederland*

SUMMARY

To obtain information about the tuberculin sensitivity in miners and in order to find out whether progressive massive fibrosis (P.M.F.) may be caused by a tuberculous infection, the tuberculin sensitivity in Dutch miners was studied by means of the Mantoux-test.

The preliminary results show a well-marked correlation between tuberculin sensitivity and age, but no correlation with category of pneumoconiosis.

There did not appear to be any difference in sensitivity between miners having P.M.F. and men of the same age who had never worked underground.

Coaiworkers' pneumoconiosis includes two different disease processes. Simple pneumoconiosis, in which small areas of dust accumulation occur throughout the lungs, associated with. only minimal fibrosis, and progressive massive fibrosis (P.M.F.) in which large areas of dense fibrosis develop, usually associated with simple pneumoconiosis. It is generally accepted that simple pneumoconi- osis is due to the retention of dust particles in the lungs. Although the factors associated with. attack rate and progression rate have been studied (Coch.rane, Moore and Thomas, 1961; Cochrane, 1962), the etiology of P.M.F. is still unknown. Of the various hypotheses about its etiology the 'tuberculous' one is very popular, and in weighing the evidence for and against this, the problem of the tuberculin sensitivity of men having P.M.F. has become increasingly important. Infection by tubercle bacilli in a given group of persons can, in fact, only be established by studying these persons' tuberculin sensitivity by means of a tuberculin test.

If, therefore, the 'tuberculous' hypothesis is to be tested, it is necessary to make use of this test to find out if there is a distinctly higher proportion of infected cases in the group of miners with. P.M.F. (e.g. a percentage of nearly 100, as is found in tuberculous patients), than in the group of men not having this form of pneumoconiosis. There have been two previous investigations. Hart & Aslett (1942) investigated a group of Welsh working miners but failed to find any relationship between x-ray category of pneumoconiosis and tuberculin sensitivity. This was confirmed by Hart, Cochrane and Higgins (1963) on a random sample of miners and ex-miners in a Welsh mining valley.

Population Studied The population to be studied was defined as" !. All underground workers. 2. All surface workers who had worked more than one year underground. 3. All apprentices for underground work at Dutch mines.

The response rate was 81%. The data on 13,907 miners are available and are issued in this prelJmt- nary report.

* The Institute for Miners' Chest Diseases, Treebeek--The Netherlands" and the Organization for Health Research T.N.O., The Hague--The Netherlands.

380 TUBERCLE

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T U B E R C U L I N S E N S I T I V I T Y IN C O A L M I N E R S 381

M a n t oux-t est Techniques

The standard W.H.O. Mantoux-test was used. Every man examined received I TU PPD Rt23 with 0.05 ~,,o Tween 80.

The injection was made into the skin of the dorsal side of the forearm; the tests were read after 3-4 days (Griep, 1957), by measuring and recording the transverse diameters of the reactions.

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The injections and the reading of the tests were done by two teams, composed of 3 specially trained nurses, who had several years of experience in Mantoux testing with recruits for the Nether- lands Army.

Chest X-rays The chest x-rays were taken either immediately before or after the Mantoux-test, during the

periodic x-ray surveys. The films were classified,, using the l.k.O. 1958 classification (|.L.O., 1959). The classification and the Mantoux testing were carried out entirely independently. There was no possibility of bias.

382 TUBERCLE

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Tuberculh~ Sensitivity Results

Fig. 1 gives the frequency dis tr ibut ion of the diameters of the indurat ions in t3,907 coal miners. This his togram shows a bimodal curve, with a 'd ip ' be tween 6 and 12 mm. The possible impor tance of infection by ' anonymous ' bacilli will not be discussed in this paper. The shape of the curve partly depends on the number of persons infected, but there is also a clear influence of age (Table I and Fig. 2). The ' tuberculin index' (i.e. the percentage of persons showing indurat ions of more than 5 mm.) for those born after 1945 is only 7.5 ~,/," this rises to 70%,~ for those born between 1921 and 1925, and 85 ~,, for those born between 1906 and 1910. The rise is less steep i fon ly the larger indura- tions are considered.

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TUBERCULIN SENSITIVITY IN COALMINERS ~83

Tuberculin Sensitivitv and X-ray Categoo' o f Pneumoconiosis The results of this comparison are shown in Table I and Fig. 3. The tuberculin sensitivity appears

to be correlated with age and not with radiographic category; the three x-ray groups do not differ signilicantly in their tuberculin sensitivity.

It can be assumed that there is no relation between P.M.F. and tuberculin sensitivity, because if such a relation existed a l,'auch higher index would have been found in the P.M.F. group, as is found in groups of tuberculous patients.

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age group who had never worked underground (! TU PPD Rt23 ' Tween 80).

in order to add more information to this assumption, a comparison was made with. tile tuberculin sensitivity of 2,173 chemical factory-workers born before 1925, who had never worked underground. The chemical factories also belonged to the Dutcll State mines and about 90 o / o f the workers in this age group were tested. Here again (Fig. 4) it is clear that men suffering from P.M.F. do not differ in their tuberculin sensitivity from those of the same age who have never worked underground. Nor does Fig. 4 suggest a higher sensitivity in men with P.M.F.

Conclusions

These results confirm those of Hart & Aslett (1942) and Hart , Cochrane & Higgins (1963).,:The tuberculous hypothesis of the etiology of P.M.F. seems even more doubtful.

This investigation was rnade with financial aid from the High Authority of the European Coal and Steel Community. We are very grateful to Professor A. L. Cochrane for his help in the preparation of this paper.

REFERENCES COCHRANE, A. L. (1962). Brit. J. industr. Med., 19, 52. COCHRAN~, A. L., MOORL F. & THOMAS J. (1961). Tubercle (Lond.), 42, 64. GmEP, W. A. (1957). De tuberculine-reactie. K.N.C.V.,'s-Gravenhage. HAg'F, J. T., COCHRANE, A. L. & HtGGtNS, 1. T. T. (1963). Tubercle Lond.), 44, 141. H^ar, P. D'A. & ASLETT, E. A. (1942). M.R.C. Special Rep. Set'., No. 243. London: H.M.S.O.