Ethnic differences in lung function: evidence for proportional differences

Our plain-English summary of Ethnic differences in lung function: evidence for proportional differences, by C.E. Rossiter, H. Weill (International Journal of Epidemiology, 1974).

The study

• Authors: C.E. Rossiter, H. Weill
• Journal: International Journal of Epidemiology
• Published: 1974;3(1):55-61
• Cited by: 163 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002365).

Abstract

In a group of 244 male low-exposure asbestos cement workers without major clinical symptoms or radiographic changes, marked ethnic differences were found in the relations of lung function to age and height There is anthropometric evidence that for given height whites, of European descent, have a 13.2 per cent larger chest volume at full inspiration than blacks, of African descent and this accounts almost completely for the differences in total lung capacity, vital capacity, forced vital capacity, forced expiratory volume, forced expiratory flow rate and alveolar volume between blacks and whites. Smaller differences occur for functional residual capacity, residual volume, diffusing capacity (transfer factor) and the diffusion constant. It is proposed that until further evidence is forthcoming, for normal values a scaling factor of 1.132 should be used for the major lung volumes to account for the ethnic differences between Africans and Europeans. Smaller scaling factors are proposed for other lung function indices.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

The data came from a study of two New Orleans-area asbestos cement plants begun in November 1969. Of 859 men, the authors studied 244 (97 white, of European descent; 147 black, of African descent) with low asbestos exposure and no major symptoms or chest X-ray changes. For most lung function measures, the groups differed markedly at the same age and height. From published chest X-ray measurements in Rhodesia, the authors estimated that, at a given height, whites had a 13.2 per cent larger chest volume at full inspiration than blacks. Raising the black men's total lung capacity by 13.2 per cent left a difference of 0.01 litres at age 40 and height 1.75 metres. For other full-breath measures, the largest remaining difference was 0.12 litres. They found no evidence of an important exposure effect within this low-exposure group. They proposed, until further evidence is available, that normal (expected) values for black men's major lung volumes be reduced by a scaling factor based on this 13.2 per cent difference, with smaller factors for other indices. They noted the study's small size (244 men) and limited anthropometric data.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cross-sectional analysis of lung function tests, questionnaire and chest radiographs in asbestos cement workers, combined with published anthropometric data used to derive scaling factors
• Who was studied: Of 859 male workers at two asbestos cement product plants in the New Orleans area, 244 low-exposure men without major clinical symptoms or radiographic changes were analysed: 97 white (of European descent) and 147 black (of African descent)
• Exposure: Low exposure to asbestos dust in asbestos cement manufacturing: a total of less than 1,000 units, one unit being 1 million particles of respirable dust per cubic foot of air for one month. The fiber type was not stated. The main comparison was between ethnic groups, not between exposure levels.
• Main results:
  • Before scaling, the regression coefficients on age and height did not differ significantly between white and black men for any index. For most indices, however, the regression lines differed markedly in position between the two groups.
  • From published chest radiograph data on Europeans and Africans in Rhodesia (Paul, Fletcher and Addison), the authors calculated that, for a given height, whites have a chest volume at full inspiration 13.2 per cent larger than blacks.
  • After increasing the black men's total lung capacity by 13.2 per cent, the white-black difference at age 40 and height 1.75 metres was only 0.01 of a litre.
  • With the 13.2 per cent factor applied to vital capacity, forced vital capacity, forced expiratory volume, forced expiratory flow rate and alveolar volumes, the remaining differences between the races were all small, the largest being 0.12 litres.
  • A smaller factor of 8.0 per cent was used for residual volume and functional residual capacity. According to Table IV, 8.0 per cent was also used for diffusing capacity, and minus 4.6 per cent for the residual volume/total lung capacity ratio and the diffusion constant.
  • No scaling factor was needed for the forced expiratory volume/vital capacity ratio, nor did one appear necessary for ventilation at standard levels of oxygen uptake.
  • After scaling the black men's values, the regression lines for the two races did not differ significantly in slope or position for any index.
  • Within this low-exposure group, there was no evidence that asbestos exposure had an important effect on any lung function index.
  • Correcting for smoking habits increased the black-white difference in total lung capacity from 0.01 litres to 0.04 litres.
  • The authors stated that this agreement supported their contention that the differences are proportional and related to chest size, rather than absolute differences.
• The authors' conclusion: The authors proposed that, until further evidence is available, a scaling factor based on the 13.2 per cent chest volume difference be used in calculating normal (expected) values for the major lung volumes, to account for ethnic differences between Africans and Europeans, with smaller factors for other indices. They suggested that normal values for blacks be reduced by these scaling factors.
• Limitations the authors state:
  • The study included only 244 men, and the scaling factors were calculated from limited anthropometric data.
  • The chest size data used to derive the 13.2 per cent factor came from Europeans and Africans in Rhodesia, not from the study population.
  • The 13.2 per cent chest volume difference applies strictly only to total lung capacity.
  • The statistical significance of the consistent pattern across lung volume indices could not be assessed, because the indices are interdependent.
  • Social or economic factors may have contributed to the differences observed, although the authors suggested these may be unimportant.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Total Lung Capacity (TLC), Diffusing Capacity (DLCO).

Related studies

• Early effects of asbestos exposure on lung function — G. Jodoin, G.W. Gibbs, et al. (1971)
• Lung function in insulation workers — J. Clausen, B. Netterstrøm, et al. (1993)
• Radiographic evidence of silicosis risk in the diatomaceous earth industry — J.M. Hughes, H. Weill, et al. (1998)
• Longitudinal decline in lung function in former asbestos exposed workers — E. Algranti, E.M. Mendonça, et al. (2013)
• Low exposure to asbestos. Gas exchange in ship pipe coverers and controls — R.L. Murphy, E.A. Gaensler, et al. (1972)
• Lung function in relation to radiographic changes in asbestos workers — S. Zedda, G. Aresini, et al. (1973)

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