Field Studies of Occupational Exposures

Our plain-English summary of Field Studies of Occupational Exposures, by J.M. Peters, R.L.H. Murphey, W.A. Burgess, et al (1971).

The study

• Authors: J.M. Peters, R.L.H. Murphey, W.A. Burgess, B.G. Ferris JR
• Published: September 1st 1971
• Type of article: Report
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This report described several field studies of workers' lungs. It covered about 1,800 Boston firefighters, for whom no results were yet available, about 1,000 granite workers, and a planned study of workers exposed to toluene diisocyanate. The part relevant to asbestos was a health survey at a Naval shipyard. It compared 61 welders with 63 pipefitters and also included pipecoverers, whom the authors described as exposed to asbestos. The asbestos fiber type was not named. Workers had questionnaires, chest exams, chest X-rays and lung function tests. No welder showed siderosis on X-ray. Lung function did not differ significantly between welders and pipefitters; the only significant difference was that pipefitters were heavier. The authors then concluded they had probably chosen the wrong comparison group, because pipefitters were themselves intermittently exposed to asbestos and welding fumes. Grouped by length of exposure, total lung capacity dropped for pipecoverers and residual volume rose for welders. The authors called this not dramatic but evidence for the proposed split between restrictive and obstructive disease. Much of the scanned text was missing or damaged.

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: Progress report on several occupational field studies. The welders study was a cross-sectional health survey in a Naval shipyard comparing welders, pipecoverers and pipefitters.
• Who was studied: Boston Naval Shipyard workers: 61 welders and 63 pipefitters (the control group) in the lung function comparison. Pipecoverers were also studied; their number is not stated directly, but the four smoking categories for pipecoverers in Table II add up to 61. Other sections covered about 1,800 Boston firefighters and about 1,000 granite workers.
• Exposure: Pipecoverers were exposed to asbestos (fiber type not stated). Welders were exposed to welding fumes, including metal fumes, ozone and oxides of nitrogen. Pipefitters turned out to be intermittently exposed to both asbestos and welding fumes.
• Main results:
  • Chronic cough was reported by ten percent of welders and nine percent of pipefitters.
  • None of the welders had siderosis on chest X-ray.
  • Lung function in welders compared with pipefitters did not differ significantly on any measure. The only significant difference was weight: pipefitters averaged 85 kg and welders 75 kg (p less than 0.05).
  • Among welders, smokers and non-smokers differed significantly only in peak flow: 516 l/min in smokers versus 467 l/min in non-smokers (p less than 0.05).
  • Pipefitters, the intended controls, were found to be intermittently exposed to asbestos and welding fumes.
  • When workers were grouped by duration of exposure, total lung capacity dropped for pipecoverers and residual volume rose for welders. The authors described the change as not dramatic.
  • In a comparison with pipefitters in new ship construction, described as not exposed to asbestos and welding fumes, the authors reported that all differences in FVC, FEV1 and PEFR were statistically significant. The surrounding text is incomplete.
  • Compared with predicted values derived from Boston policemen, observed FEV1 was 3.02 l against a predicted 3.83 l (79%) in welders, and 2.90 l against 3.80 l (76%) in pipefitters.
  • In the granite worker study there appeared to be an excess prevalence of chronic non-specific pulmonary disease, especially in smokers and ex-smokers.
  • No results were yet available for the firefighter study.
• The authors' conclusion: The authors concluded that the falling total lung capacity in pipecoverers and rising residual volume in welders was evidence for their proposed split. In that split, fibrogenic dusts such as asbestos produce restrictive lung disease and pulmonary irritants produce obstructive disease.
• Limitations the authors state:
  • The authors stated they had probably made an error in choosing pipefitters as the control group, since pipefitters were also exposed to asbestos and welding fumes.
  • The authors noted that with 15 significance tests, one statistically significant difference would be expected by chance alone.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Pipefitter, Chest X-Ray, Total Lung Capacity (TLC).

Browse return to medical research.