Pulmonary functional impairment from years of arc welding

Our plain-English summary of Pulmonary functional impairment from years of arc welding, by K.H. Kilburn, R.H. Warshaw (The American Journal of Medicine, 1989).

The study

• Authors: K.H. Kilburn, R.H. Warshaw
• Journal: The American Journal of Medicine
• Published: 1989;87(1):62-9
• Cited by: 23 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. 000105).

Abstract

Purpose: The adverse effects of arc welding on pulmonary function have been previously documented. However, in many of these studies, the effects of welding exposure and smoking were not separated. Also, some studies did not adjust for or ignored the effects of asbestosis on pulmonary function. We assessed the long-term effects of welding on pulmonary function in welders who had no evidence of asbestosis on chest radiographs, and adjusted each individual value for height, age, and years of cigarette smoking.

Patients And Methods: The study consisted of 226 male construction welders who had never worked in shipyards. Forced vital capacity (FVC) and flows were measured by spirometry, chest radiographs were obtained and examined for evidence of asbestosis using International Labor Office (ILO) criteria, and thoracic gas volume (TGV) was determined by planimetry. The subjects were also administered an occupational and respiratory questionnaire. Data on workers with asbestosis (ILO profusion 1/0 or greater) and pleural abnormalities were excluded. The mean age for the 226 subjects without asbestosis was 45 years, mean height was 175.7 cm, and mean duration of welding was 21.3 years. Pulmonary function measurements are presented as mean percentage of predicted (pop) and adjusted for height, age, and years of smoking.

Results: In 151 current cigarette smokers, mean midflows and terminal flows were decreased, FEF25-75 to 93.2 pop and FEF75-85 to 91.2 pop, but FVC, forced expiratory volume in one second (FEV1) and TGV were normal. The 43 nonsmokers also had reductions in flows but normal FVC and TGV. Flows in both groups were significantly (p less than 0.05) below those of the referent group. The regression coefficient was -0.0031 for years of welding and FVC pop, -0.0035 for FEV1 pop, and -0.0080 for midflow pop (FEF25-75) (all significant at p less than 0.05), but the coefficient for FEF75-85 pop was not significant. As calculated from regression equations, 40 years of welding would reduce FVC to 95.2 pop, FEV1 to 92.2 pop, midflow to 79.2 pop, and FEF75-85 to 81.7 pop.

Conclusion: Long-term exposure to welding gases and fumes reduced flows in small airways of welders without asbestosis.

In plain English

This cross-sectional study measured lung function in 226 male welders who had worked at construction sites and power plants but never in shipyards. They were volunteers from two midwestern locals of the boilermakers' union. Men with signs of asbestosis on chest X-rays were excluded. Each welder's exposure could not be measured, so years of welding stood in for exposure. Results were expressed as percentage of predicted, adjusted for height and age and, except for FVC, for years of smoking. In both the 151 current smokers and the 43 never-smokers, airflow was significantly below that of a referent group, while vital capacity was normal. Among all 226 welders, more years of welding went with significantly lower FVC, FEV1 and midflow. Calculated from these equations, 40 years of welding would lower FVC to 95.2, FEV1 to 92.2 and midflow to 79.2 percent of predicted. In never-smokers, significant effects were limited to small airways. The authors concluded that long-term exposure to welding gases and fumes reduced small-airway flows in welders without asbestosis. They noted the men had some asbestos exposure.

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 study
• Who was studied: 226 male welders studied in 1987, all volunteers from two midwestern locals of the International Brotherhood of Boilermakers. They had worked at construction sites and power plants, never in shipyards. Of 544 men examined, the study excluded 217 shipyard workers, 36 men who had welded less than five years and 65 men with signs of asbestosis. The 226 included 151 current smokers, 43 never-smokers and 32 ex-smokers.
• Exposure: Arc welding gases and fumes. Lifetime exposure could not be measured, so years of welding was used as a stand-in.
• Main results:
  • Lung-function values were expressed as percentage of predicted, adjusted for height, age and years of smoking. FVC, however, was not adjusted for duration of smoking; FEV1 and the flows were.
  • The 43 never-smokers had reduced flows but normal FVC and thoracic gas volume. In current smokers, mean FVC, FEV1 and thoracic gas volume were normal.
  • In both current smokers and never-smokers, flows were significantly (p less than 0.05) below those of the referent group.
  • For all 226 welders, the regression coefficients for years of welding were -0.0031 for FVC, -0.0035 for FEV1 and -0.0080 for FEF25-75, all significant. The coefficient for FEF75-85 (-0.0056) was not significant.
  • From the equations for all 226 welders, 40 years of welding was calculated to reduce FVC to 95.2, FEV1 to 92.2, FEF25-75 to 79.2 and FEF75-85 to 81.7 percent of predicted.
  • In the 43 never-smokers, significant effects of years of welding were limited to small airways. The coefficients were -0.0095 for FEF25-75 and -0.0171 for FEF75-85, both significant; those for FVC and FEV1 were not significant.
  • For never-smokers, 40 years of welding was calculated to reduce FEV1 to 93.3, midflow to 77.6 and terminal flow to 62.0 percent of predicted, with no decrease in FVC.
• The authors' conclusion: The authors concluded that long-term exposure to welding gases and fumes reduced flows in the small airways of welders without asbestosis. They also wrote that the decrease appeared smaller than that from cigarette smoke alone or from asbestosis.
• Limitations the authors state:
  • Individual lifetime exposure to welding gases and fumes could not be measured, so years of welding was used as a stand-in.
  • Years of smoking and years of welding both rise with age, which makes their effects hard to separate.
  • The men had some asbestos exposure, from insulating materials, gloves and blankets. The authors stated that excluding men with asbestosis does not guarantee the absence of subtle asbestos effects.
  • Comparison with the Michigan reference population carried possible problems: differences in methods and populations, and the Michigan men included some welders and shipyard workers. The authors argued these differences were small.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Welders.

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Spirometry, FEV1.

Related studies

• Pulmonary functional impairment and symptoms in women in the Los Angeles Harbor area — K.H. Kilburn, R. Warshaw, et al. (1985)
• Asbestosis, pulmonary symptoms and functional impairment in shipyard workers — K.H. Kilburn, R. Warshaw, et al. (1985)
• Total lung capacity. An insensitive measure of impairment in patients with asbestosis and chronic obstructive pulmonary disease? — S. Barnhart, L.D. Hudson, et al. (1988)
• Exercise performance and functional impairment in asbestos-exposed workers — J. Pearle (1981)
• Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis? — B. Clin, C. Paris, et al. (2011)
• Exposure to tremolite asbestos and respiratory health in Swedish dolomite workers — A.I. Seldén, N.P. Berg, et al. (2001)

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