Pulmonary function of nonsmoking female asbestos workers without radiographic signs of asbestosis

Our plain-English summary of Pulmonary function of nonsmoking female asbestos workers without radiographic signs of asbestosis, by X.R. Wang, E. Yano, K. Nonaka, et al (Archives of Environmental Health, 1998).

The study

• Authors: X.R. Wang, E. Yano, K. Nonaka, M. Wang, Z. Wang
• Journal: Archives of Environmental Health
• Published: 1998;53(4):292-8
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Researchers disagree about whether exposure to asbestos causes significant respiratory impairments and airway obstruction in the absence of radiographic asbestosis and smoking. To obtain confirmatory information, the authors examined pulmonary function of 208 nonsmoking female asbestos workers who did not have asbestosis and 136 controls. The authors observed an overall lower single-breath carbon monoxide diffusing capacity in the asbestos workers than in controls. In addition, significant decreases in percentage vital capacity, percentage forced vital capacity, and percentage mean forced expiratory flow during the middle half of the forced vital capacity were evident in the older workers. Logistic regression analysis revealed that asbestos exposure was associated with abnormal single-breath carbon monoxide diffusing capacity, vital capacity, and mean forced expiratory flow during the middle half of the forced vital capacity among the older workers. The age-related decline in vital capacity, forced vital capacity, and mean forced expiratory flow during the middle half of the forced vital capacity was significantly greater in the asbestos workers than the controls. The findings imply that asbestos-exposure per se contributes predominantly to restricted lung volume and reduced single-breath carbon monoxide diffusing capacity. Asbestos may also cause slight airway obstruction, especially in workers who are heavily exposed.

In plain English

This study compared lung function in 208 nonsmoking women who had worked at least 2 years at an asbestos products factory in China with 136 nonsmoking women from a nearby electronics plant who had no dust exposure. The survey was done in 1991. The factory had used mainly chrysotile to make asbestos textile and asbestos shingle. The workers averaged about 11 years of exposure, and none showed asbestosis on chest X-ray. Overall, the asbestos workers had a significantly lower carbon monoxide diffusing capacity, a measure of how well the lungs pass gas into the blood. Their other measures were lower, but not to a statistically significant degree. In workers aged 35 or older, vital capacity, forced vital capacity and mid-expiratory airflow were also significantly lower. In this older group, abnormal diffusing capacity, vital capacity and mid-expiratory flow were associated with asbestos exposure. No such associations were found under age 35. Age-related declines in vital capacity, forced vital capacity and mid-expiratory flow were steeper in the asbestos workers. The authors concluded that asbestos exposure was related to lung function loss without X-ray asbestosis or smoking, and may cause slight airway obstruction in heavily exposed workers. They noted that they lacked detailed individual exposure 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: Comparison of lung function between asbestos-exposed workers and unexposed control workers at a single survey (1991), with logistic and multiple regression analyses
• Who was studied: 208 active or retired nonsmoking female workers without radiographic asbestosis at an asbestos products factory in China, and 136 nonsmoking female controls from a nearby plant making electronic instruments and meters; the survey was conducted in 1991. The workers were split into 131 under age 35 and 77 aged 35 or over. The controls were split into 51 under 35 and 85 aged 35 or over.
• Exposure: Mainly chrysotile, used to make asbestos textile and asbestos shingle since the 1950s. Total dust concentrations sometimes exceeded 100 mg/m3 before 1970 and typically exceeded 5 mg/m3 up to 1991. Exposure was assessed as total years of dust exposure, with a mean of 10.9 years (range 2 to 26).
• Main results:
  • Overall, the asbestos workers had a significantly lower percentage-of-predicted carbon monoxide diffusing capacity (%DLco) than the controls (p less than .001). Their other ventilatory parameters were lower, but the differences were not statistically significant.
  • Among those under 35, the asbestos workers had significantly lower %DLco than the younger controls, but the other ventilatory parameters did not differ significantly.
  • Among those aged 35 or older, %DLco, %VC, %FVC and %FEF25-75 were significantly lower in the asbestos workers than in the controls.
  • In logistic regression of the younger group (n = 182), no abnormal parameter was significantly associated with asbestos exposure.
  • In logistic regression of the older group (n = 162), abnormal DLco, VC and FEF25-75 were significantly associated with asbestos exposure after adjustment for age and height (p less than .01). The FEF25-75 association remained significant after further adjustment for FVC. Abnormal FVC, FEV1.0 and FEV1.0/FVC were not significantly associated.
  • Overall, the age-related slopes of decline in VC, FVC and FEF25-75 were significantly greater in the asbestos workers than in the controls.
  • Differences in the slope of decline between older asbestos workers and older controls for FEV1.0 and FEF25-75 approached significance (p = .05 and 0.06, respectively).
• The authors' conclusion: The authors concluded that asbestos exposure is related to significant loss of lung function in the absence of radiographic asbestosis and smoking. They found this mainly as reduced lung volume and reduced diffusion, and concluded that asbestos may cause slight airway obstruction, especially in heavily exposed workers.
• Limitations the authors state:
  • Possible selection bias from the healthy-worker effect. Retired workers made up only about 10% of subjects, and the authors state this would have led to underestimating the relationship.
  • Slight pleural disease may have existed in some selected asbestos workers, because slight pleural disease alone was not regarded as evidence of asbestosis.
  • There were no detailed individual asbestos exposure data, which prevented the authors from determining an exposure-response relationship.

Topics

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

Medical terms in this study, explained in our Lexicon: Diffusing Capacity (DLCO), Asbestos Exposure.

Related studies

• The relative importance of clinical, radiological and pulmonary function variables in evaluating asbestosis and chronic obstructive airway disease in asbestos workers — G.M. Regan, B. Tagg, et al. (1971)
• Changes in pulmonary function tests predict radiological response to chemotherapy in malignant pleural mesothelioma — G. Marulli, F. Di Chiara, et al. (2013)
• Signs of asbestosis and impaired pulmonary function in women who worked in shipyards — K.H. Kilburn, R. Warshaw, et al. (1985)
• Diffusing capacity and forced vital capacity in 5,003 asbestos-exposed workers: relationships to interstitial fibrosis (ILO profusion score) and pleural thickening — A. Miller, R. Warshaw, et al. (2013)
• Pulmonary function in long-term asbestos workers in China — X.R. Wang, E. Yano, et al. (2001)
• Lung function and radiographic change in chrysotile workers in Swaziland — M. McDermott, M.M. Bevan, et al. (1982)

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