Serum protein concentrations and respiratory tract abnormalities following short-term exposure to amosite: a comparison between former asbestos workers and unexposed controls

Our plain-English summary of Serum protein concentrations and respiratory tract abnormalities following short-term exposure to amosite: a comparison between former asbestos workers and unexposed controls, by D.R. Nash, N.G. Fortson, J.W. McLarty, et al (Journal of Toxicology and Environmental Health, 1981).

The study

• Authors: D.R. Nash, N.G. Fortson, J.W. McLarty, G.A. Hurst
• Journal: Journal of Toxicology and Environmental Health
• Published: 1981;7(5):733-44
• Cited by: 4 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. 000761).

Abstract

A group of 176 former asbestos workers and 76 unexposed controls of similar age were evaluated and compared for concentrations of serum immunoglobulins, alpha 1-antitrypsin, carcinoembryonic antigen (CEA), pulmonary function, radiographic appearance of the lungs, rales, cellular atypia and ferruginous bodies in sputum, and smoking habits. Test subjects were evaluated as a single group and also according to years of exposure to asbestos. Both test and control populations were independently subjects to parametric and nonparametric correlation analyses. Partial correlations were also determined for both groups after controlling for age, race, sex and smoking habits. Analysis of variance was used to compare test and control groups. Smoking, particularly heavy smoking, was an important variable influencing abnormalities of the respiratory tract and CEA in former asbestos workers but not in controls. Except for immunoglobulin A (IgA), serum proteins, CEA, and alpha 1-antitrypsin were not significantly different between test and control subjects. Analysis of variance revealed significant increases between test and control groups for cellular atypia, X-ray abnormalities, rales, and pulmonary restriction. Partial correlation analysis of the asbestos-exposed group revealed important correlations between ferruginous bodies in sputum, rales, and radiographic appearance of the lungs.

In plain English

This study compared 176 former asbestos workers, randomly selected from a cohort of 890 in the Tyler Asbestos Workers Project in Texas, with 76 healthy local volunteers with no known asbestos exposure. The title describes the exposure as short-term exposure to amosite. The workers had been exposed on the job for periods of 1 day to 16 years, and 133 of them for less than 1 year. The researchers measured blood proteins, lung function, chest X-rays, rales (crackling lung sounds) and sputum findings. Of the blood proteins, only immunoglobulin A differed significantly between the groups. The authors called that increase slight and probably of little clinical significance. The former workers had significantly more abnormal cells in sputum, X-ray abnormalities, rales and restrictive lung function. Results for workers exposed under 1 year were similar, except that rales was not significant. Heavy smoking was linked to respiratory abnormalities in the former workers but not in the controls. The authors concluded that even exposure under 1 year can significantly influence these lung findings, including rales. However, their own comparison of that group with controls found no significant difference for rales.

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 comparison of former asbestos workers and unexposed controls, using correlation analyses and analysis of variance
• Who was studied: 176 former asbestos workers, all male, randomly selected from a cohort of 890 in the Tyler Asbestos Workers Project (Tyler, Texas). The controls were 76 age-related healthy volunteers from the Tyler community with no known asbestos exposure, 66% of them male.
• Exposure: Occupational asbestos exposure, described in the title as short-term exposure to amosite, lasting 1 day to 16 years. The workers were grouped by length of exposure: under 1 yr (n = 133), 1 to under 5 yr (n = 26) and 5 to under 16 yr (n = 17). Mean exposure time for all workers was 1.38 years, and mean time since last exposure was 12.6 years (Table 1).
• Main results:
  • Among the serum proteins, only immunoglobulin A differed significantly between the former workers and the controls. Mean IgA was 256 plus or minus 99 mg% in all former workers and 220 plus or minus 80 mg% in controls (Table 3). IgG, IgM, alpha-1-antitrypsin and CEA were not significantly different.
  • The authors described the IgA increase in the former workers as slight and probably of little, if any, clinical significance.
  • Compared with controls, all former asbestos workers had significantly more cellular atypia in sputum, X-ray abnormalities, rales and pulmonary restriction, after controlling for age, race and smoking.
  • Workers exposed for less than 1 year showed differences from controls similar to those of the whole worker group, except that rales was not significant.
  • Comparing workers exposed for less than 1 year with those exposed longer than 1 year, only X-ray appearance of the lungs and rales differed significantly.
  • In the former workers, the number of ferruginous bodies in sputum increased with exposure time. Severity of cellular atypia was strongly correlated with years of exposure.
  • In the former workers, X-ray abnormalities and rales were correlated with ferruginous bodies in sputum and with years of exposure. On partial correlation analysis, none of the serum proteins appeared affected by asbestos exposure.
  • In the former workers, heavy smoking was associated with lung abnormalities and CEA, while light smoking was not associated with lung abnormalities. No similar relations were seen in controls. Heavy smokers made up 68% of the former workers and 35% of controls (Table 1).
• The authors' conclusion: The authors concluded that asbestos exposure, even for relatively short periods (under 1 year), can significantly influence the development of restrictive lung disease, rales, cellular atypia in sputum and abnormal X-ray appearance of the lungs. Their own results, however, report that rales was not significantly different between the under-1-year group and controls. They also stated that restrictive lung disease did not increase with exposure time, and that the lack of real elevation in the serum proteins suggested minimal exposure has no long-term effect on them.
• Limitations the authors state:
  • Chest radiographs were classified only as normal or abnormal; the type of abnormality was not identified.
  • The groups differed in sex and smoking: all former workers were male while 66% of controls were male, and the exposed group had a much higher percentage of heavy smokers.

Topics

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

Medical terms in this study, explained in our Lexicon: Short-Term Exposure, Amosite, Carcinoembryonic Antigen (CEA), Ferruginous Bodies, Sputum, Habit.

Related studies

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