An 11-year longitudinal study of the occupational dust exposure and lung function of polyvinyl chloride, cement and asbestos cement factory workers

Our plain-English summary of An 11-year longitudinal study of the occupational dust exposure and lung function of polyvinyl chloride, cement and asbestos cement factory workers, by A. Siracusa, A. Forcina, R. Volpi, et al (Scandinavian Journal of Work, Environment & Health, 1988).

The study

• Authors: A. Siracusa, A. Forcina, R. Volpi, E. Mollichella, C. Cicioni, T. Fiordi
• Journal: Scandinavian Journal of Work, Environment & Health
• Published: 1988;14(3):181-8
• Cited by: 21 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. 000937).

Abstract

Standardized questionnaires and lung function tests were administered in 1973, 1980, and 1984 to 126 workers occupationally exposed to polyvinyl chloride (PVC) dust, to cement dust, or to asbestos cement dust until 1974-1978 and to PVC thereafter. The workers in the last group were assigned to two asbestos exposure categories (heavy and slight). The decline in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1.0) was analyzed with regard to the length of time since the data of first employment. After adjustment for age, height, and smoking status at the date of first employment, the decline in FVC and FEV1.0 among the nonsmokers-light smokers was slightly accelerated with length of employment in the PVC and slight asbestos exposure groups and markedly accelerated with time since first employment in the heavy asbestos exposure group. The heavy smokers in all the exposure groups had FVC and FEV1.0 predicted values that were lower than those of the nonsmokers-light smokers; these differences remained constant with length of employment. Cessation of asbestos exposure for about 10 years did not seem to change lung function decline.

In plain English

This 11-year Italian study followed 126 workers exposed to polyvinyl chloride (PVC), cement, or asbestos cement dust. Asbestos cement production was cut back from 1974 to 1978, its workers moving to PVC. Asbestos workers were classed as heavily exposed (13, in mixing and grinding areas) or slightly exposed (48). Lung capacity tests (FVC and FEV1) were done in 1973, 1980 and 1984. Decline since first employment was linear in cement workers, slightly accelerated in the PVC and slight asbestos groups, and very accelerated in the heavy asbestos group. At 20 years, the authors estimated the heavy asbestos group's extra loss at about 450 to 500 ml beyond the PVC and slight asbestos groups and 600 to 700 ml beyond cement workers. Workers with 1.25 or more pack-years of smoking at first employment ("heavy smokers") had predicted FVC and FEV1 values 196 and 214 ml lower, respectively, than nonsmokers-light smokers, a gap that stayed constant. Stopping asbestos exposure did not seem to affect the decline. The authors said cement results may be biased by heavy loss to follow-up.

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: Longitudinal (follow-up) study with lung function tests and questionnaires in three surveys (1973, 1980, 1984)
• Who was studied: 126 workers from two establishments in Italy: one that made PVC and asbestos cement from 1963, and one that made cement from 1957. Asbestos workers were split into a heavy exposure group (13 subjects) and a slight exposure group (48 subjects).
• Exposure: Occupational dust from PVC, cement, or asbestos cement production. The fiber type is not named. The mixing and grinding areas of asbestos cement production counted as heavy asbestos exposure and all other asbestos cement areas as slight exposure. Asbestos cement production was reduced from 1974 to 1978, workers were transferred to PVC, and asbestos cement manufacture stopped in December 1978. Total dust measurements suggested heavy exposure to asbestos and cement.
• Main results:
  • Loss of FVC and FEV1 with length of employment was linear for cement workers, slightly accelerated for the PVC and slight asbestos exposure groups, and very accelerated for workers with heavy asbestos exposure.
  • Twenty years after first exposure, the excess decline of FVC and FEV1 in the heavy asbestos exposure group was estimated at about 450 to 500 ml more than in the PVC and slight asbestos exposure groups.
  • The same 20-year estimate put the heavy asbestos exposure group's excess decline at 600 to 700 ml more than that of the cement workers.
  • After adjustment for height, age and smoking at first employment, heavy smokers in all four exposure groups had predicted FVC and FEV1 values 196 and 214 ml lower, respectively, than nonsmokers-light smokers. The article defines heavy smokers as 1.25 pack-years or more at the date of first employment. This difference remained constant over time. The authors described the combined effect of asbestos and smoking in this survey as additive.
  • Stopping asbestos exposure did not seem to affect lung function decline. By the 1984 survey, exposure had stopped on average 5.6 to 11.1 years earlier, depending on the subgroup.
• The authors' conclusion: The authors concluded that heavy exposure to asbestos is associated with an excessive loss of ventilatory capacity. In their view, this loss increases with time after first exposure and is unaffected even if exposure has been discontinued for up to 10 years, and cigarette smoking's contribution to lung function decline seems of minor importance compared with that of asbestos.
• Limitations the authors state:
  • The results for cement workers may be biased because only one attempt was made to find them for the 1980 and 1984 surveys.
  • Loss to follow-up in the cement group was 47.1% from 1973 to 1984. This may have led to underestimating lung function decline, because the cement workers who were lost had lower test values in 1973.
  • For nonsmokers-light smokers in the first 12 years of employment, the model fit the observed values poorly in the cement and heavy asbestos exposure groups. The authors attributed this probably to the small number of observed values.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Asbestos Exposure, FEV1.

Related studies

• Lung function among asbestos cement factory workers: cross-sectional and longitudinal study — A. Siracusa, C. Cicioni, et al. (1984)
• Biological reactivity of PVC dust — R.J. Richards, R. Desai, et al. (1975)
• Decreased lung function in long-term asbestos cement workers: a cross-sectional study — C.G. Ohlson, T. Rydman, et al. (1984)
• Past occupational dust exposure, depressive symptoms and anxiety in retired Chinese factory workers: the Guangzhou Biobank Cohort Study — Q.H. Lin, C.Q. Jiang, et al. (2014)
• Lung function predicts survival in a cohort of asbestos cement workers — H. Moshammer, M. Neuberger (2009)
• Increased mortality in COPD among construction workers exposed to inorganic dust — I.A. Bergdahl, K. Torén, et al. (2004)

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