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International Archives of Occupational and Environmental Health

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Open Access 01-01-2012 | Original Article

The association between symptoms and exposure is stronger in dropouts than in non-dropouts among employees in Norwegian smelters: a five-year follow-up study

Authors: Vidar Søyseth, Helle Laier Johnsen, Merete Drevvatne Bugge, Johny Kongerud

Published in: International Archives of Occupational and Environmental Health | Issue 1/2012

Abstract

Purpose

We have investigated the association between respiratory symptoms and dust exposure among employees in 18 Norwegian smelters using a longitudinal design.

Methods

All employees (N = 3,084) were examined annually for 5 years (12,996 health examinations). At each examination, the subjects reported if they had respiratory symptoms, coded as 1 (yes) or 0 (no), on a respiratory questionnaire. Symptom score was constructed as the sum of symptoms (0–5). Full-time workers in the production line were classified as line operators; subjects never exposed in the production line were regarded as non-exposed. The remaining individuals were classified as non-line operators. A job-exposure matrix regarding dust exposure was also available. Analyses of repeated measurements were performed using generalised linear mixed model with log-link (Poisson regression). Adjustments were made for overdispersion.

Results

The mean age at inclusion was 39.0 years, and 89% were men. The median dust exposure in tertiles 1–3 was 0.19, 1.76 and 3.47 mg/m³. The longitudinal analyses showed that the association between symptoms-score ratio (SSR) and job category was significantly stronger in dropouts compared with non-dropouts (p = 0.01). Among the dropouts, SSR was 1.61 (95% confidence interval: 1.27–2.05) and 1.39 (1.09–1.77) in line operators and non-line operators compared with non-exposed employees, respectively. The corresponding SSR for subjects who completed the study was 1.13 (1.01–1.27) and 1.12 (1.00–1.26), respectively. Similarly, among the dropouts, the SSR between the second and the first tertile was 1.28 (1.05–1.55) and 1.37 (1.13–1.66) between the third tertile and the first tertile.

Conclusions

Line operators had more respiratory symptoms than non-exposed employees. This effect was significantly stronger in dropouts than in those who continued their jobs, indicating that there is a selection of subjects without respiratory symptoms in this industry.

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Title: The association between symptoms and exposure is stronger in dropouts than in non-dropouts among employees in Norwegian smelters: a five-year follow-up study
Authors: Vidar Søyseth
Helle Laier Johnsen
Merete Drevvatne Bugge
Johny Kongerud
Publication date: 01-01-2012
Publisher: Springer-Verlag
Published in: International Archives of Occupational and Environmental Health / Issue 1/2012
Print ISSN: 0340-0131
Electronic ISSN: 1432-1246
DOI: https://doi.org/10.1007/s00420-011-0631-x

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The association between symptoms and exposure is stronger in dropouts than in non-dropouts among employees in Norwegian smelters: a five-year follow-up study

Abstract

Purpose

Methods

Results

Conclusions

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Abstract

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