Exposure to mineral oil mist and respiratory symptoms in marine engineers

Our plain-English summary of Exposure to mineral oil mist and respiratory symptoms in marine engineers, by K. Svendsen, B. Hilt (American Journal of Industrial Medicine, 1997).

The study

• Authors: K. Svendsen, B. Hilt
• Journal: American Journal of Industrial Medicine
• Published: 1997;32(1):84-9
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of the study was to see if marine engineers have an increased prevalence of respiratory symptoms, and if so whether it can be related to occupational exposures. A self-administered questionnaire was sent to 700 male seamen from three Norwegian ferry companies. Of the 492 respondents, 169 were currently working as marine engineers and 295 had never worked as marine engineers. The outcomes of cough and wheezing, chronic bronchitis, severe dyspnea, any dyspnea, and mucous membrane irritation (MMI) were defined from the questionnaire. Age and smoking-adjusted prevalences of these respiratory conditions were compared between the groups. Logistic regression was used to further elucidate the explanatory variables. The exposure assessment indicated an exposure (TWAC) to oil mist for marine engineers in the range from 0.12 to 0.74 mg/m3 (mean 0.45 mg/m3) When comparing current marine engineers with those who had never worked as marine engineers, the prevalence ratios were 1.38 (95% CI 1.0-1.9) for MMI, 1.53 (95% CI 1.2-1.9) for any dyspnea, and 1.63 (95% CI 1.0-2.6) for severe dyspnea. The differences remained for some of the symptoms after controlling for self-reported former asbestos exposure in the regression analysis. The increased prevalence of respiratory symptoms found among marine engineers in this investigation may partly be explained be oil-mist exposure, or more probably by a combination of past asbestos exposure and past and present oil-mist exposure.

In plain English

This cross-sectional study asked whether Norwegian ferry marine engineers had more respiratory symptoms than other seamen. In 1993, 492 of 700 male seamen at three Norwegian ferry companies answered a questionnaire. The authors compared 169 current marine engineers with 295 seamen who had never been engineers, adjusting for age and smoking. The authors estimated engineers' oil mist exposure at 0.12 to 0.74 mg/m3 (mean 0.45). Engineers more often reported past asbestos exposure (40.8% vs 9.8% of controls). Engineers had higher rates of mucous membrane irritation (prevalence ratio 1.38, 95% CI 1.03 to 1.86), any shortness of breath (1.53, 1.21 to 1.93) and severe shortness of breath (1.63, 1.01 to 2.63). Cough or wheezing and chronic bronchitis did not differ significantly. In a combined analysis adjusted for age and smoking, being a current engineer was associated with any shortness of breath (odds ratio 2.0, 1.3 to 3.3), and self-reported asbestos exposure with severe shortness of breath (2.4, 1.1 to 5.1). The authors concluded this may partly reflect oil mist, or more probably past asbestos plus past and present oil mist.

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 using a self-administered questionnaire, with exposure measurements of oil mist in ferry engine rooms
• Who was studied: 700 male seamen from three local ferry companies in Norway (coastal ferries in the middle part of Norway) were mailed questionnaires between June and September 1993. 492 responded: 169 current marine engineers, 295 controls who had never worked as marine engineers, and 28 former marine engineers.
• Exposure: Mineral oil mist (a lubricating oil and a fuel oil) in ship engine rooms. Estimated time-weighted average concentration for marine engineers was 0.12 to 0.74 mg/m3 (mean 0.45 mg/m3). Past asbestos exposure (asbestos insulation was used in Norwegian ship engine rooms from the 1950s to the 1970s) was assessed only by self-report. Fiber type is not named.
• Main results:
  • Past asbestos exposure was reported by 40.8% of current marine engineers and 9.8% of controls.
  • Mucous membrane irritation, current marine engineers vs controls (age- and smoking-adjusted): 35.6% vs 26.0%, prevalence ratio 1.38 (95% CI 1.03 to 1.86).
  • Any dyspnea, current marine engineers vs controls: 46.5% vs 30.8%, prevalence ratio 1.53 (95% CI 1.21 to 1.93).
  • Severe dyspnea, current marine engineers vs controls: 17.0% vs 10.3%, prevalence ratio 1.63 (95% CI 1.01 to 2.63).
  • Cough or wheezing (prevalence ratio 1.00, 95% CI 0.70 to 1.44) and chronic bronchitis (1.24, 95% CI 0.74 to 2.07) did not differ significantly between current marine engineers and controls.
  • In the subgroup of present and former engineers with more than five years of service (n = 165) compared with controls, only cough and wheezing was statistically significant: prevalence ratio 1.47 (95% CI 1.15 to 1.86).
  • In logistic regression adjusted for age, smoking and the other variables, being a current marine engineer had an odds ratio of 2.0 (95% CI 1.3 to 3.3) for any dyspnea, 1.8 (1.0 to 3.5) for severe dyspnea and 1.2 (0.7 to 2.0) for mucous membrane irritation.
  • In the same analysis, self-reported asbestos exposure had an odds ratio of 2.4 (95% CI 1.1 to 5.1) for severe dyspnea, 1.5 (0.8 to 2.7) for any dyspnea and 1.1 (0.6 to 2.1) for mucous membrane irritation.
• The authors' conclusion: The authors concluded that the increased prevalence of respiratory symptoms among marine engineers may partly be explained by oil-mist exposure, or more probably by a combination of past asbestos exposure and past and present oil-mist exposure.
• Limitations the authors state:
  • Possible selection bias. Seamen must pass a medical checkup every second year, so engineers with serious lung disease may have left the job. The authors say this would lead to an underestimate of the true relative risk.
  • The response rate may have been somewhat higher for engineers than for controls.
  • The oil-mist exposure estimate was crude and only a group average. Individual exposure assessment was not possible.
  • Dyspnea is a nonspecific symptom that may reflect conditions other than lung disease.
  • Exposures were self-reported. The authors suggest engineers may be more aware of former asbestos exposure than of oil-mist exposure.

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Dyspnea, Asbestos Exposure.

Related studies

• Cancer incidence among marine engineers, a population-based study (Iceland) — V. Rafnsson, P. Sulem (2003)
• Mortality and cancer incidence among marine engineers and machinists in Iceland — V. Rafnsson, S.G. Jóhannesdóttir, et al. (1988)
• Relation of occupational exposure to respiratory symptoms and asthma in a general population sample: self-reported versus interview-based exposure data — P.S. Bakke, R. Hanoa, et al. (2001)
• Exposure to asbestos-containing vermiculite ore and respiratory symptoms among individuals who were children while the mine was active in Libby, Montana — L.C. Vinikoor, T.C. Larson, et al. (2010)
• Longitudinal pattern of reported respiratory symptoms and accelerated ventilatory loss in asbestos-exposed workers — C.A. Brodkin, S. Barnhart, et al. (1996)
• Longitudinal analysis of respiratory symptoms in population studies with a focus on dyspnea in marine transportation workers — V.H. Arrandale, M. Koehoorn, et al. (2009)

Browse more research in American Journal of Industrial Medicine, or return to medical research.