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Metal working fluid-associated hypersensitivity pneumonitis: an outbreak investigation and case-control study
1Centers for Disease Control and Prevention, Division of Field Epidemiology, Atlanta, GA, USA. johnfox@facstaff.wwr.edu
American Journal of Industrial Medicine
|January 13, 1999
Summary
Hypersensitivity pneumonitis (HP) in manufacturing employees was linked to biocontaminants in metal working fluids (MWF). Exposure to used MWF, not MWF itself, correlated with HP, suggesting bacterial or fungal antigens are the likely cause.
Area of Science:
- Occupational Health
- Immunology
- Environmental Medicine
Background:
- Hypersensitivity pneumonitis (HP) is an immune-mediated lung disease linked to occupational antigen exposure.
- Manufacturing environments often involve exposure to metal working fluids (MWF), which can harbor microbial contaminants.
- Previous studies have not definitively identified the causative agents of HP in MWF-exposed workers.
Purpose of the Study:
- To investigate the association between metal working fluid (MWF) exposure and hypersensitivity pneumonitis (HP) in engine manufacturing plant employees.
- To identify specific antigens responsible for HP development in this occupational setting.
- To differentiate between MWF components and potential biocontaminants as causative agents.
Main Methods:
- A case-control study was conducted involving 34 clinically diagnosed HP employees and controls from an engine manufacturing plant.
- Exposure variables, including duration and intensity of MWF exposure, were assessed.
- Precipitin tests were performed against unused and used MWF samples and biocides for both cases and controls.
Main Results:
- No statistically significant association was found between general MWF exposure (duration, intensity) and HP risk.
- HP cases showed a higher prevalence of positive precipitin reactions to used oil-soluble and synthetic MWFs compared to controls.
- Reactivity was observed with used MWF but not with unused MWF or biocides, indicating a contaminant.
Conclusions:
- The causative antigen for HP in this setting is likely a biocontaminant, such as bacteria or fungi, present in used metal working fluids.
- This finding highlights the importance of controlling microbial contamination in industrial fluids to prevent occupational lung diseases.
- Further research should focus on identifying specific microbial agents within MWFs responsible for hypersensitivity pneumonitis.