Objectives Four machine manufacturing facility workers had a novel occupational lung disease of uncertain aetiology characterised by lymphocytic bronchiolitis, alveolar ductitis and emphysema (BADE). We aimed to evaluate current workers’ respiratory health in relation to job category and relative exposure to endotoxin, which is aerosolised from in-use metalworking fluid.
Methods We offered a questionnaire and spirometry at baseline and 3.5 year follow-up. Endotoxin exposures were quantified for 16 production and non-production job groups. Forced expiratory volume in one second (FEV1) decline ≥10% was considered excessive. We examined SMRs compared with US adults, adjusted prevalence ratios (aPRs) for health outcomes by endotoxin exposure tertiles and predictors of excessive FEV1 decline.
Results Among 388 (89%) baseline participants, SMRs were elevated for wheeze (2.5 (95% CI 2.1 to 3.0)), but not obstruction (0.5 (95% CI 0.3 to 1.1)). Mean endotoxin exposures (range: 0.09–28.4 EU/m3) were highest for machine shop jobs. Higher exposure was associated with exertional dyspnea (aPR=2.8 (95% CI 1.4 to 5.7)), but not lung function. Of 250 (64%) follow-up participants, 11 (4%) had excessive FEV1 decline (range: 403–2074 mL); 10 worked in production. Wheeze (aPR=3.6 (95% CI 1.1 to 12.1)) and medium (1.3–7.5 EU/m3) endotoxin exposure (aPR=10.5 (95% CI 1.3 to 83.1)) at baseline were associated with excessive decline. One production worker with excessive decline had BADE on subsequent lung biopsy.
Conclusions Lung function loss and BADE were associated with production work. Relationships with relative endotoxin exposure indicate work-related adverse respiratory health outcomes beyond the sentinel disease cluster, including an incident BADE case. Until causative factors and effective preventive strategies for BADE are determined, exposure minimisation and medical surveillance of affected workforces are recommended.
- lung function
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Contributors KJC, MLS and RJN contributed to conception and design, data acquisition, data analysis, data interpretation and drafting the manuscript. LNS, KK and MJB contributed to conception and design, and data interpretation. RJB contributed to conception and design, and data acquisition. J-HP contributed to data acquisition, data analysis and data interpretation. NTE contributed to data analysis. JMC-G and MAV contributed to conception and design, data analysis and data interpretation. DNW contributed to data analysis and data interpretation. KJC and RJN are also the guarantors, had full access to all data in the study and had final responsibility for the decision to submit for publication. All authors provided critical review of the manuscript and approved of the submission.
Funding This study was supported by intramural funding from the National Institute for Occupational Safety and Health and extramural funding from the National Institutes of Health to MJB (R01DK090989 and R01GM63270) and LNS (K23- AI102970). MJB also received support from the C & D Fund.
Disclaimer The funders did not have a role in the design or conduct of the study. The National Institute for Occupational Safety and Health reviewed the manuscript for technical accuracy prior to its submission. The other funders did not have a role in the study’s reporting. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available. Data were collected by the US government and are protected under the Federal Privacy Act.