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Exhaled Breath Condensate pH and FeNO as Biomarkers of Acute and Chronic Exposure to Hazards at Swine Farms

Ljubičić, Anita MD, PhD; Varnai, Veda Marija MD, PhD; Vučemilo, Marija PhD; Matković, Kristina SciD; Milić, Dinka PhD; Macan, Jelena MD, PhD

Journal of Occupational and Environmental Medicine: September 2014 - Volume 56 - Issue 9 - p 946–952
doi: 10.1097/JOM.0000000000000151
Original Articles

Objective: The noninvasive biomarkers of respiratory impairment were assessed in 15 swine confinement (SC) workers and 9 respiratory healthy, nonsmoking volunteers (HV).

Methods: Spirometry, fraction of exhaled nitric oxide (FeNO), and exhaled breath condensate (EBC) pH were assessed in SC workers after one working shift and one working week and in HV after 5-hour exposure in SC.

Results: Half of the respiratory symptoms (in 8 of 15 SC workers) were work-related. Basal FeNO values were 7.5 ppb higher in the SC workers compared with HV. In the SC workers, EBC pH increased for 0.17 at the end of a working week (P < 0.001). In HV, 5-hour exposure in SC induced 8% drop in forced expiratory flow at 25% of the pulmonary volume (FEF25) (P = 0.008), EBC pH drop for 0.10 units (P = 0.003), and FeNO drop by 1.8 ppb (P = 0.047).

Conclusions: EBC pH was suggested as a biomarker of acute airway acidification in HV, whereas the SC workers showed signs of the “healthy worker effect.”

From the Institute for Medical Research and Occupational Health (Drs Ljubičić, Varnai, and Macan) and The Faculty of Veterinary Medicine, University of Zagreb (Prof Vučemilo and Dr Matković); and Swine Farm “Dubravica” (Dr Milić), Croatia.

Address correspondence to: Anita Ljubičić, MD, PhD, Institute for Medical Research and Occupational Health, Occupational Health and Environmental Medicine Unit, Ksaverska cesta 2, HR-10001 Zagreb, Croatia (

This study was done within the scientific projects No. 022-0222411-2410 and No. 053-0531854-1867, financially supported by the Ministry of Science, Education and Sports of the Republic of Croatia. The projects were approved by authorized Ethical Committees.

We declare that we do not have any conflicts of interest to disclose.

Copyright © 2014 by the American College of Occupational and Environmental Medicine