ORIGINAL ARTICLE Sensitisation to cereal flour allergens is a major determinant of elevated exhaled nitric oxide in bakers Roslynn Baatjies, 1,2 Mohamed Fareed Jeebhay 2 1 Department of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town, South Africa 2 Centre for Occupational and Environmental Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa Correspondence to Professor Mohamed Fareed Jeebhay, Centre for Occupational and Environmental Health Research, School of Public Health and Family Medicine, University of Cape Town, Room 4.47, Fourth Level, Falmouth Building, Anzio Road, Observatory, Cape Town 7925, South Africa; Mohamed.Jeebhay@uct.ac.za Received 19 June 2012 Revised 12 December 2012 Accepted 27 December 2012 Published Online First 23 February 2013 To cite: Baatjies R, Jeebhay MF. Occup Environ Med 2013;70:310–316. ABSTRACT Objective Various studies of the usefulness of fractional exhaled nitric oxide (FeNO) in occupational settings remain inconclusive. The objective was to investigate the determinants of increased FeNO in bakery workers. Methods A cross-sectional study of 424 supermarket bakery workers used a questionnaire and serum specific IgE to wheat, rye and α-amylase. FeNO during the work shift were assessed using a hand-held portable sampling device (NIOX MINO). Results The median FeNO was 15 ppb, in atopics 21 ppb and current smokers 12 ppb. Increased FeNO was strongly associated with IgE to wheat independent of smoking and atopy status. In the multivariate model, IgE to wheat, current smoking, atopy and age were significantly associated with FeNO. Stratified analysis in a subgroup of atopic non-smokers demonstrated the strongest relationship between FeNO and various clinical endpoint such as wheat (OR=9.43) or rye (OR=11.76) sensitisation, work-related allergic rhinitis (OR=8.13) or asthma (OR=5.44), and probable baker’s asthma (OR=6.72). Conclusions Sensitisation to cereal flour allergens rather than asthma symptoms is a major determinant of elevated FeNO among bakers. This relationship is modified by atopy and current smoking status. BACKGROUND Various studies have demonstrated that the measure- ment of fractional exhaled nitric oxide (FeNO) is a useful non-invasive method for assessing eosino- philic inflammatory airway disease. 1 It is widely accepted that airway inflammation is associated with occupational asthma and rhinitis; however, the sen- sitivity and specificity of FeNO have not been suffi- ciently assessed in occupational settings. 2 While the predictive value of FeNO has been shown to be higher than spirometry or peak expiratory flow, 3 more studies are required to examine the effective- ness of FeNO in the early detection of respiratory disease due to workplace exposures. 4 There is currently conflicting evidence in the lit- erature concerning the role of FeNO in occupational asthma, and hence the need to clarify the interpret- ation of changes in FeNO following exposure to occupational agents. 4 FeNO has been demonstrated as a useful marker of exposure to gases and dusts in construction workers, 5 organic solvents in leather workers 6 and among aluminium potroom workers. 7 Exhaled nitric oxide is also reported to be elevated in workers exposed to organic dusts, 8 laboratory animal workers 9 and workers in swine confinement buildings. 10 The FeNO increase in the latter group was demonstrated 5 h after exposure. In another study, Baur and Barbinova 11 demonstrated a greater than 50% increase in asthmatic healthcare workers 22 h after specific inhalation challenge to latex. However, other studies on the impact of swine dust exposure showed no apparent effect on FeNO 12 while other studies showed no clear relationship between FeNO in subjects exposed to latex or iso- cyanates. 13 Recently, a strong association was reported in a subgroup of non-smoking, non-atopic farmers and agricultural processing workers exposed to endotoxin. 14 Studies have also demon- strated an increase in FeNO in relation to immuno- globulin (Ig)E sensitisation 15 16 and allergen exposure, 17 and a decrease in FeNO with allergen avoidance. 18 A recent review concluded that FeNO is a signal of allergen-triggered Th2-driven inflam- matory mechanisms within the bronchial mucosa and can be considered as a marker of allergen expos- ure in sensitised subjects. 19 Studies on the relationship between FeNO and asthma outcomes in bakers are scant. A study among bakers, farmers and healthcare workers showed a significant increase in FeNO only 24 h after a spe- cific inhalation test 20 while a 15-month follow-up study among apprentice bakers demonstrated that an increase in FeNO correlated with the occurrence of bronchial hyperresponsiveness. 21 Recently, a study by Pedrosa et al 22 demonstrated an increase in What this paper adds ▸ Studies of the relationship between FeNO and baker’s allergy and asthma are scant. ▸ This is the first detailed analysis of factors associated with changes in FeNO in supermarket bakery workers known to be at an increased risk of developing occupational allergy and asthma. ▸ This study demonstrated that sensitisation to cereal flour allergens, rather than asthma symptoms, is a major determinant of elevated FeNO among bakers. ▸ The strong relationship between FeNO and sensitisation to cereal flour allergens is modified by atopy and current smoking status. 310 Baatjies R, et al. Occup Environ Med 2013;70:310–316. doi:10.1136/oemed-2012-100990 Workplace group.bmj.com on April 9, 2013 - Published by oem.bmj.com Downloaded from