Simon Skov

Sensitisation to common allergens and respiratory symptoms in endotoxin exposed workers: a pooled analysis

Objective To test the hypotheses that current endotoxin exposure is inversely associated with allergic sensitisation and positively associated with non-allergic respiratory diseases in four occupationally exposed populations using a standardised analytical approach. Methods Data were pooled from four epidemiological studies including 3883 Dutch and Danish employees in veterinary medicine, agriculture and power plants using biofuel. Endotoxin exposure was estimated by quantitative job-exposure matrices specific for the study populations. Dose–response relationships between exposure, IgE-mediated sensitisation to common allergens and self-reported health symptoms were assessed using logistic regression and generalised additive modelling. Adjustments were made for study, age, sex, atopic predisposition, smoking habit and farm childhood. Heterogeneity was assessed by analysis stratified by study. Results Current endotoxin exposure was dose-dependently associated with a reduced prevalence of allergic sensitisation (ORs of 0.92, 0.81 and 0.66 for low mediate, high mediate and high exposure) and hay fever (ORs of 1.16, 0.81 and 0.58). Endotoxin exposure was a risk factor for organic dust toxic syndrome, and levels above 100 EU/m3 significantly increased the risk of chronic bronchitis (p<0.0001). Stratification by farm childhood showed no effect modification except for allergic sensitisation. Only among workers without a farm childhood, endotoxin exposure was inversely associated with allergic sensitisation. Heterogeneity was primarily present for biofuel workers. Conclusions Occupational endotoxin exposure has a protective effect on allergic sensitisation and hay fever but increases the risk for organic dust toxic syndrome and chronic bronchitis. Endotoxins protective effects are most clearly observed among agricultural workers.

Does the use of biofuels affect respiratory health among male Danish energy plant workers

Objectives To study asthma, respiratory symptoms and lung function among energy plant employees working with woodchip, straw or conventional fuel. Methods Respiratory symptoms in 138 woodchip workers, 94 straw workers and 107 control workers from 85 heating- or combined heating and power plants were collected by questionnaire. Spirometry, metacholine provocation tests and skin prick tests were performed on 310 workers. The work area concentrations of ‘total dust’ (n=181), airborne endotoxin (n=179), cultivable Aspergillus fumigatus (n=373) and cultivable fungi (n=406) were measured at each plant. Personal exposure was calculated from the time spent on different tasks and average work area exposures. Results Median (range) average personal exposures in biofuel plants were 0.05 (0 to 0.33) mg/m3 for ‘total’ dust and 3.5 (0 to 294) endotoxin units/m3 for endotoxin. Fungi were cultivated from filters (straw plants) or slit samplers (woodchip plants); the average personal exposures were 5.230×103 (118 to 1.85×104) and 1.03×103 (364 to 5.01×103) colony-forming units/m3 respectively. Exposure levels were increased in biofuel plants compared with conventional plants. The prevalence of respiratory symptoms among conventional plant and biofuel plant workers was comparable, except for asthma symptoms among non-smokers, which were higher among straw workers compared with controls (9.4 vs 0%, p<0.05). A trend for increasing respiratory symptoms with increasing endotoxin exposure was seen with ORs between 3.1 (1.1 to 8.8) (work-related nose symptoms) and 8.1 (1.5 to 44.4) (asthma symptoms) for the most exposed group. Associations between fungal exposure and respiratory symptoms were less clear but suggested cultivable fungi to be associated with asthma symptoms and work-related respiratory symptoms. No associations were seen between lung function and the level of endotoxin or fungal exposure. Conclusions Working with biofuel at an energy plant does not generally enhance the prevalence of respiratory symptoms. However, the exposure level to micro-organisms has an impact on the occurrence of respiratory symptoms among biofuel workers.

Change in airway inflammatory markers in Danish energy plant workers during a working week

INTRODUCTION It is well known that exposure to organic dust can cause adverse respiratory effect. The pathogen-associated molecular patterns (PAMPS) in the organic dust, such as endotoxin from Gram-negative bacteria cell wall and fungal components, can trigger the release of cytokine (e.g. Interleukin 1β (IL-1β)) and chemokine (e.g. Interleukin 8 (IL-8)) from the immune cells in the airways. OBJECTIVE To evaluate the potential inflammatory effects of organic dust exposure in energy plants in Denmark. MATERIALS AND METHODS Nasal lavage (NAL) and exhaled breath condensate (EBC) were sampled at Monday morning (referred to as before work) and again at Thursday afternoon (referred to as after work). NAL IL-8, EBC pH, IL-1β concentration were measured. Personal exposure to endotoxin and dust was calculated from time spent on different tasks and measured average work area exposures. RESULTS Before work, workers from biofuel plants had a higher IL-1β and IL-8 concentration compared to conventional fuel plants (control group). Specifically, the IL-1β level of moderately and most exposed group, and IL-8 level of the least exposed group were higher compared to the control group. The changes of IL-1β, pH and IL-8 during a work week were not significant. Workers with rhinitis had a lower percentage change of IL-8 compared to healthy workers. CONCLUSIONS An increased level of EBC IL-1β in biofuel energy plant workers before work indicated a chronic or sub-chronic inflammation. The percentage change of IL-8 was lower in workers with rhinitis compared to healthy workers.

0191 Are indoor concentrations of airborne mould spores in non-industrial environments sufficiently high to cause hypersensitivity pneumonitis?

Objectives Antigen exposure is the only diagnostic criteria specific for hypersensitivity pneumonitis (HP) compared with other interstitial lung diseases. Indoor mould exposure in non-industrial environments has been claimed to cause HP, but little is known about exposure levels. Our objective was to compare indoor concentrations of airborne mould spores for patients diagnosed with indoor HP with background levels and levels measured for patients diagnosed with farmers’ lung and suberosis. Method We included 8 patients diagnosed with HP based on characteristic clinical findings, signs of indoor mould growth at home or at their non-industrial work place, and increased levels of precipitating antibodies for moulds. We collected 110 air samples from all affected rooms, adjacent rooms, and outdoor. Results The average total spore concentrations varied between 22 000 and 36 000 spores per m3, and the average viable concentrations between 35 CFU/m3 and 457 CFU/m3, with no clear association between spore concentration and affected rooms, adjacent rooms and outdoor. Conclusions The observed levels did not exceed usual indoor and outdoor levels and were orders of magnitude below levels measured for patients diagnosed with farmers’ lung and suberosis, and we question if indoor mould levels in non-industrial environments are sufficient to cause HP. Relying solely on signs of moulds or presence of precipitating antibodies when diagnosing HP may cause other interstitial lung diseases to be overseen and patients may take initiatives such as quitting the job or leaving their homes that will not alleviate their disease but have significant social consequences.