Early incidence of occupational asthma among young bakers, pastry-makers and hairdressers: design of a retrospective cohort study

<p>Abstract</p> <p>Background</p> <p>Occupational exposures are thought to be responsible for 10-15% of new-onset asthma cases in adults, with disparities across sectors. Because most of the data are derived from registries and cross-sectional studies, little is known about incidence of occupational asthma (OA) during the first years after inception of exposure. This paper describes the design of a study that focuses on this early asthma onset period among young workers in the bakery, pastry making and hairdressing sectors in order to assess early incidence of OA in these "at risk" occupations according to exposure duration, and to identify risk factors of OA incidence.</p> <p>Methods/Design</p> <p>The study population is composed of subjects who graduated between 2001 and 2006 in these sectors where they experience exposure to organic or inorganic allergenic or irritant compounds (with an objective of 150 subjects by year) and 250 young workers with no specific occupational exposure. A phone interview focusing on respiratory and 'Ear-Nose-Throat' (ENT) work-related symptoms screen subjects considered as "possibly OA cases". Subjects are invited to participate in a medical visit to complete clinical and lung function investigations, including fractional exhaled nitric oxide (FE_NO) and carbon monoxide (CO) measurements, and to collect blood samples for IgE (Immunoglobulin E) measurements (total IgE and IgE for work-related and common allergens). Markers of oxidative stress and genetic polymorphisms exploration are also assessed. A random sample of 200 "non-cases" (controls) is also visited, following a nested case-control design.</p> <p>Discussion</p> <p>This study may allow to describ a latent period between inception of exposure and the rise of the prevalence of asthma symptoms, an information that would be useful for the prevention of OA. Such a time frame would be suited for conducting screening campaigns of this emergent asthma at a stage when occupational hygiene measures and adapted therapeutic interventions might be effective.</p> <p>Trial registration</p> <p>Clinical trial registration number is NCT01096537.</p

Sensitisation to enzymes in the animal feed industry

OBJECTIVES—To assess the prevalence of enzyme sensitisation in the animal feed industry.
METHODS—A cross sectional study was conducted in four animal feed factories, where several enzymes had been used in powder form for 7-9 years. Before this study, enzymes in liquid form had started to be used. Sensitisation to enzymes was examined by skin prick and radioallergosorbent (RAST) tests. Altogether 218 workers were tested; 140 people in various tasks in manufacturing, where exposure to various organic dusts and to enzymes was possible, and 78 non-exposed office workers. The workers were interviewed for work related respiratory and skin symptoms. Total dust concentrations were measured by a gravimetric method. The concentrations of protease and α-amylase were measured with catalytic methods and that of xylanase with an immunological method.
RESULTS—Ten workers (7%) were sensitised to enzymes in the exposed group of 140, whereas none were sensitised in the non-exposed group. Six of the sensitised people had respiratory symptoms at work: two of them especially in connection with exposure to enzymes. Enzyme concentrations in the air varied greatly: xylanase from less than 0.8 ng/m(3) up to 16 ng/m(3), α-amylase from less than 20 ng/m(3) up to 200 ng/m(3), and protease from less than 0.4 ng/m(3)up to 2900 ng/m(3). On average, highest xylanase and α-amylase concentrations were found in the various manufacturing sites, whereas the highest protease concentrations were found in areas of high total dust.
CONCLUSIONS—Industrial enzymes may cause allergies in the animal feed industry. There is a need to assess exposure to enzymes at various phases of production, and to minimise exposures.


Keywords: animal feed; enzyme allergy; occupational exposur

Immunoglobulin G4 antibodies to rat urinary allergens, sensitization and symptomatic allergy in laboratory animal workers

Background and objectives We have previously reported that high rat urinary allergen (RUA) exposure was not associated with increased risk of rat allergy in long‐term‐exposed laboratory animal (LA) workers. We aimed to assess whether strong allergen‐specific IgG4 responses could explain the absence of a dose response in these subjects. We investigated whether IgG4 was associated with allergen exposure and prevalence of sensitization or respiratory symptoms to rats. The longitudinal relation between IgG4 and rat allergy was studied using data obtained during 2 years of follow‐up. Methods Five hundred and twenty‐nine LA workers answered a questionnaire on respiratory symptoms and occupational history and participated in skin prick testing. Blood samples were analysed for specific IgG4 and IgE to RUA. Exposure to RUA was estimated based on personal air samples. The relation between IgG4 and newly occurring sensitization or rat allergy was studied in workers who were not sensitized or did not report respiratory symptoms to rats. Results IgG4 titres were higher in atopic than in non‐atopic subjects, and increased with higher allergen exposure. Titres were highest in subjects who were sensitized and reported respiratory symptoms to rats when compared with those who were not (geometric mean [geometric standard deviation]=202 [5.7] vs. 8.4 [18.3] AU). The association between IgG4 and sensitization or symptomatic rat allergy was independent of estimated allergen exposure. IgG4 was a strong predictor of newly occurring sensitization and symptomatic rat allergy during follow‐up in atopic and rat‐sensitized subjects. Conclusion High exposure to RUA is associated with a strong allergen‐specific IgG4 antibody response. High anti‐RUA IgG4 is a strong predictor of prevalent and incident sensitization and symptomatic rat allergy in atopic and rat‐sensitized subjects. IgG4 can therefore not explain the absence of a dose response between allergen exposure and allergy in long‐term‐exposed workers. We consider anti‐RUA IgG4 to be a marker that combines aspects of exposure and susceptibility