Exposures to bioaerosols in the occupational environment are associated with a wide range of health effects with major public health impact, including infectious diseases, acute toxic effects, allergies and cancer. Respiratory symptoms and lung function impairment are the most widely studied and probably among the most important bioaerosol-associated health effects. In addition to these adverse health effects some protective effects of microbial exposure on atopy and atopic conditions has also been suggested. New industrial activities have emerged in recent years in which exposures to bioaerosols can be abundant, e.g. the waste recycling and composting industry, biotechnology industries producing highly purified enzymes and the detergent and food industries that make use of these enzymes. Dose-response relationships have not been established for most biological agents and knowledge about threshold values is sparse. Exposure limits are available for some contaminants, e.g. wood dust, subtilisins (bacterial enzymes) and flour dust. Exposure limits for bacterial endotoxin have been proposed. Risk assessment is seriously hampered by the lack of valid quantitative exposure assessment methods. Traditional culture methods to quantify microbial exposures have proven to be of limited use. Non-culture methods and assessment methods for microbial constituents [e.g. allergens, endotoxin, beta(1-->3)-glucans, fungal extracellular polysaccharides] appear more successful; however, experience with these methods is generally limited. Therefore, more research is needed to establish better exposure assessment tools and validate newly developed methods. Other important areas that require further research include: potential protective effects of microbial exposures on atopy and atopic diseases, inter-individual susceptibility for biological exposures, interactions of bioaerosols with non-biological agents and other potential health effects such as skin and neurological conditions and birth effects.

/pdf/bioaerosol-health-effects-and-exposure-assessment-progress-31appz2yq3.pdf

Bioaerosol Health Effects and Exposure Assessment: Progress and Prospects

Fungal spores are ubiquitous in the environment. However, exposure levels in workplaces where mouldy materials are handled are much higher than in common indoor and outdoor environments. Spores of all tested species induced inflammation in experimental studies. The response to mycotoxin-producing and pathogenic species was much stronger. In animal studies, nonallergic responses dominated after a single dose. Allergic responses also occurred, especially to mycotoxin-producing and pathogenic species, and after repeated exposures. Inhalation of a single spore dose by subjects with sick building syndrome indicated no observed effect levels of 4 x 10(3) Trichoderma harzianum spores/m(3) and 8 x 10(3) Penicillium chrysogenum spores/m(3) for lung function, respiratory symptoms, and inflammatory cells in the blood. In asthmatic patients allergic to Penicillium sp. or Alternaria alternata, lowest observed effect levels (LOELs) for reduced airway conductance were 1 x 10(4) and 2 x 10(4) spores/m(3), respectively. In epidemiological studies of highly exposed working populations lung function decline, respiratory symptoms and airway inflammation began to appear at exposure levels of 10(5) spores/m(3). Thus, human challenge and epidemiological studies support fairly consistent LOELs of approximately 10(5) spores/m(3) for diverse fungal species in nonsensitised populations. Mycotoxin-producing and pathogenic species have to be detected specifically, however, because of their higher toxicity.

Fungal spores : A critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting

Triticum aestivum (bread wheat) is the most widely grown crop worldwide. In genetically predisposed individuals, wheat can cause specific immune responses. A food allergy to wheat is characterized by T helper type 2 activation which can result in immunoglobulin E (IgE) and non-IgE mediated reactions. IgE mediated reactions are immediate, are characterized by the presence of wheat-specific IgE antibodies, and can be life-threatening. Non-IgE mediated reactions are characterized by chronic eosinophilic and lymphocytic infiltration of the gastrointestinal tract. IgE mediated responses to wheat can be related to wheat ingestion (food allergy) or wheat inhalation (respiratory allergy). A food allergy to wheat is more common in children and can be associated with a severe reaction such as anaphylaxis and wheat-dependent, exercise-induced anaphylaxis. An inhalation induced IgE mediated wheat allergy can cause baker's asthma or rhinitis, which are common occupational diseases in workers who have significant repetitive exposure to wheat flour, such as bakers. Non-IgE mediated food allergy reactions to wheat are mainly eosinophilic esophagitis (EoE) or eosinophilic gastritis (EG), which are both characterized by chronic eosinophilic inflammation. EG is a systemic disease, and is associated with severe inflammation that requires oral steroids to resolve. EoE is a less severe disease, which can lead to complications in feeding intolerance and fibrosis. In both EoE and EG, wheat allergy diagnosis is based on both an elimination diet preceded by a tissue biopsy obtained by esophagogastroduodenoscopy in order to show the effectiveness of the diet. Diagnosis of IgE mediated wheat allergy is based on the medical history, the detection of specific IgE to wheat, and oral food challenges. Currently, the main treatment of a wheat allergy is based on avoidance of wheat altogether. However, in the near future immunotherapy may represent a valid way to treat IgE mediated reactions to wheat.

/pdf/wheat-allergy-diagnosis-and-management-24u2t0rn54.pdf

Wheat allergy: diagnosis and management.

Fungal alpha-amylase is an important occupational allergen in the bakery industry. Epidemiologic studies focusing on the relationship between alpha-amylase allergen exposure and work-related respiratory allergy, however, have not been reported yet. In this cross-sectional study, sensitization to occupational allergens and work-related symptoms were studied in 178 bakery workers and related to allergen exposure. Alpha-amylase allergen concentrations were measured in personal dust samples, using a sandwich enzyme immunoassay. All workers were categorized into groups on the basis of their job histories and the alpha-amylase exposure levels of their job titles. Of all workers 25% had one or more work-related symptoms. As much as 9% of the bakery workers showed a positive skin prick test reaction to fungal amylase, and in 8% amylase-specific IgE was demonstrated. Alpha-amylase exposure and atopy appeared to be the most important determinants of skin sensitization, with prevalence ratios for atopy of 20.8 (95% CI, 2.74 to 158) and for medium and high alpha-amylase exposure groups of 8.6 (95% CI, 1.01 to 74) and 15.9 (95% CI, 1.95 to 129), respectively. Furthermore, a positive association was found between positive skin prick tests to alpha-amylase and work-related respiratory symptoms. In conclusion, this study has shown that there is a strong and positive relationship between alpha-amylase allergen exposure levels in bakeries and specific sensitization in bakery workers.

/pdf/exposure-sensitization-relationship-for-alpha-amylase-2gp0pti7at.pdf

Exposure-sensitization relationship for alpha-amylase allergens in the baking industry.

Horizontally transmitted endophytes are an ecological group of fungi that infect living plant tissues and survive in them without causing any disease symptoms. Even as facets of the endophyte-plant symbiotic relationship are being uncovered, there is an increasing appreciation of the different growth substrates exploited by endophytes and the vast repertoire of secreted enzymes of these fungi. These attributes exemplify the striking biodiversity of fungal endophytes and should motivate bioprospecting these organisms to identify novel biocatalysts that might help address challenges in medicine, food security, energy production and environmental quality.

Fungal endophytes: an untapped source of biocatalysts

Summary
Background Asthma in bakery workers caused by exposure to wheat flour proteins is an important occupational health problem. Until recently, gravimetric dust measurements were the only available technique for quantitative exposure assessment in bakeries. However, it is questionable whether dust levels are a good exposure parameter or only give a crude approximation of the actual flour allergen concentration.

Objective In the present study we have investigated a method to measure wheat flour antigens with immunochemical methods.

Methods Wheat flour antigens were measured in 449 personal dust samples taken in bakeries, using enzyme-linked immunosorbent assay (ELISA) inhibition and an anti-wheat lgG4 serum pool. Western-blotting was performed to compare the wheat flour proteins detected by IgE and IgG4.

Results Electrophoresis and immunoblotting showed that many wheat flour proteins can bind lgG4 and IgE, but also a reasonable similarity in major allergens detected by our lgG4-serum pool and IgE-positive sera. Inhibition tests showed some cross-reactivity with some cereal species, but not with other ingredients used in bakeries. In bakeries, large differences in personal airborne flour levels were found between occupational titles. Eor several groups clear differences in wheat antigen exposure levels existed, where no difierences in dust exposure levels could be found. The relationship between dust and wheat antigen exposure varied considerably, depending on the specific bakery occupation, the size of the bakery, and the type of product produced by the bakery. This study also shows that personal sampling of wheat antigens is possible on a large scale and can be used for epidemiological field studies.

Conclusion Measurement of airborne wheat antigens in bakeries is a more specific and sensitive measurement tool than measuring dust samples, and will probably be essential for epidemiologic field studies focusing on exposure-response relationships.

Wheat antigen exposure assessment for epidemiological studies in bakeries using personal dust sampling and inhibition ELISA.

Background: In the baking industry the use of enzymes has increased throughout the 1980s. Several studies have reported sensitization and respiratory disorders among bakery workers caused by enzymes in dough improvers. Fungal α-amylase is the most frequently reported cause of allergy. α-Amylase allergen exposure levels in the bakery industry, however, have not yet been reported. Objective: The main objective of this study was to quantify personal α-amylase exposure levels of bakery workers. Methods: α-Amylase allergens were measured in 507 personal samples of airborne dust taken in bakeries by using a newly developed sandwich enzyme immunoassay with affinity-purified polyclonal rabbit IgG antibodies. A cascade impactor was used to estimate the size of dust particles carrying α-amylase allergens. Results: The rabbit IgG antibodies used in the assay showed, in immunoblotting with commercially available α-amylase, a reaction profile very similar to that of IgE from sensitized bakers. The enzyme immunoassay appeared to be highly specific for fungal amylase. Allergen exposure levels varied considerably among bakery workers, depending on the type of bakery and job category (range, 0 to 40 ng/m 3 ). In confectioneries no α-amylase allergens were detected. In other bakeries α-amylase exposure was only found for workers directly involved in dough making. Measurements of the particle size distribution in these bakeries showed that α-amylase allergens are most likely to be deposited in the nose and ciliated airways. Conclusion: This study shows that personal monitoring of fungal amylase allergen exposure in bakeries is possible. This permits the identification of high-risk tasks and allergen sources, as well as the study of exposure-response relationships. (J Allergy Clin Immunol 1997;99:286-92.)

https://www.jacionline.org/article/S0091-6749(97)70044-7/pdf

Airborne levels of alpha-amylase allergens in bakeries.

Summary
Background Laboratory animal workers are at high risk of developing occupational allergy. Little is known about the relationship between levels of exposure and the risk of developing laboratory animal allergy. Since laboratory animal work comprises a large number of different — often short lasting — tasks, it is of interest to assess which activities are associated with high. low or intermediate levels of allergen exposure. Objective To develop and evaluate highly sensitive immunoassays in order to quantify rat and mouse urinary allergens in airborne dust sampled during short-lasting tasks.

Objective Personal air dust samples were taken during full-shift periods as well as during specific tasks in seven laboratory animal facilities. Two sandwich enzyme immunoassays were developed, using rabbit antisera against rat and mouse urinary proteins. The rabbit antibodies were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting and compared with IgE antibodies from sensitized laboratory animal workers.

Results The rabbit antibodies were highly specific for rat and mouse urinary proteins and reacted with all IgE-binding allergens in either urinary protein preparation. The assays for rat and mouse urine were very sensitive, with detection limits of 0.075 ng/mL. The coefficient of variation of the analysis was 12.9% for both assays. Animal caretakers appeared to experience the highest exposure to aeroallergens. A large variation in exposure within jobs was found, due to differences between tasks performed during the sampling day and the facility worked at. The highest exposure levels were found during removal of contaminated bedding from the cages. However, rat and mouse allergen exposure levels during this task varied enormously between facilities, 1.1–158ngeq/m and 0.63– 2000ngeq/m3. respectively.

Conclusion Both sandwich immunoassays are highly specific and sensitive and are able to identify tasks of relatively short duration with high, medium and low exposure to airborne rat and mouse urinary allergens.

Exposure of laboratory animal workers to airborne rat and mouse urinary allergens.

Exposure-sensitization relationships for alpha-amylase in a baker's asthma study.

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