Can selection explain the protective effects of farming on asthma?

INTRODUCTION AND OBJECTIVE: Reduced asthma and allergy risks in farmers have been ascribed to microbial exposures. However, selection may also play a role and this was assessed in two Scandinavian farming populations. MATERIALS AND METHODS: Asthma prevalence in 739 Danish farming students was compared to that of 1,105 siblings. 8,482 Norwegian farmers were also compared with 349 early retired farmers. RESULTS: The prevalence of ever-asthma was 5.4% in farming students and 5.2% in siblings (OR 1.1; 95%CI 0.73-1.7). Current asthma in farmers was 3.0% compared to 6.3% in farmers who had retired early (OR 1.8, 95%CI 1.1-2.9). Adjustments for early retirement increased the asthma prevalence by 0.3-0.6%. Farmers who had changed production were more likely to have asthma (OR 9.8, 95% CI 6.0-16). CONCLUSIONS: No healthy worker selection into farming was observed and changes in asthma prevalence due to early retirement were small. Selection effects are therefore unlikely to explain the protective effects of farming on asthma

Hospital admission and risk assessment associated to exposure of fungal bioaerosols at a municipal landfill using statistical models

The object of this research to determine the statistical relationship and degree of association between variables: hospital admission days and diagnostic (disease) potentially associated to fungal bioaerosols exposure. Admissions included acute respiratory infections, atopic dermatitis, pharyngitis and otitis. Statistical analysis was done using Statgraphics Centurion XVI software. In addition, was estimated the occupational exposure to fungal aerosols in stages of a landfill using BIOGAVAL method and represented by Golden Surfer XVI program. Biological risk assessment with sentinel microorganism A. fumigatus and Penicillium sp, indicated that occupational exposure to fungal aerosols is Biological action level. Preventive measures should be taken to reduce the risk of acquiring acute respiratory infections, dermatitis or other skin infections

The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals : 139. Fungal Spores

Fungal spores are ubiquitous in the environment. Exposure levels in workplaces where mouldy materials are handled are much higher than in common indoor and outdoor environments. Febrile attacks of organic dust toxic syndrome (ODTS) and hypersensitivity pneumonitis may occur after episodes with excessive exposure. In common indoor environments irritation symptoms have been ascribed to fungi at much lower exposure levels, especially in damp buildings. The specificity of the response to fungi in hypersensitivity pneumonitis and asthma patients has been clearly demonstrated by bronchial provocation with the suspected organisms. In vitro and animal studies have further shown differences in the inflammatory potential of fungal species. In animal studies, non-allergic responses dominated after a single spore dose but allergic responses, especially to viable spores, were also observed. Repeated exposures induced both non-allergic and allergic pulmonary inflammation. Two human challenge studies with whole spores provide information on effect levels. A single dose study of subjects with sick building syndrome indicated no observed effect levels (NOELs) of 4*103 spores/m3 for Trichoderma harzianum and 8*103 spores/m3 for Penicillium chrysogenum. The investigated effects were lung function impairment, mucosal and systemic symptoms and inflammatory cells in the blood. A study of asthmatic patients allergic to Penicillium sp. or Alternaria alternata showed lowest observed effect levels (LOELs) for reduced airway conductance of 1*104 and 2*104 spores/m3, respectively. In epidemiological studies of highly exposed populations lung function decline, respiratory symptoms and airway inflammation began to appear at exposure levels of 105 spores/m3. LOELs of 1*105-4*105 spores/m3 have been reported in wood workers predominantly exposed to fungal spores and wood dust. The only welldesigned study on populations exposed to common indoor air indicates a NOEL of 7*102 spores/m3. The investigated effects were inflammatory markers in nasal lavage, and eye, throat, lower airways and non-specific symptoms. Fungal species were seldom identified in the epidemiological studies. In conclusion, the combined evidence from human challenge and epidemiological studies support fairly consistent LOELs of approximately 105 spores/m3 for diverse fungal species in non-sensitised populations. However, identification of the fungal biota is required in order to document the occurrence of the more toxic mycotoxin containing species and pathogenic species before measurements are evaluated. Further epidemiological studies of allergic responses to fungal spores and effects of pathogenic and mycotoxin containing species are recommended. Keywords: actinomycetes, fungal spores, hypersensitivity pneumonitis, irritation, occupational exposure limit, organic dust toxic syndrome, review, toxicitySoppsporer finnes overalt i miljøet. I arbeidsmiljø hvor materialer med soppveksthåndteres kan eksponeringen for soppsporer bli mye høyere enn det som er vanliginnendørs og utendørs. Typiske feberanfall av allergisk alveolitt og organic dusttoxic syndrome kan utløses etter massiv eksponering for soppsporer. Men også iarbeidsmiljø med mye lavere eksponering er sopp blitt assosiert med plager, foreksempel i fuktige bygninger.Bronkial provokasjon av pasienter med allergisk alveolitt eller astma medmistenkte organismer har vist tydelig at responsen er artsspesifikk. In vitro ogdyreforsøk har videre vist forskjeller i inflammatorisk potensial hos ulikesopparter. Hos dyr eksponert én gang dominerte ikke-allergiske responser.Allergiske responser ble også observert, spesielt på viable sporer, sporer sominneholder mykotoksiner, og etter gjentatte eksponeringer.Provokasjon av personer med sick building syndrome som ble eksponertén gang viste no observed effect levels (NOELs) på 4·103 sporer/m3 for Trichodermaharzianum og 8·103 sporer/m3 for Penicillium chrysogenum. Lungefunksjon,slimhinne og systemiske symptomer og inflammatoriske celler i blodble undersøkt. Provokasjon av pasienter med astma som var allergiske forPenicillium sp. eller Alternaria alternata med økende doser viste lowestobserved effect levels (LOELs) for redusert luftveismotstand ved henholdsvis1·104 sporer/m3 og 2·104 sporer/m3.I epidemiologiske undersøkelser av høyt eksponerte yrkesgrupper ble nedsattlungefunksjon, luftveissymptomer og luftveisinflammasjon funnet når eksponeringsnivåetoverskred 105 sporer/m3. Undersøkelser av trearbeidere som erhovedsakelig eksponert for soppsporer og trestøv viser LOELs på 1·105-4·105spores/m3. Få epidemiologiske undersøkelser av yrkesgrupper som jobber i vanliginnemiljø ble funnet og bare en hadde god design. Denne undersøkelsen viste enNOEL ved 7·102 sporer/m3 for inflammationsmarkører i neseskyllevæske,symptomer fra øye, hals og nedre luftveier samt ikke-spesifikke symptomer. Soppble sjeldent identifisert i epidemiologiske undersøkelser.Konklusjon: Resultatene fra humane provokasjonsstudier og epidemiologiskeundersøkelser underbygger ganske konsistente LOELs på ca. 105 sporer/m3 vedeksponering for diverse sopparter i ikke-sensibiliserte yrkesgrupper. Identifikasjonav soppfloraen er nødvendig for å dokumentere forekomst av de mer toksiskemykotoksin-produserende og patogene arter før evaluering av måleresultater.Videre epidemiologiske undersøkelser av allergiske sykdommer og effekter aveksponering for patogene og mykotoksin-produserende arter anbefales