Background: The aim of the present study was to determine the distribution of mite allergens in pig-farming environments in comparison to urban homes and the relationship between exposure to mite allergens and sensitization to the respective allergens in 100 pig farmers with work-related respiratory symptoms.
Methods: The concentration of storage mite (Lep d 2) and house-dust-mite (Der p 1, Der f 1, and Der 2) allergens in dust collected from five different sampling sites (floor, wall, grain mill, transit area between confinement house and farmer's kitchen, and farmers' mattresses) was studied in relationship to the respective sensitization rates. Allergen concentrations in the mattresses were compared to those determined in mattresses from 22 urban dwellers.
Results: Median concentrations of Der p 1 and Der 2 in the mattresses of the farmers were significantly higher than in the urban dwellers' samples (53.4 microg/g dust vs 1.05 microg/g dust, P=0.001; 19.6 microg/g dust vs 2.2 microg/g dust, P<0.0001, respectively). Allergen concentrations in the transit areas were strongly related to bedroom exposure. In a multiple logistic regression model, a weak but significant relationship between Der p 1 exposure and sensitization to Der p 1 was found. Despite these findings, the prevalence of sensitization to mite allergens in the farmers (18%) was comparable to the prevalence in the general population.
Conclusions: Allergen exposure at the workplace is strongly related to the concentration of allergens in farmers' beds. Exposure to domestic mite allergens should be taken into account when assessing occupational exposure to allergens and the respiratory health of farmers.