Exposure to organic dust and endotoxin in animal farmers

INTRODUCTION  Exposure assessment in farming populations is difficult and costly, i.e. studies on personal dust and endotoxin exposure among animal farmers have been either small in size, or limited in numbers of sectors investigated.  

OBJECTIVES  To provide comparable information on the level and determinants of dust and endotoxin exposure in different sectors of the primary animal production.  

METHODS  A comprehensive exposure assessment study including personal monitoring of 327 farmers employed in 56 pig, 26 dairy, 3 poultry, and 4 mink farms in Denmark was performed. 507 inhalable dust samples were collected throughout seasons among pig and dairy farmers and different production stages among mink and poultry farmers. Information on potential exposure determinants for pig and cattle farmers was collected through detailed activity diaries and walk-through surveys. Concentrations of dust were determined gravimetrically and of endotoxin by the Limulus amebocyte lysate assay. Simple statistics were used to describe the levels of exposure and linear-mixed effect models to describe variability and identify determinants for exposure.  

RESULTS  Overall, measured personal inhalable dust concentrations averaged (geometric mean) at 2.5 mg/m3 (range   (below LOD-47.8) and endotoxin at 992.3 EU/m3 (range below LOD-374,579).  Pig and poultry farmers were highest exposed, but levels above the currently available occupational exposure limits for dust (3 mg/m3) and endotoxin (90 EU/m3) were common also among dairy and mink farmers. Exposure among pig and cattle farmers was characterised by a pre-dominant day-to-day variability that increased from indoors-to-outdoors. Important exposure predictors included both working tasks and farming characteristics with an influence mainly on the day-to-day variability.  

DISCUSSION  The findings stretch the need for optimization of the exposure assessment strategies for farming populations and open possibilities for evidence based prevention for lung diseases among farmers. The overall results will be discussed in the presentation along with an overview of those from earlier studies.