Similar exposure group (task) based analysis of bioaerosol exposures in dairies

![CDATA[Objectives: The objective of this research was to evaluate variability in bioaerosol exposures among similar exposure groups (SEGs) based on dairy workers’ tasks. This analysis is an important step in a broader effort to develop effective interventions to reduce exposures and health effects. Methods: Bioaerosol samples were collected in workers’ breathing zones (n=116) over entire work shifts (10 – 12 hours) using Button samplers (inhalable) with PVC filters to measure organic dust, endotoxin (recombinant Factor C assay), and 3-hydroxy fatty acids (3-OHFA), ergosterol and muramic acid (GC/MSMS). Ammonia was measured using direct-reading ToxiRae samplers. To our knowledge this is the first study to include combined analysis of 3- OHFA, muramic acid and ergosterol in dairy operations. Results: SEGs were defined based on work tasks including: milking (30% of population), breeding (3%), birthing/rearing (9%), medical care (12%), feeding (4%), moving stock (4%), rebedding stalls (9%), milking parlor maintenance (3%), facility maintenance/repairs (2%), other tasks [administration] (6%) and mixed [two or more tasks] (18%). Participants were predominantly male (88%), Hispanics (91%), 25 to 40 years old. Exposures to endotoxin (p<0.001), 3-OHFA (p=0.010), and organic dust (p=0.015) differed significantly by SEG. Workers undertaking mixed tasks had the greatest dust exposures with a geometric mean (geometric standard deviation) of 1.14 (2.0) mg/m3. Those moving animals had the highest 3- OHFA [677 (2.3) ng/m3] and muramic acid [28.5 (2.5) ng/m3] exposures. Milkers had greater exposure to endotoxin [1037 (2.7) EU/m3]. Medical workers had the highest ergosterol exposures 23.1 (9.5) ng/m3 with one worker recording 536.9 ng/m3. A mixed task worker (feeding, milking and other) had the second highest ergosterol reading of 57.8 ng/m3, and the highest average ammonia result of 20.1 ppm. Workers performing milking, mixed tasks, and moving animals had higher exposures than the overall cohort for a number of bioaerosols, indicating that these groups could be at greater risk of adverse health effects. Geometric mean endotoxin concentrations for all SEGs exceeded the recommended exposure limit of 90 EU/m3. Mean ammonia and inhalable dust concentrations did not exceed recommended limits. However, there were individual exposures of concern of up to 20.1 ppm for ammonia (moving, feeding, milking , other and birthing) and up to 6.81 mg/m3 for dust (other, rebedding stalls, feeding and medical) that exceed recommended exposure limits. Characterizing the variability within and between SEGs is important for identifying at risk populations, and for developing effective interventions to reduce exposures and their associated health effects.]]