Date of Degree
Access restricted until 07/03/2019
MS (Master of Science)
Occupational and Environmental Health
Matthew W. Nonnenmann
First Committee Member
Patrick T. O'Shaughnessy
Second Committee Member
Bioaerosols are present in agricultural settings and are known to cause adverse respiratory health effects among workers. Agricultural workers exposed to bioaerosols in the workplace are often above industry guideline concentrations. Yet, there are no standardized exposure limits in place for bioaerosols due to the lack of information and no universal method. The purpose of this study is to understand bacterial bioaerosols in industries that use different treatment methods and sampling methods in order to develop standardized limits, treatment measures, and remediation in an agricultural environment.
Airborne dust was collected in a broiler poultry building equipped with a water sprinkling system and from an untreated control building. Dust concentrations were measured with inhalable dust samplers attached to a mannequin, centrally located in the room at a breathing height of 1.5 meters, sampling of inhalable dust occurred for 30 minutes at 4 liters per min (LPM).
Airborne dust was also collected in a swine farrowing production using inhalable samplers. One of the inhalable samplers was on a mobile cart at a breathing height of 1.5 meters. The cart was moved to sample at 22 locations (5 minutes per location) in a swine farrowing room. Concurrently, the other inhalable dust samplers were located in a stationary basket at breathing height positioned centrally in the room and operating simultaneously with the mobile cart for 2.5 hours.
DNA was extracted from the inhalable dust samples using a lab optimized extraction protocol called Sucrose-Tris-EDTA (STE) Method. To measure bacteria levels, the highly conserved 16S rRNA gene was targeted and quantified with qPCR as DNA copies, referred to in this paper as bacteria units. The bacterial levels were adjusted for sampler flow rate and reported as bacteria units per meter cubed of air (BU/m3).
The median bacterial concentration among samples collected in chicken production was 8.80E+09 BU/m3compared to 5.02E+08 BU/m3 in swine production. The observed difference in the median between chicken and swine production was statistically significant (p< 0.0001, CI=95.1%).
The median bacterial concentration among samples collected in sprinkler building was 6.73E+09 BU/m3 compared to 9.18E+09 BU/m3 in the un-treated building. The observed difference in the median bacterial concentration between the treated sprinkler building and the untreated control building was not statistically significant (p= 0.6249, CI=95%).
The geometric mean bacterial concentration from the cart sampling was 2.46E+09 BU/m3 (SD: 3.08E+09) and the geometric mean bacterial concentration from the basket sampling was 1.28E+09 BU/m3 (SD: 2.74E+09). The difference in the geometric mean bacterial concentration between the mobile cart and stationary basket was not statistically different (p= 0.056, CI=95%).
From this study, we concluded that there are higher concentrations of bacteria units in broiler chicken production compared to swine production (farrowing). In the chicken production, our results suggest that the use of a water sprinkler treatment does not significantly increase the bacterial concentration. Therefore, these systems are not increasing the bacterial hazards for workers or animals when used in broiler production. In addition, our results for swine production suggest that airborne bacterial concentration is similar whether a worker is primarily in one location or if they are moving throughout the whole room. These conclusions are important because by quantifying inhalable bacteria exposure we can understand the impact of building design or encompassing production practice changes on inhalation exposures in the work environment.
xi, 71 pages
Includes bibliographical references (pages 67-71).
Copyright © 2018 Kelci Rebecca Knight
Knight, Kelci Rebecca. "Bioaerosols in agriculture: quantifying total airborne bacteria concentrations using molecular biology tools." MS (Master of Science) thesis, University of Iowa, 2018.
Available for download on Wednesday, July 03, 2019