S-Space Graduate School of Public Health (보건대학원) Dept. of Public Health (보건학과) Theses (Ph.D. / Sc.D._보건학과)
생물안전시설에서 생물학적 인자에 대한 노출평가 및 환경특성
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- Objectives: Handling biological agents in biosafety laboratory can be a risk factor for laboratory occupants. High concentrations of airborne microbiological agents such as bacteria, fungi, Gram-negative-bacteira, endotoxin, and (1à3)-β-D-glucan are of concern. Biological exposures were often determined by questionnaire, survey, commentary review, and simulated exposure of airborne microorganism. Therefore, there is a need to assess biological agents in biosafety laboratory and determine factors associated with biological exposure. Biological safety cabinets (BSCs) are used for safety of researchers by safely securing materials in laboratories and also to safeguard the environment against contamination. Therefore, performance of BSCs in biosafety laboratories was evaluated.
Methods: To achieve these aims, three approaches were performed. First, airborne culturable bacteria, Gram-negative-bacteria (GNB) and endotoxin concentrations were measured in eight bio-related laboratories, two hospital diagnostic laboratories, and one biowaste site. A total of 305 samples (culturable bacteria : 109 indoor and 9 outdoor, GNB : 109 indoor and 9 outdoor, endotoxin : 60 indoor and 9 outdoor) were collected, ie., three times in each spot from the 11 facilities to compare airborne bacteria. An Andersen one-stage sampler (Quick Take 30, SKC Inc.) was used to sample air for culturable bacteria and GNB. The bacteria isolated from colonies were initially characterized by cell morphology and Gram staining.
Second, monthly concentrations of biological agents such as culturable bacteria, fungi, endotoxin, and (1à3)-β-D-glucan were performed. Culturable bacteria and fungi were incubated at temperature (35°C) for 7 days, and endotoxin and (1à3)-β-D-glucan were analyzed using the kinetic Limulus amebocyte lysate assay. A total of 491 (culturable bacteria: 176, fungi: 154, endotoxin: 82, (1à3)-β-D-glucan: 79) air samples were collected. An Andersen one-stage sampler (Quick Take 30, SKC Inc.) was used to sample air for TAB and GNB. New two-stage cyclone developed by National Institute for Occupational Safety and Health (NIOSH) was used for (1à3)-β-D-glucan sampling.
Finally, the performance of BSCs was evaluated in 31 BSCs in 14 different facilities, including six different biological test laboratories in six hospitals and eight different laboratories in three universities. The following tests were performed on the BSCs: the down-flow test, intake velocity test, high-efficiency particulate air (HEPA) filter leak test, and the airflow smoke pattern test. These performance tests were carried out in accordance with the U.S.A. and Korean standard procedures.
Results: The first study showed that airborne culturable bacteria concentrations were significantly higher in the groups; dont have ventilation system (p < 0.001), GNB present (p < 0.001), and rainy days (p < 0.001). Endotoxin concentrations were significantly correlated with humidity (r = 0.70, p < 0.01). The presence of ventilation, humidity, and the presence of open biowaste boxes were associated with endotoxin concentrations. The second study showed that airborne culturable bacteria and fungi concentrations were significantly correlated with temperature, relative humidity, CO2, lightness, air velocity of laboratory, number of human, human activity. Relative humidity was the most significant environmental factor affecting culturable bacteria and fungi concentrations. The third study demonstrated poor performance of BSCs. Only 23 % of Class II A1 (58 %), A2 (0 %), and unknown BSCs (0 %) passed these performance tests. The main reasons for the failure of BSCs were inappropriate intake velocity (65 %), leakage in the HEPA filter sealing (50 %), unbalanced airflow smoke pattern in the cabinets (39 %), and inappropriate down-flow (27 %).
Conclusions: Airborne culturable bacteria and endotoxin concentrations were significantly higher if there was no ventilation system, GNB were present, and during the rainy days. While relative humidity was the most significant environmental factor affecting culturable bacteria and fungi concentrations, lightness was the most significant environmental factor affecting endotoxin concentrations. Therefore, ventilation system and humidity control are important to improve the indoor environment of university and hospital laboratories. Finally, performance evaluation of BSCs is important to detect and measure the weak spots as observed during evaluation of the BSCs of various institutions.
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