Biological Safety Cabinet Research Articles

Comparison of Mechanical Disruption Techniques for Rapid Inactivation of Mycobacterium and Nocardia Species before Identification Using Matrix-Assisted Laser Desorption Ionization–Time of Flight (MALDI-TOF) Mass Spectrometry

Prior to protein extraction for identification by Vitek MS, mycobacterial and Nocardia samples must be inactivated for safe handling outside the biological safety cabinet ([1][1], [2][2]). Previous studies have shown bead-beating samples for 5 min in 70% ethanol (EtOH) with glass beads followed by a

Room, Suite Scale, Class III Biological Safety Cabinet, and Sensitive Equipment Decontamination and Validation Using Gaseous Chlorine Dioxide

The Tufts New England Regional Biosafety Laboratory facility has been using chlorine dioxide gas for >5 years, and >100 decontaminations have been done at the room level and on a Class III cabinet....

Biological Safety Cabinets

It is a well-known fact that personnel activities can have an adverse effect on the protective functions of biological safety cabinets. Increased air turbulence within the work area or within the s...

Effectiveness of a Hydrogen Peroxide Mist (Trophon) System in Inactivating Healthcare Pathogens on Surface and Endocavitary Probes

Effectiveness of a Hydrogen Peroxide Mist (Trophon) System in Inactivating Healthcare Pathogens on Surface and Endocavitary Probes

アイソレーターと抗がん剤自動調製ロボットを使用した新たな抗がん剤調製業務の検討

Recent guidelines issued by the Japanese Society of Hospital Pharmacists recommend the use of biological safety cabinets (BSCs) and personal protective equipment (PPE) to prevent medical staff from being exposed to antineoplastic drugs during drug preparation. However, wearing PPE costs pharmacists additional time and labor during the preparation process. Since 2012, Nagoya City University Hospital has instituted the use of compounding aseptic containment isolators (CACIs, ChemoSHIELD) and a robotic system (CytoCare) for use during antineoplastic drug preparation. We investigated the effects of introducing CACIs and CytoCare on preventing antineoplastic drug exposure and on pharmacist efficiency. To evaluate workplace contamination, antineoplastic drug residues were measured using the wipe method. We also measured antineoplastic drug urine levels in pharmacists involved in the work. The levels of three antineoplastic drugs (cyclophosphamide, ifosfamide, gemcitabine) were measured using ultra-performance liquid chromatography-tandem mass spectrometry. Further, we investigated the stand-by time of pharmacists involved in the preparation of chemotherapeutic drugs. The results demonstrated that, compared with conventional class II BSCs, CACIs demonstrated decreased workplace contamination. Before CACIs introduction, antineoplastic drugs were detected in 3 of 12 urine samples, whereas after CACIs introduction, antineoplastic drugs were not detected in the urine of pharmacists. Additionally, the CACI and CytoCare systems significantly reduced the stand-by time of pharmacists, compared with BSCs (P < 0.001). Therefore, a combination of CACIs and robotic systems allows safe and efficient chemotherapeutic preparation.

Genotoxicity biomarkers for monitoring occupational exposure to antineoplastic drugs

Context: The Institute of Oncology and Radiobiology (INOR) is the leading institution for the diagnosis, treatment and follow-up of cancer in Cuba. The main methods used in cancer treatment are surgery, radiotherapy and chemotherapy. The last one involves the handling of hazardous substances, such as cytostatics, which implies a health risk to persons occupationally exposed to it. There are two sites where a considerable among of cytostatic is handled (Ambulatory Chemotherapy Room (ACR) and the Central Unit of Cytostatic Mixture Preparation (CUCM)). Genotoxicity biomarkers of exposure and effects have been widely used to detect occupational environment hazards. Aims: To evaluate genotoxicity biomarkers indicative of exposure and effects to cytostatics. Methods: In this study were tested samples taken from the surfaces of biological safety cabinets located in the Central Unit of Cytostatic Mixture using SOS – Chromotest. We also evaluated samples of oral mucosa exfoliated cells from exposed and control subjects, by micronucleus test. Results: All subjects were exposed and subjects who administered the mixes in the institution had an increased of DNA damage in comparison with the pharmaceutical staff that prepared it and wear the primary protection barriers properly. Conclusions: These results underline the efficiency of genotoxicological biomarkers in detecting the exposure levels and the deleterious effect of cytostatics on occupationally exposed personal.

Performance of particulate containment at nanotechnology workplaces

The evaluation of engineering controls for the production or use of carbon nanotubes (CNTs) was investigated at two facilities. These controls assessments are necessary to evaluate the current status of control performance and to develop proper control strategies for these workplaces. The control systems evaluated in these studies included ventilated enclosures, exterior hoods, and exhaust filtration systems. Activity-based monitoring with direct-reading instruments and filter sampling for microscopy analysis were used to evaluate the effectiveness of control measures at study sites. Our study results showed that weighing CNTs inside the biological safety cabinet can have a 37% reduction on the particle concentration in the worker's breathing zone, and produce a 42% lower area concentration outside the enclosure. The ventilated enclosures used to reduce fugitive emissions from the production furnaces exhibited good containment characteristics when closed, but they failed to contain emissions effectively when opened during product removal/harvesting. The exhaust filtration systems employed for exhausting these ventilated enclosures did not provide promised collection efficiencies for removing engineered nanomaterials from furnace exhaust. The exterior hoods were found to be a challenge for controlling emissions from machining nanocomposites: the downdraft hood effectively contained and removed particles released from the manual cutting process, but using the canopy hood for powered cutting of nanocomposites created 15%-20% higher ultrafine (<500 nm) particle concentrations at the source and at the worker's breathing zone. The microscopy analysis showed that CNTs can only be found at production sources but not at the worker breathing zones during the tasks monitored.

Long-term Maintenance of Sterility Following Skin Transplantation in Germ-free Mice.

BackgroundThere is considerable interest in investigating the role of the microbiota in various diseases, including transplant rejection. Germ-free (GF) and gnotobiotic mice are powerful models for this line of investigation, but performing surgery within the confines of a sterile housing isolator is exceptionally challenging. Development of rigorous protocols to be able to remove axenic mice from their sterile isolator for surgical intervention in a class II biological safety cabinet (BSC) without compromising sterility would give many investigators access to this model and broaden possible studies. However, it is assumed that GF animals will most often become colonized with environmental microbiota on leaving the isolator. In this study, we tested whether applying sterile techniques for animal transport out of the isolator and skin transplantation in a class II BSC could maintain animal sterility.MethodsQuantitative polymerase chain reaction of the bacterial 16S ribosomal RNA gene, and cultures in various aerobic and anaerobic conditions were used to probe for bacterial contamination before and after transplantation.ResultsOf 28 surgeries performed, only 3 mice acquired bacterial contamination coincident with a transient shutdown of the ventilation system in the BSC.ConclusionsOur results indicate that skin transplantation can be successfully performed in GF mice using sterile conditions for transport and surgery in a class II BSC, but requires continuous positive airflow. Our approach paves the way to investigating the role of the microbiota in modulating immune responses to skin allografts as a first model of solid organ transplantation in GF mice.

Adherence to Precautionary Guidelines for Compounding Antineoplastic Drugs: A Survey of Nurses and Pharmacy Practitioners

Precautionary guidelines detailing standards of practice and equipment to eliminate or minimize exposure to antineoplastic drugs during handling activities have been available for nearly three decades. To evaluate practices for compounding antineoplastic drugs, the NIOSH Health and Safety Practices Survey of Healthcare Workers was conducted among members of professional practice organizations representing primarily oncology nurses, pharmacists, and pharmacy technicians. This national survey is the first in over 20 years to examine self-reported use of engineering, administrative, and work practice controls and PPE by pharmacy practitioners for minimizing exposure to antineoplastic drugs. The survey was completed by 241 nurses and 183 pharmacy practitioners who compounded antineoplastic drugs in the seven days prior to the survey. They reported: not always wearing two pairs of chemotherapy gloves (85%, 47%, respectively) or even a single pair (8%, 10%); not always using closed system drug-transfer devices (75%, 53%); not always wearing recommended gown (38%, 20%); I.V. lines sometimes/always primed with antineoplastic drug (19%, 30%); and not always using either a biological safety cabinet or isolator (9%, 15%). They also reported lack of: hazard awareness training (9%, 13%); safe handling procedures (20%, 11%); and medical surveillance programs (61%, 45%). Both employers and healthcare workers share responsibility for adhering to precautionary guidelines and other best practices. Employers can ensure that: workers are trained regularly; facility safe-handling procedures reflecting national guidelines are in place and support for their implementation is understood; engineering controls and PPE are available and workers know how to use them; and medical surveillance, exposure monitoring, and other administrative controls are in place. Workers can seek out training, understand and follow facility procedures, be role models for junior staff, ask questions, and report any safety concerns.

Validation of cross-contamination control in biological safety cabinet for biotech/pharmaceutical manufacturing process.

For class II, type A2 biological safety cabinets (BSC), NSF/ANSI Standard 49 should be conformed in cabinet airflow velocity derivation, particle contamination, and aerodynamic flow properties. However, there exists a potential problem. It has been built that the cabinet air flow stabilize is influenced by the quantity of downflow of air and the height above the cabinet exhaust opening. Three air downflow quantities were compared as an operating apparatus was placed from 20 to 40 cm above the bench of the cabinet. The results show that the BSC air downflow velocity is a function of increased sampling height, displaying that containment is improvingly permitted over product protection as the sampling height decreases. This study investigated the concentration gradient of particles at various heights and downflow air quantity from the bench of the BSC. Experiment results indicate that performance near the bench was better than in the rest of the BSC. In terms of height, the best cleanliness was measured at a height of 10 cm over the bench; it reduced actually with add in height. The empirical curves accommodate, founded on the concentration gradient of particle created was elaborated for evaluating the particle concentration at different heights and downflow air quantity from the source of the bench of the BSC. The particle image velocimetry system applied for BSC airflow research to fix amount of airflow patterns and air distribution measurement and results of measurements show how obstructions can greatly influence the airflow and contaminant transportation in a BSC.

Analytical performance of the Abaxis Piccolo Xpress® point of care analyzer in whole blood, serum, and plasma

ObjectivesTo examine the analytical performance of 14 comprehensive metabolic panel analytes on the Abaxis Piccolo Xpress® Point of Care analyzer in serum, plasma, and whole blood. Design and methodsPrecision was evaluated by running two levels of control material over multiple days. Linearity was evaluated using material provided by the manufacturer and the College of American Pathologists (CAP) linearity surveys. Accuracy was evaluated by comparing the results from 60 patient specimens on the Piccolo Xpress® with the Ortho Vitros® 5600 analyzer. The method comparison was performed on all three specimen types intended for use on the Piccolo Xpress®: serum, heparinized plasma, and whole blood. Manufacturer suggested reference ranges for all 14 analytes were tested in serum and plasma specimens from 23 healthy volunteers. ResultsHigh precision (CV≤10%) was noted for all the analytes. Linearity was found to span the clinically useful range for all analytes. The method comparison demonstrated minimal proportional bias and good correlation for most of the analytes in all three matrices tested. The only exceptions were for sodium and total CO2, for which either significant proportional bias and/or poor correlation was noted in all three matrices. Significant bias was noted for AST in serum as well as for total bilirubin in plasma and whole blood. ConclusionThe Piccolo Xpress® allows for the delivery of CMP results in a footprint small enough to be stored in a biological safety cabinet, while providing satisfactory performance for the majority of analytes.

Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a non-human-primate, head-only aerosol chamber

Aerosol droplets or particles produced from infected respiratory secretions have the potential to infect another host through inhalation. These respiratory particles can be polydisperse and range from 0.05 to 500 µm in diameter. Animal models of infection are generally established to facilitate the potential licensure of candidate prophylactics and/or therapeutics. Consequently, aerosol-based animal infection models are needed to properly study and counter airborne infections. Ideally, experimental aerosol exposure should reliably result in animal disease that faithfully reproduces the modeled human disease. Few studies have been performed to explore the relationship between exposure particle size and induced disease course for infectious aerosol particles. The center flow tangential aerosol generator (CenTAG™) produces large-particle aerosols capable of safely delivering a variety of infectious aerosols to non-human primates (NHPs) within a Class III Biological Safety Cabinet (BSC) for establishment or refinement of NHP infectious disease models. Here, we report the adaptation of this technology to the Animal Biosafety Level 4 (ABSL-4) environment for the future study of high-consequence viral pathogens and the characterization of CenTAG™-created sham (no animal, no virus) aerosols using a variety of viral growth media and media supplements.

Pulsed-field gel electrophoresis of Yersinia pestis.

Yersinia pestis is a human pathogen and can cause serious disease. Biosafety level 3 (BSL3) is required when handling this microorganism and all work requires a biological safety cabinet. For pulsed-field gel electrophoresis (PFGE), dedicated BSL3 PFGE equipment or a documented procedure that ensures that all viable bacteria are inactivated is required. All plasticware and glassware that comes into contact with the cultures should be disinfected/sterilized or disposed of in a safe manner, according to the guidelines of institution. This includes decontamination of pipettes, spatulas, etc. that were in contact with the cell suspensions or plugs. Disinfection of reusable plug molds should be done before they are washed; the disposable plug molds, including the tape and the tab that was used to push the plugs out of the wells, are also contaminated and should be disinfected with 10 % bleach for at least 30 min if they will be washed and reused.

Therapeutic Effects of Bone Marrow Stem Cells in Diabetic Rats

Background: Currently, diabetes mellitus, specifically, Type 2 diabetes is a multifactorial metabolic disorder that affects more than 348 million people worldwide. It is considered to be one of the main causes of mortality. The pathway of type 2 diabetes is characterized both by insulin resistance in muscle, fat, and liver and a relative failure of the pancreatic β cell. Despite extensive study, yet no unifying hypothesis exists to explain these defects and the proper treatment. The key goal of diabetes treatment is to prevent complications because over time, diabetes can damage the heart, blood vessels, eyes, kidneys, and nerves. Therefore there is a great need to develop new and effective therapies for treating diabetic complications early before it cause irreparable tissue damage. Recently, advances experimental evidence empowers the idea that diabetic patients may greatly benefit from cell-based therapies, which include the use of adult stem and/or progenitor cells in disease therapy. In particular, therapeutic effect of bone marrow stem cell in treating the type 2 diabetic patients. Motivation: Mesenchymal stem cells (MSCs) are adherent and pluripotent and non-hematopoietic progenitor cells. Human bone marrow MSCs have been shown to inhibit antigen-dependent CD4+ and CD8+ T cell proliferation in an allogeneic setting in vitro. They have been found to reside in most organs and tissues investigated to date, including bone marrow, adipose, dermis, muscular tissue, hair follicles, the periodontal ligament and the placenta. In addition, recent studies have shown that adult bone marrow stem cells can differentiate into several types such as blood, liver, lung, skin, muscle, neuron and insulin producing cells. This has motivated us to explore potentials of their therapeutic applications in treating diabetes mellitus or type-2 diabetes. This article proposes a novel mechanism to isolate adult rat bone marrow stem cells and test their ability to treat diabetic rats. The main focus of this research is to investigate the therapeutic effect of mesenchymal stem cells on the diabetic rats. Experimental methods, data and results: The experimental studies were carried out based on twelveweek old healthy Sprague Dawley (S.D) rats and it was used for isolation and transplantation of stem cells. We carried a total number of 40 Sprague Dawley (S.D) male rats; 12-14 weeks old age and weighting 180-250 gm were used in the experimental study. Rats were obtained from Animal House of Nile Center for Experimental Researches, Mansoura, Egypt. Animals were housed in separate metal cages, fresh and clean drinking water was supplied adlibtium through specific nipple. The animals were anesthetized by halothane, and then the skin was sterilized with 70% ethyl alcohol before cutting the skin. The femurs and tibia were carefully dissected from adherent soft tissues. Then they were placed into sterilized beaker containing 70% ethyl alcohol for 1-2 min. The bones were put in Petri dish contain Phosphate buffer saline 1X (PBS) (Hyclone, USA) for wash. The bones were taken to laminar air flow (unilab biological safety cabinet class II, china) to extract the BM. The two ends of the bones were removed using sterile scissors. Conclusion and future work: Currently, the obtained results revealed that diabetes caused bad effects on the blood picture, pancreas and kidney functions, as well as the immune system represented by TNF. Treatment the diabetic rats by MSCs engrafting improved the tested parameters towards the stats of normal case. Nevertheless, the wide application of the stem cells engrafting still needs more investigations to be assured.

Pathology Laboratories and Infection Prevention and Control

Laboratory health care workers are vulnerable to infection with the Hospital Acquired Infections (HAIs) while receiving, handling and disposing biological samples. Ideally the infrastructure of the lab should be according to the best practices like good ventilation, room pressure differential, lighting, space adequacy, hand hygiene facilities, personal protective equipments, biological safety cabinets etc. Disinfection of the environment, and specific precautions with sharps and microbial cultures should follow the protocols and policies of the Infection Prevention and Control Practices (IPAC). If Mycobacterium tuberculosis or Legionella pneumophila are expected, diagnostic tests should be performed in a bio-safety level 3 facilities (for agents which may cause serious or potentially lethal disease in healthy adults after inhalation). Laboratory access should be limited only to people working in it.Along with the advent of new technologies and advanced treatment we are now facing problems with the dreadful HAIs with Antimicrobial Resistant Organisms (AROs) which is taking a pandemic form. According to WHO, hundreds of millions of patients develop HAI every year worldwide and as many as 1.4 million occur each day in hospitals alone. The principal goals for hospital IPAC programs are to protect the patient, protect the health care worker (HCW), visitors, and other persons in the health environment, and to accomplish the previous goals in a cost-effective manner like hand hygiene, surveillance, training of the HCWs, initiating awareness programs and making Best Practices and Guidelines to be followed by everyone in the hospital.The initiation for the best practices in the Pathology Laboratories can be either Sporadic or Organizational. Sporadic initiation is when the laboratories make their own IPAC policies. It has been seen that in few centres these policies have been conceptualized but not materialized. Organizational initiation is much more effective since the best practices are the same for all hospitals and this helps in standardizing the policies. There are organizations which work in promoting IPAC through education, standards, and advocacy and consumer awareness. Examples of organizations working in this field are IPAC Canada, Centers for Disease Control and Prevention (CDC) USA, Infection Prevention Society UK, Asia Pacific Society of Infection Control (APSIC), World Health Organization (WHO). In Nepal organizational initiation to address the issues of IPAC has been recently taken by Healthy Life Foundation Nepal (HELF Nepal) which is an organization with the mission to inform, promote and implement best practices of IPAC to prevent HAIs in the patients as well as the healthcare workers in all healthcare settings in Nepal.In Nepal awareness on IPAC in Pathology Laboratories can be brought about by initiating trainings, surveillance, regular CMEs and demonstration of techniques to the Lab personnel. Administration will have to be involved in initiating the program and maintaining it with administrative resources and financial support. Before it is too late we have to address the issues of HAIs, AROs and safety in our laboratories.DOI: http://dx.doi.org/10.3126/jpn.v4i8.11603

Assessment of final product dosing accuracy when using volumetric technique in the preparation of chemotherapy.

Studies have compared gravimetric and volumetric dosing accuracies in chemotherapy agents, finding high accuracy in gravimetric measurements with a mean deviation of ± 0.06%, while volumetric measurements had a mean deviation of ± 3.02%. Chemotherapy doses prepared under a biological safety cabinet containing two weights from the precision scale between 15 December 2010 and 30 March 2011 were eligible for inclusion. Empty syringes attached to a closed-system transfer device were weighed prior to product manipulation. The product was then prepared using the syringe pull-back method (volumetric technique) and the same syringe containing drug was weighed (gravimetric method). A total of 1156 compounded sterile products were eligible for the study. The mean percent volume difference of preparations included was -0.53% with a range of -64.9% to 94.22% for individual doses. Of the prepared doses, 71.7% were within ± 5% and 87.4% were within ± 10% of the ordered dose. Secondary outcomes found to be associated with an increased percent volume difference were the pediatric population, smaller volumes prepared, drugs requiring reconstitution compared to already in solution, and final product dispensed to the patient in syringes. While the mean value of volumetric measurements is within the generally understood acceptable range for dispensing chemotherapy, the range of measurements is highly variable. Future studies are warranted to better understand the reasons behind the variation and to evaluate the impact of workflow changes on improving final product accuracy.

Effects of outside air temperature on the preparation of antineoplastic drug solutions in biological safety cabinets

In Japan, biological safety cabinets are commonly used by medical staff to prepare antineoplastic agents. At the Division of Chemotherapy for Outpatients, Nagoya University Hospital, a class II B2 biological safety cabinet is used. The temperature inside this biological safety cabinet decreases in winter. In this study, we investigated the effect of low outside air temperature on the biological safety cabinet temperature, time required to admix antineoplastic agents, and accuracy of epirubicin weight measurement. Studies were conducted from 1 January to 31 March 2008 (winter). The outside air temperature near the biological safety cabinet intake nozzle was compared with the biological safety cabinet temperature. The correlation between the outside air temperature and the biological safety cabinet temperature, time for cyclophosphamide and gemcitabine solubilization, and accuracy of epirubicin weight measurement were investigated at low and high biological safety cabinet temperatures. The biological safety cabinet temperature correlated with the outside air temperature of 5-20℃ (p < 0.0001). Compared to cyclophosphamide and gemcitabine solubilization in the biological safety cabinet at 25℃, solubilization at 10℃ was significantly delayed (p < 0.01 and p < 0.0001, respectively). Measurement of epirubicin weight by using a syringe lacked accuracy because of epirubicin's high viscosity at low temperatures (p < 0.01). These results suggest that the biological safety cabinet temperature decreases when cool winter air is drawn into the biological safety cabinet, affecting the solubilization of antineoplastic agents. We suggest that a decrease in biological safety cabinet temperature may increase the time required to admix antineoplastic agents, thereby increasing the time for which outpatients must wait for chemotherapy.

Syringe plunger contamination by hazardous drugs: A comparative study

The purpose of this study was to perform a comparative cyclophosphamide contamination level test with Becton Dickinson® syringe plungers with Phaseal® Closed System Transfer Devices and Equashield® syringe plungers under routine oncological compounding conditions. The ChemoGlo™ sampling kit and analysis services were used to test for cyclophosphamide contamination levels on the syringe plungers of Becton Dickinson® Phaseal and Equashield® syringes that underwent cycles of drug transfer in a Forma Class II, 2A Biological Safety Cabinet. Prior to testing, the syringes were divided into three equal groups for the Equashield® and Becton Dickinson® syringes. A 50 mL aliquot of cyclophosphamide was drawn into each syringe and then injected back into the cyclophosphamide vial. This drug transfer procedure was immediately repeated twice for the syringes in group 1, four times for group 2, and eight times for group 3. After the completion of the drug transfers with the Equashield® and Becton Dickinson® Phaseal syringes, the plungers were retracted back to the nominal syringe marking, and a wipe test of the exposed plunger was done using the ChemoGlo™ sampling kit. Significant contamination levels of 2000 ng and greater were detected on most Becton Dickinson® syringe plungers with Phaseal® Closed System Transfer Devices, whereas all Equashield® syringes remained uncontaminated at undetectable levels.

Economic assessment of aseptic compounding rooms in hospital pharmacies in five European countries

The aims of the study are to make an inventory of fixtures of aseptic compounding structures, to compare, using real examples, the design and operating costs of controlled atmosphere area (CAA) with isolators and CAA with laminar flow biological safety cabinets (BSCs) in order to determine the most economical scheme in hospitals and to give a final facilities cost calculated for one workstation. Forty-three hospitals were interviewed (21 French and 22 from four European countries) over seven months. Hospital pharmacists completed a form with 390 items. Hospitals are compared according to their workstation type: BSCII or BSCIII (group B) and isolator (group I), using Mann and Whitney's statistical test and Monte-Carlo modeling. Twenty-one hospitals responded (11 French and 10 from other European countries). All European compounding unit organizations are not significantly different. The study compared items such as infrastructure cost, equipment cost, staff cost, consumable cost, cleaning cost and control cost. A synthesis of all costs has been drafted to calculate an estimated preparation cost which seemed to be higher for group B than for group I when staff costs were included ($46 and $31, respectively, in study conditions). The different costs studied have revealed little significant difference between group B and I. The preparation cost in group B appears higher than in group I. This pilot study has resulted in the calculation of an estimated manufactured preparation cost but this work should be completed to help optimize resources and save money.

Analysis of variation in total airborne bacteria concentration to assess the performance of biological safety cabinets in microbial laboratories.

BackgroundThe purpose of this study was to compare the concentration of total airborne bacteria (TAB) in biosafety cabinets (BSCs) at universities and hospital microbial laboratories to assess the performance of BSCs.MethodsTAB was determined by using the single-stage Anderson sampler (BioStage Viable Cascade Impactor). The samples were obtained three times (with the BSC turned off and the shield open; with the BSC turned off and the shield closed; and with the BSC tuned on and operating) from the areas in front of 11 BSCs.ResultsTAB concentrations of accredited and nonaccredited BSCs were determined. No significant differences were observed in the TAB concentrations of the accredited BSCs and the nonaccredited BSCs for the areas outside the BSCs in the laboratories (p > 0.05). TAB concentrations for the BSCs sampled with the shield open and the instrument turned off showed differences based on the sampling site outside the BSC in each laboratory.ConclusionThese results imply that TAB concentration is not altered by the performance of the BSCs or TAB itself and/or concentration of TAB outside the BSC is not a good index of BSC performance.