Biological safety level

Class n cabinets are intended to be used for work with microorganisms that would be permitted in laboratories designated as biological safety levels, 1,2, and 3. Normally they are not used for work with volatile, toxic chemicals. If these are used in the cabinet, the exhaust must be to the outdoors. 

In 2015 the Hazards Identification and Evaluation Task Force of the American Chemical Society Committee on Chemical Safety issued a lengthy report that described other protocols for hazard assessment. These include (1) Control Banding Chemical Uses in Research Laboratories - similar to Biological Safety Levels as described in Section 7.3.4), (2) Job Hazard Analysis, (3) What-If Analysis, (4) Checklists, and (5) Structured Development of Standard Operating Procedures (SOPs). Each of these protocols is described in detail in the Task Force report. 

Temperature and humidity is controlled to minimize evaporation of reagents and to keep performance of electronic equipment optimal. Ventilation is adequate for the removal of noxious fumes and odors. Formaldehyde and xylene vapor concentrations must be below maximum permissible levels. For formaldehyde, this level is 0.75 ppm for an 8-h time-weighted average, or 2.0 ppm for a 15-min short-term exposure. For xylene, the level is 100 ppm for an 8-h time-weighted average and 200 ppm for a 15-min short-term exposure. The monitoring of the work area and employees can be performed on a yearly basis. Chemical and biological safety cabinets are checked for proper airflow on a yearly basis. 

Noise in excess of recommended levels within the LAP environment or clean space may cause operator discomfort and premature fatigue, and may indicate HEPA filter failure, or a malfunction of the LAFD or clean space air handling unit. ° Cabinet pressure integrity and vibration analysis are recommended for all biological safety cabinets. 

Laboratories should process specimens in a class 11 biological safety cabinet using level 3 practices. When possible, staff should pretreat serum with a combination of heat-inactivation at 56°C and polyethylene glycol p-tert-octylphenyl ether (Triton X-1(X)). Although treatment with lOuL of 10% Triton X-100 per 1 mL of serum for an hour reduces the virus titer in the serum, laboratory staff should not assume that the resulting viral titer is zero. For laboratory tests in which detergent use could alter the results, heat inactivation alone may help reduce the viral load and consequent infectivity of the sample. 

Qualification of impurities—this section addresses the evaluation data for assessing the biological safety of an individual impurity or a given impurity profile at the levels specified. 

---