In the late 1960’s, scientists often submitted their own Class II biological safety cabinet (BSC) specifications and options to manufacturers. In order to standardize cabinet design and performance used by U.S. government researchers, the National Institutes of Health (NIH) developed a specification for BSCs in 1973. The National Cancer Institute (NCI) also developed their own specifications for biological safety cabinets that same year. These specifications were demanding and differed on several design criteria; creating an impediment to development and construction by manufacturers.
In an attempt to develop impartial specifications, NIH contacted the National Sanitation Foundation (now NSF International). NSF International is an independent organization that acts as a neutral agency serving consumers, the government and various industries by developing solutions to increase public health and the environment. After numerous meetings with government officials, scientists, and manufacturers, NSF International published its Standard Number 49 in 1976.
The NSF Standard Number 49 (a.k.a. “NSF/ANSI Standard 49” or just “NSF 49”), entitled Class II (Laminar Flow) Biosafety Cabinetry, sought to address several concerns from the previous NIH and NCI standards. First, it established minimum materials, design, construction, and performance requirements for Class II BSCs. It also created quality control testing which each manufacturer must perform on every unit and the certification tests to be performed in the field. Finally, it created a “listing program,” establishing requirements for initial and periodic (re)testing of BSCs by the NSF International Laboratory in Ann Arbor, MI.
To be listed, a Class II BSC must pass every test required of NSF/ANSI Standard 49 at their laboratory. These tests include (but are not limited to) three separate biological challenge tests. The Personnel Protection Test measures the number of bacterial spores escaping from the cabinet’s work area into the environment. The Product Protection Test established the number of bacterial spores entering the work area from the outside environment. Finally, the Cross Contamination Protection Test challenges performance at various inflow and downflow velocity settings. These tests ensure that the cabinet still functions properly, even when it is not operating at the manufacturer’s recommended airflow velocity settings.
These tests are performed at NSF International before a cabinet is listed, and once every five years thereafter. Typically, most manufacturers perform biological challenge tests while their cabinets are in the prototype stage of development, and periodically during production, to ensure that the unit protects personnel, environment and product. Domestic Labconco Purifiers are built to meet or exceed minimum requirements of NSF Standard 49 and bear the NSF Mark.