Legionella Testing / Biosafety Training


Richard W Gilpin PhD Blog

UV-C for PCR and BSC Disinfection - Effective? No

Modern UV lamps create 254 ηm UV-C by electrical discharge through low-pressure gas (including mercury vapor) enclosed in an industrial quartz tube. Inorganic materials (metal and glass) are not affected by normal exposure to UV-C. Organic materials (synthetic filter media, gaskets, rubber, motor windings, electrical insulation, internal duct insulation, and plastic piping) can be rapidly degraded by UV-C. ASHRAE Journal 50:28, August 2008.

Life may have existed on Earth as early as 3.8 billion years ago. It is nevertheless reasonable to assume that early life may have been at the edge of “mutation meltdown” partly due to high levels of mutagenic UV. Early microorganisms developed strategies to repair UV damage. http://www.dnva.no/geomed/solarpdf/Nr_10_Hessen.pdf

Photoreactivation repair of germicidal UV-C damage to DNA involves rapid monomerization of pyrimidine dimers before they can enter DNA replication. Dimer splitting is accomplished by combined action of photoreactivation enzyme and visible radiation (380-430 nm wavelength). ASM News 65:795, 1999.

UV-C kill curves for microorganisms are performed in liquid or agar, not dried on surfaces. UV-C disinfection is much more efficient in aqueous environments.

UV-C does not degrade nucleic acid sequences and therefore is not effective as a method to destroy contaminant nucleic acids. Appl. Environ. Microbiol. 60:4203-4206, November 1994.

UV-C lamps with industrial quartz solarize within 6 to 9 months and no longer produce 254 ηm germicidal radiation.

NSF/ANSI Standard 49 - 2016 Biosafety Cabinetry: Design, Construction, Performance, and Field Certification does NOT recommend installation of UV-C lamps in BSC’s.