Efficacy of inactivation of human enteroviruses by dual-wavelength germicidal ultraviolet (UV-C) light emitting diodes (LEDs)

Abstract

The efficacy of germicidal ultraviolet (UV-C) light emitting diodes (LEDs) was evaluated for inactivating human enteroviruses included on the United States Environmental Protection Agency (EPA)'s Contaminant Candidate List (CCL). A UV-C LED device, emitting at peaks of 260 nm and 280 nm and the combination of 260∣280 nm together, was used to measure and compare potential synergistic effects of dual wavelengths for disinfecting viral organisms. The 260 nm LED proved to be the most effective at inactivating the CCL enteroviruses tested. To obtain 2-log₁₀ inactivation credit for the 260 nm LED, the fluences (UV doses) required are approximately 8 mJ/cm² for coxsackievirus A10 and poliovirus 1, 10 mJ/cm² for enterovirus 70, and 13 mJ/cm² for echovirus 30. No synergistic effect was detected when evaluating the log inactivation of enteroviruses irradiated by the dual-wavelength UV-C LEDs.

Keywords: UV-C LEDs; dual-wavelength; human enteroviruses; synergy; ultraviolet disinfection; viral inactivation efficacy.

Figure A1.

Comparison results of log10 inactivation rate from the 5 mJ/cm² (top), 10 mJ/cm² (middle), and 15 mJ/cm² (bottom) irradiation of UV-C LEDs for four human enteroviruses. The error bars represent 1 standard deviation. Symbol (●) represents the P value of <0.05 among three wavelengthes as determined by ANOVA. Echo30 and EV70 for a UV dose of 15 mJ/cm² were not determined. The log₁₀ inactivation rates by low-pressure UV (LPUV) at 254 nm were estimated using UV dose-response curves with a UV dose range of 10–30 mJ/cm² adapted from Ryu et al. [32].

Figure 1.

log₁₀ inactivation of four human enteroviruses after exposure to UV-C LEDs and low-pressure UV (LPUV) at 254 nm. Arrow (↑) represents detection limit. Each data point is an arithmetic average of log₁₀ inactivation from independent triplicate CB tests. Refer to Figure A1 for more detailed statistics including standard deviation. The log₁₀ inactivation rates LPUV at 254 nm were adapted from Ryu et al. [32].