Background: Hand hygiene with chemical disinfectants is an important measure to reduce the spread of infections, but frequent use can cause skin irritation. In recent years, it has become widely accepted that visible light can also have an antimicrobial effect, and visible light has even been applied to the disinfection of wounds. The present study aims to evaluate whether hand disinfection with visible light is a realistic alternative to chemical disinfectants.
Methods: Human hands were irradiated with a dose of 10 or 33 J/cm2 visible violet light (405 nm) for 3 or 10 minutes, respectively. The reducing effect of the visible violet light was determined by comparing the contact agar plate results of irradiated and non-irradiated hands. Comparative experiments with a conventional hand disinfecting gel were also performed. Applicable standards were consulted to evaluate skin exposure to the irradiation.
Results: Irradiation of the hands with 10 and 33 J/cm2 resulted in an average reduction of microorganisms on the skin of 0.43 and 0.76 log-levels, respectively. These disinfection results with visible violet light are far behind that of the disinfectant gel, which achieved a reduction of 2.17 log-levels. Additionally, due to legal limits, a 3-minute irradiation can only be performed five times per day and a 10-minute procedure even only once.
Conclusion: Since the irradiation doses applied up to now have not provided a high antimicrobial effect and an increase of the dose in a short time is not arbitrarily possible without heating the hand unpleasantly, visible light of 405 nm seems rather unsuited for repeated hand disinfection.
