M Taheri - Department of Microbiology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
M Darabyan - Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran
E Izadbakhsh - Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Science, Shiraz, Iran
F Nouri - Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Science, Shiraz, Iran
M Haghani - Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran
S A R Mortazavi - Student Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
G Mortazavi - Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran
S M J Mortazavi - Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran
M Moradi - Department of Microbiology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran

Background: Due to rapid advances in modern technologies such as telecommunication technology, the world has witnessed an exponential growth in the use of digital handheld devices (e.g. smartphones and tablets). This drastic growth has resulted in increased global concerns about the safety of these devices. Smartphones, tablets, laptops, and other digital screens emit high levels of short-wavelength visible light (i.e. blue color region in the visible light spectrum).  Material and Methods: At a dark environment, Staphylococcus aureus bacteria were exposed to the light emitted from common tablets/smartphones. The control samples were exposed to the same intensity of light generated by a conventional incandescent light bulb. The growth rate of bacteria was examined by measuring the optical density (OD) at ۶۲۵ nm by using a spectrophotometer before the light exposure and after ۳۰ to ۳۳۰ minutes of light exposure.  Results: The growth rates of bacteria in both smartphone and tablet groups were higher than that of the control group and the maximum smartphone/control and tablet/control growth ratios were observed in samples exposed to digital screens’ light for ۳۰۰ min (ratios of ۳.۷۱ and ۳.۹۵, respectively).  Conclusion: To the best of our knowledge, this is the first study that investigates the effect of exposure to light emitted from digital screens on the proliferation of Staphylococcus aureus and its association with acne pathogenesis. Our findings show that exposure to short-wavelength visible light emitted from smartphones and tablets can increase the proliferation of Staphylococcus aureus.

Smartphones, Tablets, Blue Light, Staphylococcus aureus, Acne