A French study highlights the phototoxicity of the blue and protective function of the red parts of the spectral composition in LED lighting and recommends modification of existing standards for indoor applications.

About study

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Title:	Phototoxicity of low doses of light and influence of the spectral composition on human RPE cells
Author:	Anaïs Françon, Kimberley Delaunay, Thara Jaworski, Cécile Lebon, Emilie Picard, Jenny Youale, Francine Behar-Cohen & Alicia Torriglia Centre de Recherche des Cordeliers, Université Paris Cité, Sorbonne Université
Date:	21. March 2024
Source:	https://doi.org/10.1038/s41598-024-56980-9
PDF:	Phototoxicity of low doses of light and influence of the spectral composition on human RPE cells.PDF

Brief summary

The researchers used an in vitro model of human retinal pigment epithelium (RPE) cells and exposed it to blue energy in white light from LEDs at doses lower than the currently established phototoxicity threshold of 22 J/cm². The results demonstrate that the current phototoxicity threshold for humans should be tightened, as even significantly lower doses caused eye damage. The study suggests that for indoor LED lighting, the blue energy below 450 nm should be minimized, and red energy should be maximized to compensate for the harmful effects of blue light. This should also be taken into account in interior lighting standards.

Damage to RPE cells occurred at significantly lower doses of blue energy in white light than current limits.

Exposure to white light at a CCT of 3300 K and a dose of 3.6 J/cm2 induced changes in overall cell structure, DNA damage and activation of cellular stress and autophagy (a cellular process that recycles old or damaged cellular components and proteins). By analysing biochemical markers, it was found that blue light was primarily at fault when it comes to the DNA damage.
Although the dose of blue light in white light in the study was more than 100 times lower than the current established phototoxicity threshold (0.185 J/cm² versus 22 J/cm²), RPE cells were damaged.

Red light alleviated the inflammatory response and suppressed autophagy

According to research results, red light has a protective effect on RPE cells, inhibiting inflammatory reactions and suppressing autophagy, in contrast to the harmful effects observed with exposure to blue light.