The Danger of Chromotherapy

Despite the lack of scientific evidence for its effectiveness and its use of esoteric theories to describe its mechanisms of action, chromotherapy has become popular. But is it safe?

SÉBASTIEN POINT

C-state lighting technologies, light-emitting diodes (LEDs) will probably become the most used light sources in chromotherapy. Some LED-based chromotherapy lamps are already available on the market. The main interest in LED lamps—in addition to their energy efficiency and long lifetime—is that they can provide various colors directly depending on the nature of the semiconductor inside without using any filter. Is the use of LEDs in chromotherapy without any risk?

Blue Light Hazard

In the last quarter of the twentieth century, the work of Ham, Mueller, and Sliney (Sliney et al. 1976; Ham and Mueller 1989) opened the way to the description of photochemical mechanisms of lesions on the retina during exposure to a blue light source. To prevent such damages, the International Commission on Non-Ionizing Radiation Protection (IC NIRP), in its “Guidelines on Limits of Exposure to Inco herent Visible and Infrared Radiation” (1989), defines a blue light action spectrum Bλ(λ) and exposure limits (expressed in radiance) that are used in IEC 62471, which is the stan dard when dealing with exposure to sources of broad spec trum incoherent optical radiations. The application of this standard is particularly justified for evaluating blue LED and white LED (also called White Phosphor Coated LED, or WPCLED, and made of a blue LED coated with phosphor), which combine high radiance and a blue-enhanced spectrum, as can be seen on Figure 1. In 2010, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) published a collective expert report making an up date on the blue light risk associated with the use of commer cially available blue and white LEDs (Rapport de l’ANSES 2010). The results showed that it was possible to buy white or blue LEDs lamps reaching the medium risk group (RG2), potentially harmful to the retina of the eye if not diverted in 0.25 seconds.