blue light bilirubin

Blue light converts bilirubin in the skin of jaundiced rats to metastable geometric isomers that are transported in blood and excreted in bile. The same reaction probably occurs in jaundiced babies exposed to light, particularly during treatment with phototherapy.

High levels of bilirubin can cause brain damage (kernicterus), leading to cerebral palsy, auditory neuropathy, gaze abnormalities and dental enamel hypoplasia. The therapy uses a blue light (420–470 nm) that converts bilirubin into an (E,Z)-isomer that can be excreted in the urine and feces.

Phototherapy lights emit light in the blue-green spectrum (wavelengths 430-490nm). It is NOT ultraviolet light.

In conclusion, the most effective wavelength of phototherapy for human neonatal hyperbilirubinemia lies near the green region rather than the blue region. Based on this idea, we are able to perform safer phototherapy by avoiding the wavelength 400–500 nm, which belongs to the blue region and which can be harmful.