Photochemical Effects of VIS and UV Light

1 The Treatment of the Jaundice of New-born Infants. This disease results from the accumulation of bilirubin in the blood, when the liver is not yet able to function with its full efficiency. It takes its name from the yellowish colour of the skin, due to the relatively high concentration of bilirubin which absorbs in the violet and blue regions of VIS light. 

When the red blood cells die after their average lifetime of some 120 days, their haemoglobin is degraded to bilirubin which is then filtered by the liver. In new-born infants this process cannot take place often for several days, while the liver becomes fully functional. The accumulation of bilirubin in the 

In practice, 8-methoxypsoralene is used as the photoactive agent. It can be taken orally by the patient who will then be exposed to near UV radiation some 2 hours later. The treatment has however side-effects which make it relatively dangerous. 

23 The Phototherapy of Cancer a Mode of Treatment Still at the Research Stage. Cancer is the uncontrolled proliferation of cells which build up into tumours. Treatments rely on the elimination of diseased cells, through surgery, through the effects of ionizing radiation or through chemicals. 

Cancer cells differ from normal cells in several ways, and these differences must be exploited in chemical treatments. In particular, it is found that certain chemicals concentrate in cancer cells in preference to normal cells, and phototherapy is based on a sensitized photo-oxidation process which destroys the essential components of the cell. 

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