Indirect DNA damage

Indirect DNA damage occurs when a UV-photon is absorbed in the human skin by a chromophore that does not have the ability to convert the energy into harmless heat very quickly. Molecules that do not have this ability have a long-lived excited state. This long lifetime leads to a high probability for reactions with other molecules - so-called bimolecular reactions. Melanin and DNA have extremely short excited state lifetimes in the range of a few femtoseconds (10^-15s). The excited state lifetime of these substances is 1,000 to 1,000,000 times longer than the lifetime of melanin, and therefore they may cause damage to living cells that come in contact with them.