Pyrimidine dimer excision in human cells and skin cancer.

We compared three methods for estimating the induction and removal of UV-induced pyrimidine dimers from the DNA of human fibroblasts. Results indicate that after UV doses of 5-20 J/m2, 50% of the dimers are removed by 24 hours. Almost complete excision can be observed if the cells are incubated for periods not less than 72 hours after a dose of 5 J/m2. After higher doses, it probably takes even longer for such complete removal to doses, it probably takes even longer for such complete removal to be seen.