RESUMEN
Objective To determine whether intermittence irradiation of single blue or white light have an adverse effect on the DNA of newborn infants with hyperbilirubinemia by examining the sister chromatid exchange(SCE)frequency of peripheral blood lymphocytes.Methods The frequency of SCE in lymphocytes of 40 icteric infants treated by different phototherapy(PT) methods was a nalyzed by sister chromatid differetance staining technique (SCD).The patients receiving PT were divided into three groups according to two methods of PT,group A:single blue light,20 cases; group B:single white light,20 cases.Results 1.In group A, there was no difference between the levels of SCE before and after therapy within 3 days;but after 4 days, the levels of SCE increased.2.Obvious changes were observed in group B,and the frequency of SCE increased after 1 day and increased significantly in a dose-dependant manner.3.After treatment, the SCE frequency of group B was higher than that of group A.Conclusions PT has mutagenic effect on newborns with hyperbilirubinemia. The effect of single white light on peripheral blood lymphocytes of neonates is more significant.