EFFECT OF INTENSITY AND WAVELENGTH OF FLUORESCENT LIGHT ON CHROMOSOME-DAMAGE IN CULTURED MOUSE CELLS

A single 3-20 h exposure of line NCTC 9266 [neoplastic embryonic] mouse cells to cool-white fluorescent light (4.6 W/m2) produces chromatid breaks and exchanges. The effective wavelength is in the visible range and coincides with the Hg emission peak at 405 nm. Increasing light intensity from 4.6-15.3 W/m2 for 20 h causes a concomitant increase both in production of chromosome damage and formation of hydrogen peroxide (H2O2) in the serum-free medium. Cells washed free of medium and illuminated in saline for 3 h show chromosome damage to the same extent as cells illuminated in culture medium. Addition of catalase during the exposure period of 3 h eliminates the light-induced damage. The light-induced chromatid breaks and exchanges apparently result from H2O2 production within the cell. Exogenous catalase can evidently enter the cell and prevent light-induced damage.