Sister Chromatid Exchanges and Chromosome Aberrations in Human Cells Induced by H2o2 and Other Photoproducts Generated in Fluorescent Light‐exposed Medium

Exposure of Dulbecco's modified Eagle's tissue culture medium to visible fluorescent light generated photoproducts toxic to human cells in culture. Toxicity manifested at the chromosome level was increased chromosome aberrations and sister chromatid exchanges in cells exposed to the photoproducts. Hydrogen peroxide (H2O2), a major photoproduct, induced SCE but failed to increase chromosome aberrations. Pure H2O2, or the H2O2 generated in light‐exposed medium, was necessary and sufficient for inducing all the increase in SCE. However, H2O2 was necessary but insufficient to cause most of the chromosome aberrations. Only when acting synergistically with other photoproducts did H2O, induce extensive chromosome aberrations. The relatively high cell densities at near confluence levels used in these experiments were less sensitive to light‐induced effects, nevertheless the entire light exposure dosage range effected photoproduct production adequate for inducing SCE and chromosome aberrations. Thus, mammalian tissue and cell culture media can receive sufficient dosage from fluorescent lights illuminating rooms and culture hoods for generation of photoproducts causing gross and insidious SCE and chromosome alterations.