Nature 266, 724 - 726 (21 April 1977); doi:10.1038/266724a0

Mutagenicity and toxicity of visible fluorescent light to cultured mammalian cells

MATTHEWS O. BRADLEY & NANCY A. SHARKEY

Laboratory of Molecular Pharmacology, Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20014

MANY cultured mammalian cells are characterised by karyotypic instability, high rates of spontaneous transformation and high frequencies of background mutation. The toxicity of visible light for mammalian cells¹⁻⁴ is usually attributed to photochemical reactions between light and the culture medium, and riboflavin, tryptophan and tyrosine are often thought to mediate this toxicity¹⁻³. Light has been shown to produce strand breaks in DNA^5,6. Because many tissue culture operations are conducted under fluorescent light, we have investigated whether the toxicity and DNA strand-breaking activity of light are accompanied by mutagenicity. We report here that this is the case.

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