Validation of single cell gel assay in human leukocytes with 18 reference compounds

To validate the alkaline single cell gel (SCG) assay as a tool for the dete ction of DNA damage in human leukocytes, we investigated the in vitro activ ity of 18 chemicals. Thirteen of these chemicals (pyrene (PY), benzo(a)pyre ne (BaP), cyclophosphamide (CP), 4-nitroquinoline-1-oxide (4NQO), bleomycin (BLM), methylmercury chloride (MMC), mitomycin C (MTC), hydrogen peroxide (HP), diepoxybutane (DEB), glutaraldehyde (GA), formaldehyde (FA), griseofu lvin (GF), sodium azide (NA)) are genotoxic in at least one cell system, wh ile five compounds (ascorbic acid (AA), glucose (GL), D-mannitol (MAN), O-v anillin (VAN), chlorophyllin (CHL)) are classified as non-genotoxic. In thi s in vitro SCG assay, PY, BaP and CP were positive with exogeneous metaboli c activation (rat S9 mix) while 4NQO, BLM, MR;IC, MTC, hydrogen peroxide, a nd diepoxbutane were positive in the absence of metabolic activation. CHL a nd VAN were unexpectedly found to induce a dose-dependent increase in DNA. migration. AA, GL, and MAN were negative in a non-toxic range of doses. GF gave equivocal results, while FA and GA increased DNA migration at low dose s and decreased DNA migration at higher doses. This behaviour is consistent with the known DNA damaging and crosslinking properties of these compounds . These data support the sensitivity and specificity of this assay for iden tifying genotoxic agents. (C) 2000 Elsevier Science B.V. All rights reserve d.