Dose–response relationship, kinetics of formation, and persistence of S‐[2‐(N 7 ‐guanyl)‐ethyl]glutathione–DNA adduct in livers of channel catfish ( Ictalurus punctatus ) exposed in vivo to ethylene dichloride

Formation of DNA adducts by reactive chemicals or their metabolites are often a precursor of mutagenesis and other adverse effects. Studies in juvenile channel catfish ( Ictalurus punctatus ) were conducted to determine the dose–response, kinetics of formation, and persistence of S‐[2‐(N 7 ‐guanyl)ethyl]glutathione hepatic–DNA adducts following a 4‐h in vivo aqueous exposure to ethylene dichloride (EDC) at several dose levels. S‐[2‐(N 7 ‐guanyl)ethyl] glutathione adducts were detectable in liver tissue after 2 h of exposure and were still detectable three weeks after a single pulse exposure (detection limit = ∼10 fmol, ∼1 DNA adduct in 10 7 bases). Pretreatment of catfish with the glutathione‐depleting agent diethylmaleate significantly reduced the level of tissue glutathione levels and, as a result, DNA adducts were not detected in pretreated fish. Catfish may serve as a useful sentinel species for detecting DNA‐reactive chemicals in aquatic systems. Environ. Toxicol. Chem. 2010;29:1537–1544. © 2010 SETAC