1,2-Dibromo-3-chloropropane (DBCP)-induced toxicity was studied in rat germ cells from different stages of spermatogenesis, separated by centrifugal elutriation, and in Sertoli cells prepared from sexually mature and immature animals. The in vitro metabolic activation of 50 to 250 microM DBCP, measured as covalent binding of 14C-DBCP to macromolecules, was highest in round spermatids, lowest in Sertoli cells and elongating/elongated spermatids, and intermediate in spermatocytes. High concentrations of DBCP (> or = 250 microM) caused a decrease in oxygen consumption and mitochondrial rhodamine 123 uptake, indicating an effect on mitochondrial function. Altered Sertoli cell function, measured as detachment of germ cells in Sertoli-germ cell cocultures, was evident at DBCP concentrations > or = 300 microM. DBCP-induced DNA damage occurred at much lower concentrations (10 to 30 microM) when compared to effects on mitochondrial function and Sertoli cell function. The extent of single strand DNA breaks and alkali-labile sites (ssDNA breaks) measured by the alkaline filter elution technique and the single cell gel electrophoresis assay, were greatest in the round spermatids > spermatocytes = Sertoli cells > elongating/elongated spermatids. The study demonstrates that various testicular cell types show differences in their rates of activation of DBCP to metabolites that bind to macromolecules. DNA is a more sensitive intracellular target in DBCP-induced testicular toxicity than mitochondria. Round spermatids appear to be more susceptible to DBCP-induced ssDNA breaks than spermatocytes, elongating/elongated spermatids, or Sertoli cells.