Chloroform (CHCl3)-induced hepato- and nephrotoxicity was evaluated in male, Fischer 344 rats pretreated with various dosages (1.0 to 15.0 mmol/kg, po) of acetone (Ac), 2-butanone (Bu), 2-pentanone (Pn), 2-hexanone (Hx), or 2-heptanone (Hp). The CHCl3 challenge dosage (0.5 ml/kg, ip) produced slight