TOXIC WASTE - Lex’s (Michael Rosenbaum) secret experiment at Luthorcorp goes awry and causes a dangerous toxin to be released into Smallville. Those infected by the toxin, including Clark (Tom Welling), Lana (Kristin Kreuk), Lex, and Jason (Jensen Ackles) imagine their greatest fears come true and then fall into a coma. Desperate to find a cure, Clark gives some of his blood to Lex and is stunned at what Lex does with the antidote. Allison Mack, John Glover, Annette O’Toole and John Schneider also star. David Carson directed the episode written by Kelly Souders and Brian Peterson (#410).