Try this:

    def FindLabel ([cis12DCE],[cis12DCE_Ex]):
      if int([cis12DCE_Ex]) == 1:
        return "<clr red = '255'>"+"cis-1,2-Dichloroethylene  "+str([cis12DCE])+"</clr>"
      else:   
        return "cis-1,2-Dichloroethylene  "+str([cis12DCE])