The pesticide malathion may have sickened 123 people last year when it was sprayed over two Florida communities to kill crop-eating Mediterranean fruit flies, the federal Centers for Disease Control and Prevention said yesterday. Rather than spraying only farmland, helicopters and airplanes blanketed large suburban areas with the pesticide. Malathion is used in several states to kill agricultural pests, and it was sprayed over New York City this summer to kill mosquitoes after an outbreak of encephalitis. The CDC said that none of the cases reported in Florida were severe, but it suggested using less toxic chemicals or pesticide-free approaches to pest control, such as introducing sterile males into the Medfly population to disrupt its reproduction.