Getting the lead out of gasoline has been credited for reducing the lead people breath in urban America. A new study suggests that in some areas, urban incinerators were the primary source for atmospheric lead. A team of researchers led by Steven Chillrud of Columbia University, analyzed the lead content in core samples taken from New York's Central Park Lake. They discovered that atmospheric lead peaked from the late 1930s to the early '60s - the same period operation of incinerators peaked there. Lead from gasoline use peaked in the late '60s and early '70s. It contributed a "relatively small fraction" of the lead deposited.