Rachel Carson's (1962) Silent Spring was a pivotal book in the twentieth century and the springboard for the modern environmental movement both in the United States and internationally. As a scientist, Carson was not opposed to DDT, but she did have concerns about its increased use without greater public awareness or knowledge of its full impact. Environmental historian Anthony Penna wrote: Deafening noise, the unbearable smell of rotting draft animal carcasses, the bloody remains of slaughtered cows and pig running in the gutters and alley-ways, and human waste from overflowing cesspools, cellars and privy vaults were a constant reminder of urban decay. As populations and cities grew, even developing nations increasingly struggled with environmental degradation, including air and water pollution. First coal and later automobiles would become prime pollution sources in cities around the world.