Pesticide use in the San Joaquin Valley began in the 1880s when certain insects were known to be causing harm in the region, much of whose economy is still based on the successful agriculture and farming of many different kinds of crops. Pesticides illnesses were reported sporadically during that time frame, but was not focused as a major issue until the post World War II agricultural boom in the late 1940s when pesticide poisonings became more widely publicized. Though Rachel Carson's Silent Spring and the use of chemicals in weapons during the Vietnam War led the federal government to pass restrictions on pesticide use, residents, primarily of low-income, have struggled with health impacts of pesticide use due to persistent over-spraying by agriculture companies working for profit.