In the mid-1940s, Carson became concerned about the use of synthetic pesticides, many of which had been developed through the military funding of science since World War II. The United States Department of Agriculture's 1957 fire ant eradication program, which involved aerial spraying of DDT and other pesticides mixed with fuel oil and included the spraying of private land, prompted Carson to devote her research, and her next book, to pesticides and environmental poisons. Landowners in Long Island filed a suit to have the spraying stopped, and many in affected regions followed the case closely. Though the suit was lost, the Supreme Court granted petitioners the right to gain injunctions against potential environmental damage in the future, laying the basis for later environmental actions.
The impetus for Silent Spring was a letter written in January 1958 by Carson's friend, Olga Owens Huckins, to The Boston Herald, describing the death of birds around her property resulting from the aerial spraying of DDT to kill mosquitoes, a copy of which Huckins sent to Carson. Carson later wrote that this letter prompted her to study the environmental problems caused by chemical pesticides.
The Washington, D.C. chapter of the Audubon Society actively opposed chemical spraying programs and recruited Carson to help publicize the U.S. government's spraying practices and related research. Carson began the four-year project of Silent Spring by gathering examples of environmental damage attributed to DDT. She tried to enlist essayist E. B. White and a number of journalists and scientists to her cause. By 1958, Carson had arranged a book deal, with plans to co-write with Newsweek science journalist Edwin Diamond. However, when The New Yorker commissioned a long and well-paid article on the topic from Carson, she began considering writing more than the introduction and conclusion as planned; soon it became a solo project. Diamond would later write one of the harshest critiques of Silent Spring.
As her research progressed, Carson found a sizable community of scientists who were documenting the physiological and environmental effects of pesticides. She took advantage of her personal connections with many government scientists, who supplied her with confidential information on the subject. From reading the scientific literature and interviewing scientists, Carson found two scientific camps; those who dismissed the possible danger of pesticide spraying barring conclusive proof and those who were open to the possibility of harm and were willing to consider alternative methods, such as biological pest control.
By 1959, the USDA's Agricultural Research Service responded to the criticism by Carson and others with a public service film, Fire Ants on Trial; Carson called it "flagrant propaganda" that ignored the dangers that spraying pesticides posed to humans and wildlife. That spring, Carson wrote a letter, published in The Washington Post, that attributed the recent decline in bird populations—in her words, the "silencing of birds"—to pesticide overuse. The same year, the 1957, 1958, and 1959 crops of U.S. cranberries were found to contain high levels of the herbicide aminotriazole and the sale of all cranberry products was halted. Carson attended the ensuing FDA hearings on revising pesticide regulations; she was discouraged by the aggressive tactics of the chemical industry representatives, which included expert testimony that was firmly contradicted by the bulk of the scientific literature she had been studying. She also wondered about the possible "financial inducements behind certain pesticide programs".
Research at the Library of Medicine of the National Institutes of Health brought Carson into contact with medical researchers investigating the gamut of cancer-causing chemicals. Of particular significance was the work of National Cancer Institute researcher and founding director of the environmental cancer section Wilhelm Hueper, who classified many pesticides as carcinogens. Carson and her research assistant Jeanne Davis, with the help of NIH librarian Dorothy Algire, found evidence to support the pesticide-cancer connection; to Carson the evidence for the toxicity of a wide array of synthetic pesticides was clear-cut, though such conclusions were very controversial beyond the small community of scientists studying pesticide carcinogenesis.
By 1960, Carson had sufficient research material and the writing was progressing rapidly. She had investigated hundreds of individual incidents of pesticide exposure and the resulting human sickness and ecological damage. In January 1960, she suffered an illness which kept her bedridden for weeks, delaying the book. As she was nearing full recovery in March, she discovered cysts in her left breast, requiring a mastectomy. By December that year, Carson discovered that she had breast cancer, which had metastasized. Her research was also delayed by revision work for a new edition of The Sea Around Us, and by a collaborative photo essay with Erich Hartmann. Most of the research and writing was done by the fall of 1960, except for a discussion of recent research on biological controls and investigations of some new pesticides. However, further health troubles delayed the final revisions in 1961 and early 1962.
Its title was inspired by a poem by John Keats, "La Belle Dame sans Merci", which contained the lines "The sedge is wither'd from the lake, And no birds sing." "Silent Spring" was initially suggested as a title for the chapter on birds. By August 1961, Carson agreed to the suggestion of her literary agent Marie Rodell: Silent Spring would be a metaphorical title for the entire book—suggesting a bleak future for the whole natural world—rather than a literal chapter title about the absence of birdsong. With Carson's approval, editor Paul Brooks at Houghton Mifflin arranged for illustrations by Louis and Lois Darling, who also designed the cover. The final writing was the first chapter, "A Fable for Tomorrow", which was intended to provide a gentle introduction to a serious topic. By mid-1962, Brooks and Carson had largely finished the editing and were planning to promote the book by sending the manuscript to select individuals for final suggestions. In Silent Spring, Carson relied on evidence from two New York state organic farmers, Marjorie Spock and Mary Richards, and that of biodynamic farming advocate Ehrenfried Pfeiffer in developing her case against DDT.
Frank Edwin Egler was a contributor to the book.