But Carson also described the accumulation of synthetic chemicals in people—including newborns—and these chemicals' interaction with the innermost workings of living cells. "For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death," Carson wrote. "These chemicals are now stored in the bodies of the vast majority of human beings, regardless of age. They occur in the mother's milk, and probably in the tissues of the unborn child," wrote Carson more than 40 years before an Environmental Working Group study found 287 industrial chemicals in newborns' umbilical cord blood, and decades before the Centers for Disease Control and Prevention began finding such chemicals in the majority of Americans tested.
Now almost every day brings a new report detailing health hazards associated with synthetic chemicals. Exposure to some of these substances has been linked to increasingly widespread chronic health problems, among them diabetes, obesity, and reproductive and neurological disorders. We've learned that some chemicals' adverse effects can be prompted by exceptionally low levels of exposure that occur before birth and that these biochemical alterations can be so profound that a single exposure may affect several generations. That synthetic chemicals are found routinely in human blood samples and throughout our food and water supply has become a commonplace.
We also know that chemicals like those Carson chronicled can build up in fat tissue. We know that timing of a chemical exposure is critical to its effects on health and that children are uniquely vulnerable to such exposures. The details of our knowledge of toxicity have expanded immensely but Carson described many of these effects as well: "While the quantities so received by human infants would normally be small, they are not unimportant because children are more susceptible to poisoning than adults. This situation also means that today the average individual almost certainly starts life with the first deposit of the growing load of chemicals his body will be required to carry thenceforth." Fifty years later our chemicals management policies are struggling to accommodate this reality.
"There are vast gaps in our knowledge," Carson acknowledged. She also warned that a lack of information could not be taken as proof of safety. "However, there is every indication of long storage in the human body, where deposits may lie dormant like a slumbering volcano," she wrote. "There has been no such parallel situation in medical history. No one yet knows what the ultimate consequences may be."
Carson wrote all of this in 1962—a time so different technologically and socially that it now almost seems a universe away. John F. Kennedy was president. The Cuban Missile Crisis was looming. The escalation of US military personnel in Vietnam had begun, growing from about 700 to more than 11,000 in the course of the year. In 1962, James Watson and Francis Crick were awarded the Nobel Prize in Physiology or Medicine for their work describing the double-helix structure of DNA. It was a year before Martin Luther King Jr.'s "I Have a Dream Speech" and three years before passage of the Voting Rights Act. Chubby Checker and Elvis Presley topped the Billboard Charts, with the Beach Boys and Peter, Paul and Mary bringing up the rear. In Vietnam, Operation Ranch Hand (originally called Operation Hades) was underway, conducting aerial spraying of defoliants—largely the dioxin-laden herbicide known as Agent Orange—across the countryside. The Clean Air Act, Clean Water Act, and Endangered Species Act did not yet exist, nor did the Occupational Safety and Health Administration. There was no such thing a Superfund site. Industrial plants were not required to account for their releases of toxic pollutants. There was no federal law to protect communities from hazardous waste or to protect Americans' right to know the chemicals to which they might be exposed. U.S. law did regulate how pesticides were labeled but it did not yet regulate their use. And imperfect as it has been, there was not yet a Toxic Substances Control Act to regulate chemicals in commerce. Silent Spring and the outcry it prompted—among the public and lawmakers—helped give rise to the modern American environmental movement and led to passage of our landmark pollution prevention laws.