In 1962, environmental scientist Rachel Carson published her book Silent Spring, which argued that overuse of pesticides was damaging the environment and threatening human health. Carson did not call for a ban on DDT, the most widely used pesticide at the time, but he advocated more selective use of it and similar products and attention to their effects on non-target species.
Silent Spring is widely regarded as an inspiration for the modern environmental movement. These articles from The Conversation archives focus on persistent questions about pesticides and their effects.
1. Against absolutes
Although the chemical industry attacked Silent Spring as anti-science and anti-progressive, Carson believed that chemicals had a place in agriculture. Harvard University sustainability scientist Robert Paarlberg writes that he “favored the moderate use of pesticides, but not their complete elimination, and he did not oppose the judicious use of manufactured fertilizers.”
This approach put Carson at odds with the nascent organic movement, which completely rejected synthetic pesticides and fertilizers. Early organic advocates nevertheless claimed Carson’s side, but Carson kept them at arm’s length. “The organic farming movement was suspect in Carson’s eyes because most of its early leaders were not scientists,” notes Paarlberg.
This disagreement is echoed today in debates over whether organic production or sustainable improvements in conventional farming have the greater potential to feed a growing world population.
2. Concerned farmers
Long before Silent Spring was published, a crop dusting industry developed in the Great Plains in the post-World War II years to apply newly commercialized pesticides. “Chemical companies made big promises about these ‘miracle’ products, but said little about the risks. But pilots and scientists began to take a more cautious approach,” says David Vail, a historian at the University of Nebraska-Kearney.
As Vail’s research shows, many crop duster pilots and university agricultural scientists were well aware of how little they knew about how these new tools actually worked. They attended conferences, discussed pesticide application practices, and organized flying schools that taught agricultural science along with spraying techniques. When Silent Spring was published, many of these practitioners pushed back, claiming that they had developed strategies for managing pesticide risks.
Today, aerial spraying is still practiced in the Great Plains, but it’s clear that bugs and weeds are rapidly developing resistance to each new generation of pesticides, trapping farmers in what Vail calls a “chemical pest escape.” Carson anticipated this effect in Silent Spring and called for more research into alternative pest control methods—an approach that has become mainstream today.
3. Osprey crash and recovery
In Silent Spring, Carson described in detail how chlorinated hydrocarbon pesticides remain in the environment for a long time after being sprayed, passing through the food chain and accumulating in the bodies of predators. Populations of fish-eating predators such as bald eagles and ospreys have been decimated by these chemicals, which thin the shells of the birds’ eggs and break them in the nest before hatching.
“Until 1950, ospreys were one of the most widespread and abundant falcons in North America,” writes Cornell University researcher Alan Poole. “By the mid-1960s, the number of ospreys breeding along the Atlantic coast between New York and Boston had declined by 90%.”
Bans on DDT and other highly persistent pesticides have opened the door to recovery. But by the 1970s, many old osprey nesting sites had been developed. To compensate, concerned naturalists built nesting posts along the coast. Ospreys have also learned to colonize light poles, cell towers, and other man-made structures.
Today, “On the shores of the Chesapeake Bay, about 20,000 ospreys now come to nest each spring—the largest concentration of breeding pairs in the world. Two-thirds of them nest on buoys and channel markers maintained by the U.S. Coast Guard, effectively becoming osprey watchdogs,” Poole writes. “Regaining strong numbers of this species is a reward for everyone who values wildlife and a reminder of how nature can bounce back if we address key threats.”
4. New concerns
Pesticide application methods have become more targeted in the 60 years since Silent Spring was published. A prominent example: crop seeds coated with neonicotinoids, the world’s most widely used class of insecticides. Seed coating allows pesticides to be introduced into the environment where they are needed without spraying a single drop.
But a growing body of research shows that even though coated seeds are highly targeted, much of their pesticide load is washed into nearby rivers and lakes. “Studies show that neonicotinoids poison and kill aquatic invertebrates, a vital food source for fish, birds and other creatures,” Penn State entomologist John Tooker writes.
In multiple studies, Tooker and colleagues found that using coated seeds reduced populations of beneficial insects that prey on crop-destroying pests, such as slugs.
“As I see it, neonicotinoids can provide good value for critical pest species, especially in vegetable and fruit production and in the management of invasive species such as spotted lanternfly. However, I believe the time has come to curb their use as seed covers in field crops such as corn and soybeans, where they provide little benefit and the scale of use causes the most critical environmental problems,” Tooker writes.
Editor’s note: This story is a compilation of articles from The Conversation archives.
Jennifer Weeks, Senior Environment + Energy Editor, Conversation
This article is republished from The Conversation under a Creative Commons license. Read the original article.