Rachel Carson startled the world 25 years ago with dire warnings about pesticides. Her landmark book, ``Silent Spring,'' predicted massive destruction of the planet's fragile ecosystems unless more was done to halt the ``rain of chemicals.''
Today, some of the compounds she railed against, such as DDT, have been yanked from the market. But pesticide use in the United States has more than doubled since the early 1960s.
And it continues to grow worldwide, with many countries still using pesticides banned or restricted in the US. Meanwhile, a newer generation of chemicals - once thought more congenial to the environment - are presenting problems that scientists are only beginning to understand.
In retrospect, the publication of a book such as ``Silent Spring'' was inevitable. The chemical pesticide industry grew rapidly after World War II, churning out products that promised everything from bumper crops to bug-free patios.
The chemicals truly were ``wonder'' products: cheap, easy to use, and extremely effective.
But by the 1960s, evidence was mounting that linked chlorinated hydrocarbons - a group of chemicals which includes DDT - to the decimation of some forms of wildlife. The chemicals were often overused, sometimes applied at many times the recommended dosage and several times in a season. Chlorinated hydrocarbons do not dissolve in water, but rather persist in the environment and accumulate in animal tissues.
Dr. Carson focused on these chemicals, which dominated the market at that time. The fact that she was a recognized naturalist, with a knack for describing the wonders of the natural world, helped carry her message home to the average reader.
``In the early 1960s, any environmental concern was considered almost unpatriotic,'' says Maureen Hinkle, director of agricultural policy at the National Audubon Society. The legacy of Carson, she says, is the heightened awareness she created for all ecological issues.
The most direct result of Carson's work was the cancellation of DDT's registration in 1971. All pesticides must be registered for use with the federal government. The action had the effect of pulling it off the market.
When Carson was writing, the largest use of pesticides was to kill insects. But over the years, insecticide use has held relatively steady, while the use of herbicides to kill unwanted plants has exploded.
In shifting away from chlorinated hydrocarbons, the pesticide industry relied on a group of chemicals that dissolve in water. These products are often designed to be used in small amounts that kill fast and then break down into less dangerous substances.
``Where we used to talk about 5, 6, or 10 pounds per acre, we now think in terms of ounces per acre, even grams per acre,'' says Jack Early, president of the National Agricultural Chemicals Association.
Dr. Early says that as researchers learn more about pests, they can tailor chemicals that kill selectively. Indeed, one of the things that upset Carson the most was the indiscriminate nature of the early pesticides, which killed birds and honeybees along with pests.
But new pesticides have brought new problems. For example, water-soluble chemicals that break down in days or weeks when exposed to air and sunlight are washed into the soil by rain and find their way into underground water. Once in ground water, the chemicals degrade very slowly, if they break down at all.
``A decade ago, people thought that these complex chemicals would bind to the soil or somehow miraculously disappear,'' says Erik Olson, a pesticide specialist at the National Wildlife Federation.
In Iowa, state officials figure 27 percent of the population is exposed to pesticide-laced drinking water at some point during the year. And in a federal study released in 1985, the Environmental Protection Agency reported finding 17 types of pesticide residues in ground-water samples from 23 states.
``People are starting to view this as a personal violation, the way they did with DDT in Rachel Carson's day,'' Mr. Olson says.
Ground-water contamination is already a hot topic in Washington. The nation's basic pesticide safety law is up for renewal in Congress, and environmentalists hope to expand it to include protection for ground water.
The law, known as the Federal Insecticide, Fungicide, and Rodenticide Act, or FIFRA, was originally designed to protect consumers from bogus pesticides. Over the years, amendments were tacked on that broadened its scope to include health concerns. But critics contend that it needs major revisions.
FIFRA specifies that the risks from pesticides should be balanced against the economic and health benefits derived from their use. No other environmental law allows for such balancing.
``We don't have a pesticide control law in this country, we have a marketing tool that keeps products on the shelves as long as possible,'' says Jay Feldman, a spokesman for the National Coalition Against the Misuse of Pesticides.
FIFRA was almost renewed in the last session of Congress. But a coalition of industry and environmental interests collapsed in the final rush to pass the bill.
Even if FIFRA is renewed, federal regulators face formidable challenges in carrying out its mission.
``Our main problem is the older pesticides, the ones registered in the '40s, '50s, and even through the '60s,'' says John Moore, assistant administrator for pesticides and toxic substances in the Environment Protection Agency. Only sketchy health and safety data are available for many of these chemicals. And since the science is continually advancing, gaps emerge as more is learned about the newer pesticides.
Since 1972, when Congress mandated a major review of pesticides, only two of the 600 active ingredients used in the 50,000 pesticide products now on the market have been fully reassessed. At the current pace, it could take 20 years to finish the job.
The EPA has also just begun looking at the 1,200 inert ingredients that are mixed with active toxins to make pesticides. And reassessment is only the first step. If the agency identifies a problem with a pesticide, it has several options, such as restricting its use or canceling its registration. The EPA can take an emergency action to ban a pesticide outright, but this is seldom done.
Under US law, the government has to ``indemnify'' manufacturers when it suddenly bans sale of a pesticide.
This means that US taxpayers pay the market price for all the unsold stock as well as the cost of storage and disposal. Manufacturers say this is crucial to their business, since the many tests now required have pushed the cost of developing pesticides into the stratosphere. It now costs more than $45 million to develop a new pesticide, compared with about $1 million in the 1950s.
In the case of ethylene dibromide, or EDB, which was banned in 1984, EPA figures it will cost at least $60 million to get rid of the surplus stock. That about equals the federal agency's entire pesticide program budget.
Still, the EPA's Dr. Moore insists that the US has come a long way since Carson's book was published.
``We've made more progress on some things, and less on others,'' he says. But the major change has been the greater willingness on all sides to consider the consequences of introducing new chemicals into the environment.
Next: The global pesticide market
Pesticide facts and figures
Pesticide use in the United States has more than doubled since 1962. More than 1.1 billion pounds of active ingredients are applied each year to kill insects, weeds, and other pests.
The biggest pesticide consumers are farmers, and their share of the US market has grown. Farmers used about 60 percent of all pesticides in the early 1960s, but now account for 77 percent.
Agricultural pesticides are a $4.6 billion-a-year business in the US, while the global market is estimated at $18 billion.
Pesticides are used in 75 million US homes and by 40,000 commercial pest-control companies. Technically, even a toilet-bowl cleaner is a pesticide and must be registered as such with the US Environmental Protection Agency.
Some controversial chemicals, such as DDT, are no longer used in the US but continue to be used in developing countries.
Federal efforts to reassess the older pesticides are moving at a snail's pace. The EPA has fully reevaluated only two of the 600 active ingredients that are used to make pesticide products.
How Rachel Carson came to write `Silent Spring'
``Silent Spring'' was making waves long before it hit bookstores in the fall of 1962.
The New Yorker serialized it during the summer of that year, and most major news publications carried opinion pieces about it. Rachel Carson was widely praised, but some accused her of exaggerating the problems associated with pesticides.
Ironically, Dr. Carson didn't even want to do the book. Her specialty was writing about nature, especially the sea, and she had plans to write a philosophical book about man's efforts to tame the environment. A pesticide project would only get in the way.
Then, in 1957, she got a letter from a friend in Duxbury, Mass., who had witnessed firsthand the effects of aerial spraying of DDT. The birds in her friend's backyard were dying.
Carson began probing, examining the evidence that was then available about the effects of the new chemical pesticides. What she discovered profoundly disturbed her.
She thought of doing a magazine expos'e, but none of the editors she contacted were interested.
E.B. White, one of Carson's friends, encouraged her to keep at it, and gradually the project snowballed into a book.
It became an international best seller and was translated into several European languages. The book was later published in Brazil, Japan, and Israel.
Carson never lived to see the establishment of the Environmental Protection Agency or the withdrawal of DDT from the American market in 1971. She died in 1964.