Born in Springdale, Rachel Carson offered an enviromental warning with her book, "Silent Spring." Click photo for larger image. Celebrating her life To celebrate Rachel Carson's 100th birthday, visit the Carson Homestead in Springdale. Today's activities run from 12:30-5 p.m. and include a book signing by Carson biographer Mark Hamilton Lytle, and actor Kaiulani Lee who plays Carson in "A Sense of Wonder," which starts at 3 p.m. Find more information at www.rachelcarsonhomestead.org or call 724-274-5459. On Sept. 29 at Carnegie Mellon University, the inaugural Rachel Carson Legacy Conference will address the topic "Sustaining the Web of Life in Modern Society." Harvard University Professor Emeritus E.O. Wilson will present the keynote address. On Nov. 3, Chatham College will host a "Spirit and Nature Conference," a multi-faith gathering to discuss the reverence for nature contained in all world religions. For more on Carson, read "Rachel Carson: Witness for Nature" (Owl Books) by Linda Lear, and "The Gentle Subversive: Rachel Carson, Silent Spring and the Rise of the Environmental Movement" (Oxford University Press) newly released by Mark Hamilton Lytle. -- Scott Shalaway

"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."

So reads chapter 3, verse 1 in Rachel Carson's environmental classic, "Silent Spring" (Mariner Books). In the 45 years since "Silent Spring" sounded the alarm in 1962, not much has changed. And yet everything has changed.

We still live in a world infused with chemicals from agriculture and industry. The Pennsylvania Fish and Boat Commission issues periodic warnings against ingesting fish that may contain man-made pollutants, and hunting and fishing regulations take into consideration food-cycle contamination issues that weren't included 60 years ago. All of our bodies carry a load of chemicals that can't be healthy. Yet we're still here.

So the age of synthetic pesticides, which began after World War II with the widespread use of DDT, failed to inflict the apocalypse Carson feared. Or did it?

Rachel Carson was born 100 years ago today in Springdale. In 1929, she graduated from the Pennsylvania College for Women, now Chatham College, and earned a masters in zoology in 1932 at Johns Hopkins University.

Her book "Silent Spring" was a warning, a cautionary tale. It was not a bland summary of her own original research. Rather, it was a compellingly written synthesis of others' work. But it took Carson's voice for the message to be heard. In retrospect, Carson's concern for the long term impacts of chemical pesticides on human reproduction, cancer, immune systems, brain function, embryonic development and hormonal problems seems eerily prescient.

Life at every level on the planet persists because of its inherent genetic variability. Not all individuals of every species respond to every stimulus identically. Cigarettes don't kill everyone who smokes. Fatty foods don't kill all who eat them. Alcohol doesn't hook everyone who drinks it. Why not? It's because the combination of genes that make each of us unique responds individually and unpredictably to assaults that invariably harm some. Review any family tree for evidence of individual variation in response to environmental hazards.

The good news is that it's 2007, not 1952. At that time, synthetic chemicals were seen as the answer to everyone's prayers. Fogs of DDT were spayed on tree-lined neighborhoods and playgrounds to save Main Street's elm trees and eradicate mosquito-borne diseases. The government, which had just saved the world in a great war, told our parents and grandparents it was safe. Most believed what they were told.

Carson questioned the innocence of chemical pesticides. She articulated her fear of better living through chemistry in chapter 2 of "Silent Spring" -- "Only within the moment of time represented by the present century has one species -- man -- acquired significant power to alter the nature of his world."

Carson's worst fears were justified. Metabolites of DDT accumulated in fatty tissue of aquatic organisms and concentrated at the top of the food chain. Bald eagles, ospreys and peregrine falcons stopping reproducing because their egg shells became too thin and cracked during incubation. And after forests, towns and college campuses endured aerial spraying campaigns, song birds disappeared.

Spring was indeed silenced.

"Silent Spring" marks in my mind the beginning of the environmental movement. If Aldo Leopold, author of "A Sand County Almanac and Game Management" is the father of wildlife science, then Carson is the mother of environmentalism.

Earlier conservationists rallied to halt the slaughter of bison for meat and egrets for plumes, but Carson's concern was broader. She feared for the fate of the planet.

And despite what her critics say today, Carson understood that chemical pesticides, if applied wisely, could be useful.

"It is not my contention that chemical insecticides must never be used," she wrote. "I do contend that we have put poisonous and biologically potent chemicals into the hands of persons largely or wholly ignorant of their potentials for harm. We have subjected enormous numbers of people to contact with these poisons, without their consent and often without their knowledge. If the Bill of Rights contains no guarantee that a citizen shall be secure against lethal poisons distributed either by private individuals or by public officials, it is surely only because our forefathers, despite their considerable wisdom and foresight, could conceive of no such problem."

Carson became enamored of the sea and from 1936 to 1952 worked for the U.S. Bureau of Fisheries, now the Fish and Wildlife Service. Her first book, "Under the Sea-Wind" (Penguin) in 1941, established her as a scientist whose writing style captivated the general public.

In 1951, "The Sea Around Us" (Oxford University Press) began a run on the New York Times best-seller list that lasted for 81 weeks. Its success allowed Carson to resign her government job and devote herself to writing full time. Her third book, "The Edge of the Sea" (Peter Smith Publishing) was published in 1956. During that time, Carson developed an environmental ethic that fully manifested itself in "Silent Spring."

In 1963, Carson testified before Congress on the perils of pesticides. She died of cancer in 1964. The Environmental Protection Agency banned DDT in 1972. Her legacy lives on in every bald eagle, osprey and peregrine falcon that flies today.

Thank you, Ms. Carson.