Barry Commoner, a visionary scientist and author who helped launch the environmental movement in the United States and whose ideas influenced public thinking about nuclear testing, energy consumption and recycling, died Sept. 30 at a hospital in New York. He was 95 and lived in Brooklyn.

His wife, Lisa Feiner, said she could not cite a specific cause of death.

Dr. Commoner was among the first scientists to take his findings into the public sphere and draw attention to what he considered a looming environmental disaster. His background as a scientist lent credence to his ideas, but throughout his career he coupled his scientific findings with a call to political action and even ran for president in 1980 on the ticket of the Citizens Party.

In the 1950s, Dr. Commoner was sounding alarms about the environmental consequences of industrial pollution, modern technology and the testing of nuclear weapons. He was among the first scientists to step out of the laboratory and declare that scientists had a moral obligation to keep the public informed about the dangers posed by advances in science and technology.

He challenged the petroleum industry and, long before it became politically fashionable, touted solar power as the long-term solution to the world’s energy problems.

A biologist by training, Dr. Commoner showed that traces of radioactive materials could be found in the teeth of thousands of children. With Nobel laureate Linus Pauling, he circulated a petition in the 1950s calling for an end of atmospheric testing of nuclear weapons. More than 11,000 scientists signed the petition.

He was credited with creating the momentum that led to the passage of the Nuclear Test Ban Treaty between the United States and the Soviet Union in 1963.

Along with “Silent Spring” author Rachel Carson, Sierra Club leader David Brower and scientist-author Aldo Leopold, Dr. Commoner is considered one of the primary founders of the modern environmental movement.

Time magazine put Dr. Commoner on its cover in 1970, saying he “has probably done more than any other U.S. scientist to speak out and awaken a sense of urgency about the declining quality of life.”

Consumer advocate Ralph Nader unequivocally describes Dr. Commoner as “the greatest environmentalist of the 20th century.”

“Nobody did what he did,” Nader said Tuesday in an interview. “He was a scientist, a best-selling author, a brilliant writer whose books are still read today. He ran for president. There was a tremendous variety to his efforts. When I say he’s the greatest environmentalist, it isn’t even close.”

A longtime professor at Washington University in St. Louis, Dr. Commoner was one of the country’s most visible public intellectuals during the 1960s and 1970s. His books sold hundreds of thousands of copies, he often appeared on television talk shows, and listeners flocked to his lectures throughout the country.

In one of his best-known books, “The Closing Circle” (1971), Dr. Commoner linked ecological dangers to technological advances. He argued that environmental dangers always disproportionately affect poor people and that companies should be held responsible for creating clean industrial processes.

The book contained several ideas that have since become commonplace, including “sustainability,” a concept of resource management that is now applied to energy consumption, economics, the environment and finance.

“The Closing Circle” also introduced what Dr. Commoner called the four laws of ecology: “Everything is connected to everything else. Everything must go somewhere. Nature knows best. There is no such thing as a free lunch.”

He wrote essays for magazines and newspapers, and he appeared on countless talk shows throughout the 1970s, leading other scientists to complain that he was a publicity hound who was straying into fields in which he was not an expert.

The celebrated anthropologist Margaret Mead came to Dr. Commoner’s defense. “There are those who are sheltered in their narrow expertise,” she told the New York Times Magazine in 1976, “and those who will take responsibility for the well-being of the planet.”

Barry Commoner was born May 28, 1917, in Brooklyn to Jewish immigrants from Russia. His father was a tailor before he lost his sight, and his mother was a seamstress.

He was interested in nature from childhood and collected specimens from neighborhood parks to examine under his microscope.

He graduated in 1937 from Columbia University with a bachelor’s degree in zoology and then went on to Harvard University, where received a master’s degree in biology in 1938 and doctorate in cellular biology in 1941.

After teaching at Queens College in New York, Dr. Commoner served as a Navy science officer during World War II. In one of his assignments, he studied the effects of DDT, discovering that it didn’t kill the mosquitoes for which it was intended but killed off thousands of fish instead.

In 1947, Dr. Commoner began teaching at Washington University and doing research in plant physiology and the genetic makeup of a virus affecting the tobacco plant. His work led to advances in immunization and the development of protective antibodies.

He became known for his outspoken manner and for urging scientists to enter the public sphere. In 1980, he was on the ballot in 29 states as the presidential candidate of the Citizens Party, winning more than 230,000 votes.

Dr. Commoner moved to Brooklyn in 1980 and was director of the Center for the Biology of Natural Systems, which he founded in 1966. He retired in 2000 but continued to write and lecture in his later years. His books include “The Poverty of Power” (1976), “The Politics of Energy” (1979) and “Making Peace With the Planet” (1990).

His marriage to Gloria Gordon ended in divorce.

Survivors include his wife of 32 years, Lisa Feiner of Brooklyn; two children from his first marriage, Lucy Commoner and Frederic Commoner; and a granddaughter.

In 2007, when Dr. Commoner turned 90, a New York Times reporter asked whether he had changed any of his views about energy, science and the environment.

“You mean have I made any mistakes?” Dr. Commoner replied. “Let me think a minute. The answer is no.”