John R. Froines, Chemist and Member of the Chicago Seven, Dies at 83

John R. Froines, a quiet but politically stalwart chemist who stood trial alongside six other antiwar activists — known collectively as the Chicago Seven — on charges of conspiring to incite a riot during the 1968 Democratic National Convention, and who went on to become a pioneering advocate for environmental justice, died on Wednesday in Santa Monica, Calif. He was 83.

His wife, Andrea Hricko, said the death, at a hospital, was caused by complications of Parkinson’s disease.

A recently minted Yale Ph.D. on his way to teach chemistry at the University of Oregon, Dr. Froines found himself drawn into the swirl of antiwar activism building up to the Democratic convention, to be held in August 1968 at Chicago’s International Amphitheater.

Tom Hayden and Rennie Davis, two of the protest organizers, knew Dr. Froines through his work in Connecticut with the New Haven chapter of Students for a Democratic Society, and they invited him to join their inner circle.

During the convention, tens of thousands of protesters marched in the streets and hundreds were arrested during violent clashes with the Chicago Police Department. But only eight were indicted under federal charges of crossing state lines to incite a riot; they included Mr. Hayden, Mr. Davis and Dr. Froines, who was also charged with building an incendiary device, accused of having shown three women how to make a stink bomb.

Several of those charged were already famous as radical activists and counterculture provocateurs. Bobby Seale had co-founded the Black Panther Party in 1966; Abbie Hoffman and Jerry Rubin, co-founders of the Youth International Party, or the Yippies, were renowned for antics like dropping wads of cash onto the floor of the New York Stock Exchange from the visitors gallery.

The defendants were originally known as the Chicago Eight, but became the Chicago Seven when the judge in the case, Julius Hoffman — no relation to Abbie — had Mr. Seale legally severed from the group to be tried separately. (In an extraordinary move, the judge had earlier ordered Mr. Seale bound and gagged for several days in the courtroom after Mr. Seale’s repeated protests over his treatment by the court. He was later jailed for contempt.)

Though the men stood in solidarity, Dr. Froines stuck out as particularly straight-laced and earnest, especially in contrast to the likes of Mr. Hoffman, who treated the trial with comic disdain, putting his feet on a table and referring to Judge Hoffman as his illegitimate father.

“John was straight,” Lee Weiner, one of the defendants, said in a phone interview. “I’m not going to say we didn’t get along, because that’s not true. But I never had an impulse to say to John, ‘Let’s go smoke some dope.’”

Despite what many saw as clear bias against the defendants by Judge Hoffman, in 1970 the jury acquitted Dr. Froines and Mr. Weiner of all charges. An appeals court later dismissed most of the charges against the others.

Dr. Froines eventually returned to academia, then worked for several years in Washington for the Occupational Safety and Health Administration. Under his direction, the agency wrote the first regulatory guidelines for non-carcinogenic toxins like lead and cotton dust, setting the stage for dramatic increases in workplace and public health.

He did much the same at the University of California, Los Angeles, where he moved in 1981. He directed numerous university research centers and sat on the state’s scientific review panel for air quality.

And he engaged with communities hit hard by industrial pollution and smog, tailoring his research to their needs and even accompanying neighborhood groups to meet with government and corporate officials.

“When you walk into a room with an internationally recognized expert on an issue, it makes a difference,” Angelo Logan, co-founder of one such organization, the California-based East Yard Communities for Environmental Justice, said in a phone interview. “John’s work was driven, driven to make real differences in people’s lives.”

John Radford Froines was born on June 13, 1939, in Oakland, Calif. His father, George, a shipyard worker, was murdered when John was 3, leaving his mother, Katherine (Livingston) Froines, a teacher, to raise him and his brother, Robert, by herself.

After graduating from high school, he joined the Air National Guard, then earned an associate degree from Contra Costa Community College. He went on to the University of California, Berkeley, where he received a bachelor’s degree in chemistry in 1962.

It was at Yale, where he pursued a doctorate, that he first became involved in politics. He started as a moderate, chairing the university chapter of Students for Johnson during the 1964 presidential campaign.

But, like many young people, he soured on the president after Johnson followed his landslide victory that fall with a massive expansion of the war in Vietnam. Mr. Froines joined the local branch of S.D.S., helping to organize poor white and Black residents in the city’s Hill neighborhood.

He met his first wife, Ann (Rubio) Froines, through the organization. They later divorced. In addition to his wife, Ms. Hricko, he is survived by his daughter, Rebecca Froines Stanley, and his son, Jonathan.

After his acquittal, Dr. Froines resigned from his position at the University of Oregon to continue his antiwar activism. He went back to New Haven to support the Black Panther Party during a series of trials against Mr. Seale and others, and in 1971 he helped organize the May Day antiwar protests in Washington, D.C.

The next year, he returned to academia as a professor at Goddard College, in Plainfield, Vt. He later worked for Vermont’s department of occupational health for two years before moving to Washington.

Dr. Froines’s death leaves just two surviving members of the Chicago Eight, Mr. Seale and Mr. Weiner.

The trial of the Chicago Seven became a touchstone of the era, one repeatedly mined for its historical significance. Two movies have been made about the case, most recently “The Trial of the Chicago Seven” (2020), written and directed by Aaron Sorkin, with Danny Flaherty playing Dr. Froines.

It was a personal legacy that left Dr. Froines with mixed feelings. He remained as committed to social justice as he had been in his youth, he said, but he had left his activist days behind and was eager to be known better for his work regulating lead than for standing in court beside Abbie Hoffman.

“No one is the same now as then,” he told The Los Angeles Times in 1990. “We still need student protesters because many of the problems of the ’60s continue and new issues have emerged. But nobody’s a student activist at 50. You’d have to have your head examined.”