Supported by

Nicholas Kristof

By Nicholas Kristof

Opinion Columnist

This essay is part of a series on environmental health.

It was back in 1958 that a chemical company first discovered that its new weed killer appeared toxic to humans, “mainly by affecting the central nervous system,” as one company scientist documented at the time.

The company kept its concerns to itself — as well as its later research indicating that large doses caused tremors in mice and rats. That’s because the herbicide, paraquat, was sublime at wiping out weeds. And profitable. Over the decades it became, an executive proudly declared, a “blockbuster.” By 2018, some 17 million pounds of it were used across the United States, double the figure for six years earlier.

As industry has boomed and agricultural and industrial toxins like paraquat have proliferated in the postwar period, so has something else: Parkinson’s disease. Once almost unknown, the ailment was first identified in 1817 when Dr. James Parkinson described a handful of elderly people with what he called “the shaking palsy.” That was in polluted London, and it’s now understood that air pollution is a risk factor for the disease.

Some 90,000 cases of Parkinson’s are now diagnosed each year in the United States, about one every six minutes on average. It is the world’s fastest-growing neurodegenerative disease, causing tremors, stiffness and balance problems. It is also the 13th-leading cause of death in the United States. One factor in its increase may be the way we have come to live, for there’s growing evidence linking it to a range of pesticides and industrial chemicals, including paraquat and substances used in dry cleaning.

“Chemicals in our food, water and air have created this largely man-made disease,” two Parkinson’s experts, Dr. Ray Dorsey and Dr. Michael S. Okun, write in a new book, “The Parkinson’s Plan.” “These chemicals are all around us, and none are necessary.”

Dorsey and Okun, who between them have published more than 1,000 papers and cared for more than 10,000 people with Parkinson’s, describe the disease as a pandemic, but one caused not by a virus but by “a new class of ‘vectors,’ including pesticides in our food, industrial solvents in our water and pollution in our air.”

Michael J. Fox, the actor who developed Parkinson’s and then started a foundation to tackle the disease, believes that’s how he most likely got the disease — an exposure to “some kind of chemical,” he said.

Yet for Fox and most others with the disease, causation remains murky and the mechanisms not fully understood. Genetics appear to play a role in only a small percentage of cases, while environmental factors appear dominant. Researchers and regulators dispute the degree to which pesticides bear responsibility, and the Environmental Protection Agency continues to allow paraquat to be used in the United States — even as dozens of other countries have banned it.

In that respect, paraquat symbolizes the challenges of environmental health and chemical regulation. Evidence accumulates, but invariably there are gaps and contradictions. Companies, following the tobacco playbook, hire lobbyists and highlight the uncertainties. And often the regulatory process drags on as companies make money and people get sick.

Meanwhile, there is a growing mountain of imperfect but troubling evidence. Just this year, a study found that living within a mile of a golf course more than doubles a person’s odds of developing Parkinson’s. One theory is that it is because golf courses use pesticides.

So how do we protect ourselves and our children? How do we avoid following in the footsteps of Steve Phillips, a successful leadership consultant who at age 56 was hosting a banquet for corporate executives when he noticed that his left hand wasn’t working properly? He thought it might be fatigue. But then he noticed that his left foot sometimes seemed stuck. Eventually, he was diagnosed with Parkinson’s.

“It pretty much ended my career,” Phillips, now 73, told me. “And I would say that it basically destroyed my marriage.” He initially didn’t know how he could have contracted the disease, and then he read the scientific research tying the disease to paraquat.

For two summers, when he was 16 and 17, Phillips had worked on a farm, spraying fields with paraquat. “I was a naïve teenager,” he recalled. “I had my sunglasses on and a bandanna around my face, and I thought that was all the protection I needed.”

So does Phillips know that it was the paraquat that caused his Parkinson’s? “Am I absolutely certain? No, I can’t be,” he told me. “But that’s the only thing I can really point to.”

Phillips is one of more than 6,000 people with Parkinson’s who

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