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I was gratified to be able to answer promptly, and I did. I said I didn't know. -- Mark Twain

https://www.latimes.com/environment/story/2023-12-20/california-workers-
say-herbicide-is-giving-them-parkinsons

It was the late 1980s when Gary Mund felt his pinky tremble. At first it
seemed like a random occurrence, but pretty quickly he realized something
was seriously wrong.

Within two years, Mund � a crew worker with the Eastern Municipal Water
District in Riverside County � was diagnosed with Parkinson�s disease. The
illness would eventually consume much of his life, clouding his speech,
zapping most of his motor skills and taking away his ability to work and
drive.

�It sucks,� said Mund, 69. He speaks tersely, because every word is a
hard-won battle. �I was told the herbicide wouldn�t hurt you.�

The herbicide is paraquat, an extremely powerful weed killer that Mund
sprayed on vegetation as part of his job from about 1980 to 1985. Mund
contends the product is responsible for his disease, but the manufacturer
denies there is a causal link between the chemical and Parkinson�s.

Paraquat is manufactured by Syngenta, a Swiss-based company owned by the
Chinese government. The chemical is banned in at least 58 countries �
including China and Switzerland � because of its toxicity, yet it
continues to be a popular herbicide in California and other parts of the
United States.

But research suggests the chemical may cross the blood-brain barrier in a
manner that triggers Parkinson�s disease, a progressive neurodegenerative
disorder that affects movement. Now, Mund is among thousands of workers
suing Syngenta seeking damages and hoping to see the chemical banned.

Since 2017, more than 3,600 lawsuits have been filed in state and federal
courts seeking damages from exposure to paraquat products, according to
Syngenta�s 2022 financial report.

�Despite decades of investigation and myriad epidemiological and
laboratory studies, no scientist or doctor � whether or not affiliated
with Syngenta � has ever concluded in a peer-reviewed scientific analysis
that paraquat causes Parkinson�s,� the company�s chief communications
officer, Saswato Das, wrote in an email.

Some scientists contend they commonly use paraquat to induce Parkinson�s
disease in mice as part of research studies, said Ray Dorsey, a professor
of neurology at the University of Rochester in New York and the author of
�Ending Parkinson�s Disease.�

�There have been numerous academic researchers over the last 20-plus years
� and multiple different investigators in multiple different locations �
that have found that paraquat, when fed to laboratory animals, reproduces
the features of Parkinson�s disease,� Dorsey said.

He said paraquat has been shown to damage mitochondria � the energy-
producing components of cells � and damaged mitochondria have been
implicated in the likely environmental and genetic causes of Parkinson�s.

He referenced an oft-cited 2011 study funded by the National Institutes of
Health that found a strong association between Parkinson�s and paraquat.
It found that workers exposed to paraquat had a 250% greater risk of
getting Parkinson�s disease than people not exposed to the chemical.
�Because paraquat remains one of the most widely used herbicides
worldwide, this finding potentially has great public health significance,�
the study concluded.

Currently, an estimated 1 million people in the United States are living
with Parkinson�s disease, which has no known cure. California is home to a
high incidence of cases, with large clusters found in agricultural regions
where herbicides are heavily used, including Kern, Kings, Merced and San
Joaquin counties, according to a 2022 geographic study.

Dorsey and other researchers conceded that, as with cancer and other
diseases, it can be difficult to isolate the precise cause of a patient�s
Parkinson�s. Outdoor workers may have been exposed to several chemicals
and environmental toxins over the course of their careers.

�Yes, people are exposed to several different chemicals, but we try to
control for that in epidemiology studies as best we can,� said Jeff
Bronstein, director of the Movement Disorders Program at UCLA who has
studied the link between paraquat and Parkinson�s in California�s Central
Valley. That the animal studies are done by different labs �adds to what
we call biological plausibility. It all supports that paraquat increases
the risk of developing Parkinson�s disease.�

Groups such as Earthjustice and the Michael J. Fox Foundation have been
pushing for years to ban paraquat, with the latter noting on its website
that the herbicide is �thought to increase Parkinson�s risk by 100 to 500%
, depending on overall exposure.�

Paraquat is 28 times more toxic than another controversial herbicide,
Roundup, according to a report from the Pesticide Action Network. (Roundup
has been banned in several parts of California, including a 2019
moratorium by the Los Angeles County Board of Supervisors forbidding its
use by county departments.)

Paraquat also has other known health effects. It is listed as �highly
toxic� on the U.S. Environmental Protection Agency�s website, which says
that �one small sip can be fatal and there is no antidote.� The EPA is
currently reviewing paraquat�s approval status.

However, both the EPA and Syngenta cited a 2020 U.S. government
Agricultural Health Study that found no clear link between paraquat
exposure and Parkinson�s disease. A 2021 review of reviews similarly found
no causal relationship.

Dale Sandler, senior author of the 2020 study, said the researchers
observed licensed pesticide applicators and their spouses from Iowa and
North Carolina over the course of several years. The study found a 9%
increase in the relative risk of Parkinson�s disease incidence associated
with using paraquat, which she said was �not statistically significant.�

However, paraquat was significantly associated with the disease among
those who reported a history of head injuries, with a more than threefold
increase in risk based on a small number of cases with both exposures,
said Sandler, who is also head of the epidemiology branch at the National
Institute of Environmental Health Sciences.

Multiple sources said the dizzying array of competing research is a
reflection of industry pushback, political lobbying and deep-pocketed
agribusiness. Syngenta reported a record $33 billion in sales in 2022. One
leading researcher on the matter said she has been retained as a witness
in pending lawsuits and so was not comfortable commenting publicly for
this report.

But the overall findings point in one direction, said Michael Okun,
director of the Norman Fixel Institute for Neurological Diseases at the
University of Florida. �The collective evidence really points to a serious
problem and an emerging association with paraquat that just keeps getting
stronger and stronger over time,� said Okun, who is also a medical advisor
with the Parkinson�s Foundation, a national nonprofit organization.

For the record:

12:46 p.m. Dec. 20, 2023An earlier version of this article said documents
were unveiled as part of ongoing court proceedings in Illinois. The
proceedings are in California.

Documents unveiled as part of ongoing court proceedings in California show
that Syngenta has spent decades investigating the potential side effects
of its product. This research has sometimes contradicted public statements
issued by the company, a difference first reported by the Guardian. This
includes the 2011 study that showed a 250% increase in disease incidence
among workers exposed to paraquat.

In a 2022 deposition, Syngenta�s principal science advisor, Philip Botham,
acknowledged that the company made a considerable effort to obtain the
data used in that study and conducted its own analysis, which reached the
same conclusion about the incidence of the disease, according to a
transcript of his testimony. However, the finding was not publicized and
Botham did not divulge it in a subsequent interview with the New York
Times.

Another transcript indicates that Syngenta attempted to downplay studies
showing that paraquat administered to mice caused a reduction in the
number of dopamine cells in the substantia nigra, the part of the brain
that produces dopamine, which is another hallmark of Parkinson�s disease.

In 2003, a Syngenta scientist, Louise Marks, attempted to replicate those
mice studies but found no such reduction in dopamine. However, she
expressed concerns about potential shortcomings in her methodology,
according to Botham�s testimony. Marks then traveled to California, where
a Syngenta consultant taught her an improved methodology, after which she
repeated the study multiple times and did indeed find a reduction in
dopamine cells.

Despite Marks� concerns, Syngenta publicized her original findings at an
annual meeting of the Society of Neuroscience in 2004, Botham testified.
Syngenta did not publish all of her updated studies or report her
reservations to the EPA, he said.

Das, of Syngenta, dismissed the 2011 study as an �interim study that
looked at only part of the data,� adding that the findings were later
expanded upon and improved in the 2020 study that found no clear link.

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Subject	Author
This weed killer is banned in 58 countries. U.S. workers say it's giving them Pa	Leroy N. Soetoro
Re: This weed killer is banned in 58 countries. U.S. workers say it's giving the	maus

I was gratified to be able to answer promptly, and I did. I said I didn't know. -- Mark Twain

sci / sci.agriculture / This weed killer is banned in 58 countries. U.S. workers say it's giving them Parkinson's