Many studies have linked paraquat exposure with Parkinson’s disease. The studies involved people exposed to the herbicide paraquat. Those people saw more risk of developing Parkinson’s disease.
The Guardian also published details about Syngenta documents. These details suggested the paraquat maker knew for decades that paraquat was dangerous.
Many lawsuits claim that people got Parkinson’s disease because of paraquat. A typical paraquat lawsuit claims a failure to warn. It will claim paraquat makers should have warned it could cause the disease.
Over 2,700 paraquat lawsuits are now part of a multidistrict litigation. The first trial is set to take place in October 2023.
How Does Paraquat Cause Parkinson’s Disease?
Paraquat lawsuits claim that paraquat causes Parkinson’s disease by killing dopaminergic neurons.
These neurons produce dopamine. Our bodies need dopamine for motor control, or control of our movements. Parkinson’s disease is a movement disorder. Parkinson’s symptoms occur when we don’t produce enough dopamine.
Lawsuits claim that paraquat kills these neurons through oxidative stress. Cells in our body have defenses against oxidants. Oxidative stress occurs when those defenses and oxidants in cells become unbalanced.
Lawsuits claim paraquat creates oxidative stress through “redox cycling.” They claim redox cycling occurs when oxygen is present. Our brains have a lot of oxygen.
Lawsuits claim that redox cycling creates superoxide radical molecules. These molecules lead to oxidative stress.
Lawsuits claim that redox cycling occurs forever once paraquat enters the brain. They claim even a single paraquat molecule can create countless superoxide radical molecules.
Do Studies Say Paraquat Causes Parkinson’s Disease?
Many studies suggest human exposure to paraquat leads to Parkinson’s disease.
Researchers published Rotenone, Paraquat, and Parkinson’s disease in 2011. The study examined data from the Agricultural Health Study (AHS). The AHS looked at, among other things, pesticide exposure. The exposure assessment looked to identify occupational risk factors. The 2011 study found paraquat increased Parkinson’s risk by 2.5 times. The study noted that paraquat causes oxidative stress. The study notes that paraquat use is common all over the world. The study says the finding may be very important. The study involved 110 people with Parkinson’s disease. It compared them to 358 controls.
1999
A 1999 study found the paraquat kills dopaminergic neurons.
2002
A 2002 study also found that paraquat kills these neurons.
2004
A 2004 study found that paraquat causes oxidative stress. The study also found that paraquat kills brain neurons.
2009
A 2009 study found paraquat increased risk of Parkinson’s by more than double. The study involved 519 people with Parkinson’s disease. It compared them to 511 controls.
Another 2009 study also found paraquat more than doubled Parkinson’s risk. The study involved 368 people with Parkinson’s disease. It compared them to 341 controls.
2011
A 2011 study found the herbicide kills dopaminergic neurons.
Another 2011 study also found paraquat kills these neurons.
2012
A 2012 study found paraquat raised the risk people developed Parkinson’s by 1.36 times. That study involved 356 people with Parkinson’s disease. It compared them to 754 controls.
2013
Researchers found in 2013 that paraquat raises risk of Parkinson’s by about two times. The researchers analyzed 104 studies.
2016
In 2016, researchers found “strong” evidence linking paraquat with Parkinson’s disease.
2017
A 2017 study found that paraquat led to the death of dopaminergic neurons.
Another 2017 study found paraquat raises Parkinson’s risk by 1.54 times. The study involved 619 people with Parkinson’s disease. It compared them to 854 controls.
2018
Researchers found in 2018 that paraquat increased Parkinson’s risk by 1.64 times. The researchers reviewed 13 studies involving 3,231 people who developed Parkinson’s disease. The studies compared them to 4,901 controls.
A 2018 study found that paraquat kills brain neurons.
2019
A 2019 study found that paraquat causes the death of neurons which produce dopamine. The study exposed the neurons to paraquat.
Researchers found in 2019 that paraquat raised the risk of Parkinson’s disease significantly. The critical review analyzed nine studies.
Did Paraquat Makers Know It Could Cause Parkinson’s Disease?
The Guardian published an expose on internal Syngenta documents. These documents suggest paraquat makers have known it is dangerous for a long time. The expose claims:
- Syngenta tried to influence regulators. They tried to refute science critical of paraquat. They tried their hardest to protect paraquat sales.
- Syngenta tried to stop a scientist from joining an Environmental Protection Agency panel. The respected scientist worked on linking paraquat with Parkinson’s. They also attempted to hide these efforts.
- Scientists knew paraquat accumulated in brains in the 1960s and 1970s. These included Chevron Chemical scientists. These also included Imperial Chemical Industries (ICI) scientists. ICI was a predecessor of Syngenta.
- Syngenta did research showing paraquat harmed brain tissue. This research was withheld from regulators by the company.
- Scientists with Syngenta knew paraquat harmed the central nervous system. This caused Parkinson’s-like symptoms in animals. The symptoms included tremors. A Chevron communication noted “permanent CNS effects” related to paraquat in 1975.
- A researcher with ICI noted a chemical related to paraquat in 1958. This compound seemed to affect the central nervous system.
- ICI scientists studied animal exposure to paraquat in 1966. They found the animals developed tremors and a stiff gait. These are symptoms of Parkinson’s disease.
- 1974 Chevron meeting notes mention paraquat. The notes mention toxic effects from occupational exposure to the herbicide. A lawyer with Chevron mentioned evidence a month later. The evidence suggested the herbicide might lead to “industrial injury.” It suggested Chevron might face lawsuits for millions of dollars.
- Chevron and ICI held a 1975 meeting. Notes from the meeting mention a paraquat poisoning victim’s autopsy. This autopsy discovered lesions in motor neurons.
- A 1975 letter from an ICI scientist to a Chevron toxicologist was a warning. It warned of chronic effects which could cause legal issues.
- ICI reviewed a farmworker’s autopsy in 1976. It found changes in cells in the substantia nigra section of the brain. This is a hallmark of Parkinson’s disease.
- A 1985 memo noted a Canadian study. The memo was to Chevron officials. It noted a strong connection between Parkinson’s disease and paraquat. It warned that paraquat may become a big legal liability. It compared paraquat with asbestos.
- Syngenta noted that studies showed paraquat could cause Parkinson’s. It had similar studies done by its own scientists. It ensured the scientists didn’t measure paraquat levels in the brain. It did this since detection of paraquat in the brain wouldn’t look good.
- Syngenta gave mice paraquat in a 2003 study. They measured how many dopaminergic neurons the mice lost. They used a manual counting process. They didn’t find a significant effect. They publicized the finding. A Syngenta scientist repeated the study using a more accurate method of counting. This scientist found a significant effect. This finding was not publicized by Syngenta.
- Syngenta made a claim on its website. They claimed paraquat won’t cross the human blood-brain barrier. They also said paraquat won’t reach the brain part needed to cause Parkinson’s. Syngenta made these statements knowing they were false.
Do Lawsuits Claim Paraquat Causes Parkinson’s Disease?
Over 2,700 lawsuits claim that paraquat causes Parkinson’s disease. The lawsuits claim that paraquat makers knew or should have known it causes the disease.
The lawsuits claim paraquat makers are liable for Parkinson’s caused by paraquat. They claim paraquat makers failed to warn about its link with the disease. They also claim that paraquat is defective by design.
The lawsuits also claim paraquat makers were negligent. Negligence is failing to use reasonable care to prevent harm. California law holds product makers liable for injuries caused by negligence.
How Does Paraquat Exposure Occur?
People get exposed to paraquat when they use it or are nearby its use. Exposure occurs when people spray paraquat or are near its spraying. Exposure also occurs when paraquat gets mixed and loaded into sprayers. This happens due to leaks, splashes and spills. Leaks, splashes and spills can also happen while cleaning or emptying equipment. They can happen while clearing clogged valves, lines and nozzles.
Paraquat exposure can occur due to spray drift. This is when the wind carries paraquat from its target area. It carries the herbicide to areas it isn’t intended to reach.
Paraquat can enter the body through the skin. It can make its way through mucous membranes and epithelial tissues. It can make its way through mouth, nasal, nose, airway and trachea tissues. It can enter through tissue damage like sores, rashes, abrasions or cuts.
Paraquat inhalation into the lungs can occur. Paraquat ingestion can occur after small drops of it get into the nose, mouth or airways.
Paraquat can enter the nervous system after ingestion.
Paraquat can enter the bloodstream after ingestion, inhalation or absorption.
Paraquat can enter the brain once it enters the bloodstream. It can pass through the blood-brain barrier. It can also enter the brain through places that barrier doesn’t protect.
Inhaled paraquat can enter the brain via the olfactory bulb.
Paraquat appears to cause a never-ending cycle once it enters the brain. This cycle causes constant oxidative stress. This oxidative stress kills neurons which produce dopamine. Parkinson’s symptoms occur once enough of these neurons die. These neurons do not grow back. Even a small amount of paraquat can cause this cycle to occur.
Who Is The Most Likely To Develop Parkinson’s Disease From Paraquat Exposure?
Nobody is immune to health problems from toxic chemicals. It is not always known what makes one person more likely to develop a disease than another. Genetics and the environment likely play roles.
Those with certain genes may be more likely to develop Parkinson’s from paraquat. Many have developed the disease without these genes, though.
Those most at risk are those who often use or get exposed to paraquat. These people include farmworkers. These people also include those living near places where a lot of paraquat gets sprayed.
What Is Paraquat?
Paraquat is a very popular herbicide. An herbicide is a weed killer.
Paraquat is a salt.
The herbicide kills green plants on contact. It is non-selective. It kills many broad-leaved weeds and annual grasses. It works on perennial weeds. It acts in a very quick manner. Rain does not wash it off of plants. Soil contact partly inactivates it.
Paraquat kills weeds through oxidative stress. This oxidative stress, though, appears to cause Parkinson’s disease.
No-till farming uses paraquat. No-till farming does not disturb soil by overturning, stirring or digging it.
Paraquat is often used on weeds which have become resistant to Roundup. Farmers in Australia often spray weeds with Roundup, then paraquat. This appears to prevent weeds from growing resistant to Roundup.
Paraquat was first created in 1882. ICI noted its ability to kill weeds in 1955. ICI first made and sold paraquat in 1962 under the name Gramoxone.
Paraquat is very toxic to people. Ingesting very small amounts of it can be fatal. Paraquat poisoning is fatal in 60 to 90 percent of cases.
Paraquat poisoning can cause severe lung damage. It can cause acute respiratory distress syndrome. It can cause kidney, lung, heart and liver failure.
Paraquat is often used in suicides in developing countries. This is because it is cheap and easy to get. Many murders utilized paraquat.
What Is Parkinson’s Disease?
Parkinson’s disease is a central nervous system disease. It is a degenerative disease. It is a long-term disease.
The disease affects the motor system, which controls movement.
The primary symptoms of Parkinson’s disease are:
- Tremors
- Problems with walking
- Slow movement
- Stiffness
The disease can lead to complications like:
- Dementia
- Anxiety
- Sleep issues
- Eating issues
- Depression
The usual onset of the disease occurs past the age of 60.
The disease’s motor symptoms are due to the loss of neurons which produce dopamine.
Known risk factors for the disease include head injuries and pesticide exposure.
Doctors usually diagnose the disease based upon symptoms. Motor symptoms are usually the primary complaint. Tests are sometimes given to rule out another disease.
About three men get Parkinson’s disease for every two women. 6.2 million people had the disease in 2015. By 2015, the disease killed around 117,400 people every year.
There is no cure for Parkinson’s disease. One cannot reverse its progression. One cannot slow or stop its progression. Treatments only reduce symptoms. Treatments don’t work as well over time. Treatments can produce side effects such as involuntary movements of muscles.
Those with the disease get worse over time. People with the disease face a lifetime of medical care.
Jeffrey Nadrich
Jeffrey Nadrich is a nationally-recognized California plaintiff’s personal injury attorney. He is a graduate of UC Berkeley and UC Hastings College of the Law. He has successfully represented thousands of injury clients over the last 40 years.
