Failure to Warn: What It Means for Paraquat and Roundup Lawsuits

When you purchase a product, whether it’s a household cleaner or a powerful agricultural chemical, you trust that the manufacturer has told you everything you need to know to use it safely. But what happens when that trust is broken? What if a company knows its product carries a devastating risk—like causing cancer or a neurodegenerative disease—but chooses not to put that information on the label?

This is the central question in thousands of lawsuits filed by victims who used the herbicides Paraquat and Roundup. At the heart of these legal battles is a powerful legal concept known as “failure to warn.” It is the argument that the manufacturers, despite knowing the risks, failed in their duty to adequately inform consumers, leading to life-altering health consequences.

At Walch Law, we have seen the tragic outcomes of this corporate negligence. Farmers, groundskeepers, and everyday homeowners are now battling Parkinson’s disease and non-Hodgkin’s lymphoma, and they deserve to know how the law can protect them.

What is the “Failure to Warn” Argument?

In product liability law, a “failure to warn” claim alleges that a product, even if designed and manufactured correctly, is unreasonably dangerous because it lacks adequate warnings or instructions about its potential risks. A manufacturer has a legal duty to inform consumers of any non-obvious dangers that could result from the intended or foreseeable use of their product.

To successfully prove a failure to warn claim, a plaintiff generally must show that:

The manufacturer knew or should have known about the product’s risk.
The risk was substantial enough that a reasonable person would want to be warned about it.
The manufacturer failed to provide an adequate warning.
This failure to warn was a direct cause of the plaintiff’s injury.

Essentially, the law says that consumers have a right to make an informed choice. If you had known that using a certain weedkiller could give you cancer, would you still have used it? For most people, the answer is a resounding no. The failure to provide that critical information is where the manufacturer’s liability begins.

How Failure to Warn Applies to Paraquat and Roundup

The lawsuits against the manufacturers of Paraquat (Syngenta, Chevron) and Roundup (Bayer/Monsanto) are textbook examples of failure to warn cases. Victims argue that these companies were aware of scientific evidence linking their products to severe diseases but made a calculated business decision to conceal those risks from the public.

The Case Against Paraquat

Thousands of farmers and agricultural workers who used Paraquat have been diagnosed with Parkinson’s disease, an incurable neurodegenerative disorder. The lawsuits allege that:

The company knew the risk: Internal documents reportedly show that manufacturers were aware for decades that Paraquat was neurotoxic and could accumulate in brain tissue.
The warnings were inadequate: While Paraquat labels carry strong warnings about acute poisoning (i.e., “one sip can kill”), they fail to mention the long-term risk of developing Parkinson’s disease from chronic, low-level exposure through inhalation or skin contact.
Causation: Plaintiffs argue that had they been warned about the risk of a progressive brain disease, they would have taken different precautions or used alternative products, thereby avoiding their diagnosis.

The Case Against Roundup

Roundup, a product once ubiquitous in residential garages, has been linked to non-Hodgkin’s lymphoma, a type of cancer that affects the immune system. The failure to warn claims against Bayer/Monsanto focus on:

The IARC Classification: In 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) classified glyphosate, Roundup’s active ingredient, as “probably carcinogenic to humans.” Plaintiffs argue the company knew of these risks long before this public declaration.
Misleading Marketing: For years, Roundup was marketed as being “safer than table salt” and environmentally friendly. This advertising actively downplayed any potential health risks and lulled consumers into a false sense of security.
Lack of Cancer Warning: The product label has never included a warning about the risk of cancer. Victims claim this omission deprived them of the ability to make an informed decision about their safety.

In both cases, the argument is simple: the manufacturers chose profits over people by hiding the truth.

The Federal Preemption Defense: A Manufacturer’s Shield

Manufacturers like Bayer have attempted to use a legal defense called “federal preemption” to block these lawsuits. They argue that because the U.S. Environmental Protection Agency (EPA) approved their product labels without requiring a cancer or Parkinson’s warning, they cannot be sued under state “failure to warn” laws.

This argument essentially claims that federal regulations should override a company’s duty to warn under state law. However, juries and courts have frequently rejected this defense, siding with victims. They have determined that EPA approval represents a minimum safety standard, not a free pass for manufacturers to hide known dangers from the public. This ongoing legal battle, which has even reached the steps of the U.S. Supreme Court, highlights the tenacity of these corporations and the importance of having a strong legal team on your side.

Why You Need an Experienced Product Liability Attorney

Taking on a multi-billion dollar agrochemical corporation is not something you can do alone. These companies have vast legal teams dedicated to denying liability and minimizing payouts. A failure to warn case requires a deep understanding of product liability law, complex scientific evidence, and the tactics these corporate giants use.

At Walch Law, we are prepared for this fight. We help victims by:

Investigating Corporate Knowledge: We dig into the evidence to prove what the manufacturer knew and when they knew it, building a powerful case that they deliberately hid the risks from you.
Working with Experts: We consult with leading medical and scientific experts to establish the causal link between the herbicide and your disease.
Navigating Complex Litigation: We have the experience to manage your case within the large, consolidated Multi-District Litigations (MDLs) where thousands of these claims are handled.
Fighting for Maximum Compensation: We calculate the full extent of your damages—including all past and future medical bills, lost income, and the immense pain and suffering you have endured—and fight for the settlement or verdict you deserve.

Contact Walch Law Today for a Free, Confidential Consultation

You were not given the chance to make an informed choice about your health. The manufacturers of Paraquat and Roundup took that choice away from you. Now, the law provides a path to hold them accountable.

If you or a family member was diagnosed with Parkinson’s disease after using Paraquat, or non-Hodgkin’s lymphoma after using Roundup, do not wait to seek legal help. Statutes of limitations restrict the time you have to file a claim. Contact the dedicated legal team at Walch Law today for a free, confidential consultation. We will listen to your story, explain your rights, and help you take the first step toward justice. You pay nothing unless we win your case.