Could a Chemical in Weed Killer Roundup Lead to Cancer?

The Doctors continue the debate about the safety of the popular herbicide glyphosate, which is a key ingredient in the popular weed killer Roundup.

We first discussed glyphosate in 2015 after a report from the International Agency for Research on Cancer (IARC) determined that the chemical is “probably carcinogenic to humans," a claim which Monsanto, the chemical's creator, disputed.

Watch: Is Key Chemical in Roundup and Other Herbicides a Known Carcinogen?

We welcome attorney Brent Wisner, who is the lead attorney in a lawsuit claiming glyphosate led to non-Hodgkin lymphoma. He claims that in addition to the to the 2015 IARC report, there have been numerous studies claiming that glyphosate poses a risk. He says thousands of people who used the product -- individuals who he says did not smoke, were young and not likely to develop cancer -- now have non-Hodgkin lymphoma. As part of the litigation, Brent says he has access to millions of pages of documents that Monsanto has produced, which he alleges contain "real concerns about public health." He claims in addition to agriculture workers, people who have been exposed to glyphosate through home-use have developed non-Hodgkin lymphoma.

Watch: What is Glyphosate and Is It a Health Risk?

Also joining the discussion is Jeffery Smith, founder of the Institute for Responsible Technology and author of "Seeds of Deception" and oncologist Dr. Joseph Tuscano. Monsanto declined our invitation to be part of the conversation.

Watch: Were Potential Cancer Links Covered Up By Monsanto?

Dr. Tuscano shares his thoughts on the researching surrounding glyphosate.

"The data is conflicting. There are multiple good studies in several counties that show exposure can lead to an increased risk of cancers.... but the problem is that there are other studies that really don't show an association," he says. "But clearly, there is a signal there that needs to be investigated. There needs to be additional research."

Watch: Will We Ever Know The Truth About Glyphosate?

Brent goes on to claim that Monsanto buried a study from 1999 that allegedly found that Roundup might cause cancer.

The Doctors also speak with Teri, whose husband Jack, an avocado farmer, died of non-Hodgkin lymphoma, which she claims was caused by the use of Roundup. She also says that the family dog died of cancer as well. Learn more about her story, here.

Watch: Could Eating GMO Foods Harm Your Health?

Scott Partridge, Vice President of Strategy, Monsanto Company, released the following statement to The Doctors:

“While we have sympathy for anyone who is suffering from or who has lost a loved one to cancer, glyphosate is not the cause. Hundreds of scientific studies over 40 years have determined that glyphosate is safe for use, and no regulatory agency in the world has concluded that glyphosate is carcinogenic. The IARC opinion is a complete outlier and has been shown to be based on manipulated data. IARC members distorted scientific data, concealed vital studies and accepted secret payments from trial attorneys. Glyphosate is a vital and safe tool for millions of farmers around the world.

Watch: Widow of Farmer Says She “Watched Husband Deteriorate”

An Environmental Protection Agency spokesperson released the following statement:

“EPA is currently re-evaluating the safety of glyphosate through our registration review program. This re-evaluation process occurs every 15 years and is mandated by federal law.

In December 2016, EPA convened its FIFRA Scientific Advisory Panel (SAP) to review and solicit comments on our findings that glyphosate is not likely to be carcinogenic to humans at doses relevant for human health risk assessment. Once EPA has reviewed the SAP report and made any appropriate changes to our risk assessment, we intend to release the draft human health and ecological risk assessments for a 60-day public comment period in the Federal Register.

We are currently scheduled to complete the draft risk assessments no later than 2017. After consideration of the public comments on the draft risk assessments, EPA will determine whether any risk management is needed. We intend to complete our evaluation, consistent with the statutory deadline for registration review, ensuring that the best science is considered in making our regulatory decision.”

The Doctors also reached out to The California Farm Bureau Federation for a statement, which reads:

“Glyphosate-based herbicides have been valuable tools for weed control for California growers and other users (e.g., homeowners, landscaping and lawn care professionals, foresters, etc.) for more than 40 years. Globally, the overall safety profile has contributed to the adoption of glyphosate-based herbicides in more than 160 countries.

Agricultural systems have evolved over the last 20 years to become more productive and environmentally sustainable. The principal barrier to reducing or eliminating tillage is the challenge of controlling weeds with available soil-applied herbicides. Glyphosate has allowed farmers to increase the incorporation of more sustainable practices into production, including no-till and conservation tillage systems. Reducing tillage has enormous environmental benefits, such as less soil erosion, improved soil organic matter, less soil compaction, increased soil moisture, cleaner water, reduced energy use, more wildlife habitat, and less greenhouse emissions.

U.S. EPA has placed glyphosate in its most favorable category for carcinogenicity and is currently conducting another registration review. Glyphosate’s history of safe use is supported by decades of data from more than 800 scientific studies and no regulatory agency in the world considers glyphosate to be a carcinogen.”

More resources on organic food and genetically modified organisms can be found on the World Health Organization website, the Department of Agriculture Organic Food Production website, and on the Mayo Clinic website.