Scientist Reaffirms Contention That Roundup Leads to Cancer

By - February 11, 2019
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After a second round of expert testimony about the link between the Roundup weedkiller made by Monsanto and non-Hodgkin lymphoma, a scientist in April 2018 stated that a recent study that found no link between them was seriously flawed. (

The cancer expert, Christopher Portier stated that the 2018 study that was published in the Journal of the National Cancer Institute had measurement errors. Portier said that its authors erroneously concluded there is no link between cancer and glyphosate, which is the active ingredient in the weedkiller.

He noted that from the faulty analysis they conducted, they saw no connection. Also, he said that you would see no connection because of the way they misclassified the exposure.

Key Testimony Could Advance Hundreds of Lawsuits

Portier’s testimony is significant because it could help to advance at least 300 lawsuits that have been filed against Monsanto and were consolidated in a multi-district lawsuit in San Francisco. The lawsuits have been filed by farmers and landscapers who allege that being exposed to glyphosate caused them to develop a deadly cancer of the lymph nodes – non-Hodgkin lymphoma.

US District Judge Vince Chhabria has to decide which expert testimony a jury should hear according to whether the claims of the experts meet tough scientific standards.

IARC Labeled Glyphosate as Probable Human Carcinogen in 2015

In 2015, WHO’s International Agency for Research on Cancer found that glyphosate is probably dangerous to humans and is a carcinogen.

Earlier in 2018, Monsanto introduced its own expert on the subject, Christopher Corcoran. He is a biostatistician who attempted to refute the IARC study on which Portier served as an advisor.

Corcoran protested how Portier used meta-analysis. This is a statistical technique that combines results from several studies and clinical trials to arrive at a clear answer. He stated that it is a seriously flawed approach that can lead to associations that are spurious in nature.

Portier responded regarding the meta-analysis, and confirmed that his view of the connection between glyphosate and non-Hodgkin lymphoma is largely driven by the results and that the 2018 study was not included.

That study is often referred to as the Andreotti study, and was named after principal author Gabriella Andreotti. She is an epidemiologist at the National Cancer Institute.

Portier noted that he did not include that study in his meta analysis because of its failures and because the approach used was so different from other epidemiological studies on that subject.

Portier said that after he reviewed the Andreottti study, he thought that the strength of the association between the chemical and cancer is strong enough to warrant a very strong opinion. He noted that there exist epidemiological studies, which is evident in the real world, in real human beings at current exposure to glyphosate.

Chhabria asked the scientist to talk about latency, which is the time between the first carcinogen exposure and when cancer is actually diagnosed.

The concern was that case-control studies looking for possible connections between cancer and the chemical looked at patients who had latency periods as low as seven years.

Chhabria noted that some patients in the studies were diagnosed with lymphoma in the 1980s, and Roundup was introduced on the market in 1974.

Chhabria said that with these types of studies, it is preferred to have longer periods between diagnosis and exposure. He noted if there is not a long period, there is a concern that cancer may have had another cause. The judge said the first question to ask is if the pesticide that was used before glyphosate was the pesticide that led to the lymphoma.

Portier responded that some patient cohorts had a latency period of 10 to 12 years. He noted the studies represent as many as four million people. From such a large number of people, you can find the ones with sharp latencies and see the effects. He also said that one study found a link between glyphosate and NHL was adjusted for 48 pesticides, which made latency less important.

He noted unless there is some kind of phantom pesticide that is causing NHL, then seeing the cancer in the study should concern use.

If it had not been seen, it could be said that it was not of enough length. But if everything has been adjusted for, Portier said he would conclude that the pesticide is causing NHL.

Glyphosate Used Around the World on Crops and More

Glyphosate is the most commonly used pesticide and agrochemical in world history. Monsanto put it on the market in 1974, and its use increased greatly in 1996 after the company brought out Roundup Ready seeds to resist the harshness of glyphosate. It is estimated that more than 2.6 billion pounds of the chemical were used on farmlands in the US and consumer yards from 1992 to 2012, per the US Geological Survey.

But the connection between non-Hodgkin lymphoma and glyphosate has always been strongly disputed by various stakeholders.

While the International Agency for Research on Cancer found that glyphosate is probably carcinogenic, the EPA has found that the opposite is the case, according to its latest research.

Glyphosate-Cancer Connection and the $289 Million Verdict

The issue about glyphosate use leading to cancer exploded in the headlines last year when Monsanto was slapped with a $289 million cancer lawsuit judgment in the first trial ever that claimed the weed killer causes cancer.

Dewayne Johnson, a groundskeeper who used Roundup regularly on his job in San Francisco for years, won in 2018 in state court after jurors deliberated for three days. The trial was a vital test of the evidence that is available to be used against Monsanto and will be a template for the litigation of many other cancer claims over Roundup. (

Johnson worked for a school district in Benicia, California, where he mixed and sprayed hundreds of gallons of the weedkiller. He was first diagnosed with cancer in 2014, and in 2017, his oncologist said he had only six months to live.

Monsanto tried to argue that the cancer Johnson had taken many years to form, and his exposure to Roundup from 2012 until his 2014 diagnosis was far too short for the chemical to have caused the cancer.


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