Update: The Association Between Weed Killer and Chronic Lymphocytic Leukemia

Published Feb 14, 2019

There is new evidence that weed killer is associated with increased risk of Leukemia.

A major new piece of research finds evidence that exposure to something called glyphosate increases the risk for developing one form of leukemia by 41%. Glyphosate herbicides are the most widely used weed killer in the world. Agricultural giant Monsanto uses glyphosate for its “Roundup” herbicide. The study was led by respected researchers at a number of institutions who used a technique called “meta analysis,” looking at a number of previous pieces of research. The findings seem to directly contract the EPA’s assurance that the weed killer is not likely to be carcinogenic for humans.

SurvivorNet previously asked a leading expert about what he thinks.

“Based on the available data that we have and the correlations, it does seem that there is an association between exposure to herbicides and pesticides and increased risk for developing Chronic Lymphocytic Leukemia (CLL),” says Dr. William Weirda, Director of Leukemia at MD Anderson Cancer Center. “It’s easier to make an association like smoking and lung cancer than it is to make these associations, but there are data that have accumulated over the years that do suggest that herbicides and pesticides are a risk for developing CLL.”

“CLL is a very slow growing disease,” says Dr. Wierda. “Usually people have it for many years before they get the diagnosis. The exposures happened many years ago. But the connection and the association that’s made, and why we say Roundup is a potential exposure, is because they have these cohorts of individuals who had these exposures and there’s a high incidence among those individuals of CLL than there is in the general population.”

Leukemia is a cancer of the white blood cells. White blood cells form in your bone marrow, and they fight infections in the body. In Leukemia, the bone marrow produces abnormal white blood cells which crowd out the healthy cells, and make it harder for the blood to operate properly. In Chronic Lymphocytic Lymphoma, there are too many lymphocytes, a type of white blood cell, according to the CDC website.

The results come as a contradiction to the U.S. Environmental Protection Agency’s recent release of a Draft Risk Assessment for Glyphosate. “The draft human health risk assessment concludes that glyphosate is not likely to be carcinogenic to humans.  The Agency’s assessment found no other meaningful risks to human health when the product is used according to the pesticide label,” says the EPA website.

Thousands of people are suing the agricultural giant Monsanto, claiming that Roundup caused their cancer, according to The Guardian. “The first plaintiff to go to trial won a unanimous jury verdict against Monsanto in August, a verdict the company is appealing. The next trial, involving a separate plaintiff, is set to begin on 25 February, and several more trials are set for this year and into 2020,” the article reports.

“Monsanto maintains there is no legitimate scientific research showing a definitive association between glyphosate and NHL or any type of cancer. Company officials say the EPA’s finding that glyphosate is ‘not likely’ to cause cancer is backed by hundreds of studies finding no such connection,” reports The Guardian.

“Overall, in accordance with evidence from experimental animal and mechanistic studies, our current meta-analysis of human epidemiological studies suggests a compelling link between exposures to GBHs and increased risk for NHL,” the study says.

“We investigated whether there was an association between high cumulative exposures to GBHs and increased risk of non-Hodgkin lymphoma (NHL) in humans,” the study says. GBH stands for glyphosate-based herbicides. “We conducted a new meta-analysis that included the most recent update of the Agricultural Health Study (AHS) cohort published in 2018 along with five case-control studies.” That means that researchers used the most updated set of data they had, and a few studies that controlled for variables that could otherwise skew the results.


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Diagnosing and Treating CLL

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. It starts in the bone marrow with lymphocyte cells before moving into the blood. Learn more here: