09
Oct
Glyphosate, When Combined with Other Stressors, Results in Breast Cancer Development
(Beyond Pesticides, October 9, 2019) Pesticide industry propaganda promoting the safety of glyphosate-based herbicides took another hit last month, as a study published by an international team of researchers found the chemical had the potential to induce breast cancer when combined with other risk factors. The study, Glyphosate Primes Mammary Cells for Tumorigenesis by Reprogramming the Epigenome in a TET3-Dependent Manner, led by scientists from Indiana’s Purdue University and the Institut National de la Santé et de la Recherche Médicale (INSERM)/Institut de Cancérologie de L’Ouest (ICO) in Nantes, France, provides an important new lens through which to view pesticide-induced cancer development.
“This is a major result and nobody has ever shown this before,” says Sophie Lelièvre, PhD, a professor of cancer pharmacology in Purdue’s College of Veterinary Medicine and co-leader of IBCN. “Showing that glyphosate can trigger tumor growth, when combined with another frequently observed risk, is an important missing link when it comes to determining what causes cancer.”
To make their determination, scientists exposed human breast cells low levels of glyphosate every three to four days over the course of 21 days. A control group was also dosed with a known cancer-promoting peptide. Glyphosate caused the same changes to exposed cells as the cancer-promoting peptide, indicating that glyphosate promotes DNA hypomethylation, a process denoted by the loss of methyl groups to a certain nucleotide. DNA methyl groups control the way DNA is expressed, and there has long been concern regarding the way pesticides adversely interfere with gene expression in the lead up to diseases like cancer.
To test whether DNA hypomethylation in exposed cells would in fact lead to cancer, researchers implanted the breast cells into mice. While cells exposed to the cancer-promoting peptide developed cancer in all implanted mice, none of those exposed to glyphosate developed into cancer. However, drawing upon scientific hypotheses on the role of multiple stressors in cancer development, scientists created a “two factor hit” whereby molecules known to cause oxidative stress were added to glyphosate exposed cells that were subsequently implanted into mice. These molecules were linked to stress caused by factors such as aging, diet, alcohol consumption, or smoking. Mice exposed to this “two factor hit” developed cancer 50% of the time.
“What was particularly alarming about the tumor growth was that it wasn’t the usual type of breast cancer we see in older women,” Dr. Lelièvre said. “It was the more aggressive form found in younger women, also known as luminal B cancer.”
Importantly, through this research scientists were able to determine the epigenetic pathway through which glyphosate and other stressors induced breast cancer development. The results suggest additional investigation into methyl groups that control certain genes as an avenue for mitigating breast cancer risk.
“There has been a heavy focus on research for both treatment and detection, but prevention just isn’t as prevalent,” Dr. Lelièvre said. “If we can find a way to mitigate the risks, we can have hope for fewer cases.”
The study underlines the importance of preventing similar “two-factor hits” in the real world. While many will dismiss concerns over exposure to various toxic substances by saying “everything causes cancer” the study shows that, in fact, it is very likely the combination of multiple exposures that will ultimately result in cancer. In that way, any method that reduces exposure to carcinogenic agents in our environment is a benefit for health.
“There is a huge gap in the research that is targeted at understanding why cancer develops,” Dr. Lelièvre said. “This discovery is novel, primarily because until now, there hasn’t been any scientific evidence to show that a second factor when associated with common pollutants would be sufficient for cancer to develop.”
Pesticides represent a low hanging fruit for reducing carcinogenic risks. Their use, in the vast majority of cases, is simply not necessary given the availability of alternative products and practices. To avoid exposure to carcinogenic herbicides like glyphosate, choose organic whenever possible.
Beyond Pesticides continues to advocate against the use of glyphosate and other carcinogenic pesticides in farming, landscaping, and other outdoor areas. Join this effort by urging your local government to eliminate glyphosate use and adopt organic land management practices. Follow the links below based on your region to send a letter to your local leaders:
WEST
- Mountain West: Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming
- Pacific West: Alaska, California, Hawaii, Oregon, and Washington
MIDWEST
- East North Central: Illinois, Indiana, Michigan, Ohio, and Wisconsin
- West North Central: Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota
SOUTH
- South Atlantic: Delaware, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, District of Columbia, and West Virginia
- East South Central: Alabama, Kentucky, Mississippi, and Tennessee
- West South Central: Arkansas, Louisiana, Oklahoma, and Texas
NORTH EAST
- North East: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont, New Jersey, New York, and Pennsylvania
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Purdue University press release, Frontiers in Genetics (peer-reviewed journal)
