While other forms of cancer have been linked to glyphosate, most of the currently-pending Roundup cases claim the herbicide causes various types of non-Hodgkin’s lymphoma, including multiple myeloma, chronic lymphocytic leukemia and several common B-cell lymphomas.
What Is Non-Hodgkin’s Lymphoma?
Non-Hodgkin’s lymphoma, or NHL, refers to a group of cancers that all begin when lymphocytes, a type of white blood cell essential to the human immune system, start to divide and multiply uncontrollably. Lymphoma can develop wherever lymphatic tissue is found, according to the National Cancer Institute, from lymph nodes and bone marrow to organs like the spleen and thymus.
NHL refers to an extremely diverse array of cancers. There are numerous subtypes, spanning diffuse large B-cell lymphoma to multiple myeloma. Each form of non-Hodgkin’s lymphoma behaves differently. Diffuse large B-cell lymphoma, which is the most common form of NHL, is aggressive, growing rapidly to colonize other body tissues. Follicular lymphoma, on the other hand, is considered indolent, growing at such a slow pace that some patients won’t ever need treatment.
Symptoms Of NHL
Despite their varying natures, most cases of non-Hodgkin’s lymphoma present with similar symptoms:
- swollen lymph nodes
- fever and night sweats
- chest pain
- weight loss
Other signs, like the decrease in red blood cells known as anemia, can only be discovered after a blood test. In any case, biopsy is the definitive diagnostic method for lymphoma.
Glyphosate’s Association To Lymphoma
In March of 2015, one of the world’s most prestigious cancer organizations, the International Agency for Research on Cancer (IARC), appeared to confirm what numerous public health advocates had suspected for years: “glyphosate is probably carcinogenic to humans.” Citing a number of large studies performed in the US, Canada and Sweden, the group’s experts noted a specific concern, identifying a “positive association” between glyphosate and non-Hodgkin’s lymphoma.
The Agency’s determination quickly ignited a firestorm of controversy. Widely-considered the “gold standard” for carcinogen research, IARC’s determinations can have a ground-shaking effect. The group’s classification of glyphosate was no exception. In the wake of glyphosate’s new categorization, multiple countries banned a substantial percentage of Roundup sales to protect their citizens. California moved to label glyphosate-containing products with a new cancer warning, even as critics of genetically-modified technologies gained new support for their worst suspicions.
IARC Represents “Gold Standard” Of Cancer Research
Take even a cursory look at the International Agency for Research on Cancer’s credentials and the reaction of government health regulators becomes easy to explain.
The International Agency for Research on Cancer is a specialized agency of the World Health Organization, an arm of the United Nations dedicated to promoting public health around the world. As the World Health Organization’s cancer research group, IARC works to improve collaboration between scientists in the global fight to end a disease that kills nearly 9 million people every year.
How IARC Classifies Carcinogens
Identifying the causes of cancer, including potential environmental exposures, is a top priority. IARC has gained particular recognition for classifying chemicals and other agents that may have carcinogenic effects. Every year, the organization gathers a roster of distinguished cancer experts, bringing doctors, epidemiologists, biostatisticians, toxicologists, veterinarians and public health researchers together in Lyon, France. In France, the team reviews a broad array of research:
- epidemiological studies, which seek to find patterns in disease incidence by analyzing populations of exposed and non-exposed people
- bioassays in experimental animals, which examine the effects of a particular chemical or agent on living animal tissue under laboratory conditions
- mechanistic data, which seeks to understand the specific biological pathways by which an agent under investigation could cause cancer to develop
- meta-analyses, which systematically combine the data from multiple separate studies to reach a more comprehensive conclusion with greater statistical power
- exposure data, which surveys how wide potential exposure could be in the general population along with specific subgroups of the population
After a week of intense discussion and analysis, the IARC working group makes its decision, categorizing the agent under investigation into one of five categories:
- Group 1 – carcinogenic to humans
- Group 2A – probably carcinogenic to humans
- Group 2B – possibly carcinogenic to humans
- Group 3 – not classifiable as to its carcinogenicity to humans
- Group 4 – probably not carcinogenic to humans
The result is a monograph, often ranging over hundreds of pages, that exhaustively analyzes the relevant data used to reach a classification. Glyphosate, the International Agency for Research on Cancer, says is a Group 2A agent and “probably carcinogenic to humans.”
Highest Standards Lead To Troubling Conclusion
Cleaving to the highest standards of medical research, IARC relies solely on reports that have been published or approved for publication in the publicly-available scientific literature. This requirement rules out many studies funded by corporations and other industry players, who often keep their internal tests confidential.
While industry-funded studies are extremely common in the world of GM technologically, public safety advocates point to an obvious conflict of interest. With billions to be made on the sale of herbicides and GM seeds, can we really count on the manufacturers to present their findings in an objective light? In the realm of pharmaceutical drugs, researchers at Harvard University have found that studies funded by Big Pharma are consistently skewed, presenting more “positive” results than reports from independent analysts.
The Environmental Protection Agency, for example, has come under fire for using Monsanto-funded studies to assess the safety of glyphosate. In 2015, an EPA review of the chemical on which Roundup is based looked at 32 different studies – 27 of which had been conducted or funded by agrochemical companies. As The Intercept reports, these funding sources matter. Three out of the five independently-funded studies that made their way into the EPA’s review shared a similar conclusion: glyphosate poses a risk to the human endocrine system. All 27 of the studies funded by Monsanto, on the other hand, found that glyphosate exposure was perfectly safe.
Strong Studies Support Glyphosate – NHL Link
In their own analysis, experts at the International Agency for Research on Cancer make a telling point: stronger studies appear to show a more-pronounced link between glyphosate and lymphoma than studies using weaker methods. As just one example, the researchers point to a 2003 report, in which scientists from the National Cancer Institute combined data from three smaller studies.
By pooling data sets together, the researchers were able to create a nuanced population for their analysis, identifying 650 male farmers with Non-Hodgkin’s lymphoma hailing from agricultural areas in Iowa, Kansas and Minnesota. Alongside these 650 men with cancer, the scientists ranked 2,659 farmers without NHL from the same regions. Men exposed to glyphosate were between 1.6 and 2.1 times more likely to develop non-Hodgkin’s lymphoma than farmers who used other herbicides.
This study was particularly strong, scientists at the IARC say, not just because thousands of farmers were examined. The link between glyphosate and NHL held up under two separate statistical analyses, further improving the study’s power. Even more importantly, the National Cancer Institute researchers were able to tease out the individual effects of herbicides, rather than lumping all chemical exposures under the same umbrella. In several smaller herbicide studies, which did not report an increased risk for non-Hodgkin’s lymphoma, researchers had failed to adjust their results for exposure to other herbicides.
More revealing evidence has come out of Canada. In two studies that reviewed a total of 3,722 people, including farmers, garden center workers and home gardeners, teams of Canadian researchers have found that glyphosate appears to have a dose-response relationship with non-Hodgkin’s lymphoma. In other words, the more a person is exposed to glyphosate the higher their risk of developing NHL becomes.
Exposure: 2+ Days Per Year
In a 2001 study published by Cancer Epidemiology, Biomarkers & Prevention, Doctor Helen H. McDuffie and her colleagues found that men exposed to glyphosate at work were between 20% and 26% more likely to develop non-Hodgkin’s lymphoma. But when the researchers delved deeper, analyzing their data by frequency of exposure, a troubling relationship emerged. Men who were exposed to glyphosate for more than 2 days per year were at a far higher risk than workers with limited exposure. In fact, workers who came into contact with Roundup for 2 or more days ever year were 212% more likely to get lymphoma than people with fewer than 2 days of exposure.
A subsequent Canadian study added more support for this dose-response relationship, but focused on a specific subtype of non-Hodgkin’s lymphoma, multiple myeloma. In their preliminary analysis, scientists at the Occupational Cancer Research Centre found that men who had been exposed to glyphosate for any period of time were around 20% more likely to develop NHL than unexposed workers. A more careful analysis, though, revealed the same dose-response relationship observed earlier. Men who were exposed to glyphosate fewer than 2 days per year were actually less likely to develop non-Hodgkin’s lymphoma than men in the general population. Men exposed to the chemical for more than 2 days every year were over twice as likely to develop NHL.
Swedish researchers have backed up these conclusions. In one 2008 study of more than 1,000 male and female Swedish citizens between the ages of 18 and 74, researchers at Lund’s University Hospital found that the risk for non-Hodgkin’s lymphoma appeared to increase, from 151% to 236%, after more than 10 days per year of glyphosate exposure.
Further Reading On Roundup