EPA Refutes IARC Findings On Roundup Side Effects, Says Glyphosate “Not Likely” To Cause Cancer

Despite a number of studies suggesting a link between side effects of Roundup and cancer, a recent review by the U.S. Environmental Protection Agency (EPA) indicates the popular weedkiller, as well as other herbicides containing the active ingredient glyphosate, are not likely to cause cancer among humans. However, the agency could not rule out a link between glyphosate and non-Hodgkins lymphoma.

The EPA issued a position paper (PDF) on glyphosate on September 16, indicating that the popular weed killer was not “likely” a cancer-causing agent at human relevant doses. The paper comes after more than a year of international debate on the risks of the chemical, which Monsanto uses in its Roundup herbicide products.

The 227-page report details the EPA’s latest evaluation of glyphosate, which began in September 2015, and also details previous evaluations dating back to 1985. Originally, the agency deemed the chemical a probable carcinogen, then backed off that assessment a year later.

The findings contradict an assessment by the World Health Organization’s International Agency for Research on Cancer (IARC), which was published in March 2015, indicating that glyphosate is likely a cancer-causing agent. In particular, the IARC report linked the side effects of Roundup and other glyphosate-based herbicides may increase the risk of non-Hodgkins lymphoma (NHL).

The latest EPA report looks at a number of different studies conducted throughout the years and weighs a number of different exposure levels among different classes of individuals, from young children who have incidental contact, to agricultural users who have the highest levels of exposure.

While the EPA excluded most types of cancer as linked to glyphosate, researchers were unable to totally exclude the risk of a link between glyphosate and NHL.

The EPA’s conclusion was based on a number of factors. The agency determined that many of the previous studies did not account for co-exposure to other pesticides, which have been linked to cancer, particularly non-Hodgkins lymphoma. The EPA also found that the previous studies did not show an increase in the prevalence of NHL as the popularity of glyphosate grew due to the use of so-called “Roundup Ready” transgenic crops which were designed for heavy glyphosate exposure.

Many of the studies also had very small sample sizes, according to the findings. In addition, the EPA report points out that the latency period of NHL, how long it takes between exposure and the development of the cancer, is undetermined and could range from a few years to a quarter of a century.

“Based on the weight-of-evidence, the agency cannot exclude chance and/or bias as an explanation for observed associations in the database,” the EPA paper states. “Due to study limitations and contradictory results across studies of at least equal quality, a conclusion regarding the association between glyphosate exposure and the risk of NHL cannot be determined based on the available data.”

While the EPA issued a final determination that glyphosate was not likely to be carcinogenic to humans, the report leaves the door open that glyphosate could qualify for a more stringent classification.

“It could be argued that the ‘suggestive evidence of carcinogenic potential’ descriptor would be appropriate,” the report states.

The EPA researchers note that the evidence to support such a classification comes from studies on NHL and some animal studies, as well as a number of genotoxicity assays that found chromosomal and primary DNA damage. However, the EPA notes that it cannot give such a description because of contradictory evidence from other studies, as per its 2005 EPA Guidelines for Carcinogenic Risk Assessment.

The review of Roundup safety risks has come under fire from both sides of the debate over the safety of the weedkiller. A report on the review was due last summer, but is still incomplete. However, in April the EPA accidentally posted what was labeled as a final report on it’s website, indicating that it did not consider glyphosate a carcinogen. The report was quickly taken down, but not before it was widely disseminated. It is unclear what differences there may be between this report and the accidentally released report in April.

Monsanto has aggressively defended the safety of Roundup, one of the most import products for the company, criticizing the IARC’s decision and dismissing safety concerns as agenda driven and based on “junk science.”

The European Food Safety Authority (EFSA) has also conflicted with the IARC findings, declaring glyphosate to be safe. However, several countries in the EU have moved to ban glyphosate use, despite the European Commission’s decision to extend the license for glyphosate use for 12 to 18 months in late June.

Roundup Litigation

Amid the continuing debate within the regulatory community, Monsanto now faces a growing number of Roundup cancer lawsuits in the United States, typically involving individuals diagnosed with a form of non-Hodgkin’s lymphoma following heavy exposure to the herbicide as a farm or agricultural worker.

The complaints allege that the manufacturer recklessly promoted Roundup and pushed greater and greater use of the chemical, without disclosing the potential health risks.

A recent U.S. Geological Survey on glyphosate usage nationwide found that an estimated 2.6 billion pounds of the herbicide has been sprayed on America’s agricultural land over the two decades since the mid-1990s, when Monsanto introduced “Roundup Ready” crops that are designed to survive being sprayed with glyphosate, killing the weeds but not the crops.

In all that time, the FDA has never tested for residue or buildup in the food sold to Americans nationwide. In a report published in 2014, the Government Accountability Office (GAO) criticized the FDA for this deficiency in its pesticide program.

The lawsuits over Roundup allege that plaintiffs may have avoided a diagnosis of non-Hodgkin’s lymphoma or other cancers if they had been warned about the Roundup risks for farmers, landscapers and others in the agricultural industry, as safety precautions could have been taken or other products could have been used to control the growth of weeds.