New Study finds no Cancer Link to Glyphosate

A new study published last week in the Journal of the National Cancer Institute found no association between cancer and exposure to glyphosate, the active ingredient in the herbicide “Roupndup” and the most commonly used herbicide worldwide. In 2015, the International Agency for Research on Cancer classified glyphosate as “probably carcinogenic to humans,” noting strong mechanistic evidence and positive associations for non-Hodgkin lymphoma (NHL) in some epidemiologic studies; though previous evaluations had found no statistically significant associations with glyphosate use and any cancer,

This new study is part of the Agricultural Health Study which has been tracking the health of thousands of agricultural workers and pesticide applicators and their families in Iowa and North Carolina for over 20 years. The study was led by Laura Beane Freeman of the National Cancer Institute. The Agricultural Health Study has tracked and studied 54,251 pesticide applicators, 44,932 or 82.9% who had used glyphosate since the 1990’s.

The scientists studied of glyphosate use and cancer occurrence in this large group of pesticide applicators, and observed no associations between glyphosate use and overall cancer risk or with total lymphohematopoietic cancers, including NHL and multiple myeloma. However, the scientist found some evidence of an increased risk of acute myeloid leukemia (AML) for applicators, particularly in the highest category of glyphosate exposure compared with those who never used glyphosate. The fact that no other studies have reported an association between glyphosate and AML risk calls for cautious interpretation of the results. However, the observed pattern of increasing risk with increasing exposure and the lagged exposure of 10 or more years raises concern and the need for additional long term studies.

Today, Americans spray an estimated 180-185 million pounds of the weed killer, on their yards and farms every year. All the acute toxicity tests have indicated glyphosate is nearly nontoxic to mammals, but concern has been raised about long term exposure. The current findings are reassuring, but given the prevalence of use of this herbicide not only in the United States but worldwide, efforts should be undertaken to replicate these findings as soon as possible.