ORIGINAL ABSTRACT

Glyphosate-based formulations (GBFs), such as Roundup, are the most heavily used herbicides in the world. In 2015, the International Agency for Research on Cancer (IARC) concluded that glyphosate and GBFs are probably carcinogenic to humans (group 2A), mainly for non-Hodgkin lymphoma (NHL). However, this finding has been controversial and most pesticide regulatory agencies have not followed their lead. The purpose of this review is to update the scientific literature linking exposure to glyphosate and GBFs to the development of NHL, with emphasis on new findings over the last 5 years. The recent epidemiologic studies provide new evidence for an association between exposure to GBFs and an increased risk of NHL. A new animal study has also shown that glyphosate and GBFs are carcinogenic in rats and also cause acute leukemia. Mechanistic studies have continued to demonstrate that glyphosate and GBFs are genotoxic to human lymphocytes and other cells. Genotoxic and other biological effects have also been shown in human studies and in various animal and cell models with these agents even at low doses. A novel mechanism of chelation and sequestration of glyphosate in bone with slow release over days to weeks resulting in prolonged bone marrow and blood exposure may lead to the development of acute leukemia and other hematologic malignancies. These new findings continue to provide consistent, coherent and compelling evidence that glyphosate and GBFs are a cause of NHL in humans exposed to these agents, and should prompt new reviews by pesticide regulatory agencies around the world.