Since the introduction of
glyphosate-tolerant genetically-modified plants, the global use of
glyphosate has increased dramatically making it the most widely used
pesticide on the planet. There is considerable controversy concerning the carcinogenicity of
glyphosate with scientists and regulatory authorities involved in the review of
glyphosate having markedly different opinions. One key aspect of these opinions is the degree to which
glyphosate causes
cancer in laboratory animals after lifetime exposure. In this review, twenty-one chronic exposure animal carcinogenicity studies of
glyphosate are identified from regulatory documents and reviews; 13 studies are of sufficient quality and detail to be reanalyzed in this review using trend tests, historical control tests and pooled analyses. The analyses identify 37 significant
tumor findings in these studies and demonstrate consistency across studies in the same sex/species/strain for many of these
tumors. Considering analyses of the individual studies, the consistency of the data across studies, the pooled analyses, the historical control data, non-neoplastic lesions, mechanistic evidence and the associated scientific literature, the
tumor increases seen in this review are categorized as to the strength of the evidence that
glyphosate causes these
cancers. The strongest evidence shows that
glyphosate causes
hemangiosarcomas, kidney
tumors and
malignant lymphomas in male CD-1 mice,
hemangiomas and
malignant lymphomas in female CD-1 mice,
hemangiomas in female Swiss albino mice, kidney
adenomas, liver
adenomas, skin
keratoacanthomas and skin basal cell
tumors in male Sprague-Dawley rats,
adrenal cortical carcinomas in female Sprague-Dawley rats and
hepatocellular adenomas and skin keratocanthomas in male Wistar rats.