Systematic Review: Does Glyphosate Exposure Cause Cancer?

Introduction: Glyphosate is the active ingredient in more than 750 herbicides, marketed for over 40 years. The IARC was the only authority to classify glyphosate as probably carcinogenic to humans. The aim of this study was to evaluate whether exposure to the herbicide glyphosate causes cancer.

Methods: Approved by the Institutional Research Advisory Committee of the proposing institution (Protocol 6681). A systematic literature review of observational studies was conducted, with the inclusion criteria being: studies that assessed cancer incidence and exposure to the herbicide glyphosate; cohort studies; case-control studies; case series or case reports; experimental studies with animals; and in vitro studies. The systematic review question was: Can exposure to the herbicide glyphosate cause cancer? The research period was from 1983 to 2026. The generic search strategies were: (glyphosate OR roundup) AND (Neoplasms OR cancer OR "carcinogenicity tests" OR Carcinogenicity).

Results: 737 articles were found, of which 245 duplicate were excluded, 79 were subsequently excluded for not being object of study, and finally, 33 complete articles evaluated were excluded because they were review articles, conference abstracts, or were out scope. Of 46 articles included for qualitative analysis, 8 were in vitro studies, 5 were experimental studies with animals, and 33 were observational studies with humans. All the studies evaluated showed some relationship between glyphosate and cancer. In vitro studies showed a relationship between glyphosate exposure and breast, skin, and prostate cancer. Experimental studies with animals showed a relationship with breast, skin, liver, kidney, and lymphoid neoplasms. Observational studies with humans showed a stronger relationship with lymphoid neoplasms, breast, pancreas, and bladder cancer.

Conclusion: Exposure to glyphosate is a risk factor for the development of cancer, and not only for lymphoid neoplasms. However, more studies are needed to establish this relationship properly.

Keywords

roundup; ghyphosate; neoplasms; cancer; carcinogenicity