Glyphosate & Glyphosate Formulations
Nominated: December 1984
Human exposure usually occurs in the form of glyphosate-based formulations. Few studies have made side-by-side comparisons of the toxicity of glyphosate and glyphosate-based formulations using the same experimental methods. NTP is currently proceeding with an investigation that includes comparing the toxicity of both, using the same methods. Specifically, NTP aims to:
- Evaluate whether glyphosate causes genotoxicity, or damage to DNA
- Evaluate whether glyphosate induces oxidative damage, the harm that cells and tissues experience when they are not able to keep up with free radical production
- Compare the effects of glyphosate on measures of genotoxicity, oxidative stress, and cell viability with the effects of glyphosate-based formulations
What did the studies find?
See the table below for the most up-to-date information on the variety of projects taking place at NTP.
|Study||Description||Status||Findings & Supporting Files|
In Vitro Screening Tests
|Cell-based tests to study DNA damage, oxidative stress, and cell viability||Ongoing||Supporting files
|Genetic Toxicity Testing||Cell-based studies to determine the potential of glyphosate to cause DNA damage (genotoxicity)||Ongoing||Supporting files
Research at Other Agencies
The informational resources below provide additional details on NTP's research on glyphosate and glyphosate formulations.
Q: Why does NTP care about studying glyphosate?
A: In 1992, NTP reported that rodents exposed to glyphosate in feed showed little evidence of toxicity, and there was no evidence of glyphosate causing damage to DNA. Since then, several public health agencies have reviewed the scientific literature to learn whether exposure to glyphosate is a cancer hazard for humans.
- In March 2015, the International Agency for Research on Cancer concluded that glyphosate is a likely human carcinogen based on findings in studies on humans and animals. It also reported that glyphosate-based formulations are often more toxic than glyphosate alone.
- In November 2015, the European Food Safety Authority (EFSA) concluded that glyphosate is unlikely to pose a carcinogenic hazard to humans.
- In May 2016, the Joint Food and Agricultural Organization of the United Nations/World Health Organization Meeting on Pesticide Residues concluded that glyphosate is unlikely to pose a carcinogenic risk to humans from exposure in the diet.
- Currently, the United States Environmental Protection Agency (EPA) is completing a new human health risk assessment on glyphosate, including an evaluation of its cancer-causing potential.
Due to different interpretations of the potential health risks of glyphosate exposure, major public concern about exposure risks, and reported differences in the toxicity of different glyphosate products, NTP is conducting more research on glyphosate and its formulations, including testing the potential genetic and mechanistic toxicity.
Q: When will the data become available?
A: NTP hopes to make available some of the data from its genetic toxicity tests by early 2020. The data will be placed into the Chemical Effects in Biological Systems database. NTP anticipates releasing the oxidative stress data later in 2020.
Q: What types of things is NTP testing that are related to glyphosate?
A: NTP is testing glyphosate and several glyphosate-based formulations used for either agricultural or residential purposes. Formulations were selected to span a range of glyphosate concentrations. NTP is also testing (aminomethyl)phosphonic acid (AMPA), a metabolite of glyphosate that is produced by microbes, including the mammalian microbiome.
Substances are tested in the following cell-based genotoxicity assays, in the presence or absence of an exogenous rat liver metabolic activation system:
- Bacterial mutagenicity assays with S. typhimurium tester strains TA100, TA98, TA97, TA1535, and E. coli tester strain WP2
- Micronucleus assay (human TK6 cells)
- MultiFlow DNA Damage Assay (human TK6 cells)
- NTP Board of Scientific Counselors Meeting, Research Triangle Park, NC, June 15, 2016
- NTP Board of Scientific Counselors Meeting, Research Triangle Park, NC, December 7, 2017
- Society of Toxicology 57th Annual Meeting and ToxExpo, San Antonio, TX, March 11-15, 2018
- Society of Toxicology 58th Annual Meeting and ToxExpo, Baltimore, MD, March 10-14, 2019
- Environmental Mutagenesis & Genomics Society Annual Meeting, Washington, DC, September 19-23, 2019
- Poster: Comparison of the Genotoxicity of Glyphosate, (Aminomethyl)phosphonic Acid, and Glyphosate-Based Formulations Using In Vitro Approaches
- Slides: Evaluation of Glyphosate, (Aminomethyl)phosphonic Acid, and Glyphosate-Based Formulations for Genotoxicity and Oxidative Stress Using In Vitro Approaches
- National Toxicology Program (US). NTP technical report on toxicity studies of glyphosate (CASRN 1071-83-6) administered in dosed feed to F344/N rats and B6C3F1 mice. (NTP Toxicity Reports Series; No. 16). 1992. https://
ntp.niehs.nih.gov/ results/ pubs/ shortterm/ reports/ abstracts/ tox016/index.html
- International Agency for Research on Cancer (FR). Some organophosphate insecticides and herbicides. (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans; Vol. 112). 2015. http://
monographs.iarc.fr/ ENG/ Monographs/ vol112/ index.php
- Mason RP. Imaging free radicals in organelles, cells, tissue, and in vitro with immuno-spin trapping. Redox Biol. 2016 Aug;8:422-9. PubMed PMID: 27203617; PubMed Central PMCID: PMC4878322. https://
www. ncbi. nlm. nih. gov/ pubmed/ 27203617
- Food and Agriculture Organization of the United Nations. Pesticide residues in food 2016: special session of the joint FAO/WHO meeting on pesticide residues. (FAO Plant Production and Protection Paper; No. 227:1-123). 2016. http://
www. fao. org/ publications/ card/ en/ c/ 22b948ec-af63-45c9-8de1-34153d2482c5/
- Howard BE, Phillips J, Miller K, Tandon A, Mav D, Shah MR, et al. SWIFT-Review: a text-mining workbench for systematic review. Syst Rev. 2016; 5(1): 87. PubMed PMID: 27216467; PubMed Central PMCID: PMC4877757. https://
www. ncbi. nlm. nih. gov/ pubmed/ 27216467
- EPA's evaluation of the carcinogenic potential of glyphosate. Environmental Protection Agency (US); 2018. https://
cfpub. epa. gov/ si/ si_ public_ record_ Report. cfm? dirEntryId =337935
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