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https://ntp.niehs.nih.gov/go/glyphosate

Glyphosate & Glyphosate Formulations

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Research Overview

Status: Ongoing
Substances: Glyphosate
Nominated: December 1984

Background Information

Glyphosate, a chemical that controls weeds and grasses, is the most widely used herbicide worldwide. The major reason glyphosate is used so broadly is because many crops have been genetically engineered to be resistant to glyphosate, allowing it to target weeds while leaving crops unaffected. When applied as a mixture with other substances, plants can more readily absorb glyphosate, making it more effective. People can be exposed to residual amounts of glyphosate by ingestion of food or water; however, individuals who regularly handle glyphosate products as part of their occupation experience higher exposures.
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NTP Studies

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
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Research at Other Agencies

United States
International
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Informational Resources

The informational resources below provide additional details on NTP's research on glyphosate and glyphosate formulations.

FAQs

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.

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)
Presentations
Supporting Documents
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