It’s been a decade since the International Agency for Research on Cancer (IARC) classified glyphosate as a probable carcinogen in 2015, and its use all over the world has significantly increased in terms of both volume and intensity. Even with such a grave, alarming indictment, applications of glyphosate have extended beyond croplands to non-agricultural settings, such as in lawns and gardens, and alongside it has been the rise of cancer incidences, especially childhood cancers. Glyphosate has become highly profitable, making €2.647 billion (~USD 2.9B) for Bayer in 2024. It is considered the most-used herbicide in history, with 18.9 billion pounds of the chemical sprayed since 1974. Behind such capture of food and agriculture is the unrelenting industry influence over policy and science, reinforced by PR tactics of denial and disinformation to dismiss growing health concerns.
Pesticide Action Network – Asia Pacific (PANAP) welcomes the public release of the latest independent animal study on glyphosate’s carcinogenicity, which shows that the public’s pressing demand for glyphosate’s global ban is warranted and that delays have deadly consequences on public health.
Animal carcinogenicity studies help provide evidence of the ability of glyphosate and its commercial formulations, glyphosate-based herbicides (GBHs), to increase incidences of multiple types of cancers; thus, they need to be conducted without industry influence. Free from profit motive, they support the IARC’s findings – contested by industry – by showing how pesticides like glyphosate can cause cancer, reinforcing growing epidemiological evidence linking exposure to rising cancer rates.
Results of the study
Over two years, the Ramazzini Institute’s (RI) carcinogenicity arm – part of the long-term Global Glyphosate Study (GGS) – tested the herbicide’s toxic effects. The independent, non-profit group found that certain doses of pure glyphosate and two commercial GBHs (Roundup Bioflow in the EU and RangerPro in the US) caused multiple cancers in Sprague-Dawley (SD) rats, including rare tumors. These findings were compared to both GGS control groups and historical data, which showed no such cancers.
The study gave rats three doses of glyphosate and GBHs in their drinking water from before birth (starting on the sixth day of pregnancy) until they were two years old. The doses included levels used by EU regulators: the acceptable daily intake (0.5 mg/kg/day) and the no-observed adverse-effect level (50 mg/kg/day). The results showed an apparent, dose-related rise in both benign and malignant tumors across several organs in male and female rats. Some tumors – like those in the skin, liver, and thyroid – matched earlier studies, while others, including leukemia and nervous system cancers, appeared only in this study.
Other key characteristics and findings of the GGS carcinogenicity study, in broad strokes, are as follows:
- Early-life onset and early mortality were observed for multiple cancers. Malignant tumors in the liver, ovary, blood, and nervous system occurred early, likely from prenatal exposure through the mothers’ drinking water, leading to early deaths, especially in groups with solid tumors. Half of the leukemia deaths in glyphosate and GBH-exposed rats occurred before one year (comparable to under 35-40 human years). Leukemia appeared in both sexes, but results were stronger in males and became more statistically significant when both sexes were combined. These findings are groundbreaking, capturing early-life exposures often missed in studies starting only in adulthood.
- Increased carcinogenic effects of commercial formulations vs. pure glyphosate. While glyphosate alone can cause various tumors, the study found that GBH co-formulants likely add to its cancer risk, especially for leukemia. Tumors in organs like the adrenal glands, kidneys, bladder, and pancreas appeared only with Roundup Bioflow and RangerPro, not pure glyphosate. This suggests these formulations either share a carcinogenic mechanism or amplify glyphosate’s effects. A key limitation is that their exact ingredients are proprietary, preventing a complete health impact analysis.
- Incidences of cancers considered rare for the SD rats were observed. The study found that glyphosate and GBHs triggered rare cancers (incidence <1%), including liver cancer and aggressive adrenal cortical carcinoma. While liver cancer rates weren’t statistically significant, multiple cases appeared across treated groups. Adrenal cortex cancer was found in male rats exposed to GBHs, aligning with earlier findings linking Roundup Bioflow to rare ovarian tumors and early deaths.
Greater urgency towards a global ban
These findings underscore the greater urgency in Pesticide Action Network – Asia Pacific’s (PANAP) work to phase out highly hazardous pesticides (HHPs) like glyphosate. The fact that it is the most widely used herbicide on the planet means that there is a staggering number of farmers and agricultural workers, as well as the communities surrounding the farmlands, who are routinely exposed to it both through direct occupational use with crop applications as herbicide and desiccant, and indirectly through pesticide drift. Skin contact has been identified as an effective route of exposure, and these people have increased susceptibility to developing not just skin tumors but various forms of cancers over their lifetimes.
The GGS initiative has sparked urgent calls for review, challenging EU-approved glyphosate exposure levels and pushing for its 10-year approval to be revoked. This study and many others including IARC’s classification of glyphosate as a probable human carcinogen should push all countries to ban glyphosate to protect human health and the environment.
A key insight is that commercial formulations – how most people and animals are exposed – may enhance glyphosate’s cancer risk. A recent meta-analysis links GBHs to a 41% higher risk of non-Hodgkin lymphoma in highly exposed individuals. This is alarming, especially since GBH ingredients are protected as trade secrets, limiting transparency and shielding agrochemical corporations from accountability.
Furthermore, the study highlights the risks of glyphosate exposure even at low doses during prenatal and early-life stages, linking it to early-onset cancer and premature deaths. The study’s authors note that prenatal carcinogenicity models in SD rats are now considered reliable predictors for humans, based on the concept of developmental origins of health and disease – a key public health strategy. Unlike earlier studies that tested only post-natal exposure at higher doses, GGS used lower doses and still found significant tumor increases in organs like the pancreas, testes, and thyroid.
The GGS findings add to the growing body of literature on the potential connection between glyphosate and childhood cancer, an area of focus of PANAP under the Protect Our Children campaign. The network’s monitoring has shown that children are sicker today than they were compared to previous generations, and that early exposure to toxic chemicals in food and agriculture is a major contributor. We need to continue building on such science and evidence-based documentation to support our campaign and advocacy against HHPs.
PANAP’s Community-based Pesticide Action Monitoring (CPAM) initiative, for instance, documents the harmful effects of pesticide use, providing evidence-based reports that strengthen calls for governments and corporations to phase out HHPs and adopt ecosystem-based alternatives. In 2024, it published a Consolidated List of Banned Pesticides and the List of Highly Hazardous Pesticides as its contribution to the global commitment to phase out HHPs as mandated by the United Nations Environment Assembly (UNEA) resolution on Highly Hazardous Pesticides and by the newly adopted Global Framework on Chemicals (GFC). ###
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