07
May
Farmers Face Elevated Cancer Risks Tied to Chemical Soup of Pesticide Exposure
(Beyond Pesticides, May 7, 2025) Researchers at the University of Caxias do Sul (Brazil) identify 29 peer-reviewed scientific studies with statistically significant findings that tie pesticide use to cancer diagnoses. The literature review is published in Saúde Debate. This collection of clinical trials, as well as epidemiologic, case-control, and experimental studies—from the United States, Brazil, India, France, Egypt, Columbia, Ecuador, Mexico, Italy, and Spain—add to the hundreds of peer-reviewed independent analyses connecting synthetic chemical dependency in food production and land management with mounting public health concerns.
Advocates continue to call for holistic solutions that move away from toxic inputs that disproportionately harm the communities responsible for the food on dinner tables, and instead cultivate microbial diversity in soil, rather than prophylactically spray for the sake of pest control. Beyond Pesticides values the importance of scientific integrity and open access to data to inform decision makers on how to adopt healthier practices for their communities. Reliable information for good governance is critical, which is a driving factor in the ongoing compilation of thousands of peer-reviewed literature compiled and curated in the Pesticide-Induced Disease Database and Gateway on Pesticide Hazards and Safe Pest Management.
Background and Methodology
The main objective of this review is to determine the relationship between the use of pesticides and the elevated risk of cancer among farmer populations. The researchers, as noted in their introduction, aimed to achieve this by engaging in a broad literature review, pulling in different types of studies with strict criteria to sort through the several subpopulations who face elevated chemical risks from occupational exposure. A search methodology was established to pull peer-reviewed journal articles from various scientific databases across the globe.
“The inclusion criteria for selecting articles were: original articles; applied research articles; published in full, from 2012 to 2021; with open access; in English and Portuguese; that addressed the relationship between the use of pesticides and the onset of cancer in the farming population,†say the researchers. The exclusion criteria include studies unrelated to pesticides, those with participants who have only indirect exposure to pesticides, studies that do not identify cancer biomarkers, or other meta-analyses.
Saúde Debate, translated as “Health in Debate,†is a peer-reviewed journal hosted by the Brazilian Center for Health Studies. The journal receives funding from the Center, Oswaldo Cruz Foundation, and National Council for Scientific and Technological Development. The review follows Preferred Reporting Items for systematic Reviews and Meta-Analyses Extension for Scoping Reviews, a study protocol registered on the Open Science Framework platform on August 22, 2022. The authors also disclose that this scoping review is part of their research project, ‘The use of pesticides in family farming and its implications for farmers’ health and environmental health,’ which was “approved by the Research Ethics Committee, Opinion No. 3,481,277 (CAAE 17010519.1.0000.5341).â€
Results
In terms of best practices for identifying reliable sources, the authors note that all the studies of interest include the following two features:
- “biomarkers for early prediction of cancer (case-control studies and clinical trials); and
- risk associations (sociodemographic data, use of pesticides, types of pesticides, exposure to products, frequency and duration of exposure and agricultural tasks).â€
Fourteen of the studies signal elevated risk for numerous cancers, including breast cancer, central nervous system, lung, as well as general cancer risk. In studies that consider multiple pesticides, associations are made between exposure and “lung, hematological, breast, and prostate cancer.†Associations between pesticide exposure and melanoma, non-melanoma, and lip cancer were excluded because of sun exposure as a significant confounding factor. This is important to note in the context of organochlorine pesticides, which have been determined to be carcinogenic and widely considered a leading cause of cancer among farmers and agricultural communities for decades. (See here for Daily News coverage of the latest scientific literature on organochlorine pesticides and health impacts.)
The results originating in the U.S.-based studies, which make up the largest number of studies identified in this literature review, highlight a demonstrable pattern between long-term exposure to chemical mixtures and heightened risks of health hazards. There are several studies in this review, as well as studies covered in the Daily News, that leverage data from the Agricultural Health Study, a prospective study of licensed applicators recruiting nearly 53,000 private applicators and more than 75 percent of their spouses in Iowa and North Carolina enrolled in a cohort between 1993 and 1997.
For example, a 2015 study published in PloS One found that pesticides, including the weed killer 2,4-D, were “borderline significant†for acting as a potential intermediary for certain diseases, including cancer. The researchers in this prospective population cohort study considered geographical location, smoking history, body mass index, and other potentially confounding variables in their assessment. A 2017 population study published in Environmental Health Perspectives contributes to the literature on linkages between occupational pesticide exposure and lung cancer. High pesticide exposure events are also found to contribute to “increased DNA methylation in GSTp1 promoter and subsequent gene inactivation have been consistently associated with prostate cancer[,]†based on a 2016 study published in Environmental and Molecular Mutagenesis from this same cohort.
Agricultural Community Impacted by Pesticides
Farmers, farmworkers, and their families face disproportionate risks from toxic pesticide exposure.
A recent Daily News post, Dramatic Array of Pesticides Used Outdoors Make Their Way Inside, Contaminating the Indoor Environment, reviews two recent studies from European and Argentine-based populations, highlighting the implications of pesticide contamination in an indoor environment. The Argentine study found 41 compounds or metabolites of the 49 pesticides it tested for in its study, speaking to the pervasiveness of chemical residues that can be tracked into homes. Pesticide residues have been detected in the urine samples of farmers and nonfarmers alike, in addition to being linked to an elevated risk of depression, cognitive decline, obesity, sleep issues/disorders, and various cancers, including brain cancer.
As previously covered in the Daily News, farmworkers face the brunt of pesticide exposure on a daily basis, not just in the form of acute exposure but also long-term residues that drift in from the field on clothing, footwear, or other mediums. Peer-reviewed studies have linked pesticide exposure to sleep disorders, respiratory harms, DNA damage, and mental health disorders, including depression and suicide. Farmworker children are particularly vulnerable given the bioaccumulative impacts and amplified toxicity potential that they face compared to their parents. See Agricultural Justice to learn about the history of Beyond Pesticides’ engagement with farmworkers and the U.S. Environmental Protection Agency as one of the driving forces for Beyond Pesticides’ mission to eliminate toxic petrochemical-based pesticides and transition to organic.
Call to Action
Beyond Pesticides continues to support coalitions and campaigns across the nation that protect people’s rights to safety from environmental and occupational exposure to toxic pesticides, including protection of “failure-to-warn” claims against chemical manufacturers, central to pesticide injury litigation in the U.S. In an era of federal deregulation and the inability of political leaders to initiate and enact substantial reforms, litigation remains a critical backstop for corporate accountability.
For more information, see the latest Action of the Week, Don’t Allow Chemical Companies To Exempt Themselves from Responsibility. See the Pesticide Immunity Bill Resource Hub to stay updated on related state and federal campaigns.
 All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Saúde Debate
