29
May
Farmers and Farmworkers Face DNA and Cellular Damage with Chronic Pesticide Exposure, Study Finds
(Beyond Pesticides, May 29, 2025) A study, published in Environmental Toxicology and Pharmacology, “investigates genotoxic effects on farmers in ParaÃba, Brazil, analyzing buccal mucosa cells [cells from inside the cheek] for DNA and cellular damage,†the authors write. In comparing data from 33 pesticide-exposed agricultural workers to 29 unexposed people in a control group, the researchers report that the “findings revealed significantly higher frequencies of cellular alterations and DNA damage among exposed farmers relative to the control group, with no significant impact from factors such as smoking, alcohol consumption, or family cancer history.â€
They continue, “These results underscore the genotoxic risks linked to prolonged pesticide exposure and highlight the necessity for stricter regulatory measures.†As Beyond Pesticides documents in Disproportionate Pesticide Hazards to Farmworkers and People of Color Documented… Again, farmworkers have been excluded from labor and occupational safety protection laws since their inception. The Occupational Safety and Health Administration (OSHA) defers all policy on pesticide protections to the U.S. Environmental Protection Agency (EPA), which has been widely criticized for providing inadequate worker protection standards.
This study focuses on workers in Brazil, but represents issues that impact communities worldwide. “The agricultural sector plays a pivotal role in Brazil’s economy, encompassing both family farming for food production and agribusiness for exporting commodities,†the authors state. They continue: “This growth has resulted in a substantial rise in pesticide usage, making Brazil one of the world’s largest consumers of these chemicals. Alarmingly, about 80% of pesticides sold in Brazil lack approval in at least three OECD [Organisation for Economic Co-operation and Development] countries.†(See here, here, here, and here.)
Farmers, farmworkers, and their families around the world face disproportionate risks from pesticide exposure. (See more here and here.) As the researchers explain, “Farmers are particularly vulnerable to pesticide exposure, frequently experiencing continuous contact over long periods. They are often subjected to multiple pesticide compounds simultaneously, as various substances are applied during planting and harvesting seasons.†(See study here.)
Methodology
To assess the impacts on DNA and cellular health from occupational pesticide exposure, this study uses biomonitoring, a tool for assessing health risks associated with exposure to chemicals and genotoxicity markers that “play a crucial role in assessing the impact of chemical substance exposure on genetic material, encompassing gene mutations and chromosomal damage.†Specifically, the authors use the Buccal Micronucleus Cytome (BMCyt) assay, which they describe as “a minimally invasive method [that] has shown advantages as it is used not only for detecting micronuclei (MN) but also for other nuclear abnormalities (nuclear buds, binucleated cells, condensed chromatin, karyorrhexis, karyolysis, and pyknosis) and for assessing proliferative potential through the frequency of basal cells.â€
In the study, the 33 agricultural workers report direct exposure to pesticides in the field, while the 29 individuals from the control group do not. “In terms of pesticide usage duration, 7 respondents (21.21%) reported using pesticides for less than 5 years, 4 respondents (12.12%) have used them for 5–10 years, and 22 respondents (66.67%) have been using pesticides for more than 10 years,†the researchers note.
In disclosing information regarding their exposure, the farmworkers were unable to report specific pesticide dosages or duration of pesticide applications, as they commented that they do not follow product instructions and applications vary by day, crop, and product type. “Additionally, it is important to note that they do not properly use personal protective equipment, which leads to potential pesticide exposure through various routes (e.g., dermal, inhalation, etc.),†the authors say.
The pesticides that the agricultural workers identified as being utilized include the insecticides deltamethrin, methamidophos, methomyl, teflubenzuron, abamectin, imidacloprid, beta-cyfluthrin, cypermethrin, and chlorfenapyr, as well as the herbicides 2,4-D, ametryn, hexazinone, diuron, and glyphosate. Of these active ingredients, the most commonly reported by the farmworkers is 2,4-D.
Once samples of buccal mucosa cells were obtained through cheek swabs from each participant, an analysis of the micronuclei and other nuclear abnormalities was performed under a microscope. The researchers identify DNA and cellular damage by utilizing a damage index, where the damage frequency represents the percentage of cells that suffered DNA damage, and from a comet assay, which “visually assesses DNA damage by scoring comet tail size and intensity, categorizing damage into five levels (0–4) to indicate cell damage severity.â€
Study Results
Based on the researchers’ observations of the assays from the agricultural workers’ samples, there are cellular alterations such as micronucleus (broken chromosome fragment within nucleus), cells with nuclear buds (protrusions on nucleus), binucleation (cell with two nuclei), and karyolysis (dissolution/degradation of nucleus). “The frequencies of these alterations found in the cell samples from the farmers showed statistically significant higher values when compared to the control group,†the authors report.
They continue: “The comet assay revealed the presence of genotoxicity in the cells of farmers exposed to pesticides. Based on images obtained through laser confocal microscopy, it is possible to observe the presence of cells with tails, known as ‘comets,’ in the farmer group, which is not seen in the control group.â€
In the pesticide-exposed group, a significant decrease in cells without DNA damage is observed, as well as a visible increase in the number of cells with DNA damage (comets). “The comet assay results showed that the farmers experienced a higher level of cellular damage compared to the control group,†the researchers note. “It is important to emphasize that most participants had already been using pesticides for over 10 years… Thus, we may suggest that the genotoxic and cytological effects observed would be related to long-term exposure.â€
Previous Research
The authors reference multiple studies that support their data, as well as offer additional plausible explanations for the study results:
- A study “revealed that the frequency of micronuclei among younger participants (ages 19–36) was 0.53%, while in older participants (ages 46–71), it rose to 0.87%. This research also noted a consistent increase in the occurrence of micronuclei with advancing age. Notably, among farmers over 50 years old, there was a marked increase in the frequency of micronuclei, binucleations, and other abnormalities compared to those aged 18–30 years.â€
- “Advancing age is a significant factor that may lead to a higher frequency of nuclear abnormalities in rural workers. As individuals grow older, genetic damage can accumulate due to the increase in mutations and a reduced capacity for the body to repair DNA damage.†(See studies here and here.)
- Studies of 2,4-D report “that this pesticide is associated with cellular malformations linked to the cytotoxic and genotoxic effects… with the presence of micronuclei (MN) serving as a genotoxicity indicator and nuclear abnormalities signaling cytotoxic damage, potentially representing nuclear lesions similar to MN. The formation of micronuclei (MN) suggests disruptions in mitotic division, potentially involving chromosome segregation errors and deficiencies in DNA damage repair mechanisms, which can be triggered by oxidative stress induced by pesticide exposure.†(See here, here, here, and here.)
- “[O]rganophosphate pesticides, such as methamidophos, induce toxicity via mechanisms involving DNA damage and the subsequent repair processes.†(See studies here, here, and here.)
- “The literature highlights that glyphosate and its metabolite AMPA can induce genotoxicity and cell death in vitro. Organophosphates react with DNA through electrolytic centers, causing nitrogenous base substitutions, enzyme inhibition, caspase activation, and membrane damage. Similar effects are seen with 2,4-D metabolites, which also trigger apoptosis via caspases and disrupt transcription factors.†(See here and here.)
- “Several studies indicate that rural workers routinely exposed to pesticides show an elevated frequency of MN, binucleated cells (BN), budded cells (BT), and other forms of DNA damage. These findings are consistent with existing literature that underscores the genetic damage associated with prolonged exposure to pesticides.†(See studies here and here.)
- Another study identifies “a significant disparity in the rate of DNA damage between workers involved in pesticide production and individuals not exposed to these chemicals. Specifically, the average damage rate among the workers was 60.8±18.2, contrasted with a much lower rate of 10.5±1.1 in the control group.â€
Beyond Pesticides’ Daily News coverage on farmworkers, including EPA’s Worker Protection Standard Fails to Protect Farmworkers’ Health, Report Finds, highlights the long history of health threats, regulatory failures, and structural racism that is imbued in the chemical-intensive agricultural system that feeds the nation and world. The pesticide problem is not unique to farmworkers, but they and their families suffer a disproportionate burden of the hazards. (See additional coverage here.)
As previously shared by Beyond Pesticides, DNA damage is significantly higher in Latinx children from rural, farmworker families than children in urban, non-farmworker families, according to a recent study published by French and American authors in the journal Exposure and Health. Not only do farmworker children test positive for organophosphate pesticides more frequently than non-farmworker children, but the study finds that farmworker children also experience an increased frequency of DNA damage associated with the presence of organophosphate exposure. These results highlight the disparities in exposures and outcomes for children from vulnerable immigrant communities.
Organic Solution
Advocates note that as long as pesticides remain in use, farmworkers and their families will continue to shoulder a disproportionate share of the toxic effects of these chemicals; another in a long line of reasons to shift away from toxic synthetic pesticide use to the adoption of proven organic, regenerative agricultural practices.
Learn more about the benefits of organic agriculture here and here, as well as how to create nontoxic lawns and landscapes in your community here. Are you an artist, writer, or photographer? Help us celebrate the beauty of nature that deserves to be protected from toxic chemicals by submitting your artwork to our Art Page.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Carvalho-Gonçalves, L. et al. (2025) Assessment of genetic damage levels in agricultural workers exposed to pesticides in ParaÃba, Brazil, Environmental Toxicology and Pharmacology. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1382668925000900.
