Chromatographic Analysis of Digestion-Driven Pesticide Transformation in Apples

Most pesticide risk assessments today assume that all pesticides present can be absorbed by the body and that does not change during digestion. This often ignores how the food itself and the digestive process can affect the absorbance process.To close this knowledge gap, researchers took a systematic, multi-technique approach to track how digestion alters pesticide toxicity in apples. They examined three widely used pesticides (thiram, atrazine, and isocarbophos) by simulating gastrointestinal digestion and then probing the outcomes with a suite of analytical tools. Cytotoxicity was measured using electrochemical cell-based biosensors, while gut microbiota effects were evaluated through in vitro fermentation combined with 16S rRNA sequencing. At the same time, high-performance liquid chromatography-mass spectrometry (HPLC-MS) was used to quantify bioaccessibility and map metabolic transformations, providing mechanistic insight into how digestion reshapes pesticide toxicity. A paper based on their efforts was published in Food Research International.¹

Why May Current Pesticide Risk Assessments Be Misleading, and What is Missing from Them?

Most current pesticide risk assessments assume that the entire pesticide can be absorbed by the body and that it doesn’t change during digestion, which can lead to inaccurate estimates of the real health risks.²In reality, when pesticides are eaten, they pass through the digestive system where they are exposed to digestive enzymes, changing acidity levels, and interactions with the food they’re in.^3,4These conditions can greatly change how much of the pesticide the body can absorb, how stable it remains, and whether it breaks down into substances that are more harmful or less harmful.^5,6Also, the gut microbiota—a large and diverse group of microbes living in the colon—plays an important role in breaking down foreign chemicals. At the same time, these microbes can be harmed by pesticides and can also influence how toxic those pesticides end up being.⁷ Recent research suggests that leftover pesticides in food can disturb the balance of gut bacteria, which may lead to an unhealthy gut and related health problems.^8,9 “Therefore,” write the authors of the paper,¹ “integrating food matrix effects, gastrointestinal digestion, and gut microbiota interactions is essential for a realistic evaluation of pesticide hazards.”

How Does Digestion Change the Toxicity of Different Pesticides?

The results showed that digestion affects each pesticide differently. For thiram, digestion broke it down into several byproducts, but its harmful effects on cells stayed about the same, and its impact on gut bacteria slightly increased, which suggests that some of the breakdown products may still be harmful or even more so. Atrazine, on the other hand, remained mostly unchanged during digestion and tended to stick to the food, so very little of it was actually absorbed, and its effects on cells and gut bacteria didn’t change much. In contrast, isocarbophos was partly broken down during digestion, which reduced its harmful effects on both cells and gut bacteria, suggesting that digestion helped make it less toxic.¹

“These findings,” write the authors of the paper,¹ “underscore the critical necessity of incorporating food matrix effects and digestive transformations into dietary risk assessments to accurately evaluate the health impacts of pesticide exposure.”

The researchers, however, admit that their study has some limitations. The lab-based digestion model is a simplified version of what happens in the human body; the team did not dtest the effects on cells after fermentation and only looked at the toxicity of breakdown products to a limited extent. Future studies in their opinion, should confirm these results in real-life conditions and improve the experimental approach, which will help provide more accurate assessments of the risks from pesticide residues in food.¹

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References

1. Wei, X.; Wu, Y.; Zhou, X. et al. Impact of in vitro Digestion on the Cytotoxicity and Gut Microbiota Toxicity of Three Representative Pesticides in Apples. Food Res Int. 2026, 235, 119264. DOI: 10.1016/j.foodres.2026.119264
2. Tian, W.; Zhang, M.; Zong, D. et al. Are High-Risk Heavy Metal(loid)s Contaminated Vegetables Detrimental to Human Health? A Study of Incorporating Bioaccessibility and Toxicity into Accurate Health Risk Assessment. Sci Total Environ. 2023, 897, 165514. DOI: 10.1016/j.scitotenv.2023.165514
3. Faria, M. A.; Melo, A.; Ferreira, A. Influence of Dietary Patterns on Contaminants Bioaccessibility and Intestinal Transport by in vitro Assays. Food Res Int. 2020, 137, 109358. DOI: 10.1016/j.foodres.2020.109358
4. Qin, W.; Ketnawa, S.; Ogawa, Y. Effect of Digestive Enzymes and pH on Variation of Bioavailability of Green Tea During Simulated in vitro Gastrointestinal Digestion. FSHW2022, 11 (3), 669-675. DOI: 10.1016/j.fshw.2021.12.024
5. Chen, A. S.; Liu, D. H.; Hou, H. N. et al. Dietary Pattern Interfered with the Impacts of Pesticide Exposure by Regulating the Bioavailability and Gut Microbiota. Sci Total Environ.2023, 858 (Pt 2), 159936. DOI: 10.1016/j.scitotenv.2022.159936
6. Ma, C.; Zhang, Q.; Lv, D. Z. et al. Study of Factors Influencing the Oral Bioaccessibility of Commonly Used and Detected Pesticides in Bananas and Mangoes Based on in vitro Methods. Foods 2024, 13 (13), 2019. DOI: 10.3390/foods13132019
7. Sharma, T.; Sirpu Natesh, N.; Pothuraju, R. et al. Gut Microbiota: A Non-Target Victim of Pesticide-Induced Toxicity. Gut Microbes 2023, 15 (1), 2187578, 10.1080/19490976.2023.2187578
8. Matsuzaki, R.; Gunnigle, E.; Geissen, V. et al. Pesticide Exposure and the Microbiota-Gut-Brain Axis. ISME J.2023, 17 (8), 1153-1166. DOI: 10.1038/s41396-023-01450-9
9. Yuan, X.; Pan, Z.; Jin, C, et al. Gut Microbiota: An Underestimated and Unintended Recipient for Pesticide-Induced Toxicity. Chemosphere 2019, 227, 425-434. DOI: 10.1016/j.chemosphere.2019.04.088