When Medicinal Residues End Up in Our Dishes

Minh Anh Hoang

Trade Union University, Hanoi, Vietnam

*Contact: anhhm@dhcd.edu.vn

12-06-2026

© Wix

Medicines save lives. Antibiotics fight infections, painkillers ease suffering, and veterinary drugs help keep livestock healthy. But what happens after these medicines leave our bodies?

The answer is more surprising than many people realize.

Many pharmaceuticals are not fully broken down by humans or animals. In fact, between 30–90% of some antibiotics can be excreted unchanged or as active metabolites through urine and feces within 8–24 h of intake (Frade et al., 2014). When wastewater is reused for irrigation or when biosolids and manure are applied as fertilizers, these compounds can enter agricultural soils and eventually become part of the food-growing environment (Boxall, 2018; Gros et al., 2019; Nguyen et al., 2023).

Researchers have found pharmaceutical residues in a wide range of crops. Compounds such as carbamazepine, triclosan, sulphamethoxazole, and enrofloxacin can be absorbed by plant roots and transported into leaves, stems, and edible tissues (Wu et al., 2010; Al-Farsi et al., 2018). In some cases, concentrations in crops reached levels measurable in milligrams per kilogram of dry weight.

Whether a pharmaceutical enters a plant depends on its chemical characteristics. Small, water-soluble compounds often move more easily through roots and into shoots, while larger molecules may accumulate primarily in roots. Soil properties also matter. Clay content, organic matter, and microbial activity can either trap pharmaceuticals or make them more available for uptake (Garazade et al., 2026).

The story becomes even more complicated after the drugs enter the environment.

Most discussions focus on the original pharmaceutical compounds. However, medicines rarely remain unchanged. In humans and animals, drugs are transformed through metabolic processes in the liver. Once released into the environment, they can undergo further transformations through sunlight, microbial activity, oxidation, hydrolysis, and wastewater treatment processes. These transformations generate a diverse array of metabolites and transformation products.

Ironically, breaking down a pharmaceutical does not always make it safer.

Studies have shown that some transformation products can be as toxic—or even more toxic—than the original drug. For example, degradation of certain antibiotics and antiviral drugs can produce intermediate compounds that pose risks to aquatic organisms. Plants themselves can also metabolize absorbed pharmaceuticals, creating new compounds whose ecological and health effects remain poorly understood (Garazade et al., 2026).

The consequences extend beyond crop productivity. Pharmaceutical residues have been linked to reduced seed germination, lower plant biomass, disrupted hormone systems, and decreased yields in some crops (Wang et al., 2016; Zezulka et al., 2019). More concerningly, antimicrobial residues moving through food systems may contribute to the global challenge of antimicrobial resistance (Miller et al., 2022).

This raises a broader question about how humans view medicines. We often see pharmaceuticals as tools designed exclusively for human or animal health. Yet once released into the environment, they become participants in a much larger ecological network (Vuong, 2025; Nguyen, 2026). A pill swallowed by a patient may eventually interact with soil microbes, plant roots, insects, aquatic organisms, and even future consumers.

Understanding these hidden pathways requires looking beyond immediate human benefits and recognizing the interconnected systems that sustain life. The fate of pharmaceuticals is not merely a medical issue. It is also a reminder that human actions continue long after they leave our bodies, flowing through soils, crops, waterways, and ecosystems in ways we are only beginning to understand. This broader perspective is increasingly important for protecting both public health and the ecological foundations upon which it ultimately depends (Khuc & Nguyen, 2026; Tran, 2026).

References

Al-Farsi, R., et al. (2018). Assessing the presence of pharmaceuticals in soil and plants irrigated with treated wastewater in Oman. International Journal of Recycling of Organic Waste in Agriculture, 7(2), 165–172. https://doi.org/10.1007/s40093-018-0202-1

Boxall, A. B. A. (2018). Pharmaceuticals in the environment and human health. In A. B. A. Boxall & R. S. Kookana (Eds.), Health care and environmental contamination (pp. 123–136). Elsevier. https://doi.org/10.1016/B978-0-444-63857-1.00007-3

Frade, V. M. F., et al. (2014). Environmental contamination by fluoroquinolones. Brazilian Journal of Pharmaceutical Sciences, 50(1), 41–54. https://doi.org/10.1590/S1984-82502011000100004

Garazade, N. et al. (2026). Pharmaceuticals and their transformation products in agroecosystems: Threats to plant–soil sustainability. Critical Reviews in Environmental Science and Technology, 56(6), 269-299. https://doi.org/10.1080/10643389.2025.2585891

Gros, M., et al. (2019). Veterinary pharmaceuticals and antibiotics in manure and slurry and their fate in amended agricultural soils: Findings from an experimental field site (Baix Empordà, NE Catalonia). The Science of the Total Environment, 654, 1337–1349. https://doi.org/10.1016/j.scitotenv.2018.11.061

Khuc, V. Q., & Nguyen, M. H. (2026). Cultural Additivity Theory. Available at SSRN 6767760. https://ssrn.com/abstract=6767760  

Miller, S. A., Ferreira, J. P., & LeJeune, J. T. (2022). Antimicrobial use and resistance in plant agriculture: A one health perspective. Agriculture, 12(2), 289. https://doi.org/10.3390/agriculture12020289

Nguyen, M.-H. (2026). Ayn Rand and Kingfisher on zero-carbon bombs and a sustainable future. Visions for Sustainability, 25(13474), 1-13. http://dx.doi.org/10.13135/2384-8677/13474

Nguyen, M.-K., et al. (2023). Occurrence, fate, and potential risk of pharmaceutical pollutants in agriculture: Challenges and environmentally friendly solutions. The Science of the Total Environment, 899, 165323. https://doi.org/10.1016/j.scitotenv.2023.165323

Tran, T. M. A. (2026). Conversations with Kingfisher: Wisdom from Vuong’s wild wise weird stories. Planet Forward. https://planetforward.org/story/kingfisher-stories/

Vuong, Q. H. (2025). Wild Wise Weird. AISDL. https://books.google.com/books?id=C5dDEQAAQBAJ

Wang, J., et al. (2016). Variations in the fate and biological effects of sulfamethoxazole, norfloxacin and doxycycline in different vegetable-soil systems following manure application. Journal of Hazardous Materials, 304, 49–57. https://doi.org/10.1016/j.jhazmat.2015.10.038

Wu, C., et al. (2010). Uptake of pharmaceutical and personal care products by soybean plants from soils applied with biosolids and irrigated with contaminated water. Environmental Science & Technology, 44(16), 6157–6161. https://doi.org/10.1021/es1011115

Zezulka, Š., et al. (2019). Sensitivity of physiological and biochemical endpoints in early ontogenetic stages of crops under diclofenac and paracetamol treatments. Environmental Science and Pollution Research İnternational, 26(4), 3965–3979. https://doi.org/10.1007/s11356-018-3930-x