lunes, 15 de diciembre de 2025

Microplastics in the Food Chain: A Silent Threat to Public Health


By:

Jürgen Mahlknecht, Leader of the Climate and Sustainability Research Center;

and Cristina Chuck, Leader of the Health and Food Safety Research Center

School of Engineering and Sciences, Tecnologico de Monterrey, Mexico

Plastic has transformed modern life, but its residues are transforming our health. From bottled water to seafood and even table salt, microplastics have infiltrated the global food chain. It is estimated that humans could ingest between 11,000 and 193,000 particles annually through beverages, with bottled water consumption being a risk factor that considerably increases exposure.

These tiny particles—less than 5 mm in size—result from the degradation of plastic through physical, chemical, and biological processes. Today, microplastics are not just an environmental concern: they represent an emerging public health challenge that requires urgent action and coordinated global policies.

Contaminants in Food: Infiltration into the Trophic Chain

Various international studies have confirmed the presence of microplastics in virtually all analyzed water and food sources:

       Marine Food Chains: Microplastics primarily affect filter feeders and small fish, which are then ingested by larger predators. This accumulation allows microplastics to transfer along the trophic chain and ultimately reach humans.

       Direct Consumption Risk: The most robust evidence comes from the marine environment: multiple studies have revealed the presence of the endocrine disruptor bisphenol A (BPA) and the plasticizer DEHP (a phthalate) in a high percentage of seafood samples, with variations depending on the species and region. These findings imply a direct and relevant exposure for the consumer.

       Other Food Sources: In addition to seafood, microplastics have been detected in table salt, honey, and beer, confirming the omnipresence of these particles in the everyday diet.

Although water is a primary route of exposure, especially bottled water (which can contain from less than one particle up to more than 6,000 per liter), other foods contribute significantly to the total ingestion. Ingestion is the predominant route of exposure, followed by inhalation and, to a lesser extent, dermal contact.

Vectors of Toxicity and Mechanisms of Cellular Damage

Microplastics represent a dual risk: physical and chemical.

  1. Physical Damage and Cellular Stress (Direct Risk): Due to their size and shape, they can interact directly with cells and tissues, causing oxidative stress, inflammation, and cellular damage. The evidence is especially solid for nanoplastics, which have been shown to cross biological barriers. For larger microplastics, the evidence is emerging but still limited.

       Oxidative Stress and Inflammation: Exposure to microplastics, including nanoparticles, induces oxidative stress and chronic inflammatory processes, which are associated with neurological disorders, cardiovascular diseases, and certain types of cancer.

       Cellular and Mitochondrial Damage: In vitro experiments with intestinal cell lines (Caco-2) and dermal cell lines (HaCaT) have shown reduced cell viability, mitochondrial damage, and increased pro-inflammatory cytokines. Mitochondrial damage is particularly critical, given the essential role of mitochondria in cellular energy generation.

       Barrier Disruption and Translocation: Nanoplastics ($<1 \mu m$) can cross biological barriers, reaching the liver, kidneys, and lymphatic system, leading to hepatotoxic and systemic effects. These findings underscore the importance of differentially evaluating micro- and nanoplastics.

  1. Vector Effect (Chemichal risk): Microplastics also act as vectors for toxic additives, such as BPA, phthalates, and other components, transferring persistent, bioaccumulative, and toxic substances to the food web.

       Endocrine Disruption: BPA, phthalates, and other components can mimic or block natural hormones, affecting the cardiovascular, renal, gastrointestinal, neurological, and reproductive systems.

       Carcinogenicity Risks: Some plastic compounds—such as styrene and certain phthalates—are classified as probable carcinogens or are linked to genotoxicity after prolonged exposure.

These discoveries suggest the imperative need to apply the precautionary principle: it is crucial to reduce exposure to microplastics and their additives immediately, without needing to wait for conclusive epidemiological evidence.

 

The Water Paradox and Methodological Challenges

Paradoxically, the infrastructure designed to protect us, such as wastewater treatment plants, can become microplastic redistribution points. Although they capture some of the particles, they discharge significant quantities into rivers and coasts, while residual sludge—used as fertilizer—reintroduces microplastics into the agricultural environment.

The metropolitan area of Monterrey, Mexico, exemplifies this paradox: a high dependence on bottled water, water scarcity, and increasing accumulation of plastic waste elevate the risk of exposure.

To face this global challenge, the scientific community and health authorities must close three critical gaps:

  1. Standardize methods for sampling, treatment, capture, and identification using methods such as FT-IR or Raman, in addition to AI-assisted analysis.
  2. Strengthen health surveillance, integrating exposure data in water and food, with attention to vulnerable populations.
  3. Implement preventive policies, reducing single-use plastics, improving filtration in treatment plants, and reinforcing extended producer responsibility.

The future of public health depends on how quickly we act with the evidence already available. The cost of inaction is not theoretical: it accumulates, particle by particle.

Key figures on the microplastics issue:

       < 5 mm: Definition of microplastics; nanoparticles (< 1 µm) represent an emerging risk.

       6,000+ particles/L: Maximum levels detected in bottled water worldwide.

       42 particles/L: Average found in tap water and dispensers in Mexico City.

       193,000 particles/year: Estimated maximum ingestion by an adult through water consumption.

       70–80%: Proportion of seafood samples containing BPA and phthalates.

       50x: Some studies report that bottled water can contain up to 50 times more microplastics than tap water.

       100–300 particles/kg: Average levels found in commercial table salt.

       2,400–9,400 particles/kg: Abundance reported in certain edible seaweeds.

(Figures can vary widely depending on analytical methods and minimum detectable sizes.)

 

References:

        AINIA. (2022). Riesgos alimentarios: Presencia de microplásticos en alimentos. https://www.ainia.com/ainia-news/riesgos-alimentarios-microplasticos-efecto-salud-caraterizacion/

        CIEL. (2023). El plástico y la salud. Center for International Environmental Law. https://www.ciel.org/wp-content/uploads/2019/03/Plastic-Health-Spanish.pdf

        Ciencia. (2023). Contaminación por microplásticos. Revista Ciencia. https://www.revistaciencia.amc.edu.mx/index.php/vol-74-num-4/252-contaminacion-por-microplasticos.

        Greenpeace España. (2023). Plásticos en el pescado y el marisco. https://es.greenpeace.org/es/trabajamos-en/plasticos/plasticos-en-el-pescado-y-el-marisco/

        Hoang, H. G., Nguyen, N. S. H., Zhang, T., Tran, H.-T., Mukherjee, S., & Naidu, R. (2025). A review of microplastic pollution and human health risk assessment: Current knowledge and future outlook. Frontiers in Environmental Science, 13, 1606332. https://doi.org/10.3389/fenvs.2025.1606332

        INS. (2023). Perfil de riesgo: Identificación y caracterización toxicológica de microplásticos como peligro por vía alimentaria. Instituto Nacional de Salud.https://www.ins.gov.co/Direcciones/RedesDeLaboratorios/LABSALUD/RiesgosQu%C3%ADmicos/Perfil%20de%20Riesgo%20Micropl%C3%A1sticos%20en%20Alimentos.pdf

        IPEN. (2022). Plásticos, salud y perturbadores endocrinos. International Pollutants Elimination Network. https://ipen.org/sites/default/files/documents/edc_guide_2020_v1_6bw-es.pdf

        Mesquita, D. P., Quintelas, C., & Ferreira, E. C. (2023). Fate and occurrence of microplastics in wastewater treatment plants. Environmental Science: Advances, 2, 1616–1628. https://doi.org/10.1039/d3va00167a

        Montero, V., Chinchilla, Y., Gómez, L., Flores, A., Medaglia, A., Guillén, R., & Montero, E. (2023). Human health risk assessment for consumption of microplastics and plasticizing substances through marine species. Environmental Research, 237, 116843. https://doi.org/10.1016/j.envres.2023.116843

        NutritionFacts.org. (2023). Los microplásticos en el marisco y su riesgo de cáncer.https://nutritionfacts.org/es/video/los-microplasticos-en-el-marisco-y-su-riesgo-de-cancer/.

        SciELO México. (2024). Estudio de los efectos toxicológicos de los nanoplásticos en células de colon. https://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S2448-56912023000200202

        UN News. (2022). Los microplásticos en el pescado y los mariscos, ¿deberíamos preocuparnos? Naciones Unidas. https://news.un.org/es/story/2022/02/1505372.

        Universidad de Guadalajara. (2024). Microplásticos: Amenaza para los ecosistemas y la salud humana. Centro Universitario de la Costa.https://www.cuc.udg.mx/noticias/microplasticos-amenaza-para-los-ecosistemas-y-la-salud-humana.

        Valverde Arámbula, F. A. (2025). Assessment of the presence and potential toxicity of microplastics in bottled and tap water from the metropolitan area of Monterrey using human intestinal and dermal cell lines. Qualifying Exam Proposal, PhD in Biotechnology, Tecnológico de Monterrey.

        Zuri, G., Karanasiou, A., & Lacorte, S. (2023). Microplastics: Human exposure assessment through air, water, and food. Environment International, 179, 108150. https://doi.org/10.1016/j.envint.2023.108150

        D.A. Syamsu, D. Deswati, S. Syafrizayanti, A. Putra, Y. Suteja. (2024). Presence of microplastics contamination in table salt and estimated exposure in humans. Global Journal of Environmental Science and Management (GJESM). https://www.gjesm.net/article_707785_285503fd22e49b04fa945bda724c3ae2.pdf

        Gurusamy Kutralam-Muniasamy, V. C. Shruti, Fermín Pérez-Guevara (2024). Microplastic contamination in commercially packaged edible seaweeds and exposure of the ethnic minority and local population in Mexico. (PubMed). https://pubmed.ncbi.nlm.nih.gov/38163691/

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About Tecnológico de Monterrey

Tecnológico de Monterrey (http://www.tec.mx) is a private, non-profit university recognized for its academic excellence, educational innovation, and global vision. It was founded in 1943 and currently has a presence in 33 municipalities across 20 states of Mexico, with an enrollment of 60,000 undergraduate and graduate students, as well as more than 27,000 high school students. Accredited by SACSCOC since 1950. It is ranked #187 in the QS World University Rankings 2026 and #7 in Latin America according to the THE Latin America University Rankings 2024. It also stands out in global employability and entrepreneurship programs, and is part of international networks such as APRU and U21.

About the School of Engineering and Sciences of Tecnológico de Monterrey

The School of Engineering and Sciences (EIC) of Tecnológico de Monterrey is a leading institution in the training of engineers and scientists in Mexico and Latin America. With a focus on academic excellence, cutting-edge research, and engagement with industry, the EIC prepares its students to face the challenges of the 21st century and to become agents of change in their communities.

Its research strategy is focused on applied science and centers on three main research cores: Health (Application of biotechnology, nanotechnology, informatics, and electronics to improve human health), Climate and Sustainability (Addressing environmental issues such as climate change and the transition to renewable energies), and Industrial Transformation (Implementation of digital technologies, artificial intelligence, and innovative processes in manufacturing and supply chains). These cores are interconnected with three strategic initiatives: the first dedicated to artificial intelligence, the second to nanotechnology, and the third to semiconductors. To learn more, visit: https://eic.tec.mx/es

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