Spatial Exposomics Links Pesticide Mixtures to Cancer Risk in Peru, Promoting Carcinogenesis Without Direct DNA Damage
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MEDIA RELEASE
HKU-Pasteur Research Pole, Hong Kong, April 2026
Hong Kong, 27/04/26
A new study in Nature Health (published on 01 April 2026) links environmental exposure to agricultural pesticides with increased cancer risk.
Combining environmental modeling, a nationwide cancer registry and molecular analyses, researchers from theIRD (National Research Institute for Sustainable Development, France), the Pasteur Network (HKU-Pasteur Research Pole and the Institut Pasteur in Paris, France) and Peru’s National Institute of Neoplastic Diseases (INEN) clarify how pesticide mixtures may contribute to certain cancers.
Pesticides are a major public-health concern because they persist in food, water and the environment and often occur as complex mixtures. Demonstrating a causal link between environmental pesticide exposure and cancer is difficult due to chronic, mixed exposures and limitations of conventional approaches. A new study published in Nature Healthby researchers from the IRD (National Research Institute for Sustainable Development, France), the HKU-Pasteur Research Pole (Hong Kong SAR, China), the Institut Pasteur (Paris, France) and the National Institute of Neoplastic Diseases (INEN, Peru) provides robust evidence tying environmental pesticide mixtures to an increased cancer risk.
Study design
The team built a high-resolution geospatial model of pesticide dispersal across Peru (from 2014 to 2019), mapping 31 commonly used active ingredients (none of which are classified by the International Agency for Research on Cancer as group 1 carcinogens).
The model simulated monthly runoff and transport across a 100 m × 100 m grid for nearly the entire country, producing a national exposure map with unprecedented spatial precision.
The map identified zones of elevated cumulative pesticide exposure, with contamination extending 30–50 km beyond farmed fields.
Epidemiology and spatial analysis
Researchers overlaid the exposure map with 158,072 primary cancer cases from INEN (2007–2020), geocoded and validated for at least five years of residency before diagnosis. Instead of grouping tumours by organ, they classified tumours by developmental cell lineage, representing a novel and innovative approach that reveals patterns missed by organ-based groupings. They identified 436 pesticide-associated cancer hotspots where average cancer risk was ~150% above expectation, with some local peaks approaching ten times the national average. Highest-risk zones clustered in the Andean highlands and western slopes, where low precipitation promotes pesticide accumulation.
Molecular evidence and proposed mechanism
Hepatic tissue from 36 liver cancer patients in high-risk areas was used as a sentinel site to reflect environmental exposure. Transcriptomic profiling of histologically normal liver adjacent to tumours showed a molecular signature consistent with exposure to non-genotoxic agents: altered transcriptional regulatory networks and disrupted “master regulators” that preserve hepatocyte identity. These changes suggest a metastable, pre-neoplastic state that increases vulnerability to secondary insults (e.g., infection, metabolic stress), facilitating malignant transformation. This signature was absent in liver cancer cohorts from France, Taiwan and Turkey, supporting its specificity to pesticide-exposed populations in Peru.
Environmental justice and climate interactions
High-exposure areas overlap with rural, agriculturally pressured, deforested and socioeconomically marginalized regions. Andean–Amazonian Indigenous communities showed substantially higher concurrent exposures (on average to 12 different compounds). The authors note that climatic variability, such as El Niño, can alter pesticide use and transport, potentially increasing exposures; climate change may amplify these effects.
Limitations and implications
Limitations include lack of individual exposure measurements and potential residual confounding. Nonetheless, the concordance of environmental modelling, epidemiology and molecular data supports a biologically plausible association. The study introduces a transferable, high-resolution method for mapping oncogenic risk from environmental chemical mixtures at national scale.
It underscores that chronic exposure to complex mixtures, rather than single regulated compounds, can drive cancer risk and calls for revisiting risk assessment, surveillance and prevention policies with attention to mixture effects, socioecological contexts and vulnerable populations.
"Major agricultural producers and food import hubs worldwide—including China—need comprehensive research data to strengthen monitoring, enforce residue limits and better protect consumers. We are looking forward to discuss these findings during the World Cancer Congress 2026* in Hong Kong, in September 2026" according to Dr. Stéphane Bertani, consortium leader.
"Aligning with the Institut Pasteur’s “Pasteur 2030” strategic plan, this study paves the way for joint research, capacity‑building, validation and supports mapping of rural exposure hotspots around the world, including Asia" adds Dr. Eric Deharo, Co‑Director of the HKU‑Pasteur Research Pole.
Reference
J.Honles, JP.Cerapio, C.Monge, A.Marchio, E.Ruiz, R.Fernández, S.Casavilca-Zambrano, J.Contreras Mancilla, T.Vidaurre, T.Condom, S.Zerathe, O.Dangles, E.Deharo, J.Herrera-Zuñiga, P.Pineau, S.Bertani
Institut Pasteur (Paris)
A non-profit foundation created in 1887 by Louis Pasteur, the Institut Pasteur is a world-renowned biomedical research center dedicated to the study of and fight against diseases, particularly infectious ones. From the invention of the rabies vaccine to the identification of HIV, including the discovery of messenger RNA, some of the greatest discoveries in modern biomedical science have been made there. Member of a network of more than 30 institutes across five continents—the Pasteur Network—and host to nearly ten collaborating centers of the World Health Organization (WHO), the Institut Pasteur is actively engaged in the field alongside populations to advance global public health.
HKU-Pasteur Research Pole (HKU-PRP)
The HKU-Pasteur Research Pole (HKU-PRP) is a medical research laboratory that brings together two world-class academic and research institutions, the University of Hong Kong (HKU) and Institut Pasteur, for the common goal of generating biological knowledge to advance the understanding and treatment of infectious diseases.
HKU-PRP provides opportunities and support for outstanding young scientists to undertake interdisciplinary research by harnessing the resources of the local and international environments in HKU and Institut Pasteur.
HKU-PRP is a member of the Pasteur Network which comprises more than 30 institutes sharing the same vision and engaging in collaborative work for scientific research on the curbing of infectious diseases, training of specialists and improvement of public health services.
Pasteur Network
The Pasteur Network is an alliance of 32 organisations playing a crucial role in addressing global health challenges through science, innovation, and public health. Its distinctive strength lies in the diversity and extensive geographic reach of its membership, spanning 25 countries across five continents, united by shared values and missions for the benefit of populations. The Network fosters a dynamic community of scientific knowledge and expertise that is both locally embedded and globally connected. Recognised as a WHO non‑state actor, the Pasteur Network maintains close ties with public authorities, with many members embedded within national Ministries of Health. It sustains a global infrastructure encompassing more than 50 national and regional reference laboratories, including multiple Biosafety Level 3 laboratories, as well as 17 WHO Collaborating Centres.
IRD
IRD is a French institute for sustainable development that strengthens societal resilience to global change across 50+ countries (Africa, Latin America, Asia, the Pacific, mainland France and overseas territories). Working with local partners, its multidisciplinary teams tackle practical priorities—climate adaptation, poverty reduction, biodiversity protection, health access, and social dynamics—through long-term partnerships, open sharing of results, and action-oriented science to promote fairer, sustainable socio-economic and ecological models.
INEN
The National Institute of Neoplastic Diseases is the main national reference institution for oncology in Peru. Responsible for cancer epidemiological surveillance, the technical leadership of the National Oncology Network, and the implementation of the National Cancer Law. It houses the National Tumor Bank, a leading regional platform for translational research.
Contact information:
Eric DEHARO: edeharo@hku.hk
Stéphane BERTANI: stephane.bertani@ird.fr
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