Keeping Our Water Safe - Impact Story
Translation & Impact What We Do Impact Unit

Keeping Our Water Safe

Guiding water quality standards in Barcelona and globally

Photo: Canva

Millions of people worldwide face health risks from pollutants in drinking water. ISGlobal’s Water Pollution and Health Group is addressing these critical issues by assessing known and emerging water pollutants and evaluating their impact on health. Through pioneering research and partnerships, ISGlobal has influenced water quality policies in Barcelona and beyond, while raising public awareness of the health and environmental impacts of drinking water.

What is the problem?

The United Nations Environment Programme has emphasised the health dangers of consuming water contaminated with chemical pollutants. Substances such as nitrate, trihalomethanes and disinfection by-products, have been linked to serious health effects, including an increased risk of certain cancers. Emerging contaminants, such as per- and polyfluoroalkyl substances (PFAS) and microplastics, also raise growing concerns, though their full impact on health is not yet well understood. This underscores the urgent need to better monitor contaminant levels in drinking water, expand research to include emerging pollutants, and reevaluate safety standards to protect public health.

Key facts

1,400 times greater impact on ecosystems if bottled water is used instead of tap water
3,500 times higher economic cost of bottled water compared to tap water
1st map of tap water quality in Barcelona

What did our researchers do?

ISGlobal researcher Cristina Villanueva and her team have made significant advances in tackling water contamination through innovative research and partnerships.

  • Nitrates and cancer: Nitrate levels in water have increased in many areas of the world, largely due to the use of agricultural fertilisers and intensive farming. Villanueva’s work linked long-term, low-level exposure to nitrate in drinking water—even below European regulatory limits—with an increased risk of colorectal cancer and potentially prostate cancer. This effect was stronger in people with a low intake of fibre, fruit and vegetables, suggesting that a healthy diet may mitigate some of these risks. 
  • Disinfection byproducts (DBP): Villanueva led seminal studies on the health effects of chemicals used to disinfect water. Using trihalomethanes (THMs) as a surrogate for exposure, her research revealed that long-term exposure to disinfection byproducts (DBP) is linked to a higher risk of bladder cancer. Further research by her team concluded that some of these chemicals are present in significant quantities in drinking water and require more stringent regulation. While some countries are much better at tracking and controlling DBP, others have significant regulatory gaps. Villanueva was recently invited to write a historical perspective on the topic.
  • Emerging contaminants : The team expanded its research to other emerging water pollutants such as perfluorinated substances (PFAS), bisphenol A (BPA), nonylphenol and unregulated DBPs. A first project launched in 2020 and funded by the Barcelona city council, indicated good quality in Barcelona’s drinking water but highlighted the importance of continued monitoring. A second project in partnership with Aigues de Barcelona (Agbar), launched in 2021, assessed human exposure to nanoplastics, microplastics and plastic additives via drinking water. In collaboration with the Institute of Environmental Diagnostics and Water Studies (IDAEA), Villanueva and colleagues used a newly developed high-resolution methodology to quantify micro- and nanoplastics in bottled water, which will guide future directives to set safety limits.
  • Tap vs. bottled water: Combining environmental and health impact assessments for the first time, Villanueva’s team showed that tap water is significantly better for health and ecosystems as compared to bottled water. If Barcelona’s entire population drank bottled water, it would lead to the loss of 1.43 species and a cost of USD 83.9 million every year – an impact 1,400 times greater on ecosystems and 3,500 times costlier than if everyone opted for tap water. Additional home filtration of tap water would be enough to reduce from 94 to 36 the number of life years lost every year to bladder cancer linked to THMs.

What changes has our research contributed to?

IARC includes disinfection by-products in its high-priority list 

ISGlobal’s research on water pollutants has directly contributed to the International Agency of Research on Cancer’s (IARC) updated priorities for carcinogen evaluation. In March 2024, the IARC advisory group, including ISGlobal researcher Manolis Kogevinas, recognised disinfection byproducts as a high-priority concern for carcinogenic evaluation due to relevant evidence across human, animal, and mechanistic studies. Ingested nitrates, already classified as probable carcinogens (group 2A), were maintained for re-evaluation for the 2025-2029 period. In 2012 and 2014, Villanueva was invited to participate as an expert in the IARC monographs 101 (assessing the carcinogenicity of 18 chemicals in industrial and consumer products or food, or occurring as water-chlorination by-products) and 106 (re-evaluating evidence on the carcinogenicity of chlorinated solvents, including trichloroethylene, tetrachloroethylene). For 50 years, the IARC monographs have been a premier global resource for identifying agents that can cause cancer, a crucial first step towards its prevention. National and international authorities and organisations use this information to support policies that reduce cancer risk. 

First data on emerging water pollutants in Barcelona 

The collaboration with Barcelona’s city council generated the first complete map of exposure to emerging compounds in the city’s drinking water.  This mapping opens new avenues for studies exploring links between water quality and health outcomes, such as the impact of ageing on the population.

The landmark collaboration between ISGlobal and Agbar, initiated in 2020, exemplifies successful academia-industry partnerships and is setting new standards for assessing exposure to these substances and helping to understand how they affect human health. This new, actionable data on microplastic exposure through Barcelona’s drinking water supports potential policy interventions to safeguard public health. 

New water quality chapter in Spain’s Strategic Health and Environment Plan

Villanueva has personally helped to shape Spain’s Plan Estratégico de Salud y Medio Ambiente (Strategic Health and Environment Plan), particularly the chapter on water quality Specifically, she provided information that helped inform the final version of the Plan and she was also part of its review process. This input has ensured that regulations are updated to reflect emerging contaminants such as nitrates and microplastics. research is integrated into national health policy, emphasising prevention and risk reduction.

Informed policy and regulations beyond Spain

ISGlobal’s research has helped shape water quality policies beyond Spain. In particular, Villanueva’s 2003 studies on DBP were used by the American Environmental Protection Agency (EPA) in their economic studies on the costs of water contamination. This demonstrated the real-world applicability of ISGlobal's research, influencing U.S. policy on water safety and ensuring stricter controls on water pollutants.

In its report Publication of the Superior Health Council No. 8748, the Superior Health Council of Belgium refers to several studies by Villanueva on the health risks associated with DBPs in swimming pools. This evidence has contributed to the Council’s reflections on the use of chlorine in swimming pools, particularly regarding vulnerable groups such as infants. The report contributes to policy recommendations on water disinfection methods and hygiene in Belgium.

More recently, Villanueva met with a UK Parliament representative to discuss PFAS contamination in water. Her insights will contribute to a POSTnote—an executive summary to inform Members of Parliament—on PFAS pollution. The goal is to drive regulatory action and remediation efforts to tackle these ‘forever’ chemicals.

Increased awareness about water consumption choices

ISGlobal’s outreach efforts have led to a greater public awareness of water quality and environmental issues. Villanueva’s research received wide media coverage, including interviews and features in prominent outlets. Highlights include an article on human and planetary health in La Maleta de Portbou, the BBC’s coverage of bottled water waste and a VoxPop documentary on water pollution on the Arte channel. These stories reached a broad audience, encouraging consumers to reflect on the health and environmental impacts of their daily water choices.

Links and References