Background: Safe and clean drinking water is essential for human life. Persistent, mobile and toxic (PMT) substances and/or very persistent and very mobile (vPvM) substances are an important group of substances for which additional measures to protect water resources may be needed to avoid negative environmental and human health effects. PMT/vPvM substances do not sufficiently biodegrade in the environment, they can travel long distances with water and are toxic (those that are PMT substances) to the environment and/or human health. PMT/vPvM substance research and regulation is arguably in its infancy and in order to get in control of these substances the following (non-exhaustive list of) knowledge gaps should to be addressed: environmental occurrence; the suitability of currently available analytical methods; the effectiveness and availability of treatment technologies; the ability of regional governance and industrial stewardship to contribute to safe drinking water while supporting innovation; the ways in which policies and regulations can be used most effectively to govern these substances; and, the identification of safe and sustainable alternatives. Methods: The work is the outcome of the third PMT workshop, held in March 2021, that brought together diverse scientists, regulators, NGOs, and representatives from the water sector and the chemical sector, all concerned with protecting the quality of our water resources. The online workshop was attended by over 700 people. The knowledge gaps above were discussed in the presentations given and the attendees were invited to provide their opinions about knowledge gaps related to PMT/vPvM substance research and regulation. Results: Strategies to closing the knowledge, technical and practical gaps to get in control of PMT/vPvM substances can be rooted in the Chemicals Strategy for Sustainability Towards a Toxic Free Environment from the European Commission, as well as recent advances in the research and industrial stewardship. Key to closing these gaps are: (i) advancing remediation and removal strategies for PMT/vPvM substances that are already in the environment, however this is not an effective long-term strategy; (ii) clear and harmonized definitions of PMT/vPvM substances across diverse European and international legislations; (iii) ensuring wider availability of analytical methods and reference standards; (iv) addressing data gaps related to persistence, mobility and toxicity of chemical substances, particularly transformation products and those within complex substance mixtures; and (v) advancing monitoring and risk assessment tools for stewardship and regulatory compliance. The two most effective ways to get in control were identified to be source control through risk governance efforts, and enhancing market incentives for alternatives to PMT/vPvM substances by using safe and sustainable by design strategies.

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“Access to safe drinking water is a fundamental human need and, therefore, a basic human right. Contaminated water jeopardizes both the physical and social health of all people”: such is the importance of safe drinking water, as stated by Kofi Annan, former Secretary-General of the United Nations, on World Water Day 2001. While some countries are still struggling to protect their citizens from well-known drinking water contaminants, potential new drinking water risks from newly-identified chemical and microbial aquatic contaminants are appearing globally. The increasing detection of these emerging contaminants has been advanced by a combination of social, technological, regulatory, climatological and demographic developments. Recent examples of emerging contaminants are perfluoroalkyl and polyfluoroalkyl substances (PFAS), sapoviruses, pharmaceuticals and colistin resistant bacteria. Whether emerging aquatic contaminants are a concern for drinking water safety depends on their exposure and hazard potential, which is influenced by a range of various determinants, including their mobility, toxicity and persistence in the environment, the severity and duration of the health effects caused by the contaminant, and the possibility for, and efficacy of, protective measures. Evidence, however, of these determinants is often limited. The challenge of protecting public health from emerging drinking water contaminants, therefore, does not only relate to identifying emerging contaminants as soon as possible, but also to prioritising the impact on human health which these contaminants have when evidence on their exposure and hazard potential is limited. Once identified and assessed, the challenge of effective risk communication under uncertainty needs to be dealt with as well. In this dissertation, an integrated approach to facilitate the early warning of, and communication on, emerging chemical and microbial drinking water contaminants has been developed...@en

The perceived safety of tap water is an important condition for consumers to drink it. Therefore, addressing consumers’ concerns should be included in the roadmap towards the UN SDG 6 on safe drinking water for all. This paper studies consumers’ information needs regarding emerging contaminants in drinking water using a mental model approach for the development of targeted risk communication. As most consumers expect safe drinking water, free of contamination, communication on emerging contaminants may increase concerns. Here, we showed that communication strategies better tailored to consumers’ information needs result in smaller increases in risk perception compared with existing strategies.@en

While the burden of disease from well-studied drinking water contaminants is declining, risks from emerging chemical and microbial contaminants arise because of social, technological, demographic and climatological developments. At present, emerging chemical and microbial drinking water contaminants are not assessed in a systematic way, but reactively and incidence based. Furthermore, they are assessed separately despite similar pollution sources. As a result, risks might be addressed ineffectively. Integrated risk assessment approaches are thus needed that elucidate the uncertainties in the risk evaluation of emerging drinking water contaminants, while considering risk assessors’ values. This study therefore aimed to (1) construct an assessment hierarchy for the integrated evaluation of the potential risks from emerging chemical and microbial contaminants in drinking water and (2) develop a decision support tool, based on the agreed assessment hierarchy, to quantify (uncertain) risk scores. A multi-actor approach was used to construct the assessment hierarchy, involving chemical and microbial risk assessors, drinking water experts and members of responsible authorities. The concept of value- focused thinking was applied to guide the problem-structuring and model-building process. The development of the decision support tool was done using Decisi-o-rama, an open-source Python library. With the developed decision support tool (uncertain) risk scores can be calculated for emerging chemical and microbial drinking water contaminants, which can be used for the evidence-based prioritisation of actions on emerging chemical and microbial drinking water risks. The decision support tool improves existing prioritisation approaches as it combines uncertain indicator levels with a multi-stakeholder approach and integrated the risk assessment of chemical and microbial contaminants. By applying the concept of value-focused thinking, this study addressed difficulties in evidence-based decision-making related to emerging drinking water contaminants. Suggestions to improve the model were made to guide future research in assisting policy makers to effectively protect public health from emerging drinking water risks. @en

As well as known contaminants, surface waters also contain an unknown variety of chemical and microbial contaminants which can pose a risk to humans if surface water is used for the production of drinking water. To protect human health proactively, and in a cost-efficient way, water authorities and drinking water companies need early warning systems. This study aimed to (1) assess the effectiveness of screening the scientific literature to direct sampling campaigns for early warning purposes, and (2) detect new aquatic contaminants of concern to public health in the Netherlands. By screening the scientific literature, six example contaminants (3 chemical and 3 microbial) were selected as potential aquatic contaminants of concern to the quality of Dutch drinking water. Stakeholders from the Dutch water sector and various information sources were consulted to identify the potential sources of these contaminants. Based on these potential contamination sources, two sampling sequences were set up from contamination sources (municipal and industrial wastewater treatment plants), via surface water used for the production of drinking water to treated drinking water. The chemical contaminants, mycophenolic acid, tetrabutylphosphonium compounds and Hexafluoropropylene Oxide Trimer Acid, were detected in low concentrations and were thus not expected to pose a risk to Dutch drinking water. Colistin resistant Escherichia coli was detected for the first time in Dutch wastewater not influenced by hospital wastewater, indicating circulation of bacteria resistant to this last-resort antibiotic in the open Dutch population. Four out of six contaminants were thus detected in surface or wastewater samples, which showed that screening the scientific literature to direct sampling campaigns for both microbial and chemical contaminants is effective for early warning purposes.@en

Chemical and microbial contaminants in the aquatic environment pose a potential threat to humans and to ecosystems. Humans may be exposed to contaminants in water resources when used for drinking water production, agriculture, aquaculture or recreation. Climatological, social and demographic changes, as well as the increasing sensitivity of analytical techniques, may result in the augmented detection of contaminants. Recent research has shown that it takes about 15 years from the time of the first scientific study mentioning the presence of a contaminant in the environment for the issue to peak in scientific attention and regulatory action. One possible factor influencing this lengthy period is that the first article becomes lost in the vast number of publications. In this study, we therefore developed a methodology using literature mining to identify the first scientific study which reports the presence of a contaminant in the aquatic environment. The developed semi-automated methodology enables health and environment agencies to inform policy makers about contaminants in the aquatic environment that could be significant for public and environmental health in national, international and river basin settings. The methodology thereby assists the proactive governance of emerging contaminants in the aquatic environment. This was illustrated by a retrospective analysis of the period of emergence in the Netherlands of: (1) perfluorooctanoic acid in surface water, and (2) biological industrial wastewater treatment systems as potential infection sources for Legionnaireś disease.

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The presence of emerging contaminants in the aquatic environment may affect human health via exposure to drinking water. And, even if some of these emerging contaminants are not a threat to human health, their presence might still influence the public perception of drinking water quality. Over the last decades, much research has been done on emerging contaminants in the aquatic environment, most of which has focused on the identification of emerging contaminants and the characterisation of their toxic potential. However, only limited information is available on if, and how, scientific information is implemented in current policy approaches. The opportunities for science to contribute to the policy of emerging contaminants in drinking water have, therefore, not yet been identified. A comparative analysis was performed of current approaches to the risk governance of emerging chemical contaminants in drinking water (resources) to identify any areas for improvement. The policy approaches used in the Netherlands, Germany, Switzerland and the state of Minnesota were analysed using the International Risk Governance Council framework as a normative concept. Quality indicators for the analysis were selected based on recent literature. Information sources used were scientific literature, policy documents, and newspaper articles. Subsequently, suggestions for future research for proactive risk governance are given. Suggestions include the development of systematic analytical approaches to various information sources so that potential emerging contaminants to drinking water quality can be identified quickly. In addition, an investigation into the possibility and benefit of including the public concern about emerging contaminants into the risk governance process was encouraged.

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