Editorial Perspectives: could water fingerprinting help with community-wide health assessment?

Rapid assessment of public health is essential for the prevention, control or mitigation of exposure risks (e.g. to chemical contaminants, lifestyle chemicals or pathogenic organisms) and for improving health. There is growing, albeit still limited, evidence of association between man-made chemicals present in industrial and household products, often leaching into the environment, and public health outcomes. These include poor air quality linked with higher prevalence of asthma in urban populations, and presence of endocrine disrupting chemicals in household products linked with diabetes or infertility. Strategies to control and regulate anthropogenic chemicals are limited due to gaps in evidence resulting from limited risk assessment methods. More efficient approaches are critically needed to identify cause–effect linkages between environmental contaminants and human health. Attempts to link environmental stressors with health effects are currently undertaken via molecular epidemiology and human biomonitoring. However, the limitations of molecular epidemiology, due to logistical difficulties and high cost, are the restricted size of study groups and inability to gather comprehensive information on combined spatiotemporal exposure to mixtures of stressors, and their effects. In order to improve environmental and public health, there is a need for an evidence-based public health risk prediction system, which will collate long-term comprehensive, spatiotemporal datasets on public health status and trigger rapid response from regulatory and public health sectors with the aim of disease prevention and environmental health promotion. This system, if operated in real-time and if linked with timely response systems, could allow public health threats to be rapidly identified, at low cost, and instantly dealt with, reducing the global burden on public health. A new concept of urban water fingerprinting (UWF) provides a promising solution.

Urban water is a complex mixture of substances including a wide range of human excretion products resulting from public exposure to stressors (e.g. toxicants and infectious agents) and physiological processes (e.g. specific disease-linked proteins, genes and metabolites). The quantitative measurement of these endo- and exogenous environment and human derived residues continuously pooled by the sewerage system serving different communities can provide evidence of the quantity and type of chemical, biological or physical stressor to which the surveyed population was exposed and can profile the effects of this exposure, anonymously, at low cost and in real time (Fig. 1). This approach of extracting epidemiological information from water is also known as wastewater-based epidemiology (WBE). WBE has been significantly progressed via a strong collaborative ethos in the EU (http://www.score-cost.eu and https://sewprofitn.eu/) and internationally. WBE currently informs worldwide illicit drug use trends¹ and feeds into the Europe-wide early warning system (EWS) by the European Monitoring Centre for Drugs & Drug Addiction (EMCDDA; http://www.emcdda.europa.eu/wastewater-analysis). WBE has been also applied in proof-of-concept international studies to estimate public exposure to lifestyle chemicals (alcohol, tobacco, caffeine, illicit drugs, counterfeit medicines), pharmaceuticals, pesticides, industrial chemicals and health markers – isoprostanes.^2–5

Fig. 1 Water fingerprinting.

The results are very promising and therefore widespread use of UWF as an epidemiology tool in future public health diagnostics is anticipated. UWF capable of collating and analysing long term datasets derived from comprehensive water fingerprinting and socioeconomic indicator datasets has the potential to unravel complexities behind key 21st century public health issues focused on NCD (non-communicable diseases) and CD (communicable diseases) epidemics which are rapidly spreading globally. For example, only one daily urban water sample is needed to evaluate community-wide health for a community (e.g. of 100 thousand inhabitants) served by one wastewater treatment works or disposing directly to the local river or open sewer, using a suite of >300 markers. If undertaken every day for a year, temporal variabilities in public exposure (e.g. pollution events and resulting disease), as well as infectious disease spread and the appearance of new pathogenic strains, could be surveyed for the whole community at a relatively low cost. Such a tool does not exist but, if developed would have the potential to vastly improve health outcomes, provide quality-of-life benefits and reduce cost of healthcare globally. Most importantly it could benefit all community members, irrespective of socioeconomic status.

Further work is critically needed to develop a system that is recognised internationally to influence regulatory and political decisions both of localised importance (e.g. air pollution in urban areas or infectious disease spread in low resource settings) and at an international scale (e.g. antimicrobial resistance). Several aspects require further investigation. Among them are:

(1) Accurate measurement of population size. Lack of robust tools enabling more accurate estimation of population size contributing to a water sample especially in low resource settings (i.e. without the sewerage system) is a limiting factor making spatiotemporal comparisons of different locations challenging.

(2) Discovery of biomarkers. UWF uses clinically relevant biomarkers. However, not all clinical markers are amenable to UWF as it requires urinary excretion at moderately high levels allowing quantification despite extensive dilution in the sewerage system (e.g. with runoff), as well as high stability (e.g. resistant to microbial metabolism) in water. A limited suite of UWF markers is currently a significant obstacle to UWF development. Use of high resolution mass spectrometry combined with non-target screening and data mining should facilitate progress in this area.

(3) Development of methods and sensors for accurate identification and quantification of biomarkers. The ultimate goal of UWF is to use low cost easy to operate, sensitive and selective sensors deployed at various locations and providing data in real time. This is anticipated but not achievable at the moment. Mass spectrometry will therefore remain a key tool in progressing research in this area. High resolution mass spectrometry will grow in importance mainly due to its potential for obtaining true biochemical water fingerprints. The anticipated miniaturisation of mass spectrometers could prove very useful in sensitive and selective multi-residue on-site measurements in real time.

(4) Integration of biomarker data with socioeconomic indicators. UWF is inherently interdisciplinary. WBE was developed by natural scientists and engineers. In order to enable its full integration with existing epidemiology tools and realisation of its potential in disease prediction, management or prevention, strong collaboration with other specialists such as social scientists, epidemiologists and public health specialists is needed. A major limitation of UWF is its inability to provide information on the health of individuals and, as a consequence, it needs to be used in conjunction with other epidemiology tools.

As with many other scientific innovations, UWF is not immune to misuse and misrepresentation. As UWF does not collect data on individuals, the ethical risks are low. However, it will be necessary to manage privacy issues and the potential for stigmatisation of certain societal groups if attempting e.g. to quantify illicit drug usage at a city district level, in prisons, hospitals, schools or at a workplace. Strong ethical guidelines will need to be developed to ensure that the privacy of communities is respected. WBE researchers in Europe and Australia have taken the lead in drafting ethical guidelines for WBE and associated fields (http://score-cost.eu/ethical-guidelines-for-wbe/). While the media play a critical role in the public understanding of science, sensationalised and misleading press releases regarding published data could harm vulnerable communities. High ethical standards need therefore to be carefully followed by all involved in both the generation and dissemination of data and research outputs.

Acknowledgements

Prof. Paige Novak and the Environmental Science: Water Research & Technology Editorial Team are thanked for their helpful remarks. Support from the EPSRC Global Challenges Research Fund (project number: EP/P028403/1, the ReNEW project) and the European Union's Seventh Framework Programme for Research, Technological Development and Demonstration (grant agreement: 317205, the SEWPROF MC ITN project) is gratefully acknowledged.

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