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Natural Toxins and Drinking Water Quality - From Source to Tap

Periodic Reporting for period 1 - NaToxAq (Natural Toxins and Drinking Water Quality - From Source to Tap)

Reporting period: 2017-01-01 to 2018-12-31

Do natural toxins from plants and cyanobacteria present a risk resulting in impacts on the quality of drinking water? This question serves as the driver for the NaToxAq ITN. All living organisms produce secondary metabolites (also called biotoxins, plant specialized compounds). For plants more than 20,000 toxic metabolites – or natural toxins – are known, and the figure is probably much larger. For cyanobacteria typically evolving to dramatic numbers during algal blooms, there are several hundred well known cyanotoxins, but also more compounds to be identified. Plant and cyanotoxins are medium to highly toxic to humans, some even carcinogenic, and hence these toxins should be taken serious. We know that we should not eat the berries of deadly nightshade or the hull of castor beans, or drink green water from an eutrophied lake. But less people are aware that water leaching from a Bracken infested area, or any area covered by wild plants or crops producing toxins may contain these toxins. The NaToxAq ESRs are all working on adding bricks to the puzzle on natural toxin contamination of water. How much toxin is produced, do the toxins transport to surface and/or groundwater, how stable are the toxins, how toxic, and if the toxins are present, what do we do? Can we remove the toxins from water or do we need to do something at catchment scale. Many natural toxins are not very well known and hence the first challenge we meet is often how to extract and analyse the toxins in environmental samples.

The overarching aim of NaToxAq is to contribute to the science base for protecting the health of EU citizens when they drink water. As the natural toxin contamination question has never been addressed with respect to drinking water we have structured the NaToxAq ITN to be able to bring an answer for prioritization of further efforts in the field. EU has a clear appraisal and prioritization on the importance of clean water for both ecosystems and for humans, primarily via the Water Framework Directive and the Drinking Water Directive. NaToxAq aligns with these directives and the embedded policy goals, and aims to expand the knowledge database for improving the quality of European drinking water all along the track from source to tap. Climate change affects migration of plants and algae and stimulates the invasiveness of certain toxin producing plants which hence causes new natural toxins to appear in areas where they have not been seen previously. Thus, there is also a climate change dimension included in NaToxAq.

In summary, the main objectives of the NaToxAq ITN are:
• To develop predictive tools (in silico) and analytical approaches to screen for and quantify natural toxins in European waters
• To quantify production of natural toxins and to describe the spatial and temporal variation of toxin occurrence in water bodies, and its dependence of land cover, climate, soil types, nutrient status and other variables
• To quantify the environmental fate of natural toxins in soils and water, first of all sorption, biotic and abiotic degradation including photodegradation, as input for modelling of natural toxin leaching to water reservoirs, and risk assessment
• To investigate most suitable technologies for natural toxin removal at water works
• To quantify human toxicity of certain toxic classes with focus on cyanotoxins
• To aggregate data in terms of databases and land use based models to guide land (catchment) management, and for risk mapping and communication on natural toxin contamination of drinking water
• And not at least – to train 16 ESRs to work in the cross field between academia, industry and the public sector – for handling the different aspects of natural toxin contamination and in more general emerging toxins in drinking water.
From the start high priority has been given to recruit the best ESRs for the jobs described above, to design and implement a coherent and strong training programme for the ESRs with strong academia-industry collaboration, and to stimulate the research work and interactions among the ESRs. In the initial part of their PhD projects, many ESRs have been working with development of methods, tools, theories and models, and field monitoring data are being collected. Many ESR students are now in their first or second secondment, typically a water supply sector institution. The ESRs participate intensively in communication at conferences, on the NaToxAq homepage ( and via other media; science communication in form of journal papers of course has high priority.
There are many interesting results being generated. To mention a few:
• New targeted, and non-targeted analytical methods, e.g. for Bracken sesquiterpenoids, alkaloids, new classes of cyanotoxins and for phytosteroids.
• Effect-based screening methods for toxins from invasive plants
• Upload of full scan mass spectra of natural toxins to MassBank for use in suspect screening.
• In-silico methods for estimation of phys-chem and tox properties adapted to phytotoxins
• Sorption, degradation kinetics and photolysis of natural toxins
• Modelling leaching of natural toxins in the vadose zone – developments towards GIS based tools for estimating natural toxin exposure
• Methods for testing human toxicity of cyanotoxins
• Monitoring of natural toxins from local to regional scales
• Advanced oxidation applied to toxin removal in water purification
At termination of NaToxAq we expect to be able to provide a first answer to our key question: Should we care about natural toxins in drinking water? Our research however opens for many new questions, such as the effect of natural toxins in ecosystems and for ecosystem stability, and it challenges our current water quality concept. At the moment, there are no legal requests for monitoring of natural toxins in drinking water. Should we measure for that in the future? How shall we balance monitoring for the thousands of natural toxins with monitoring for industrial chemicals, and how should we prioritize measurements? Do we go for the most toxic chemicals – in which case most of our concern is with natural toxins, as a fair share of these are very toxic. At the moment, commercial laboratories performing water analyses for the water supply sector are not geared for analysis for natural toxins, they may not even have access to standards. In addition monitoring for natural toxins is a challenge. The occurrence of natural toxins in water reservoirs may be highly seasonal and event-driven; thus toxins may leach during rain events, or seasons where plants exudate or release higher concentrations of the toxins. In dry years the toxins may not be present as no leaching takes place, while in wet years high loads may be seen. Hence, sampling is an issue where new practices need to be developed.

We are now awaiting results of the project, and in particular the monitoring work. As soon as we have more data we will make a first assessment of the challenge, which is also of high interest for the water supply sector. The main concern for society is of course the human health aspects. NaToxAq prepare for this by also bringing solutions for toxin mitigation, both at catchment scale and at water works.
Sixteen ESRs are trained to continue work in academia and in the industry – on the many new aspects on natural toxin fate and effects, water quality concepts and toxicity that the project brings forward.