ESR14 Barbara Kubíčková

Project: Health risks of natural toxins in surface waters

Principal supervisor: Dr. Klára Hilscherová

Intro to project:

Quality of drinking water is governed by a number of EU regulations, assuring an internationally high standard. Nevertheless, a growing population and global warming challenge the ubiquitous access to clean and safe drinking water. The Initial Training Network (ITN) NaToxAq aims to maintain safe drinking water despite climate change and ongoing pollution of freshwater bodies. Besides xenobiotic compounds, toxic compounds of biological origin may have severe adverse effects on human health, hence deserve scientific vigilance.

Especially bacteria and photosynthetic organisms – plants and blue-green algae (cyanobacteria) – are known to produce a large variety of secondary metabolites leaching to and accumulating in soil and water reservoirs. Excessive use of fertilizers, insufficient wastewater treatment and global warming lead to an increase in frequency and intensity of cyanobacterial blooms. Especially these massive proliferation events lead to the release of cyanobacterial toxic compounds – cyanotoxins – to water and may threaten human health in several ways. Exposure may occur directly through inhalation, ingestion or skin contact or indirectly by consumption of contaminated food, e.g. fish or shellfish. Besides several routes of exposure, cyanotoxins may target different organs: while many described toxins target the liver or kidney as the main detoxifying and excreting organs (e.g. cyclic peptides microcystins, cylindrospermopsin), others have neurotoxic properties (e.g. anatoxin, all-trans-retinoic acid).

While many of the projects within this ITN focus on identification of natural toxins, their fate and degradation, the aim of my project is to discover, examine and describe health effects of surface water-borne toxins and their degradation (by)-products with a special focus on cyanobacterial toxins and their effects on airway epithelia, the immune system and digestive tract, as well as neurotoxic effects in human. In order to replace, reduce and refine animal testing (3R principle), as imposed by the European Union Directive 2010/63/EU (, all experiments will be conducted in vitro using state-of-the-art methods of molecular and cell biology. Experiments will be conducted preferably on cells originating from human to avoid interspecies approximations during risk assessment, which should be the final and conclusive outcome of this project.

Progress after 1 year

This project is comprised of four major tasks:

  • Investigation of the toxic potential of selected cyanobacterial toxins on the human respiratory tract
  • Research on the contribution of cyanobacterial bloom components to acute gastroenteritis
  • Identification and characterization of the neurotoxic potential of cyanobacterial blooms and selected metabolites
  • Human health risk assessment, combining hazard and exposure data to potentially guide risk management measures

One year ago, after reviewing literature for relevant and emergent health risks, I started addressing the hazard of the invasive cyanobacterial toxin cylindrospermopsin (CYN) on the upper human respiratory tract. Drinking water-borne compounds may reach the respiratory tract for example in aerosol droplets during bathing or from cosmetic inhalation devices. In both human bronchial cell lines tested cytotoxic effects and altered cell signaling were observed at CYN concentrations in the same order of magnitude as detected in freshwater reservoirs (data are not available for aerosol concentrations). An original research article on this task is already in preparation.

For the second task, I am systematically reviewing published literature reporting effects on the (human) gastrointestinal tract (GIT) and/or the humoral immune system. Even though gastrointestinal illness is the most commonly reported adverse health outcome upon exposure to cyanobacterial blooms, most research focusses on organ-specific toxicity, especially liver-, kidney- and neurotoxicity. Upon oral exposure, the first barrier to be overcome are epithelia lining the GIT. Disturbances in the delicately balanced mucosal immune responses and the barrier function of the GIT epithelia lead to the observed effects of severe diarrhea, abdominal pain and vomiting, but the causative agent(s?) in the complex mixture remains to be determined. A scientific publication comprehensively summarizing available information on this topic is, as well, in preparation.

Besides Addressing tasks related to the project I was happy to attend two international scientific meetings: The European Union’s Joint Research Centre (JRC) Summer School on Alternative Approaches for Risk Assessment 2017 in Ispra (Italy) and the Symposium on risk assessment and risk management cooperation on environmental protection goals, organized by the European Food Safety Agency (EFSA) and the Norwegian Scientific Committee for Food and Environment (VKM) in Oslo (Norway, 2017). These experiences gave me valuable insight into risk assessment and policy-making at an international level and unique networking opportunities.

In the next months, I will hopefully publish the scientific reports that are currently in preparation and address the third, experimentally most extensive part of establishing an assay for the testing of neurotoxicity.

Where am I? – at the summit!
Midterm progress update

20 months into the project I successfully published experimental results in a scientific journal!

My research on the effects of cylindrospermopsin, a potent cyanobacterial toxin, on cells from the respiratory tract has been accepted for publication in Chemosphere – have a look here:

Also, a literature review on the contribution of cyanobacterial metabolites to acute gastroenteritis is close to submission, hence will be available soon.

With the first two tasks in my project (nearly) finished, I am embarking in the third journey: implementing a human health-relevant in vitro model to study neurotoxicity and altered neural differentiation. Upon consultation with Dr. Anna Bal-Price (European Union Joint Research Centre, Ispra, Italy; EURL ECVAM) who is highly involved in the validation and integration of 3R-compliant, alternative methods for developmental neurotoxicity testing (DNT) for regulatory purposes. Following her advice, I teamed up with a senior researcher colleague, Dr. Dáša Bohačiaková (Institute of Histology and Embryology, Masaryk University) and started implementing a human neural stem cell model. I will use this model to assess the acute toxicity of single cyanobacterial toxins and binary mixtures. Concentrations of no or little cytotoxicity will then be tested in a mixed culture of differentiating neural progenitors, neurons and glial cells.

Together, these results will contribute to a risk assessment I will conduct at the end of this year at the NaToxAq beneficiary Fera Science Ltd. (York, UK) under the supervision of Dr. Carmel Ramwell.

Besides work at my place of employment, I was very happy to present preliminary results at two international conferences: SETAC Europe conference (May 2018, Rome) and the International Conference on Harmful Algae (October 2018, Nantes). These offered me a great opportunity for networking and knowledge exchange with international experts in the field of phycology and (eco-) toxicology – the interface and professional niche of my highest scientific interest.