Overdose under water

Fish, crayfish and snails: Pharmaceuticals and chemicals  in water endanger their health. Biologist Rita  Triebskorn is advocating  for better protection – and is making herself heard worldwide.

Initially, Rita Triebskorn wanted to become a teacher. She passed her state examination in biology and German literature in Heidelberg.  Afterwards she traveled to the Philippines on a marine biology  internship at the University of San Carlos. She assisted in  research on snails and their parasites, and how mussels react to  heavy metals, inspiring her to write a doctoral  thesis instead of becoming a teacher.

At the end of 1986, after a major fire at the pharmaceutical company Sandoz in Switzerland, toxic extinguishing water flowed into the Rhine and triggered a fish kill. The disaster also triggered a boom in environmental research. For her doctoral thesis on the mechanism of action of snail control agents, Triebskorn received funding from industry and the state of Baden-Württemberg – the beginning of a career in ecotoxicology. As Professor at the University of Tübingen since 2006, Triebskorn is currently exploring effects of environmental chemicals in surface waters on wildlife.

In addition to snails, crayfish, trout and diplostraca, chironomid larvae are now among the organisms she studies in the field and in the laboratory. She describes her specialty as “Research on fish  and crayfish” and is particularly concerned with the welfare of  the natural inhabitants of local waters. It is imperative that they are not poisoned by the chemicals that humans carelessly flush  down the toilet or tip into the sink, be it drug residues, pesticides, or even seemingly harmless substances such as the sweetener sucralose, contained in lemonade, sweets or cough syrup.

“Humans only take medication occasionally, but fish swim in it all  their lives,” says Triebskorn. Sucralose is one of the most common sugar substitutes, along with acesulfame, cyclamate and saccharin. In particular, diet  foods are sweetened artificially. Trichlorinated sucralose isn’t a tasty meal for intestinal bacteria, they do not break down the substance and it ends up in the wastewater. Bacteria in the water do not break it down either. Although it took a while for sucralose to be detected in the environment after it was approved in Europe in 2004, it is now increasingly found in Lake Constance – and in the groundwater of Germany and Switzerland.

Sucralose is not safe for animals: It has been proven to trigger diabetes in rats and mice, as it does in humans. It also causes inflammation of the liver in mice and disturbs the composition of their intestinal flora. This makes the sweetener, which is difficult to break down, part of the man-made and poisonous cocktail in our water cycle. And this must – as the ecotoxicologist demands – “be reduced in favor of the organisms living in it”. Triebskorn would like to start a research project on sucralose and is only waiting for a suitable call for proposals.

Humans only take medication occasionally, but fish swim in it all their lives.

Fourth purification stage for Europe’s sewage treatment plants

Together with a team of thirty early career researchers and technicians, Triebskorn is focused on improving sewage treatment plants. A fourth cleaning stage is currently being introduced  throughout Europe also thanks to her work. In additional settling tanks, ozone is used with granulated activated carbon or a  sand filter, or powdered activated carbon is combined with a  sand filter.

In the joint project funded by the Federal Ministry of  Research, SchussenAktivplus, Triebskorn investigated the biological effects of sewage treatment plants on the Schussen river,  which flows into Lake Constance. At the time, engineers, authorities  and fishing associations, a total of about 150 people, were  involved in her project. It led to an important finding: The additional cleaning stage reduces trace substances and their effects by 80 to 90 percent. The bacterial load of the water also decreases.

Measurements and experiments were conducted in the field,  in the laboratory and in a sophisticated bypass system co-developed by Triebskorn that directs river water through aquaria housed on the shore in construction trailers. Trouts also live in  these aquaria. Their eggs and newly hatched embryos are counted and examined for developmental disorders. Crayfish are also monitored actively using tea infusers which are  held by floating rafts at a certain point in the river, so that the crayfish and their offspring can be collected again after the experiment.

Mapping complex relationships

In the warm season, teams from Triebskorn’s  working group are on the road in a packed van – with buckets, sieves,   measuring instruments, lab  supplies, animal cages and protective clothing such  as waders and rubber boots. The researchers know the rivers and lakes around Tübingen quite well.

Pioneering projects such as SchussenAktivplus made Triebskorn known worldwide. In 2013, she and Heinz-Rüdiger Köhler were asked by the “Science”  magazine to write a review article on pesticides  and their effect on the environment. Köhler  heads the Department of Animal Physiological Ecology, which includes Triebskorn’s working  group. He is also her husband, with whom she has  published many research papers together.

“Science” offered the researchers a platform for fundamental statements: They argued that it was difficult to demonstrate seamless cause-andeffect chains under field conditions, as is common in the laboratory. “We are trying to establish a  plausibility chain that covers everything from the  molecular effects of pesticides on individuals to  the effects on the entire ecosystem.” Triebskorn is  convinced that this is the only way to tackle the  complexity of ecological issues. The work made  headlines including reports from the French “Le  Temps” and the American “Washington Post”.

We are trying to establish a plausibility chain that covers everything from the molecular effects of pesticides on individuals to the effects on the entire ecosystem.

The glyphosate debate

The importance of such research is demonstrated by the heated debate surrounding the plant protection  product glyphosate. Its approval was extended by the EU Commission for ten years in December 2023. In a statement to the Science Media Center, Triebskorn, also a member of the Federal Government’s expert panel on the assessment of the relevance of  trace substances, warned against this step.

“The EU Commission’s explanatory memorandum refers to the fact that there are gaps in knowledge regarding toxicological and ecotoxicological endpoints  and that the approval of glyphosate can be justified for this reason. However, this is unfounded from a technical point of view, ignores new scientific findings and the precautionary principle,” says Triebskorn.  The risk of cancer in humans remains at the heart of the glyphosate debate. Data on  effects on the environment are hardly taken into account. This includes proven tissue damage in fish or changes in the microbiome (bacteria that live  in the digestive tract, for example) in fish and bees.

The researcher has dedicated herself to a science that has many political ramifications. She enjoys outreach work, giving lectures (whether at Children’s University or in a sewage treatment plant), advising politicians, giving interviews or meeting with fishermen who appreciate her expertise. In this way, she has become a teacher in a roundabout way. In May 2023, the University awarded her the Tübingen Prize for Science Communication.  The jury’s statement: “Over the past ten years, Rita Triebskorn has worked continuously and tenaciously to create awareness of her central research topic, the ecological protection of water.”

Text: Judith Rauch


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