Plea for integrated approach when tackling pollutants

Doctorate research demonstrates the importance of assessing the effects of mixture toxicity in water

The combined effect of pollutants – even when they occur in low concentrations individually – can be significant. This knowledge is crucial for the development of more detailed guidelines for water quality. That is the view of KWR researcher Sanah Majid Shaikh, who successfully defended her dissertation on mixture toxicity at the University of Antwerp on 3 June. “I hope my work contributes to the water sector taking a more integrated approach to water quality. That is needed for both ecosystem and human health.”

Shaikh has been working at KWR as a scientific researcher and toxicologist since 2021. In addition to her full-time job, she devoted the past few years to completing her dissertation. Shaikh completed the practical side of the research before joining KWR. Her doctoral supervisors were Professor Ronny Blust (University of Antwerp) and Professor Karen Smeet (Hasselt University). At KWR, Shaikh is transforming her expertise relating to the assessment of the effects of chemical mixtures into research on the toxicity of pollutants in relation to water quality and potential health risks. Her work is for drinking water utilities, government and industry. Now she has completed her Ph.D., Shaikh is a European Registered Toxicologist (ERT). “I really enjoyed the intense focus on fundamental research during my work at the university,” says Shaikh. “At KWR, I appreciate the applied nature of our work, with research leading directly to practical solutions for water management. I find that transition from theory to application both challenging and enriching.”

KWR researcher Sanah Majid Shaikh received her doctorate on 3 June at the University of Antwerp in Belgium.

Combined effects

Shaikh’s doctoral research centres on understanding specific mechanisms behind the toxicological effects of mixtures of substances. That is needed to get to grips better with the extent of toxicity in biological systems and humans. Shaikh believes that her doctoral research fits in seamlessly with her ongoing concern about the combined effects of chemicals in the aquatic environment. “In my dissertation, I studied these effects for metals, and specifically copper and cadmium. Metals in the environment are often associated with harmful effects on living organisms, including humans. Because they are so widespread, metals tend to be found in complex mixtures. Despite the intense focus on this subject, we still don’t know exactly how individual metals or mixtures harm living beings. In addition, there has been only limited international research targeting the effects of metal mixtures in different animal species.”

Shaikh used three alternative animal models in her study: the zebrafish (Danio rerio), the water flea (Daphnia magna) and the flatworm (Schmidtea mediterranea).

The complete picture

Shaikh’s research helps to understand better how combinations of metals affect living beings and emphasises the importance of thorough research for assessing the risks of metal contaminants. The researcher also discusses the significance of her findings for the EU regulatory framework. Shaikh: “My work has shown that, even when the concentrations of the individual pollutants are low, there are significant toxicological effects when they are mixed together. I hope these results will help the water sector to take these combined effects into account more. Chemicals – including metals – are regulated on an individual basis at present. But in the real environment, where flora, fauna and also humans are exposed to multiple substances at the same time, you have to look at mixture toxicity to establish a complete picture. That makes a better risk assessment possible for the establishment of more effective regulatory standards. All with a view to improving water safety and public health.”

Robust foundation for toxicology

For KWR, Shaikh’s recent doctorate means that the field of toxicology now has an even more robust foundation. Chief Science Officer Milou Dingemans – who, as a toxicologist, is also one of Shaikh’s colleagues – is enthusiastic. “Emerging substances are a huge challenge for the water sector,” explains the researcher. “Developments are so fast that we almost can’t keep up, and they involve numerous questions about toxicity and health risks. As toxicologists, we feel a responsibility to be in a position to make sound judgements about what is happening, and to communicate clearly why protective measures may be needed. On top of that, I’m also very proud and happy for my colleague. This doctorate confirms her scientific skills and perseverance”.

Continuous development

In her future work at KWR, the ambitious Shaikh plans to engage in projects relating to emerging contaminants, both within and beyond our national borders. “That involves more than just chemical pollutants,” she explains. “There are also biological pollutants such as pathogens. And physical pollutants with micro- and nanomaterials, for example. I very much want to seek opportunities in emerging markets where water quality is becoming an increasing problem and where tailored solutions are needed. In addition, I want to continue developing professionally. Training courses are on my bucket list!”

Sanah Majid Shaikh’s dissertation ‘Comparative Analysis of Metal Toxicity Responses in Aquatic Invertebrate and Vertebrate Model Organisms’ is available for download via this link.