Impact of Microplastics in the Freshwater Environment (IMP)

The Irish Environmental Protection Agency (EPA) has funded a 3-year research project that aims to quantify the impacts of microplastics on fresh water organisms. The project is supervised by Prof Marcel Jansen, Dr Frank van Pelt, and Prof John O’Halloran. PhD student Ms Alicia Mateos Cárdenas has already initiated the first exposure studies, to explore whether plastic beads have harmful effects on freshwater organisms. Ms Sandra Jansen is responsible for outreach. Progress can be followed on the website: of Microplastics in the Freshwater Environment - Research Project


The central objective of this project is to explore the impacts of microplastics on Irish fresh water aquatic organisms and ecosystems. This knowledge will inform monitoring programmes and regulatory policy by identifying those microplastics that pose the biggest risks to the freshwater environment.

Microplastics are plastic particles smaller than 5mm. These particles are widespread in seas and oceans, and their harmful effects on many different marine animals are well known. In contrast, we know relatively little about microplastics in fresh water: its sources, environmental fate, and biological impacts. Several large scale projects are currently working to develop monitoring technology for microplastics, as well as creating models to explain its spread and build-up. This is the approach taken by our collaborators at GMIT (see GMIT However, microplastics can vary greatly in chemical composition, size, shape and concentration, and may have different toxic effects under fresh water conditions than in the marine environment. Therefore, more information is needed to identify those microplastics posing the biggest risk for fresh water species and the freshwater environment.

Microplastics in the environment

Microplastics are either resulting from fragmentation of larger plastic objects, or specifically produced as small plastic microparticles for use in products such as cleaning agents, cosmetics, and toiletries. It is estimated that the island of Ireland emits some 5700 kg microplastics per year. Fibres released when washing (synthetic) clothes could produce even more microplastics again. Microplastics end up in the fresh water environment, either via a sewage/waste treatment plant, or directly (e.g. road run-off).

Once in the environment, microplastics are extremely persistent, although we need to know more about their fate in the fresh water environment.

Uptake of microplastics

Microplastics enter the food chain when they are consumed by small filter feeders (e.g. mussels, krill), or grazers (e.g. snails), or taken up by plants. These in turn are eaten by larger organisms, leading to a build-up of microplastic levels. High concentrations of microplastics have been found in organisms like fish, whales, turtles and birds. Little is known about microplastics in the fresh water food chain. This is an important issue, since evidence is emerging that microplastics are present in food, although neither the source nor the impact on human consumers is well studied.


Regulation of production and emission of microplastics will be a key component of any strategy that aims to reduce environmental pollution by microplastics. The data generated in this project will inform policy makers, enabling development of a targeted legislative approach that focusses on those microplastics that are of most environmental concern. Furthermore, the data generated will be a stepping stone towards biomonitoring and bioremediation approaches. This project will focus on developing more in-depth knowledge, which will further define the specifics of the pathways and the impacts of microplastics on humans, species and habitats.