Dr. Anne Marie Mahon:

I thank the joint committee for inviting us to engage on this topic. It is of particular interest to us as we are very active in the area of research on microplastics pollution. The statement submitted outlines the sources and some potential impacts of microplastics. I reiterate our support for the proposed Bill.

I will present some of our current and previous work in which we investigated sources and pathways of microplastics. I will begin with the sources of microplastics and what we know about pathways to the freshwater environment. A desktop study in 2015, which was funded by the Environmental Protection Agency, EPA, outlined some potential sources of microplastics pollution in freshwater environments.

The study identified some catchments which had potentially high-risk microplastic pollution. We also did a smaller scale study in which we were able to quantify some of these microplastic levels and describe some of the sources.

With particular relevance to microplastics coming from industry, we visited some industry polymer companies. In one of these, polymerisation processes took place, while another had machining of microplastics. We found that even though these were quite well regulated plastics industries with their own on-site treatment, they still emitted substantial amounts of microplastics to the sewer. As well as accidental emissions to a sewer, we also identified some allowable discharges to a sewer which take place due to the current lack of regulation of microplastics in industry. In our plastics industries, there is an allowable suspended solid loading which is quantified in milligrams per litre. This can equate to quite high levels of microplastics emissions. This problem of allowable emissions has also been flagged internationally by Lechner and Ramler in 2015, as they quantified high numbers of microplastics coming out of an Austrian recycling industry.

As well as the accidental and allowable emissions to a sewer, there is also a potential for accidental spillages within industry, such as spillages onto factory floors or onto the surrounding hard substrate outside. There remains potential for run-off in the storm water drain or perhaps direct run-off into freshwater. The EPA has funded GMIT and UCD to carry out a project, Sources, Pathways and Environmental Fate of Microplastics, in which we are examining the potential for plastics to be found in the vicinity of plastics industries by sampling the sewer drain and assessing the potential for direct input by looking at nearby water courses. This work is ongoing.

Pathways from the sources into our sewers have been examined in recent years by several researchers, including us. In summary, many sources such as those emanating from industry, landfill, storm water drains and domestic use such as washing machines drainage enter the wastewater treatment plant system. Upon entering, the microplastic loading is partitioned into what comes out in the receiving waters and what is captured in the sewage sludge. We found there is a high capture rate within wastewater treatment plants of roughly 90%. In Ireland, microplastics which are incorporated into the sewage sludge may find their way back onto the land due to spreading of sewage sludge practices. The remaining 10%, which is not a low figure, ends up in our rivers and lakes. We do not really know where the microplastics go from there or what impact they may have on the environment or human health.

Some other sources we are currently investigating include microplastics emanating from the construction industry, as it has a very high plastics demand, and from AstroTurf or artificial pitches and playgrounds. We have carried out sampling and are currently analysing some of our data. What we want to see is how plastics are spread or transported from these sources and if there is a danger to nearby water courses. Preliminary results show that aspects of construction design dramatically reduce the leakage of microplastics from AstroTurf pitches.

They include microplastics from AstroTurf pitches, used in the construction of boundaries and other features. Other sources and pathways for microplastics which we really want to investigate include how microplastics, once they become land-spread, are transported overland into nearby watercourses. In our current study we are investigating the potential for and the mechanisms for overland movement and run-off from rainwater, as well as the vertical migration of microplastics. This is being done via a series of experiments and fieldwork. We are also investigating the potential for microplastics in the freshwater environment to be transferred through the food chain and monitoring microplastics in a number of watercourses, particularly in the River Slaney catchment. Preliminary results of this work show that all of the river water samples obtained so far contain microplastics, the majority of which are microplastic fibres. We have found that microplastics are present in all of the invertebrate species we have captured from rivers.

There are certain points at which we might be able to intervene. There is a high number of clean-up initiatives under way on beaches and rivers. While this is very useful and important for the surrounding ecosystem, more emphasis should be placed on intervention at an earlier stage. Of course, prevention is the best solution to the problem; therefore, we very much support legislation or regulations to reduce the production and use of plastics. This might also be feasible through awareness campaigns, or consumer-driven initiatives. Furthermore, there is great scope for intervention at the product design stage. Once microplastics or plastics reach the environment or are in use, effective waste management and potential change of industrial practices are very important means by which to decrease dramatically their leakage into the environment. They can be captured and well managed once they reach receptors such as a wastewater treatment plant. Technological upgrades to treatment plants to deal with microplastics and allow improved waste management of sludge derived from the plants could also help. There are a number of clean-up initiatives available once microplastics reach the environment.

The last slide shows my team which helps to make this research become a reality. My colleague, Dr. Róisin Nash, will give the committee an insight into microplastics in the marine environment.