Mayo site part of study which shows 50% of 'flushable' wipes contain microplastics

AN NUI Galway study has found that wet wipes and sanitary towels are an underestimated source of white microplastic fibres in the marine environment.

A Mayo site was among the locations studied by researchers from Earth and Ocean Sciences and the Ryan Institute at NUI Galway on the contribution of widely flushed personal care textile products (wet wipes and sanitary towels) to the ocean plastic crisis.

Researchers found that 50% of the wipes labelled 'flushable' in the study were shown to contain microplastics.

Dr. Liam Morrison led the study, which showed that sediments adjacent to a wastewater treatment plant are consistently strewn with white microplastic fibres that are comparable to those from commercially available consumer sanitary products (wet wipes and sanitary towels). The article has been published in the international journal Water Research and was co-authored by NUI Galway PhD student Ana Mendes and Maynooth University graduate Oisín Ó Briain.

In most studies to date, white fibres are likely underestimated, because of the commonly used filtration procedure to capture microplastic fibres as filters are commonly white, making visual identification of microscopic white fibres against a white background difficult. This is significant given the global growth of non-woven synthetic fibre products and their ubiquity in wastewater.

Speaking today, President of NUI Galway, Professor Ciarán Ó hÓgartaigh, said the research highlights the need for us to adapt our behaviours and tackle the ubiquity of plastic in so many products.

An urban rural gradient involving three locations from Galway City (close to Mutton Island and adjacent to a wastewater treatment plant) to counties Clare (Bell Harbour) and Mayo (Bellacragher) were investigated in the study.

The total number of fibres found near Mutton Island was 6,083 microplastics fibres per kilogram of sediment, while the rural sites had much lower levels (Bell Harbour, 1,627, and Bellacragher 316). The total number of white fibres was 5,536, 788, and 265 per kilogram of sediment for Mutton Island, Bell harbour and Bellacragher respectively.

Incredibly, 91% of microplastic fibres at Mutton Island are likely derived from wet wipes and sanitary towels.

Dr. Morrison, from Earth and Ocean Sciences and Ryan Institute at NUI Galway, said: “Covid-19 may have brought its own challenges for the oceans including the increased use of disinfectant wipes during the pandemic which potentially may end up as microplastic fibres in the sea. It is widely known that microplastics can act as vectors for contaminants including bacteria and viruses and are potentially harmful for public health and marine life.”

The nearby intertidal zone at Mutton Island is prone to the accumulation of high volumes of washed-up sewage-derived debris on a frequent basis. Excessive microplastic loading in sediments in December 2017 was likely induced by heavy precipitation episodes during a south-westerly storm front. Elevated debris loading on this occasion may result from combined sewer overflows, where excessive input of drainage water exceeds wastewater treatment effluent capacity and is released untreated in the overflow.

Dr. Morrison said: “This was significant in the context of climate change, where we are likely to see increased rainfall events and flooding.”

While most microplastics may be removed by the wastewater treatment process, combined sewage overflows associated with periods of heavy rainfall give rise to the release of sewage waste containing wipes and sanitary towels, impacting on public health and the environment.

Combined sewer overflows and the subsequent shoreline deposition of sanitary waste have not previously been thoroughly investigated as a source of white microplastic fibres in the marine environment.

The study found that wet wipes and sanitary towels are a source of unaccounted white microplastic fibres in the marine environment and not all flushable wipes are biodegradable. In fact 50% of the wipes labelled 'flushable' in this study were shown to contain microplastics.

The lack of regulation for hygiene and sanitary products results in a failure to identify the plastic composition of these materials. This demonstrates the consequences of misleading labelling of non-woven textile personal care products.

Dr. Morrison said there is a need for increased public awareness of microplastic pollution in the environment and human behaviour should shift away from the inapt disposal of sanitary products down the toilet and instead divert to alternative land-based waste management.

* Pictured, from left, are Dr. Liam Morrison of NUI Galway with PhD student Ana Mendes and Maynooth University graduate student Oisín Ó Briain at Grattan beach near Galway City. Photo: Aengus McMahon