August 22, 2019

expert reaction to WHO report on microplastics in drinking water

A report, published by the World Health Organisation (WHO), examines the potential human health risks associated with exposure to microplastics in the environment. 

David Green, Chair of IChemE’s Environment Special Interest Group, said:

“The WHO study is to be welcomed as a starting point in gaining greater understanding of the effects of microplastics in drinking water. The authors have limited their study to bottled and tap water which is understandable and they acknowledge the dearth of available data. Nonetheless they have accurately summarised the current understanding and applied suitable risk assessment methodologies.

“Within the limits of the study they have shown that existing treatment methods are effective at limiting exposure to microplastics. The initial conclusions give some measure of comfort for the current situation but do highlight that the future may not be as optimistic. The call for greater research into uptake from other water sources is appropriate as is the precautionary recommendation to limit plastic releases. We await further studies with interest.”

Javier Mateo-Sagasta, Senior Researcher in Water Quality, International Water Management Institute (IWMI), said:

“This latest report only adds to the growing body of evidence that microplastics are a huge issue, both for our health and for the environment, and that this needs urgent addressing. IWMI is working with the UN Environment Programme to assess what is the most cost-effective – cheapest but yet effective – combination of solutions to solve this challenge. 

 “Such solutions must include addressing the issue of macro plastics first, which, once in the environment, degrade over time into smaller plastic particles and become microplastics. Banning single use plastics such as plastic bags and plastic bottles is a growing trend. But more broadly we need to rethink how to design, produce, consume and dispose of the plastics that we’ll still use in the decades to come. 

 “Some microplastics are purposefully made to carry out certain functions, such as abrasives in toothpaste and skin cleaners or for industrial purposes. Here again, prevention, including banning or substituting, looks to be more cost-effective. Microplastics can also originate from the abrasion of large plastic objects during manufacturing use or maintenance such as the erosion of tyres when driving or the abrasion of synthetic textiles during washing. Here, solutions need to include new engineered materials and smart design, such as clothes that shed fewer fibres or washing machines equipped with filters. 

 “All these efforts must be supported by legislation and on-the-ground policies that force real change. Once microplastics are in water systems – be it stormwater, wastewater, or ultimately rivers and lakes – one is left with advanced water treatment, such as micro or nanofiltration, as almost the only solution. And that may be too costly.”

Alice Horton, Anthropogenic Contaminants Scientist (microplastics researcher), National Oceanography Centre (NOC), said:

“This report highlights the need to improve our understanding of human exposure to microplastics from a variety of sources, including drinking water.

“To date there are no data available to show that microplastics pose a hazard to human health, however this does not necessarily mean that they are harmless. It is therefore essential to understand how and where exposure to microplastics is most likely, and to understand any possible health risks as a result of this exposure.

“It is important to put concerns about exposure to microplastics from drinking water into context: we are widely exposed to microplastics in our daily lives via a wide number of sources, of which drinking water is just one. Rather than focus on one route of exposure, a broader understanding of the wider sources and interactions of microplastics within the environment is needed.”

Dr Andrew Mayes, Senior Lecturer in Chemistry, University of East Anglia (UEA), said:

“As might be expected from a WHO-commissioned report, this is a pretty comprehensive synthesis of all the currently-available scientific evidence.  The report is well balanced and seeks to assess the risks in an overall context relative to other likely risk factors.  By drawing together all the available and often disparate evidence, the working group has added considerable value to the literature through thoughtful and detailed analysis.

“The key finding, that microplastics in drinking water pose a low risk to human health, based on current available evidence, will no doubt come as a relief to worried members of the public, who may have been alarmed following widespread media attention to scientific reports of microplastics in mains water and bottled water over the last couple of years.

“The recommendation that routine monitoring of microplastics in drinking water is NOT necessary at present will also be a huge relief to the UK water industry, since it will no doubt reduce pressure on the water regulator to act in this way.  It is also sensible, since it would place a huge financial burden on the industry and would be premature, since there are no cost-effective and validated methods that could be applied for this purpose currently.

“The report does highlight the lack of detailed understanding of the fate and behaviour of microplastics in water and wastewater treatment processes, however, so while routine monitoring is NOT recommended, further research certainly is, especially in relation to the transfer of microplastics (particularly microfibers from washing clothes) through the wastewater treatment process and back onto agricultural land through use of solid wastes as fertilizer.

“The report also emphasizes that, while risks to health of microplastics through ingestion in water may be low, there is a continuing need to reduce plastic inputs into the environment at source, in order to prevent the problem becoming worse.  This can be enacted through better waste management and implementation of incentive schemes and governments should prioritise such actions in the overall global strategy to reduce plastic inputs into oceans (the ultimate sink for all of the waste).

“As a researcher focused on developing new analytical methods for studying microplastics, I am naturally gratified that the report highlights development of improved and standardized methods for microplastic analysis at the top of its list of knowledge gaps and research needs.  Lack of rapid, cost effective and reliable methods for detecting and analysing microplastics is a key bottleneck in much of the required research effort to understand the sources, distributions behaviour and fate of microplastics, both in environmental and medical contexts.  Hopefully, highlighting this issue in such a prominent way in the report will encourage the research community and funding agencies to address this gap in an urgent and concerted way.”

‘Microplastics in drinking water’ by the World Health Organisation et al. was published at 01:01 UK time on Thursday 22nd August. 

Declared interests

Javier Mateo-Sagasta: No declarations of interest

Alice Horton: I was recently involved in the UK Water Industry Research (UKWIR) project on microplastics in drinking water and wastewater, therefore working for and alongside the UK water industry. I may work on similar projects for this or other clients in the future.

Dr Andrew Mayes: I have no conflicts of interest here.  I did not contribute to any part of the production of this report, though I obviously know some of the experts involved and collaborate formally with one or two of them on microplastic-related projects.  I am, of course, interacting with the water industry, but the opinions expressed are my own and I am in no way a spokesman for the water industry.

None others received.