Microplastics in drinking water “don’t appear to pose a health risk” at current levels but there are a number of “gaps” in the research, according to the World Health Organization (WHO). “Quality-assured toxicological data are needed on the most common forms of plastic particles relevant for human health risk assessment,” WHO noted in its new 124-page analysis.
There also needs to be better understanding on the uptake and fate of microplastics and nanoplastics following ingestion. More research on overall exposure, for example through food and air, should also be conducted. “We urgently need to know more about the health impact of microplastics because they are everywhere – including in our drinking water,” said Dr Maria Neira, director at WHO’s department of public health, environment and social determinants of health. “We also need to stop the rise in plastic pollution worldwide,” she added.
In June, research published by WWF showed the average person is consuming a credit card’s worth of plastic every week (5 grams) in products such as shellfish, water (bottled and tap), beer and salt. Indeed, what started as an environmental disaster, thrust into the public psyche with images of choking turtles, is now snowballing into a worldwide public health crisis that the food sector and regulators will find it increasingly hard to ignore.
At just 15 pages, WWF’s report was short and the findings not so sweet. However, it’s just the latest layer in a rising pile of research showing that wherever researchers have looked in the human food and drink chain, they’ve found plastic: honey, beer, bottled and tap water, sea salt and, of course, seafood. "The problem is wide-scale and the concentrations are low,” Richard Thompson, professor of marine biology at Plymouth University, UK, said in an interview for EUObserver in December 2017, “but if we carry on as normal and have this conversation again in 20 years’ time we may well have reached concentration levels that are a concern.”
WHO has now echoed his concerns. “If plastic emissions into the environment continue at current rates, there may be widespread risks associated with microplastics to aquatic ecosystems within a century, with potentially concurrent increases in human exposure.”
WHO’s experts identified three forms in which microplastics are potentially hazardous to human health: the particles themselves, which present a physical hazard; chemicals (unbound monomers, additives, and sorbed chemicals from the environment); and microorganisms that may attach and colonise on microplastics, known as “biofilm”.
“Although there is insufficient information to draw firm conclusions on the toxicity of plastic particles and particularly the nanosize particles, no reliable information suggests it is a concern,” WHO noted.
It is the ability of microplastics to suck up pollutants (including those that are now banned but still hanging around) as they float around in the sea that is causing much concern. "There is enough information that this is having an impact and has the potential to have a very serious impact," Dr Sherri Mason, a professor of chemistry at the State University of New York has warned. “We are sounding the alarm loudly because of what happened with climate change. We have enough information to take a precautionary approach … and [implement] serious regulation."
In its most recent opinion, in 2016, the European Food Safety Authority (EFSA) said it is “too early to say” if microplastics are harmful to humans. However, it called for more work on the toxicity of nanoplastics given that they could penetrate all kinds of tissues and eventually end up in cells.
Here in the UK, ministers have avoided bringing up the health issues when talking about plastic pollution. The chief medical officer has also been keen not to rock the boat and create a food scare based on current evidence. In her 2017 report – “Health impacts of all pollution – what do we know?” – Professor Dame Sally Davies dedicated just six paragraphs of the 187 pages to microplastics. “Exposure to microplastics through food is possible, based on studies of seafood; however, it is unknown if this translates into meaningful exposure in the population,” the report reads, while human exposure, hazard and therefore consequences of exposure to these microplastics are “largely unquantified”.
This is scant consolation for some. “This is a very new area of research, and the fact that microplastics persist in the environment, are very mobile and also show signs of accumulating in wildlife is of great concern,” said Dr Michael Warhurst, executive director at the Chem Trust. “To put it at its most basic, whatever toxic effects we may find in the future, it is going to be impossible to withdraw all the microplastics from the environment.”