Plastic inaction may pose real risk to human health 

Plastic pollution began as an environmental disaster with choking turtles and birds feeding their young on packaging. But it’s evolving into a public health crisis that food brands and regulators can no longer ignore. David Burrows reports.

Last year’s Volvo Ocean Race lasted eight months and covered 45,000 nautical miles. En route, one of the teams, Turn the Tide on Plastic, diligently collected water samples that could be tested for the presence of microplastics – small pieces of plastic measuring less than 5mm. The data was used to create a microplastics map of the world’s oceans, which highlights just how ubiquitous these particles are: only three of the 75 samples collected contained no microplastics.

Few of those close to the topic of plastic pollution – arguably the environmental issue of the day – will have been surprised by the findings. “Plastic is everywhere, and suddenly we have decided that is a very bad thing,” noted Stephen Buranyi in an article for the Guardian in November 2018. The public is up in arms – thousands of them posted crisp packets back to Walkers, and many more have ripped off excessive packaging at supermarket checkouts in “plastic attacks”. And in the past 12 months only animal welfare and caged poultry attracted more activity from campaign groups, according to tracking firm Sigwatch.

Those in the food sector have been forced to react – many have whipped up new packaging policies and been quick to sign up to industry commitments like the UK Plastics Pact, which has just told signatories to eliminate eight “problematic or unnecessary plastic items” by 2020. The development of government policy has also been uncharacteristically rapid too, forcing many in foodservice to rethink their strategies and even their business models as they face up to far heftier extended producer responsibility fees and a tax on plastic. As Buranyi wrote: “At the highest levels of government the plastic panic can resemble a scrambled response to a natural disaster, or a public health crisis.”

His choice of words is particularly noteworthy. One person is dying every 30 seconds in developing countries from diseases and illnesses caused by plastic pollution and uncollected rubbish dumped or burnt near homes, according to a recent report commissioned by Flora and Fauna International. These nations are at the sharp end of the plastic pollution crisis, and action needs to be swift and successful. There is a chance, too, that plastic pollution is slowly putting us all at risk.

Indeed, what started as an environmental disaster, thrust into the public psyche with images of choking turtles, is snowballing into a worldwide public health crisis that the food sector and regulators can no longer ignore.

Last month, research published by the 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. “Developing a method for transforming counts of microplastic particles into masses will help determine the potential toxicological risks for humans moving forward,” said Dr Thava Palanisami, project co-lead and microplastics researcher at the University of Newcastle, Australia.

At just 15 pages, the 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 our 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, told me 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.”

It was Thompson and his team who, all the way back in 2004, showed that waters around the north-east Atlantic had become contaminated by microscopic fragments of plastic and that the abundance of this material had increased significantly over time. In 2013, their research published in the journal Marine Pollution Bulletin showed plastics in 184 of the 504 fish they examined from the English Channel. Species assessed included whiting, horse mackerel, John Dory and red gurnard. There is now a rich library of similar research.

In 2016, for example, a study published in the journal Nature, showed that 28% of fish and shellfish on sale in Indonesia had eaten man-made debris – and all of it was plastic. The authors said that because anthropogenic debris is associated with a “cocktail of priority pollutants”, some of which can transfer to animals upon ingestion, their findings support concern that chemicals from man-made debris may be transferring to humans via diets containing fish and shellfish. This, they added, raises important questions regarding the bioaccumulation and biomagnification of chemicals and the consequences for human health.

Indeed, the tiny plastic particles floating about in the sea can act like sponges for persistent bioaccumulating toxins, so anything that mistakenly eats them gets a shot of this chemical cocktail. The plastics sector has played this effect down, but the impact this could have further up the food chain is not yet clear. “In marine animals, higher concentrations of microplastics in their digestive and respiratory system can lead to early death,” noted the WWF in its report, rather ominously. “Some types of plastic carry chemicals and additives with potential effects on human health”.

Last year, the journal Current Opinion in Environmental Science & Health ran a special issue on micro- and nanoplastics – the latter measured in the millionths of a millimetre. A paper by Messika Revel, Amélie Châtel and Catherine Mouneyrac reviewed the evidence to date. They concluded that the adverse effects from micro- and nanoplastics may result from a combination of the plastic's intrinsic toxicity (such as physical damage); chemical composition (for example, the leaching of additives); and ability to adsorb, concentrate, and release environmental pollutants into the organisms. Microplastics could also serve as a vector for pathogens, they said, and since they have been detected in various trophic levels, additional studies are needed to assess the bioaccumulation of adsorbed contaminants and eventually biomagnification, which “may occur in higher trophic levels, and could eventually affect human health”.

In October 2018, experts at the Medical University of Vienna and the Environment Agency Austria published the results of a pilot study involving a small group of eight participants from Finland, Italy, Japan, the Netherlands, Poland, Russia, the UK and Austria. Each person kept a food diary in the week leading up to a stool sampling. The diaries showed that all participants were exposed to plastics by consuming plastic-wrapped foods or drinking from plastic bottles. None of the participants were vegetarians and six of them consumed sea fish. Up to nine different plastics, sized between 50 and 500 micrometres, were found, with polypropylene (PP) and polyethylene terephthalate (PET) the most common. On average, the researchers found 20 microplastic particles per 10g of stool. Microplastic may impact human health via the gastrointestinal tract, the team noted, where it could affect the tolerance and immune response of the gut by bioaccumulation or aiding transmission of toxic chemicals and pathogens. Dr Philipp Schwabl led the research. “While the highest plastic concentrations in animal studies have been found in the gut, the smallest microplastic particles are capable of entering the blood stream, lymphatic system and may even reach the liver,” he said. “Now that we have the first evidence for microplastics inside humans, we need further research to understand what this means for human health."

So, the warning signs are there. But what do the regulators and government advisors think? Is the establishment of a “safe” threshold for plastic in water and food on the cards?

The most recent opinion published by the European Food Safety Authority (EFSA) on this subject was in 2016, and addressed whether plastics were harmful to consumers. “It’s too early to say but it seems unlikely, at least for microplastics,” said Dr Peter Hollman, a member of the working group that helped EFSA’s Panel on Contaminants in the Food Chain (CONTAM) draft the statement. However, nanoplastics, which have received less attention to date, could pose more problems. “Knowledge on the toxicity of nanoplastics is particularly needed because these particles may penetrate all kinds of tissues and eventually end up in cells,” Hollman said. “Research should generate data on the occurrence of microplastics and especially nanoplastics in food, their fate in the gastrointestinal tract, and their toxicity.”  Researchers at Lund University, Sweden, have since discovered that nano-sized plastic particles can accumulate in fish brains and cause damage. The European Commission has also recognised publicly that “plastics are even reaching people's lungs and dinner tables, with microplastics in the air, water and food having an unknown impact on their health”.

In the UK ministers have avoided bringing up the health issues. 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”.

In January, the Science Advice for Policy by European Academies (SAPEA) working group produced the latest review of the evidence to date. “A scientific perspective on microplastics in nature and society” concluded that there is “no evidence of widespread risk to human health from [nano- and microplastics] at present”. Still, a lack of evidence for risk doesn’t mean we should assume that there is no risk, said SAPEA’s Professor Bart Koelmans. “It’s vital we communicate clearly about uncertainties in the evidence, rather than just assuming that everything is fine just because we don’t know for sure.”

This is not just about plastic in the sea, either. In fact, dietary exposure to microplastic particles is likely to be relatively low compared with inhalation of microplastics, according to Food Standards Agency evidence submitted to an Environmental Audit Committee enquiry in 2016. “We need to establish the toxic characteristics of microplastics, their behaviour in the body, and what constitutes a safe threshold for exposure when plastics are either ingested or inhaled,” explained Stephanie Wright from King’s College London in an article for the British Medical Journal in September 2017. “We must also relate these data to the different sources, types of plastic, and concentrations we are currently exposed to and, importantly, will be exposed to in the future thanks to the growing global addiction to plastic in all its forms.”

Almost two years on, this remains a moot point. Production of plastic packaging is forecast to double in the next 15 years, to more than 150 million tonnes. Currently, 32% of what is produced leaks into the environment. The various voluntary agreements, pacts and government policies all hope to plug these holes, recycling more plastic within closed loops to increase levels of “recycled content”. WRAP’s Plastic Pact, for example, hopes to substantially increase the recycled content of plastic bottles, trays, pots, tubs and even films by 2025, which will see the market for recycled plastic of food-grade quality explode.

Less plastic dumped in the sea or on developing nations can only be a good thing. However, very close attention needs to be paid to how the various chemicals used in plastic packaging travel, persist and potentially accumulate within these new circular solutions. Something is often missing from the statements made by the world’s biggest food brands on plastic, said the US-based NGO Environmental Defense Fund in February, and “that’s commitments for safer packaging free of toxic chemicals”.

A toxic circular economy must be avoided at all costs. But whatever toxic effects from plastic ingestion are discovered in the future, it is going also to be impossible to withdraw all the particles floating around in the environment already. What’s more, one of the reasons research on the health impacts is so difficult is that the presence of plastic in our daily life makes it very hard to isolate the effect of a specific exposure pathway. Food safety issue or not, it’s certainly a scary thought. "We have enough information to take a precautionary approach … and [implement] serious regulation," Sherri Mason, a professor of chemistry at the State University of New York at Fredonia told me in 2017. "There is enough information that this is having an impact and has the potential to have a very serious impact."

This is an edited and extended version of an article originally published by SafeFood in May.

 

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