“Research should generate data on the occurrence of microplastics and especially nanoplastics in food, their fate in the gastrointestinal tract, and their toxicity,” explained lead researcher Dr Peter Hollman, an associate professor for nutrition and health at Wageningen University in The Netherlands.
“Knowledge on the toxicity of nanoplastics is particularly needed because these particles may penetrate all kinds of tissues and eventually end up in cells,” he added.
Experts warned that the plausibility of the risk to humans makes further investigations a public health priority.
Fish food – not
Plastic pollution of the world’s oceans has been a high profile environmental issue of late, but the impact this could have further up the food chain – when humans consume seafood – has been less widely documented.
Fish and other sea-life mistake microplastics and nanonplastics (see box) for food – in fact, research published earlier this month suggested young fish are hooked on plastic in the same that humans are on fast food. These microplastics can contain chemicals (on average 4%). What is more, they act like micro-sponges, sucking up other persistent bioaccumulating toxins (PBTs) in the water around them.
Tiny plastics: Big problem
Increased use of plastics has seen levels of plastic pollution in the world’s oceans soar. A report by the Ellen MacArthur Foundation, published in January, warned that by 2050 oceans will contain more plastic than fish (by weight).
EFSA defines microplastics as ranging in size from 0.1 to 5000 micrometres (µm), or 5 millimetres. Nanoplastics measure from 0.001 to 0.1 µm (i.e. 1 to 100 nanometres).
Microplastics and nanoplastics can be formed as larger pieces of litter fragment. However, they also include engineered flakes, beads and pellets (research published in April by Scottish environmental charity Fidra estimated that up to 53 billion pellets used in the pre-production of all plastic goods were escaping into UK seas every year).
The European Commission is currently considering a target to reduce marine litter by 50% by 2030 as part of its circular economy package.
Could this pose a health risk when consuming seafood, though? “It’s too early to say but it seems unlikely, at least for microplastics,” said Dr Hollman.
His team used the example of a plate of mussels – a seafood eaten without the removal of the digestive tract offered potentially higher levels of exposure. The mussels could contain up to 900 pieces of tiny plastic pieces, they said, but even considering the highest concentrations of additives or contaminants in the plastics the exposure to chemicals like bisphenol A would be “small”.
Based on a conservative estimate, therefore, the panel concluded that the presence of microplastics in seafood would have a “small effect on the overall exposure to additives or contaminants”. More research is needed, though. “There are insufficient data on the occurrence, toxicity and fate – what happens after digestion – of these materials for a full risk assessment,” Dr Hollman said.
Ample evidence
Professor Tamara Galloway, an ecotoxicologist at the University of Exeter in the UK, agreed that there is currently no firm evidence that microplastics pose a risk to human health through the consumption of contaminated seafood. Nevertheless, exposure science, ecology, epidemiology and particle toxicity fields provide “ample evidence” for the plausibility of such a risk, making it a public health priority for further research, she told FoodNavigator.
Experts at neighbouring Plymouth University found plastics in 184 of the 504 fish they examined – including whiting and gurnard – from the English Channel. Professor Richard Thompson, who led the research, said he supported EFSA’s finding that there is very little evidence of any substantive pathway to humans at present levels of microplastic contamination.
However, “there is concern from some of the seafood industry that the presence of microplastic in seafood, even if not at a harmful level for consumption, could be deleterious to the public perception of seafood”, he told FoodNavigator. “In my view, [EFSA’s] statement does not reduce the importance or urgency of taking steps to reduce inputs of plastic to the ocean as a priority,” he added.
There is no legislation for microplastics and nanoplastics as contaminants in food. EFSA recommended that analytical methods should be further developed for microplastics and developed for nanoplastics; these should be standardised in order to assess their presence, identity and to quantify their levels in food.
“For microplastics and nanoplastics, occurrence data in food, including effects of food processing, in particular, for the smaller sized particles (<150 micrometeres) should be generated. Research on the toxicokinetics and toxicity, including studies on local effects in the gastrointestinal (GI) tract, are needed as is research on the degradation of microplastics and potential formation of nanoplastics in the human GI tract,” noted the panel.