What are microplastics?
Microplastics can be divided into two categories – primary and secondary. Primary microplastics are manufactured particles, such as pellets used as the raw material to make almost every plastic product (also known as “nurdles”), or microbeads used in cosmetics and industrial abrasives. Secondary microplastics are when larger plastic items, such as bags and bottles, break down into tiny fragments.
Where do they come from?
There are a number of ways that microplastics can find their way into the sea: littering by the public, poor waste management systems for handling larger plastic items, or microbeads from cosmetics being washed down the sink. Poor site management by plastics manufacturers can result in pellets being washed into drains and “escaping” into the sea. The pellets can also be spilled at sea – in October thousands of them washed up on Cornish beaches.
Who is to blame?
The UK plastics industry tends to point the finger firmly at the public, blaming them for littering and calling for “behaviour change”. Environmental groups would argue that not enough is being done to reduce primary microplastics either. Progress has been made on microbeads in cosmetics. With plastic pellets, in the UK, some other European countries and China, there is a project called Operation Clean Sweep through which companies voluntarily take action to limit pellet loss. But the system isn’t audited and progress is hard to define.
How many are out there?
A recent paper in the journal Science suggested that coastal communities dumped 8m tonnes of plastics in 2010. Another international team of researchers reported 5.25 trillion pieces of marine plastic – most of them microplastics measuring less than 5mm. But these are estimates. It’s pretty easy to spot marine litter when it’s a bottle or a bag, but the fragmented pieces can be microscopic. Plastic pellets are also difficult to see with the naked eye – 500 of them would fit in an eggcup. The Global Ocean Commission has estimated there are 3,500 plastic pellets per square kilometre floating on the Sargasso Sea. Near industrial centres in New Zealand, 100,000 pellets per square kilometre have been observed on the beach.
Where do they end up?
That’s the big issue. Studies have show that alarming numbers of seabirds have ingested plastic (every fulmar tested in the English Channel since 1979 has had plastic in its gut). But more recently the debris is cropping up in the fish that we eat.
How much is in the fish we eat?
Research at Plymouth University found plastics in 184 of 504 fish they examined, including whiting and gurnard. There were about two pieces per fish, mostly polyamide and the semi-synthetic fibre rayon, which is found in everything from clothing to tyres and industrial hoses. Only three fish had gobbled up any polystyrene. Another study of Norway lobsters collected in the Clyde Sea found 83% had ingested plastic including fragments of plastic bags.
But it doesn’t do any harm, does it?
We’re not sure. Recent research, 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. They noted: “Because anthropogenic debris is associated with a cocktail of priority pollutants, some of which can transfer to animals upon ingestion, this work supports concern that chemicals from anthropogenic debris may be transferring to humans via diets containing fish and shellfish, raising important questions regarding the bioaccumulation and biomagnification of chemicals and consequences for human health.”
Why are the plastics toxic?
The British Plastics Federation asserts that “the notion that plastics materials and products are ‘toxic’ is both misleading and incorrect”. Most persistent bioaccumulating toxins (PBTs) are banned but they remain in the marine environment. Microplastic particles readily attract PBTs, as well as other chemicals including DDT. The plastics can suck up the PBTs like a sponge, giving the organism a chemical cocktail when it ingests them. One study has also shown zooplankton gobbling up microplastics.
So is this a health risk?
Not necessarily. We don’t know how this toxicity is transferred to the organism or how it accumulates further up the food chain. “These chemicals can come off in the gut quite rapidly,” notes Professor Richard Thompson from Plymouth University’s school of marine science, “but that doesn’t prove harm. My intuition is that the quantities are low in individual [fish] and there’s no clear evidence that the transfer of chemicals is that substantial.”
But what about that study in Belgium?
The study, reported widely, suggested that the average seafood consumer would ingest 11,000 plastic particles a year. Thompson has calculated that in order to achieve that “you’d have to eat 22,000 mussels a year”. But this doesn’t mean the UK can turn a blind eye. “The message isn’t ‘toxic seafood is going to ruin our health’,” says Professor Tamara Galloway, an ecotoxicologist at the University of Exeter. However, given the “massive amounts” of microplastics circulating in the marine environment it’s “only sensible that we look at this”.
What does the Food Standards Agency say?
It’s certainly on the agency’s radar. A spokesman explains: “We are aware of the evidence of a potential risk that chemicals present in plastic particles could contribute to the transfer of chemical contaminants through the marine food chain. This is an emerging issue and we are currently assessing the available information.”
Do I need to take any action?
Microplastics might become a concern for consumers – whether for health or environmental reasons – but it has already come to the attention of some well-known food and drink brands and companies that are keen to ensure the packaging they use is responsibly manufactured. An Operation Clean Sweep-certified packaging system may be some way off, but it wouldn’t hurt to ask questions of your packaging suppliers to see if they are reducing pellet loss.