Fancy a pinch of plastic with that shellfish dish?
New research combining the results of more than 50 studies globally has found that on average, people could be ingesting about 5g of plastic every week - equivalent to a credit card - in the air they breathe, the food they eat and especially the water they drink.
This amounts to about 100,000 tiny pieces of plastic - or 250g - every year, said the World Wide Fund for Nature (WWF) and the University of Newcastle yesterday.
The study was commissioned by WWF and carried out by the Australian university.
"These findings must serve as a wake-up call to governments. If we don't want plastic in our bodies, we need to stop the millions of tonnes of plastic that continue leaking into nature every year," said WWF International director-general Marco Lambertini.
He said urgent action at the government, business and consumer levels was needed to tackle the plastic crisis, as well as a worldwide treaty with global targets to address plastic pollution.
The latest research is the first to combine insights from studies across the world on people's ingestion of plastic, said the WWF.
Of the 52 studies included in the study's calculations, 33 looked at plastic consumption through foods and beverages. Some common foods and beverages containing microplastics are drinking water, beer, shellfish and salt.
But the WWF said the findings may be an underestimate, as the microplastic contamination of staple foods such as milk, rice, wheat, corn, bread, pasta and oils has not yet been studied.
Microplastics are plastic particles measuring 5mm in size or smaller.
The largest source of plastic ingestion is drinking water, with plastic particles found in bottled, tap, surface and groundwater worldwide.
Another key source is shellfish, accounting for as much as 0.5g a week. Shellfish are eaten whole, including their digestive systems, after a life in plastic-polluted seas.
But inhalation represented a negligible proportion of microplastics entering the human body, though this might vary heavily, depending on the environment.
Results from 16 papers on outdoor and indoor air quality showed that indoor air is more heavily polluted with plastic than the outdoors. Indoor air circulation is limited, and synthetic textiles and household dust are among the most significant sources of airborne microplastics.
While the study represents a synthesis of the best available data, it builds on a restricted set of evidence and comes with other limitations, the WWF acknowledged in the report - titled No Plastic In Nature: Assessing Plastic Ingestion From Nature To People - which was prepared by strategy consulting firm Dalberg Advisors.
It also said further studies were needed to get a specific estimate.
Scientists are working to obtain more precise information on pollution from plastic, how it is distributed and how much is consumed, the WWF added.
The research community is now exploring areas such as mapping the size and weight distribution of plastic waste particles, and how plastic particles travel into muscle tissue when consumed by an animal. For instance, scientists are tracking plastic in the oceans to create a 3D map of ocean plastic litter.
Another key research area is in identifying the health effects of plastic ingestion on humans, as these are not yet well documented.
On the economic front, the United Nations Environment Programme has estimated that the economic impact of plastic pollution on marine ecosystems is at least US$8 billion (S$10.9 billion) a year.
The current global approach to addressing the plastic crisis is failing, said the WWF.
It called for governments to take greater action by, among other things, supporting further research, establishing a global scientific body to assess and synthesise the best available research on plastic and microplastics in nature, and agreeing to a legally binding international treaty to stop plastic pollution from leaking into the oceans.
You can find out how much plastic you are consuming at: yourplasticdiet.org
PLASTIC, PLASTIC EVERYWHERE
1. Since 2000, the world has produced as much plastic as all the preceding years combined, a third of which is leaked into nature. The production of virgin plastic has increased 200 times since 1950 and has grown at 4 per cent a year since 2000. If all predicted plastic production capacity is reached, current production could increase by 40 per cent by 2030.
2. One-third of plastic waste ends up in nature, accounting for 100 million tonnes of plastic waste in 2016. More than 75 per cent of all plastic produced is waste. If nothing changes, the ocean will contain one tonne of plastic for every three tonnes of fish by 2025.
3. Plastic has been found at the bottom of the Mariana Trench and in arctic sea ice, in addition to covering coastal ecosystems and accumulating in ocean currents in all parts of the world. Animals get entangled in large plastic debris, leading to injury or death. Wildlife entanglement has been recorded in more than 270 different species. Animals also ingest large quantities of plastic that they cannot pass through their digestive systems, resulting in internal abrasion, digestive blockage and death. Toxins from ingested plastic also harm breeding and impair immune systems.
S'pore's drinking water 'free of microplastics'
Monitoring by national water agency PUB shows Singapore's drinking water is free from microplastics, Minister for the Environment and Water Resources Masagos Zulkifli told Parliament last year.
Singapore is monitoring international developments on microplastics, including microbeads in cosmetics, and is committed to keeping its water channels free from pollution, he said in a written reply.
Microplastics, which include microbeads, are removed at waterworks that treat water for potable supply. At Singapore's Newater and desalination plants, microplastics are removed using reverse osmosis membranes. PUB also ensures all used water is collected and treated at water reclamation plants to internationally recognised discharge standards, Mr Masagos said.
During the treatment process, microplastics in used water are substantially removed as sludge and incinerated. Just a minuscule amount of microplastics is discharged into the sea, the minister said.
PUB is also looking into incorporating membrane bioreactor technology in Singapore's used water treatment process to improve the microplastics removal rate.
The Singapore Food Agency (SFA) told The Straits Times that while microplastics are an emerging area of concern, the World Health Organisation (WHO) has indicated there is no evidence that it has an impact on human health.
Still, WHO is investigating the potential health risk of microplastics in drinking water, and other agencies, such as the European Food Safety Authority and the United Nations Food and Agriculture Organisation, said more scientific evidence would be needed for such an assessment, said the SFA.
No country has imposed legislation to regulate microplastics in food products, noted SFA.
It routinely takes samples of locally available food, including seafood and bottled water, for testing to ensure compliance with food safety standards.