Humans may be inadvertently consuming approximately five grammes of plastic every week -- equivalent weight of a credit card -- from various sources, a study warns.
The research, by University of Newcastle in Australia, suggests that people are consuming about 2,000 tiny pieces of plastic every week -- amounting to about 21 grammes a month, just over 250 grammes a year.
The study, commissioned by World Wildlife Fund (WWF), is the first to combine data from over 50 studies on the ingestion of microplastic by people.
The findings highlights the urgent need to address the plastic menace so that it does not pollute ecosystems in the first place.
"These findings must serve as a wake-up call to governments. Not only are plastics polluting our oceans and waterways and killing marine life -- it's in all of us and we can't escape consuming plastics," said Marco Lambertini, WWF International Director General.
"While research is investigating potential negative effects of plastic on human health, we are all clear that this is a worldwide problem that can only be solved by addressing the root cause of plastic pollution," Lambertini said.
"If we don't want plastic in our bodies, we need to stop the millions of tons of plastic that continue leaking into nature every year," he said.
The study demonstrated a wide range in ingestion patterns.
While being mindful of the limitations of this evolving field of research, initial findings point towards a global average ingestion rate of plastic by humans of approximately five grammes per week.
The single largest source of plastic ingestion is through water, both bottled and tap, all over the world.
Large regional variations are reflected again, with twice as much plastic found in the US or India than in European or Indonesian water.
Of the consumables studied, those with the highest recorded plastic levels include shellfish, beer and salt.
The findings demonstrate that the problem of plastic pollution is a universal one and directly affecting people.
Leakage of plastic into our environment and food chain has been met so far with an inadequate global response by governments.
"While the awareness of microplastics and their impact on the environment is increasing, this study has helped to provide an accurate calculation of ingestion rates for the first time," said Thava Palanisami, a microplastics researcher at the University of Newcastle.
"Developing a method for transforming counts of microplastic particles into masses will help determine the potential toxicological risks for humans moving forward," Palanisami said.
Ingestion is just one aspect of a much wider plastics crisis. Plastic pollution is a major threat to wildlife, not only through microplastic ingestion but via entanglement and habitat destruction.
Plastic pollution also has damaging economic consequences, with the UN Environment Programme (UNEP) estimating its annual economic impact on the ocean economy at USD 8 billion.