159 tap water samples were analysed for the survey of which "83 percent were found to contain plastic particles ," researchers from the University of Minnesota and the State University of New York wrote in a report entitled: "Invisibles: The plastic inside us".
While much research has focused on plastic pollution of lakes, rivers, the ocean, beaches, even the air we breathe, less attention has been paid to its presence in human consumables, said the team.
Samples were collected in the first three months of the year in Kampala, Uganda; New Delhi, India; Jakarta, Indonesia; Beirut, Lebanon; Quito, Ecuador; several cities in the United States and in seven European countries.
All were sent to the University of Minnesota, Minneapolis, for lab testing.
By far the majority of particles found were fibres ranging from 0.1 to five millimetres (0.004-0.2 inches) in length.
Based on liquid consumption of three litres (6.3 US pints) per day, as recommended, a man may consume as many as 14 plastic particles daily if his chosen beverages were tap water or made with tap water , said the authors.
For women, this would amount to about 10 particles for an intake of 2.2 litres.
"These daily doses add up to an annual total of over 4,000 for men and over 3,000 for women," wrote the team.
A study in January said a European shellfish consumer may be ingesting up to 11,000 micro plastics per year from that source alone.
"The results of this study serve... as an initial glimpse at the consequences of human plastic use (and) disposal rather than a comprehensive assessment of global plastic contamination," the team concluded.
They called for further tests to gather more data about potential pollution sources and pathways, as well as the risks to human health .
Micro-plastics are less than 5 mm long, about the size of a sesame seed. They come in the form of "micro-beads" used in scrubs and toothpaste, and can also be created when larger pieces of plastic waste degrade.