More research is needed to study the effects posed by microplastics in drinking water, the World Health Organisation (WHO) has said.
The international public health body has also called for a reduction in plastic pollution to reduce the global populations exposed to the substance.
WHO said in a new report there is not enough data on the effects on humans of microplastics in drinking water, and what may happen if those concentrations continue to rise.
How to classify microplastics, which come in an array of different shapes and sizes, is one of the key problems faced by scientists studying the particles.
They can also be combined with numerous different chemicals – for example, flame retardants – depending on their original purpose.
Plastic fragments and fibres from synthetic fabrics were the most commonly identified microplastics found in drinking water, the researchers learned.
Microplastics could pose three major risks, researchers say. These include the physical risk from the particles themselves, the chemicals absorbed by the plastics, and "biofilms".
Biofilms are microplastics which have been attacked and taken over by microorganisms, which may lead to infection.
Existing data suggests microplastic risk to humans are low as particles large than 150 micrometres are unlikely to be absorbed into the human body through the gut.
The report also added that existing filtration methods to separate drinking water and microplastics were highly effective.
Up to 90 per cent of microplastics can be removed using water treatments which prevent human waste contamination, with filtration found to be the most effective method.
Dr Maria Neira, head of the department of public health, environment and social determinants at WHO, emphasised that swathes of the global population does not have access to effective water treatment infrastructure.
According to WHO data, around 67 per cent of people in low and middle-income countries lack access to sewage connections, while about 20% of household sewage does not undergo at least secondary treatment.
Dr Neira said: “We urgently need to know more about the health impact of microplastics because they are everywhere – including in our drinking-water.
“Based on the limited information we have, microplastics in drinking water don’t appear to pose a health risk at current levels.
“But we need to find out more. We also need to stop the rise in plastic pollution worldwide.”