The World Health Organization (WHO) has called for more research into the health impact of microplastics in the environment, particularly in drinking water.

It is also calling for an overall reduction in plastic pollution "to benefit the environment and reduce human exposure".

Microplastics are tiny pieces of plastic resulting from the disposal and breakdown of consumer products and industrial waste. According to the WHO, microplastics are now ubiquitous in the environment, having been detected everywhere from marine and fresh water to drinking water, food and air.

It is highlighting this issue following the publication of an analysis of current research related to microplastics in drinking water. According to its findings, microplastics larger than 150 micrometres are not likely to be absorbed in the human body and the uptake of smaller particles is thought to be limited.

The analysis warned that absorption of very small particles may be higher, however the data in this area is very limited. There are currently few reliable studies that have used different methods and tools to sample and analyse microplastic particles.

As a result, more research is needed to paint a more accurate picture of exposure to these particles and the impact they may be having on human health.

"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," commented Dr Maria Neira, director of the Department of Public Health, Environment and Social Determinants of Health at the WHO.

The WHO said further research needs to be carried out in a range of areas, including more studies on the sources and occurrence of microplastics in fresh water.

It pointed out that wastewater and drinking water treatment systems are highly effective at removing particles of similar characteristics and sizes to microplastics. Data suggests that wastewater treatment can effectively remove over 90% of microplastics.

Furthermore, drinking water treatment has been found to be effective at removing particles that are smaller than microplastics and are present in much higher concentrations.

The WHO recommends that suppliers and regulators of drinking water should prioritise the removal of microbial pathogens and chemicals that are known to be a risk to human health, such as those that cause diarrhoea-related diseases.

"This has a double advantage - wastewater and drinking water treatment systems that treat faecal content and chemicals are also effective in removing microplastics.

"A significant proportion of the global population currently does not benefit from adequate water and sewage treatment. By addressing the problem of human exposure to faecally contaminated water, communities can simultaneously address the concern related to microplastics," the WHO said.

However, it also emphasised that policy makers and the public need to do more to reduce plastic pollution.

"Irrespective of any human health risks posed by microplastics in drinking water, policy makers and the public should take action to minimise plastics released into the environment, since these actions will confer multiple other benefits for the environment and human wellbeing.

"Actions could include reducing the use of plastics where possible, improving recycling programmes, reducing littering and decreasing industrial waste inputs into the environment," it said.

The analysis, Microplastics in Drinking Water, can be viewed here.