An exclusive in last week’s Guardian reported microplastic contamination has been found in tap water in countries around the world, leading to calls from scientists for urgent research on the implications for health.

Scores of tap water samples from more than a dozen nations were analysed by scientists for an investigation by Orb Media, who shared the findings with the Guardian. Overall, 83% of the samples were contaminated with plastic fibres. In Europe, the figure was 72%.

A new report from the Chartered Institution of Water and Environmental Management (CIWEM) has found  although plastics in the marine environment have received worldwide attention, it is estimated that more than half of microplastic losses remain in soils when wastewater sewage sludge is used as fertiliser and when particulates are washed from road surfaces.

Whilst the damage to the marine environment should not be overlooked, the authors believe we should be looking further upstream for both pollution and its prevention.

Microplastics are tiny particles that form from the weathering and breakdown of larger plastics or that are released in the form of manufactured beads, granules and fibres. The largest proportion arise from the washing of synthetic textiles and from the breakdown of road markings and tyres from driving. They can then be transported via the wind, through surface waters and sewers, and by rivers.

Microplastics have the potential to accumulate in the environment and the ability to release harmful chemicals which can then be transferred to water, sediments and organisms. Scientists also believe they may provide a medium for exotic species and pathogens to grow.

Where microplastics reach wastewater treatment plants, research has shown that treatment processes can be highly effective with reductions between 97 and 99 per cent. Yet due to the large volumes of wastewater that are processed, millions of microplastics are still being released back into the freshwater environment each day in effluent.

A high proportion of particles that are removed at wastewater treatment works become trapped in sewage sludge. These microplastics can then be transferred back into the environment where sewage sludge is spread on land to provide the nutrients needed for agriculture. The report finds that data on the environmental and health impacts of microplastics on land are sparse and calls for much greater research into the impact associated with the application of sewage sludge containing microplastics to farmland.

Read the briefing paper: Addicted to plastic: microplastic pollution and prevention

A policy position paper which outlines the research needs in this area is also available: Microplastic pollution