"We urgently need to know more about the health impact of microplastics because they are everywhere – including in our drinking-water," says Dr Maria Neira, Director, Department of Public Health, Environment and Social Determinants of Health, at WHO. "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."
According to the analysis, which summarizes the latest knowledge on microplastics in drinking-water, microplastics larger than 150 micrometres are not likely to be absorbed in the human body and uptake of smaller particles is expected to be limited. Absorption and distribution of very small microplastic particles including in the nano size range may, however, be higher, although the data is extremely limited.
Further research needed
Further research is needed to obtain a more accurate assessment of exposure to microplastics and their potential impacts on human health. These include developing standard methods for measuring microplastic particles in water; more studies on the sources and occurrence of microplastics in fresh water; and the efficacy of different treatment processes.
WHO recommends drinking-water suppliers and regulators prioritize removing microbial pathogens and chemicals that are known risks to human health, such as those causing deadly diarrhoeal diseases. This has a double advantage: waste water and drinking-water treatment systems that treat faecal content and chemicals are also effective in removing microplastics.
Waste water treatment can remove more than 90% of microplastics from waste water, with the highest removal coming from tertiary treatment such as filtration. Conventional drinking-water treatment can remove particles smaller than a micrometre. 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.