Plastics are widespread in everyday life. About 8 million metric tons of plastic are dumped into the ocean annually. Once in the water, which is not discharged from the waves on the shore, for the most part it breaks into tiny particles. The smallest particles – those smaller than 5 millimeters – are called microplastics. According to the data, the world’s oceans contain about 236,000 tonnes of microplastics. Some debris is swept away by the water, others sink depending on their own density, while others are swallowed by fish and crustaceans, which in turn become food for other animals, including birds and humans.
Currently effect on human health is a relatively unexplored area, but experts worry that the plastic material can contain high concentrations of pollutants such as polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Although experiments have not been conducted on humans, those on animals have shown that microparticles are capable of penetrating the blood of the affected creature, the lymphatic system and possibly the liver, while collecting in the intestine and having potentially harmful effects on organs and hormonal regulation.
The World Health Organization monitors and analyzes the incoming evidence and issued a news release on August 22, 2019, which reads as follows:
The World Health Organization (WHO) today calls for a further assessment of microplastics in the environment and their potential impacts on human health, following the release of an analysis of current research related to microplastics in drinking-water. The Organization also calls for a reduction in plastic pollution to benefit the environment and reduce human exposure.
“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 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: wastewater and drinking-water treatment systems that treat faecal content and chemicals are also effective in removing microplastics.
Wastewater treatment can remove more than 90% of microplastics from wastewater, 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.
You can download the WHO report for 2019 here: