Ingestion of microplastics present in drinking water has an extremely low impact on human health, a first-ever report based on “limited research” released by the World Health Organization (WHO) on Wednesday said.

In recent years, plastic contamination in the deepest oceans and cleanest drinking water sources has triggered a serious public health concern. But in the absence of authoritative research, governments and policymakers were clueless about the action required to tackle the issue.

“Based on the limited information we have, microplastics in drinking water don’t appear to pose a health risk at current levels," said Dr Maria Neira, director of the department of public health, environment and social determinants of health at the WHO.

The researchers examined a series of factors related to plastic particles that can potentially harm human health. It included the particle’s ability to cause physical hazards, chemical reaction, dissemination in organs and colonies of bacteria thriving on the particle surface during ingestion.

“Our findings show most of these microplastics pass through the gut and has an extremely low impact on human health,” said Dr Bruce Gordon, coordinator of water sanitation at public health and environment department at the WHO.

Smaller than the diameter of human hair, microplastics are mostly invisible in drinking water. Once ingested, tiny plastics particles larger than 150 micrometers are not likely to be absorbed into the human body and uptake of smaller particles is expected to be limited, the report found.

More research needed

There is a severe lack of academic research that can explain the impact of such fine particles on the human body. An array of factors like varying sizes, shapes, toxicity and chemical composition of the microplastics further makes the research complicated.

So far, only nine studies have analyzed microplastics in drinking water, explaining size, shape and toxicity. A few studies probed the impact on rats and mice after they ingest microplastics. But these studies are not very reliable.

“These investigative studies should be well designed and quality controlled to know the number of plastic particles, size, chemical composition and the source of contamination to clearly understand its impact on human health” co-author of the report Jennifer de France said.

The contamination can be primarily controlled through the treatment of wastewater that can effectively remove more than 90 percent of plastic particles. Even conventional treatment plants can be upgraded to remove extremely fine plastic particles, the report said.

Researchers also suggested that regulators and policymakers should continue to focus on known risks related to drinking water. According to the WHO and UNICEF, nearly two billion people drink water contaminated with fecal waste, leading to one million deaths globally.

“We do not recommend regulators to monitor microplastic in the water regularly, but we do need more research on the issue,” Gordon added.