The World Health Organization concluded that the current risk to human health of microplastics in drinking-water is low, according to a report released today. However, it says that further research is needed to more accurately assess the effects of exposure to microplastics.

“We urgently need to know more about the health impact of microplastics because they are everywhere – including in our drinking-water,” said Dr Maria Neira, Director of the Department of Public Health, Environment and Social Determinants of Health at WHO, quoted in a press release. “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.”

The main message of the report is “to reassure drinking-water consumers around the world that based on this assessment, the risk [to human health] is low,” said Dr Bruce Gordon, Coordinator of the Department of Water and Sanitation at WHO, in a press conference on the release of the analysis.

“This report focused on drinking-water, and there’s [also] a need to consider the other environmental pathways,” noted Jennifer de France, Technical Expert at WHO’s Department of Water and Sanitation and co-author of the report, in the press conference.

The WHO is now calling for more data collection in three priority areas: the occurrence of microplastics in the water cycle, the physical impacts of smaller microplastic particles, and the risk from total exposure to microplastics.

In the meantime, WHO recommends that global stakeholders focus on the known health risks of microplastics in drinking-water and pre-emptively reduce plastic pollution to limit human exposure and protect the environment.

This report was produced in response to an analysis released in 2018 that detected the presence of microplastics in tap water and bottled water, leading to concerns about the potential health risks.

Review of existing research has found that microplastics above 150 micrometers are not readily absorbed by the human body; concentrations of chemical additives found in microplastics in drinking-water are currently too low to cause adverse effects; and harmful bacteria are not likely to colonize the small particles.

WHO has therefore concluded that microplastics in drinking-water currently do not represent a significant hazard to human health, and does not recommend routine monitoring of microplastics in drinking-water at this time.

Stimulating Research on Microplastics

However, WHO says that additional investigative research is warranted based on the poor quality of existing studies and the proliferation of plastics in the environment.

Although research published in the last two years showed improved scientific rigor, most of the studies reviewed for the report lacked sufficient quality controls. Thus, WHO recommends that results from existing studies should be interpreted with caution.

Additionally, the report is limited to examining microplastic exposure only in the context of drinking-water.

Microplastics have also been found in air and food. In response, WHO has initiated a review on the potential health effects from microplastics due to total environmental exposure.

The research pipeline for microplastics in drinking-water is growing. According to Gordon, there has been an exponential increase in the number of studies published in the past year.

Live from Geneva: WHO calls for more research on microplastics in drinking water. Q&A with Bruce Gordon. #AskWHO https://t.co/FlApsaZiLB

— World Health Organization (WHO) (@WHO) August 22, 2019

Keeping the Focus on Known Risks

In addition to motivating new research, WHO is pushing to reduce plastic pollution and prioritise increasing access to existing water treatment technologies to protect against known hazardous chemicals and water-borne diseases.

“We know from WHO data and UNICEF data that over 2 billion people drink water that is faecally contaminated, and that causes almost 1 million deaths per year. That has got to be the focus of regulators around the world,” said Gordon.

Unsafe drinking and tap water is a leading cause of diarrheal diseases such as cholera. Taken together, diarrheal diseases are the second leading cause of death in children under 5, and kill more children annually than AIDS, malaria, and measles combined.

Safe water treatment systems also reduce exposure to microplastics. Proper wastewater treatment can remove more than 90 percent of microplastic particles. Drinking-water systems are optimised to remove particles of even smaller size, filtering out microplastics smaller than one micrometer.

Ensuring the quality of water treatment systems and using existing guidelines and knowledge on water safety will also improve the removal of microplastics from drinking-water as a by-product.

The WHO report on microplastics in drinking-water was released on the heels of a World Bank Report that called attention to the economic effects of worsening water quality in many developing nations.

According to the World Bank analysis, poor water quality limits economic growth in some countries by one-third.

Both reports recommend increasing efforts to reduce plastic pollution and invest in improving water treatment systems.

“We strongly are pushing or promoting around the world to reduce plastic pollution. And that is out of great concern for this occurrence we’re seeing; it’s everywhere. And that is irrespective of any human health assessment,” said Gordon.

Plastics in the Environment

Global plastic production has increased exponentially since the 1950’s.

In 2017, approximately 407 million tons of plastic were produced, with intentional microplastics estimated to represent less than 0.1% of total plastics production. Unintentional, or secondary microplastics, break off of larger plastic pieces with regular wear and tear, and represent a larger share of microplastics found in the environment.

Researchers estimate that by 2050, over 12 billion tons of plastic could end up in landfills or the environment.

Image Credits: WHO/European Pressphoto Agency (EPA).