A comprehensive global study has confirmed that persistent organic pollutants (POPs), harmful chemicals that remain in the environment for decades, continue to be found in human milk, air, water, soil, food, and various ecosystems. This extensive research, conducted by the UN Environment Programme (UNEP) and funded by the Global Environment Facility (GEF), underscores the importance of monitoring POPs, exercising caution in introducing alternatives, and addressing gaps in awareness and regulation.
The study, spanning 42 countries with limited data on POPs, focused on regions including Africa, Asia, Latin America and the Caribbean, and the Pacific Islands. Researchers monitored 30 POPs listed under the Stockholm Convention as of 2021, collecting samples between 2016 and 2019.
The findings have been released as government representatives gather in Geneva for an ad hoc open-ended working group on establishing a science-policy panel for chemicals, waste, and pollution prevention.
"Despite efforts to reduce their use and production, POPs remain omnipresent," said Andrea Hinwood, UNEP’s Chief Scientist. "Monitoring these chemicals in the environment and in our bodies is crucial, especially in low- and middle-income countries, to assess contamination, emissions, and exposure, thereby enabling informed decision-making."
The study's list of 30 monitored POPs includes pesticides, industrial chemicals, and unintentionally released POPs from industrial processes and incomplete combustion, such as open waste burning. These chemicals were found in over 900 samples, generating more than 50,000 data points across various mediums, including air, water, human milk, soil, beef, milk products, mutton, pork, chicken, eggs, fish, shellfish, and oils.
Data reveals a global decline in the levels of 12 POPs initially listed in the 2004 Stockholm Convention, attributed to regulatory actions. Notably, the use of DDT, once widespread in agriculture and now highly restricted, has decreased in human milk samples by over 70% since 2004. However, DDT remains the most prevalent POP in human milk, particularly in countries with extensive historical use.
The study also discovered the presence of other POPs in regions far from known sources of contamination. Long-regulated chemicals, such as dieldrin and polychlorinated biphenyls (PCBs), were found at elevated levels in the air across Africa, the Caribbean, and Latin America. Additionally, industry-replaced chemicals like per- and polyfluoroalkyl substances (PFAS) were also detected. Three key PFAS chemicals (PFOS, PFOA, PFHxS) listed under the Stockholm Convention were found in human milk and drinking water on remote islands, exceeding EU and US standards.
Newly listed POPs are increasingly challenging to monitor, even for the world’s top laboratories. While data collection is improving, with more labs in low-income countries participating in POPs monitoring, the quality of POPs analysis needs continuous enhancement.
"Governments should not be drawn into a toxic game of hide and seek, where one regulated POP is replaced with another," warned Jacqueline Alvarez, Chief of UNEP’s Chemicals and Health Branch. "This troubling pattern means these substances are still present in products we use, eat, wear, and in our air and water. It highlights the risk of regrettable substitutions and the need to prioritize sustainability in industrial product design and consumer behavior."
UNEP remains committed to supporting governments, collaborating with industries to address POPs, identifying critical areas for immediate action, tracking pollution reduction progress, and preventing further contamination.
