Persistent organic pollutants (POPs) are hazardous chemicals that threaten human health and the planet’s ecosystems. POPs remain intact for a long time, widely distributed throughout the environment, accumulate and magnify in living organisms through the food chain, and are toxic to both humans and wildlife.
POPs have been widely used throughout the supply chain, in all kinds of products including pesticides, in industry processes and can also be released into the environment unintentionally. Some POPs banned decades ago (mirex, dieldrin, hexachlorobenzene) are still detected at elevated level around us today as these chemicals were made with the intention to last ‘forever’. With global chemical sales projected to grow to euro 6.6 trillion by 2030, and so many new chemicals and materials continuously being designed and released on the market - many of which could eventually become a POP - POPs are an increasing threat.
POPs travel long distances, they are found in the environment around the globe, including close to industrial and urban settings, but also in remote locations such as the Arctic, high mountains and Pacific Ocean trenches at 7-10,000 meters below sea level.
Why do POPs concern me?
Humans are exposed to POPs in a variety of ways, mainly through the food we eat, the air we breathe, in the outdoors, indoors and at the workplaces. Many products we use in our daily lives used to contain and/or may still contain POPs, which have been added to improve product characteristics, such as flame retardant or waterproofing.
Should I be worried by POPs?
Scientific evidence shows that long‐term exposure – to certain compounds under certain conditions – even to low levels of POPs can lead to increased cancer risk, reproductive disorders, alteration of the immune system, neurobehavioral impairment, endocrine disruption, genotoxicity and increased birth defects.
Some large/medium fish/mammals are considered unfit for consumption because of their PCB concentrations exceeding the standards.
A global treaty to protect human health and the environment from POPs
Entered into force in 2004, the Stockholm Convention on persistent organic pollutants calls for reduction or elimination of releases of POPs globally. Parties to the Convention commit to not produce or use of the chemicals listed in its annexes. New chemicals get added regularly. To date, 185 countries have ratified the Convention and 34 POPs are listed under the Convention as 17 pesticides, 15 industrial chemicals, 7 unintentional by-products.*
Pesticide use is a well-documented threat to birdlife, with bird populations having declined 20-25% since pre-agricultural times with one of the major causes being pesticides. The insects population’s decline linked to pesticides is also well documented.
Interactive timeline of POPs listed under the Stockholm Convention
The letter(s) in brackets indicate in which annex(es) the POP is listed [A = Elimination, B = Restriction, C = Unintentional production].
Science for evidence-based policy, action and measuring progress
Availability of data, information and knowledge on exposure to POPs is essential for a clean, healthy and sustainable environment. UNEP ensures data is collected and analyzed for informed decision making and effective actions at the national, regional and global level.
The Stockholm Convention sets a process to measure how effective it is at protecting humans and the environment from POPs. The Global Monitoring Plan is a framework for the collection of comparable data on the presence of POPs in all regions, in order to identify changes in concentrations over time and provide information on their regional and global environmental transport.
Concentration of POPs are measured worldwide in “core matrices” air, human milk and water as well as in matrices of national interest (e.g., fish, butter, sediment…).
GMP Dashboard
UNEP assist developing countries in collecting data, sampling and analysing, and in improving the national laboratories analytical capability. Over 900 samples were analysed under the UNEP/GEF GMP projects with over 50,000 data points generated on POPs. Globally, decrease of many POPs was detected, which indicated a periodic success of the Stockholm Convention, of the actions taken on sound management of POPs, and of the global monitoring plan. However, some of the “oldest” POPs such as DDT or PCB are still present all over the world in all matrices.
The interactive GMP Dashboard presents the UNEP/GEF GMP Projects activities and results.
What does my country do to POPs?
Parties to the Stockholm Convention are required to prepare a plan on how they are going to implement their obligations under the Convention and make efforts to put such plan into operation. The National Implementation Plan (NIP) is a part of the sustainable development strategy of each country. The NIP is a dynamic document to be reviewed periodically and updated as new POPs get listed under the Convention. The plan covers sources of POPs, inventories, releases of POPs estimates, evaluation of the national laws, policies and strategies set in place, as well as awareness raising to the danger of POPs.
Polychlorinated biphenyls PCBs
PCBs, or polychlorinated biphenyls, are a class of POPs produced in large quantities between the 1930s and 1980s. They were used in closed applications, such as electric transformers and capacitors and in open applications such as paint, buildings, installations and machinery where they are more easily released into the environment and therefore pose a significant risk to direct human exposure in daily life. Although no longer allowed to be produced, PCB can still be found everywhere. It is a global issue, everyone in the world is likely to have PCB quantities in their body.
Prevention of regrettable substitutions is essential to avoid continuous addition of new POPs
During the POPs monitoring, newly listed POPs that were introduced as substitutions to old POPs have been detected at elevated levels globally including in small islands and developing states. So far, there is no trend information available for the newly listed POPs. Most countries, including developed countries, still have difficulties with analysing and soundly manage POPs and particularly new POPs or their regrettable substitutions.
Results of the monitoring show presence of POPs in developing countries - many of which are not producers or users - emphasizing the fact that POPs are a global issue. This further indicate that the continuous creation and usage of new POPs is adding additional burdens to these countries with limited capacity for monitoring, legislation and sound management.
Safer alternatives to POPs
One of the essential aims of the Stockholm Convention is to support the transition to safer alternatives. Some of the POPs targeted by the Convention are already virtually obsolete. Their toxic effects became obvious early on and they have been banned or severely restricted in many countries for years or even decades, even before the Convention was adopted. Replacement chemicals and techniques are in place. The remaining challenge is to find any leftover stocks and prevent them from being used.
But with other POPs the transition to safer alternatives will require more effort. Alternatives may be more expensive and their manufacture and use more complicated. To avoid regrettable substitution, Parties need to make sure the alternatives do not have the same properties as the POPs they are replacing.
The Stockholm Convention cannot simply to say “NO” to its target list of POPs, it must also help governments find a way to say “Yes” to replacement solutions.
Knowledge generated on POPs is critical to address other global challenges such as plastics, air pollution, climate change and biodiversity loss
Remarkable decline of unintentional POPs has been detected in all countries, which indicated that the effective implementation of the Stockholm Convention contributed to air quality control.
POPs are currently the greatest threat to the Andean condor in South America and bald eagle populations in North America that declined in part because of exposure to DDT.
The decline of pesticides globally indicates a good opportunity to prevent biodiversity loss. Remarkable decline was observed in countries which regulated DDT. In all countries, decrease observed in comparison to previous surveys, over 10 years was nearly 60% the decreasing rate.
Plastics may contain persistent organic pollutants (POPs) such as short-chain chlorinated paraffins (SCCPs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA).
Marine plastic debris is made of chemicals including POPs
PFAS in water were detected in all the 22 countries where water samples were collected, including in 9 Pacific Islands countries. Though the level is low, the accumulation of these forever chemicals and their impacts on the aquatic environment and aquatic life remain a critical question for further research.
Further Resources
Chemicals in Plastics UNEP, May 2023
Stockholm Convention website
POPs in the news
Stop the POPs - Understand the danger of POPs
