The Persistent Problem Of Organic Pollutants: Are They Still Used?

Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. POPs are not easily degraded in the environment due to their stability and low decomposition rates. They can be transported by wind and water, affecting people and wildlife far from where they are used and released. Many products used in our daily lives may still contain POPs, added to improve characteristics such as flame retardance or waterproofing. The Stockholm Convention, a legally binding international agreement finalized in 2001, aims to reduce or eliminate the production, use, and release of certain POPs.

The Stockholm Convention

The treaty was signed on 22 May 2001 in Stockholm, Sweden, and was adopted by the United Nations Environment Programme (UNEP) in 1995. The UNEP called for global action to be taken on POPs, and the Intergovernmental Forum on Chemical Safety (IFCS) and the International Programme on Chemical Safety (IPCS) prepared an assessment of the 12 worst offenders, known as the "dirty dozen".

Pesticides

Many pesticides have been shown to cause harm to non-target organisms, including birds, fish, aquatic invertebrates, and algae. For example, dicofol, a pesticide structurally similar to DDT, is highly toxic to these organisms and causes skin irritation in humans after prolonged exposure. Another pesticide, endosulfan, used to control crop pests, has been banned globally under the Stockholm Convention due to its harmful effects.

The use of pesticides has offered significant economic benefits by increasing food and fiber production and preventing vector-borne diseases. However, evidence suggests that pesticides have negatively impacted human health and the environment. Pesticide residues have been detected in the air, water, soil, and crops in various regions, including India, Trinidad and Tobago, and the Caribbean.

Some countries, like India, have banned certain pesticides like DDT and HCH, but they remain in use in other parts of the world. The Stockholm Convention, signed by 90 countries and the European Community in 2001, aims to reduce or eliminate the production and use of 12 key POPs, including several pesticides. Despite these efforts, the use of pesticides continues, and their impact on the environment and human health remains a global concern.

Industrial chemicals

Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Most POPs are pesticides or insecticides, and some are also solvents, pharmaceuticals, and industrial chemicals.

The Stockholm Convention on Persistent Organic Pollutants, which came into force in 2004, aims to reduce or eliminate the production, use, and release of POPs globally. As of 2024, 185 countries have ratified the convention, and 34 POPs are listed, including 15 industrial chemicals.

The two types of industrial chemical POPs specifically targeted by the convention are polychlorinated biphenyls (PCBs) and hexachlorobenzene. PCBs have been detected in caribou, wolves, and lichen in Canada's Northwest Territories, with levels magnifying as they move up the food chain. They are also commonly found in plastics and have been detected in water samples from 22 countries, including nine Pacific Island countries.

Other industrial chemicals that are POPs include tetrabromodiphenyl ether (tetraBDE) and pentabromodiphenyl ether (pentaBDE), which have been detected in humans worldwide. Dioxins and furans, discharged from paper bleaching and incineration plants in Venezuela, are also industrial chemical POPs.

The use of POPs in industry has led to environmental contamination and adverse effects on human and wildlife health. The transition to safer alternatives is challenging due to the cost and complexity of alternative chemicals and techniques.

Unintentional by-products

Unintentional Persistent Organic Pollutants (UPOPs) are toxic, man-made, hazardous chemicals that have dangerous effects on the environment and human health. UPOPs are not voluntarily produced or released into the environment but they derive from anthropogenic sources. They are emitted during the incomplete combustion of organic matter and chlorine or are created as by-products of manufacturing other chemicals.

UPOPs are listed in Annex C of the Stockholm Convention on POPs, a global treaty to protect human health and the environment from persistent organic pollutants. The treaty entered into force in 2004. Seven UPOPs are listed in Annex C, including:

• Hexachlorobutadiene (HCBD)
• Polychlorinated naphthalenes (PCN)
• Polychlorinated dibenzo-p-dioxins (PCDD)
• Dibenzofurans (PCDF)

One unintentional chemical that has been proposed for listing under the Stockholm Convention is long-chain perfluorocarboxylic acids (PFCAs). UPOPs are also addressed in Article 5 of the Stockholm Convention, which states that parties must take measures to reduce and, where feasible, eliminate releases of unintentionally produced POPs.

The United States is not yet a party to the Stockholm Convention, but the convention has played a prominent role in controlling harmful chemicals on both a national and global level. Many of the POPs included in the Stockholm Convention are no longer produced in the US, but US citizens and habitats can still be at risk from unintentionally produced POPs that are released in the country or transported there from elsewhere.

Global chemical sales

Persistent organic pollutants (POPs) are toxic chemicals that adversely affect human health and the environment. They are resistant to degradation through chemical, biological, and photolytic processes and can be transported by wind and water, affecting people and wildlife far from where they were initially released. POPs are often pesticides or insecticides, but they can also be solvents, pharmaceuticals, and industrial chemicals.

In 2001, the United Nations Environment Programme (UNEP) adopted the Stockholm Convention, which aimed to reduce or eliminate the production and use of POPs. As of 2024, 185 countries and the European Union have ratified the convention, and 34 POPs are listed, including 17 pesticides, 15 industrial chemicals, and 7 unintentional by-products.

Despite global efforts to reduce and eliminate POPs, they continue to pose a significant threat. Global chemical sales are projected to grow to 6.6 trillion euros by 2030, with numerous new chemicals and materials continuously being introduced to the market. Many of these new substances could potentially become POPs, and the continuous creation and usage of new POPs add to the challenge of monitoring and managing these harmful chemicals.

Furthermore, while some POPs have been banned or restricted, they are still detected at elevated levels due to their designed longevity. For example, mirex, dieldrin, and hexachlorobenzene, which were banned decades ago, are still present in the environment. The replacement chemicals for POPs also often become banned later due to their similar properties, as seen with PFAS, which replaced DDT and other POPs.

The complex global supply chain and the varying capacities for monitoring, legislation, and management across countries further complicate the issue. For instance, POPs have been detected in developing countries that are not producers or users of these chemicals, demonstrating the far-reaching impact of POPs.

To address these challenges, organizations like UNEP are working with governments and industries to improve data collection and analysis, identify areas for immediate action, and support the transition to safer alternatives. The decline in the levels of 12 POPs initially listed in the 2004 Stockholm Convention is a positive sign, but more intensive global initiatives are needed to protect human health and the environment from the harmful effects of POPs.

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