What Are POPs?

Persistent organic pollutants, widely abbreviated as POPs, are a broad category of toxic chemicals that persist in our environments for long periods of time. Resistant to degradation and bioaccumulative, these substances can negatively affect the health of human beings, wildlife, and ecosystems all over the world. 

What Are Persistent Organic Pollutants?

Many of the chemicals we understand to be POPs today were first created in the decades following WWII. During this period of rapid industrialization, scientists created a variety of new substances used to combat diseases, protect crops, and improve everyday products. These chemicals, which included insecticides, herbicides, coolants, and plasticizers, appeared highly advantageous at the time. They were capable of boosting agricultural production, refining manufacturing processes, and even cutting down on the prevalence of deadly infections. 

Over time, however, researchers began finding that chemicals like polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) were demonstrating alarming levels of persistence in the environment. These compounds and other similar POPs were accumulating in soil, water, and even wildlife, in some cases causing irreparable damage to individual species. Equally worrisome was the increasing evidence that POPs could travel vast distances via wind and water, leading to chemical contamination in countries and continents far away from where the substances were originally produced. Scientists would eventually discover the presence of POPs in some of the most isolated, uninhabited regions on earth, including the Arctic and Antarctica.

These compounds and other similar POPs were accumulating in soil, water, and even wildlife, in some cases causing irreparable damage to individual species

The Health Effects of Persistent Organic Pollutants 

A number of studies carried out over the past several decades have proven that persistent organic pollutants pose a significant health risk to human beings. According to the EPA, “In people, reproductive, developmental, behavioral, neurologic, endocrine, and immunologic adverse health effects have been linked to POPs.”

“In people, reproductive, developmental, behavioral, neurologic, endocrine, and immunologic adverse health effects have been linked to POPs.”  

A 2002 study found that human beings chronically exposed to POPs during critical developmental periods experienced disruptions to their endocrine systems, affecting key hormones and permanently altering their trajectory of development. The same study also established connections between POPs exposure and specific reproductive health effects, including reduced fertility in women, endometriosis, and earlier onset of reproductive senescence. 

How these chemicals negatively affect wildlife is equally damning. One of the earliest known examples of how harmful POPs could be to other species is the bald eagle. After DDT came into widespread use in the 1950s and 60s, the chemical began infiltrating waterways all over the U.S., contaminating fish and marine flora. Eagles were exposed to DDT through a variety of fish species that form a cornerstone of their diet, and the results were catastrophic. The chemical critically interfered with their reproductive systems, causing them to produce eggshells that, according to the U.S. Fish and Wildlife Service, were “so thin that they often broke during incubation or otherwise failed to hatch.” By 1963, less than two decades after DDT had first been introduced in America, the bald eagle population in the U.S. had plummeted to seemingly irrecoverable levels. A raptor that once numbered north of 100,000 in the country was reduced to 417 nesting pairs. 

The Stockholm Convention and Its Restrictions on POPs

In May 2001, a United Nations conference that would eventually come to be known as the 

Stockholm Convention was held in Sweden. Organized by the UN’s Environment Programme, the conference sought to restrict or eliminate the production and use of a number of the most toxic, pervasive POPs on the planet. The global treaty was initially ratified by 128 parties, and today includes 186. (While the U.S. was a signatory at the convention in 2001, it has yet to ratify the treaty’s provisions.)

Organized by the UN’s Environment Programme, the conference sought to restrict or eliminate the production and use of a number of the most toxic, pervasive POPs on the planet.

The Stockholm Convention can be distilled into four primary provisions participating countries are responsible for carrying out

• Strictly prohibiting the use of nine persistent organic pollutants, restricting the use of DDT to fight malaria, and minimizing the creation of dioxins and furans as byproducts in chemical combustion and industrial processes. 
• Utilizing the best available techniques to reduce or completely eliminate the release of POPs unintentionally produced during manufacturing processes—including dioxins and furans—into the environment.
• Identify and manage existing waste and stockpiles containing POPs, and take all necessary measures to prevent these chemicals from leaching into the surrounding environment. 
• Begin the process of targeting additional POPs for regulatory action, including by establishing a persistent organic pollutants review committee tasked with assessing proposals for new chemicals to be restricted through the Stockholm Convention. 

The “Dirty Dozen” of Toxic Chemicals 

When the Stockholm Convention entered into force in May 2004, three years after it was initially adopted, it focused on 12 of the most pervasive man-made chemical pollutants. These so-called “dirty dozen” included a raft of pesticides, industrial chemicals, and toxic byproducts produced during chemical combustion processes and waste incineration. 

1. Dichlorodiphenyltrichloroethane (DDT): Arguably the most notorious of all the POPs, DDT was initially developed as an insecticide in the 1940s and quickly became a fixture in the agriculture industry. In 1972, the EPA banned DDT use in the U.S. The chemical can persist in soil for up to 15 years, and has a range of adverse health effects on humans that include a heightened risk of cancer and diabetes and reduced fertility. 

2. Polychlorinated biphenyls (PCBs): PCBs are a family of man-made chemicals with a broad range of applications, including as lubricants, plasticizers, and as part of the manufacturing process for paper. PCBs are toxic for a variety of marine life, and have been linked to disruptions in the immune and reproductive systems of humans. 

3. Hexachlorobenzene (HCB): Originally used as a fungicide to protect the seeds of wheat and other grains, HCB causes skin lesions, colic, and other symptoms in humans, and the EPA has classified the chemical as a probable human carcinogen. 

4. Dieldrin and Aldrin: These POPs possess a slew of detrimental health effects, including increasing a person’s risk of developing breast cancer and Parkinson’s disease. They have been classified as immunotoxic and neurotoxic, and are known endocrine disruptors. 

5. Chlordane: Another insecticide developed in the 1940s, chlordane causes gastrointestinal issues and neurological symptoms following short-term exposure, and the EPA has classified the chemical as a probable human carcinogen. 

6. Toxaphene: Primarily used as a pesticide on crops, livestock, and poultry in the 1960s and 70s, toxaphene has various toxic effects on animals exposed to the chemical, including damage to the thyroid, immune system, and central nervous system. As with HCB and chlordane, the EPA has classified the compound as a probable human carcinogen. 

7. Heptachlor: An insecticide used widely for over two decades beginning in 1953, heptachlor has been linked to a cluster of neurological effects in humans chronically exposed to the chemical. 

8. Mirex: Mirex was a popular flame retardant for plastics, rubbers, and a variety of other materials from the late 1950s to the early 1970s. The chemical has a half-life of up to a decade, and is toxic to a variety of aquatic species. 

9. Endrin: A pesticide developed to repel insects, birds, and rodents, endrin can cause a host of neurological symptoms in humans with prolonged exposure to the chemical, including convulsions, twitching, and physical collapse. 

10. Dioxins: Dioxins are a family of several hundred chemical compounds that are byproducts of waste incineration, car emissions, and other forms of combustion. The EPA has characterized the compounds as highly toxic, and they have been linked to issues with the immune, reproductive, and endocrine systems. The agency has also identified the substance as a probable human carcinogen. 

11. Furans (polychlorinated dibenzofurans): Furans are also byproducts of combustion and incineration processes. These chemicals, which are similar to dioxins, have been shown to cause a variety of adverse health impacts on animals, including reduced fertility, immune system suppression, and developmental changes. 

How The Stockholm Convention and POPs Regulations Are Enforced 

The UN Environment Programme has established a compliance committee to oversee implementation of and adherence to the Stockholm Convention. As the UNEP explains, the compliance mechanisms for this committee and the organization more broadly are “non-confrontational, transparent, cost-effective and preventive in nature, simple, flexible, non-binding and oriented in the direction of helping parties to implement the provisions of the Stockholm Convention.” Though the Stockholm Convention is considered legally binding, the UNEP does not impose any concrete enforcement mechanisms or other types of penalties for noncompliant countries. 

POPs Compliance Obligations for Businesses 

The “non-confrontational,” non-punitive approach of the Stockholm Convention does not mean, however, that there is no enforcement at all for businesses, organizations, or other parties in violation of the treaty’s regulatory mandates. Rather, it’s up to the individual countries adhering to the convention to determine their own penalties for noncompliance. 

In much of Europe, for example, the EU has adopted the Stockholm Convention through the implementation of the POPs Regulation (which has also expanded on the original 12 chemicals targeted by the UNEP). This directive stipulates that the EU’s 27 member states must “lay down rules on penalties applicable to infringements of this Regulation and shall take all measures necessary to ensure that they are implemented. The penalties provided for must be effective, proportionate and dissuasive.” 

In other words, while the EU requires member states to implement dissuasive penalties, those countries are ultimately responsible for conceiving of their own enforcement mechanisms. While penalties vary between EU states, they may include fines, sanctions, or even legal action. The U.S., which has not ratified the Stockholm Convention, has enacted individual bans and restrictions on many POPs through other international agreements, and penalties for violations vary. 

While penalties vary between EU states, they may include fines, sanctions, or even legal action.

Businesses operating in any of the EU’s 27 member states that are involved in manufacturing, importing, or selling chemicals or products that contain or release persistent organic pollutants are required to report on that usage to their respective member country. In addition to adhering to these reporting requirements, companies should also carry out several other critical compliance measures. These include carefully examining the specific legislation and accompanying penalties in the markets in which they operate, carrying out due diligence to gauge their level of POPs exposure, and devising strategic plans to phase out any banned pollutants in their products and identify viable substitutes. 

Businesses operating in any of the EU’s 27 member states that are involved in manufacturing, importing, or selling chemicals or products that contain or release persistent organic pollutants are required to report on that usage to their respective member country.

Beyond the obvious ethical considerations, the legal, financial, and reputational costs of producing and releasing chemical pollutants banned by the EU are significant enough to warrant comprehensive mitigation efforts. Companies working in the EU do not want to be guilty of subjecting human and wildlife populations to grave health risks because they were negligent and failed to sufficiently comprehend the risks posed by their own products. With a repository of evidence spanning over seven decades, no manufacturer, importer, or other stakeholder should be unaware of the innumerable health hazards associated with persistent organic pollutants.