Stockholm Convention on Persistent Organic Pollutants

What are Persistent Organic Pollutants? 

Persistent organic pollutants (POPs) are a class of highly hazardous chemical pollutants that are a serious, global threat to human health and to ecosystems. POPs are substances that specifically:

• remain intact for exceptionally long periods of time (many years);
• become widely distributed throughout the environment as a result of natural processes involving soil, water and, most notably, air;
• accumulate in living organisms including humans, and are found at higher concentrations at higher levels in the food chain; and
• are toxic to both humans and wildlife.

Many POPs were developed after World War II, when thousands of synthetic chemicals were introduced into commercial use. Some POPs are pesticides, some are industrial chemicals, and some are unintentionally produced by-products that are formed during certain combustion and chemical processes. Many of these chemicals proved beneficial in pest and disease control, crop production, and industry. Examples include polychlorinated biphenyls (PCBs), which have been useful in a variety of industrial applications, such as in electrical transformers and large capacitors, as hydraulic and heat exchange fluids, and as additives to paints and lubricants, and DDT, which is still used to control mosquitoes that carry malaria. Unintentionally produced chemicals include dioxins, which result from some industrial processes and from combustion, such as municipal and medical waste incineration and backyard burning of trash.

Why was the Stockholm Convention developed?

In the 1980s and early 1990s, there was increasing scientific evidence about the dangers from POPs. For example, when people eat POPs-contaminated foods, the POPs accumulate in their fatty tissue. Mothers pass on POPs from their own bodies to their offspring. POPs contamination can lead to cancers and tumors, neurological disorders, immune suppression, reproductive disorders, and other diseases, including increased incidence of type 2 diabetes, endometriosis, hepatitis, and cirrhosis.

In May 1995, the United Nations Environment Programme’s (UNEP) Governing Council adopted decision 18/32, which called for undertaking an international assessment process of an initial list of 12 POPs and further called on the Intergovernmental Forum on Chemical Safety (IFCS) to develop recommendations for international action, to be considered by the UNEP Governing Council and World Health Assembly no later than 1997. The 12 POPs, sometimes called the “dirty dozen,” include:

• pesticides: aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, and toxaphene;
• industrial chemicals: hexachlorobenzene and PCBs; and
• unintentionally produced POPs: dioxins and furans.

In June 1996, the IFCS concluded that international action, including a global legally binding instrument, was required to minimize the risks from the 12 POPs through measures to reduce and/or eliminate their emissions or discharges. So, in February 1997, the UNEP Governing Council in its decision 19/13C established an intergovernmental negotiating committee (INC), with a mandate to prepare an international legally binding instrument for implementing international action beginning with the 12 POPs. The INC met five times between June 1998 and December 2000. The Stockholm Convention was adopted and opened for signature in May 2001 in Stockholm, Sweden. The Convention entered into force on 17 May 2004.

How does the Stockholm Convention work? 

The Stockholm Convention lists chemicals in three annexes: Annex A lists chemicals to be eliminated; Annex B lists chemicals to be restricted; and Annex C calls for minimizing unintentional production and release of listed chemicals.

Beyond the first 12 POPs, the Stockholm Convention established specific scientific criteria and a step-by-step procedure for identifying, evaluating, and adding chemicals to the treaty. At the first meeting of the Conference of the Parties (COP1) in 2005, the COP established the Persistent Organic Pollutants Review Committee (POPRC) to consider additional substances for listing under the Convention.

The Committee is comprised of 31 government-designated experts who review nominated chemicals in three stages. The Committee first determines whether the substance fulfils the screening criteria detailed in Annex D of the Convention, relating to the chemical’s persistence, bioaccumulation, potential for long-range environmental transport, and adverse effects on human health or the environment. If a substance fulfils these requirements, the Committee drafts a risk profile according to Annex E to evaluate whether the substance is likely, as a result of its long-range environmental transport, to lead to significant adverse human health and/or environmental effects and therefore warrants global action. Finally, if the POPRC finds that global action is warranted, it develops a risk management evaluation according to Annex F, reflecting socio-economic considerations associated with possible control measures. Based on this, the POPRC decides whether to recommend that the COP list the substance under Annexes A, B, and/or C.

Under the treaty, any party may nominate a chemical for evaluation. Each stage (criteria, risk profile, risk-management evaluation) typically takes one year, but some chemicals progress more slowly if the POPRC requires additional time to gather and review relevant information. Since 2005, the COP has added 22 POPs to the original dirty dozen that are now controlled under the Convention (See Table 1).

What are the Challenges in Dealing with “Live” Chemicals?

While the process of adding new substances works well, there are some obstacles. By creating the POPRC, the Stockholm Convention attempted to separate the scientific and technical consideration of nominated POPs, which are the purview of the POPRC, from the political concerns of parties, which are discussed by the COP. In essence, the POPRC addresses whether the convention can control a substance and how it would do so. Then the COP decides if it should.

However, new challenge emerged as the convention shifted to the evaluation of toxic chemicals still in widespread production and use (“live” chemicals), especially with regard to socioeconomic considerations in the risk-management evaluation phase. This transition from “dead” to “live” chemicals illustrates the challenges of recommending policy responses to protect human health and the environment for chemicals that are still being used in applications such as fire-fighting foams, which are important for human safety.

With live chemicals, the POPRC is forced to consider both the science and the socioeconomic implications of its recommendations to eliminate or reduce chemicals, including recommendations to allow some uses of the chemical to continue for a limited time, when use of safe alternative chemicals is not economically or technically feasible. At the political level, however, the COP has sometimes agreed to allow additional uses of these live chemicals, for longer time periods than the POPRC recommended, which delays the elimination or reduction of POPs production and use.

Fire-fighting foams, for example, presented a particularly difficult conundrum when weighing the dangers to human health and the environment, with the public safety risks posed by fires at places like airports and oil refineries (so-called “class B” fires) where PFOA-containing fire-fighting foams are used. The POPRC considered the dangers of continuing releases of PFOA from fire-fighting foams, particularly given their widespread use and the large amounts of foam dispersed when fighting a fire, which can cause both local contamination and global dispersion of PFOA. But, on the socioeconomic side, an estimated USD 80 billion would be required to replace these foams, which led to a call for exemptions. PFOA was ultimately added to the Stockholm Convention in 2019, with specific exemptions. 

What Other Challenges does the Stockholm Convention face?

At COP11, the Stockholm Convention took a big step in addressing some of its implementation challenges, by finally adopting a decision on procedures and mechanisms on compliance, a historical achievement after two decades of work. The decision established a Compliance Committee—the members of which will be elected at COP12—and which will help Parties to fulfill their obligations under the Convention by examining systemic issues of interest to all Parties and challenges faced by individual Parties. With this agreement, the last mechanism in the Convention is in place. While the compliance measures will help Parties to comply, they won’t hold them to account or even necessarily publicly share which Parties are not in compliance. But for developing countries, this was a red line. As the obligations grow at every COP, they underlined the challenges in keeping up.

And, in fact, these challenges are now at the heart of the Convention. The addition of each new chemical to the Convention mean Parties must develop new national implementation plans, new inventories, and work out how to handle the wastes. Increasingly, the listed POPs are used in consumer products, from Teflon pans to plastic. For national regulators often juggling multiple portfolios of work, the Stockholm Convention is becoming more time and resource intensive. This is particularly challenging for developing countries, who need more technical assistance and financial resources to implement the Convention—resources that are increasingly difficult to come by.

Governments also need to strengthen environmentally sound management of POPs waste, by taking appropriate measures to manage stockpiles and wastes, particularly obsolete pesticides, in an environmentally sound manner and do not enter recycling streams. Governments also need to strengthen awareness-raising and information exchange through, for example, engagement with populations most at risk to the exposure of POPs.

Overall, the second effectiveness evaluation showed that regulations targeting POPs have succeeded in reducing levels of POPs in humans and the environment. For the initial POPs, concentrations measured in air and in human populations have declined and continue to decline or remain at low levels due to restrictions on POPs, some of which predated the Stockholm Convention and are now incorporated in it. For the newly listed POPs, concentrations are beginning to show decreases, although in a few instances, increasing and/or stable levels are observed. But the Convention cannot afford to rest on its laurels as these “forever chemicals” will take years to eliminate. And while they are still in the environment, human health and ecosystems remain at risk.