Long-banned toxic chemicals remain a global threat

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that are distributed globally, from the high Arctic and Antarctic to the Mariana Trench in the deep Pacific Ocean. Once used in dielectric fluids to reduce the risk of explosion in capacitors and transformers, and also used as plasticizers and flame retardants in products such as building materials and paints, the production of these chemicals was banned in most countries in the 1970s and 1980s. Today, the remaining stocks are managed globally under the Stockholm Convention on POPs, which requires signatory countries to have strategies for environmentally sound management (ESM) of PCBs by 2028. 

In a new analysis of the progress towards environmentally sound management of PCBs, researchers from Masaryk University, the University of Toronto, and NRDC (Natural Resources Defense Council) have found that considerable impediments still exist in many countries, making the achievement of the goal of removing all stocks of these highly hazardous chemicals by the 2028 deadline almost unattainable. 

The report, published in the journal Environmental Science & Technology, states that an estimated 1.3 million tons of pure PCBs were manufactured between 1930 and 1993 in at least 10 countries, primarily in the USA, followed by West Germany, the USSR, and France. These PCBs were widely exported from manufacturing countries, resulting in their use in at least 114 countries. 

Through use and subsequent poor management, the 1.3 million tons initially produced expanded to 17 million tons of PCB-contaminated materials and waste. It is estimated that 20–35 percent of PCBs have already been released into the environment while more than 10 million tons of PCB-containing materials remain and pose public health and environmental threats globally.

The Stockholm Convention on POPs currently has 185 signatories (184 countries plus the European Union). It aims to ban the production of PCBs totally, and to phase out in-use PCBs by 2025. It also requires that signatory countries introduce inventories of their current stocks of the chemicals and establish strategies to ensure environmentally sound management (ESM) of materials with >0.005% (50 mg/kg) PCB content by 2028. ESM largely consists of chemical destruction by high-temperature combustion methods for waste with high PCB content and burial in specially engineered landfills or underground mines for waste with low PCB content. 

The purpose of the current report was primarily to understand the extent of the future threat still posed by PCBs to human and ecosystem health. In addition, it sought to assess the successes and failures of the world’s countries in managing PCBs and in moving towards environmentally sound management and permanent removal of these hazardous substances. 

Some of the most important findings from the report, titled Persistent Problem: Global Challenges to Managing PCBs, include the following: 

• forty-two percent of signatories to the Stockholm Convention have no PCB inventories and are unaware of the amounts and locations of PCB stocks in their countries;
• only 30 percent of signatories to the Stockholm Convention are on track to meet the target of environmentally sound management of all PCBs by 2028; 
• a lack of administrative, financial, and political capacities are key impediments to successfully managing PCB stocks, especially in low-income countries, despite these countries not being responsible for most PCB production or use;
• the U.S., the world’s largest producer and user of PCBs, was found to have decreased its sizable stocks by only about 3 percent since 2006. Despite having the financial capacity to responsibly eliminate PCBs, the U.S. has no regulatory deadlines to do so, is not a party to the Stockholm Convention, and its PCB inventory is poorly documented compared to those of Canada and Czechia;
• Canada and Czechia, both parties to the Stockholm Convention, are close to achieving the 2028 goal, having reduced their stocks of pure PCBs by 99% in the past ten years.

The analysis of progress towards ESM showed that, of the 174 signatory countries that have submitted reports, 72 national PCB inventories (42 percent) are partial or preliminary. Many inventories are limited to transformers and/or only to the public electricity sector, which may capture only half of the uses of PCBs (considering 48 percent of the chemicals produced were used in transformers). An additional 23 countries (13 percent) reported complete PCB inventories but no capacity to achieve ESM, while 11 countries had inventories and capacity to manage PCBs but had made no significant progress toward ESM. One country, the Democratic People’s Republic of Korea), still manufactures PCBs. 

The number of countries achieving or progressing toward ESM was small; 34 countries (18 percent) are progressing toward ESM through removal from use and destruction of PCB materials. Only 23 countries (13 percent) have achieved ESM of PCBs and, with three exceptions (Nepal, Kenya, and Micronesia), all of these 23 countries are classified as “high income” countries by the World Bank. Only three countries classified as “low development”/“low income” are currently making substantial progress toward ESM of PCBs: Benin, Rwanda, and Uganda.

The authors of the report state that their analysis has limitations and may therefore not be fully accurate. They say they may be presenting the worst-case scenario since countries may have made unreported progress toward PCB elimination. But conversely, many countries reported incomplete inventories (e.g., only inventories of transformers owned by a national electricity provider), and thus most may have under-recorded true stocks.

They conclude that the failure to manage global PCB stocks more than 30 years after the end of production highlights the possibility that similar problems may well plague the future control and management of other POPs. There is thus an urgent need to prioritize the reduction of manufacture and use of newer, more widely distributed POPs such as chlorinated paraffins and per- and polyfluorinated alkyl substances, as these management challenges are unlikely to be resolved in the coming decades.

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By Alison Bosman, Earth.com Staff Writer