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Persistent Pollutants

Toxic PCBs managed poorly decades after production ceased

Global inaction portends poorly for cleanup of PFAS, researchers say

by Cheryl Hogue
June 2, 2022 | A version of this story appeared in Volume 100, Issue 20


A man applies a sign reading "This equipment contains PCBs" to a wall next to electrical equipment.
Credit: US Army Corps of Engineers/Wikimedia Commons
Polychlorinated biphenyls (PCBs) were used for decades in electrical equipment such as electrical transformers. Tons of PCBs and wastes tainted with them await destruction and disposal worldwide.

The poster child for environmentally persistent synthetic chemicals is arguably polychlorinated biphenyls (PCBs), heat-resistant commercial chemicals whose production was phased out decades ago everywhere except North Korea.

But most countries are not managing the remaining PCB stocks and contaminated materials, leaving people, fish, and wildlife at risk from adverse toxic effects to their nervous systems that many of these chemicals can cause, an international team of researchers says (Environ. Sci. Technol. 2022, DOI: 10.1021/acs.est.2c01204). The failure to properly manage this group of compounds, which haven’t been produced in most of the world in the past 30 years, bodes poorly for the control of other persistent organic pollutants (POPs) such as per- and polyfluoroalkyl substances (PFAS), the researchers from Canada, the Czech Republic, and the US say.

“This analysis is an international wake-up call to limit the production of hazardous chemicals like PCBs,” coauthor Veena Singla, a senior scientist with the Natural Resources Defense Council, says in an emailed statement. “We just can’t clean up the mess these chemicals create.”

Factories churned out more than 1.3 million metric tons (t) of pure PCBs from 1930 to 1993, the researchers say. US-based Monsanto—a company that Bayer bought in 2016—produced half the global total. The substances were used in at least 114 countries. Applications included dielectric fluid in electrical transformers and capacitors, hydraulic or heat-transfer fluid, and flame retardants. PCBs were also used in paints, pesticides, carbonless copy paper, and building sealants.

Under an international treaty, the Stockholm Convention on POPs, 183 countries agreed to manage PCBs in an environmentally sound way by 2028. The treaty endorses high-temperature incineration to demolish pure or heavily concentrated PCBs and chemical destruction to break apart PCBs in lower concentrations, coauthor Miriam L. Diamond, an earth sciences professor at the University of Toronto, tells C&EN.

Canada, which imported an estimated 40,000 t of PCBs, and the Czech Republic, which used about 12,000 t, have reduced their stocks of pure PCBs by 99% in the past 10 years, the researchers found.

Only about 30% of countries are on track to meet the 2028 deadline under the Stockholm Convention. More than 10 million t of PCB-containing wastes remain worldwide, mainly in countries that don’t have the technological capacity or money to manage the material, the paper says.

The US, which is not a party to the Stockholm Convention, also has a substantial inventory of PCB-containing materials and waste that has decreased only about 3% since 2006, the authors found. As of 2020, federal records indicated stocks of transformers containing some 776 t of pure PCBs and nearly 14,000 t of PCB-tainted materials. In the US, PCBs and waste containing them may legally be deposited in landfills. The Stockholm Convention does not generally consider this practice to be environmentally sound because PCBs can leak from dumps.

The financial onus for getting rid of PCBs has fallen on national governments or international agencies, the authors say. “Producer financial responsibility to date has only been in the form of legal settlements,” they add.

The convention’s 2028 deadline for PCBs is unachievable because of the lack of financial and technical resources and political will, they conclude. Given this, they say, “we question the feasibility of removing other new POPs that have entered widespread use,” such as chlorinated paraffins, which replaced PCBs in many applications, and PFAS.

Cleaning up widespread POPs will require more money than public coffers can provide, says Vito A. Buonsante, policy and technical adviser for the International Pollutants Elimination Network, a coalition of environmental and health groups. Buonsante, who was not involved with the paper, tells C&EN that manufacturers need to be held financially accountable for health and environmental harms their chemicals have caused.


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