This month, we are going to dive into the topic of Polychlorinated biphenyls or PCBs. These are a class of chemicals that were produced for a variety of industrial purposes but were ultimately banned in the United States in 1979. PCBs are chemicals made of a combination of carbon, hydrogen, and chlorine atoms, have no known taste or smell, persist in the environment for long periods of time, and can have serious health effects on animals and humans. In some industries, PCBs are still produced under close supervision by the EPA.
Even though most production of PCBs stopped decades ago, scientists are still finding these chemicals in the environment. This might be from contamination that happened before production of PCBs ended (since they stick around for a long time) or it might be contamination being released from items that were made prior to the ban (such as industrial oil, old electrical equipment, adhesives, paint, and caulking). PCBs are concerning because they stick around in the environment in soil, water, and even air and they also bioaccumulate in organisms, meaning we can see high concentrations of these chemicals in living organisms like fish, crabs, and more. As humans, we are most likely to be exposed to PCBs in our diet through fish, meat, and dairy products.
When it comes to chemicals in the environment, over 78% of the Chesapeake Bay is considered impaired by toxic contaminants including PCBs, pesticides, mercury, and PFAs. Many of the Chesapeake Bay’s tributaries are considered impaired by PCB contamination; over 63% of the Bay is considered contaminated by PCBs in some form.
Unfortunately, there is no quick or easy way to test for PCBs; all tests involve collecting a sample and taking it to a lab for more in depth processing. A sample of a specific volume is collected and a color change can indicate the abundance of PCBs through a biological or chemical reaction. A sample might be collected through swabbing non-porous surfaces (like a flat, metal surface) or taking a specific volume of a material that needs to be sampled (like water, soil, concrete, or wood). The sample is then mixed with a reagent that reacts with the PCBs, in some cases, reacting with the chlorine and providing an estimate for how many chlorine atoms were present in the sample. In other cases, the PCBs are extracted and separated through gas chromatography and then identified through mass spectrometry. You can also use an immunoassay that uses PCB specific antibodies to bind to the target PCBs and produces a color change based on the amount of PCBs present.
Work is being done throughout the Chesapeake Bay to determine the concentration and source of PCB contamination. Unfortunately, many areas have contaminated soils, which readily transfer the PCBs to the water, air, and living animals depending on environmental conditions. Some remediation methods do exist and involve deploying carbon pellets into contaminated soils to bind the PCBs and make them inert. Other methods involve PCB degrading bacteria to break the molecule down. In the Chesapeake Bay, many regions have Total Maximum Daily Load (TMDL) plans in place to help regulate PCBs and manage remediation.
However, only the Corsica River on Maryland’s Eastern Shore has a plan in place. According to Chesapeake Progress, which tracks the Chesapeake Bay Watershed Agreement’s goals and benchmarks, there are no plans in place or being developed for the Choptank, Chester, Nanticoke, or Wicomico Rivers, all of which have fish consumption advisories for some species due to PCB contamination.
As regular citizens, the PCB contamination that is in the Chesapeake Bay is not something we are creating or can control by simple actions at home. Instead, we need to call on legislators and resource managers to implement TMDLs for our region and provide money to make those plans a reality. We need to support continued monitoring of PCBs in our environment and food supply and we need to hold manufacturers, disposal sites, and the federal government (ie the EPA) accountable for ensuring proper management, cleanup, and disposal of PCB containing waste.
However, it is on us to be aware that this source of contamination exists and to follow consumption advisories, especially for at-risk populations such as children and pregnant women.
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