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Diving Deeper: Episode 11 (June 17, 2009) —
What are PCBs?

HOST: Welcome to Diving Deeper where we interview National Ocean Service scientists on the ocean topics and information that are important to you! I’m your host Kate Nielsen.

Today’s question is….What are PCBs?

PCBs, or polychlorinated biphenyls, are industrial products or chemicals that were in use since the 1920s. These chemicals were banned in the U.S. in 1979 amid suggestions that PCBs could have unintended impacts on human and environmental health.

To help us dive a little deeper into this question, we will talk with Lisa DiPinto on PCBs – what they are and why they matter to us. Lisa is the Southeast Region Branch Chief at the Office of Response and Restoration in the Assessment and Restoration Division. Hi Lisa, welcome to our show.

LISA DIPINTO: Hi Kate, it’s great to be here to talk a little more about a topic that really impacts so many and that it’s definitely near and dear to my heart. I’ve been looking at PCBs and evaluating their effects on the environment since way back in grad school in the 1980s.   

HOST: Lisa, let’s start off with a little more background first on PCBs. Is DDT, another chemical that I think most of us are familiar with, in the same class or category as PCBs?

LISA DIPINTO: Well Kate, DDT and PCBs are actually different chemicals. DDT is a pesticide, where PCBs were developed for a wide range of more industrially oriented applications. But they do have some similarities. They’re both presently banned chemicals and they’re both very persistent, so we’re still finding them both in the environment. From the 1920s until their ban in 1979, there were an estimated 1.5 billion pounds of PCBs that were made for things such as microscope oils, electrical insulators, capacitors, to even electric appliances like old TV sets or refrigerators that we can still occasionally find in households today. They were even sprayed on dirt roads to keep the dust down before they really knew what some of the unintended consequences of widespread use of PCBs were. 

HOST: Wow. Thanks Lisa. I had no idea that these were some of the many uses for PCBs in the past. Are PCBs only found close to city centers or other populated or industrial areas since it sounds like they were commonly developed for industrial applications?

LISA DIPINTO: Actually no, PCBs aren’t just located near the more populated areas or just near places where they were manufactured and used. Back in the 60s when some of the first research was coming out, traces of PCBs could be detected in people and in animals around the world and not only in heavily populated areas such as New York City, but they were also finding them in remote areas as far out as the Arctic. And these findings of such widespread and persistent contamination contributed to the banning of the chemical in 1979.

HOST: Why do we still study PCBs today if they have been banned since 1979?

LISA DIPINTO: Like so many things in the environment, these chemicals they don’t actually breakdown quickly, therefore they don’t necessarily disappear once they’re banned from use. A lot depends on their chemical makeup – the size, the structure, and the chemical composition of the PCBs all that affects how long it takes them to breakdown in the environment. But it can take years to remove these chemicals from the environment and that’s why we’re still seeing them present decades later.

For an example that people might be familiar with, we’re still finding PCBs in the sediments in contaminated areas such as the Hudson River, long after their industrial use has stopped. These findings have caused many disputes and legal discussions between industry, community groups, and regulatory agencies about what the dangers from these chemicals are and what are the best ways to remove them from the environment.

HOST: Lisa, can we actually see or smell PCBs?

LISA DIPINTO: No, PCBs don’t have a known smell or taste. They’re typically either oily liquids or sometimes solids and they’re colorless or may be a very light yellow in color.

HOST: How do PCBs degrade or breakdown in the environment?

LISA DIPINTO: Well, for the process of degrading, a lot depends on the chemical makeup of the PCBs. Because PCBs are actually used as mixtures of individual PCBs, and there are over 200 different configurations with different shapes and sizes to the different, they’re called congeners. The degrading process depends on also where the PCBs are in the environment. Typically, they’re either broken down in the environment by sunlight or by microorganisms. Sunlight plays an important role in the breakdown of PCBs when they’re in the air, in shallow water, and in surface soils. And microorganisms such as bacteria, algae, or fungi biodegrade the PCBs mainly when they’re found in soil or sediments.

Now, how fast this happens, this biodegradation, depends on the number and type of the microorganisms that are present in the environment, the concentration of the PCBs because it has to be just the right amount – it can’t be too high or else it will be toxic to the organisms, whether there are enough nutrients in the environment to feed the microorganisms, and the temperature. So, typically the process of degradation is rather slow and the bottom line is that degradation is limited and their long-term persistence is the key reason that they’re still problematic in the environment today. 

HOST: How did PCBs get into the environment in the first place?

LISA DIPINTO: Well, there are lots of different ways that PCBs entered our environment. Back before the ban of the chemicals, PCBs entered the air and the water and the soil during their manufacture and during their use. Typically wastes that contained PCBs from the manufacturing process were placed in dump sites or landfills. There were often some accidental spills and leaks from facilities or transformer fires that could result in PCBs entering the environment.

Today, we’re still seeing PCBs released into the environment from things like poorly maintained hazardous waste sites that contain PCBs. The dump sites that I just mentioned weren’t always designed to contain these hazardous materials, especially over such long timeframes. They’re also released through illegal or improper dumping of wastes such as transformer fluids and disposal of PCB-containing consumer products, things that were produced back when PCB use was legal like some of our household electrical appliances that are now not used anymore, and then put in landfills that were not designed to handle the wastes.

HOST: OK, so there are still some PCBs getting into the environment even today, 30 years after the initial ban. How is it that these chemicals affect humans and animals? Is it just if you come in direct contact with it somehow?

LISA DIPINTO: Well, there’s a lot of chemistry here, but to provide some of the basics. There are certain characteristics of the molecules that affect the way that they’re going to behave in the environment and then therefore how they can affect humans and animals. First of all, PCBs are what we call hydrophobic and that that means that they don’t dissolve readily in water. So, because of this, when PCBs enter the waterways, they want to attach themselves to sediment particles or other particles floating in the water column and then they can drop out and get stored in sediments.

PCBs are also lipophilic and that means they’re attracted to and dissolve in fats and oils, so we also find them in the fat tissue of animals. These features allow PCBs to persist and remain in the environment and in the tissues of animals for really long periods of time and cause more unintended consequences. 

People and animals then can become exposed to PCBs through exposure to these chronically contaminated sediments, or from eating contaminated prey, which for humans could be contaminated seafood as an example. And as we know, there’s a number of PCB fish advisories throughout waterways in the United States.

HOST: Lisa, what are some of the health impacts associated with PCBs?

LISA DIPINTO: Well, one of the things that we have noticed about PCBs over time is their ability to bioaccumulate or biomagnify in organisms, which can intensify health impacts associated with these chemicals. As the word implies, bioaccumulation is essentially an accumulation of PCBs over time. So an organism, over its lifespan, is going to be exposed to PCBs through sources such as food or sediments and, let me give you an example to explain.

Because PCBs are hydrophobic, in aquatic environments they’re going to be stored in the sediments because they want to attach themselves to particles. Then, the bottom-feeding critters such as little sediment-dwelling crustaceans - copepods or amphipods they’re called – ingest and accumulate PCBs while feeding. The amount of PCBs that’s ingested every time these small animal feeds is small, but over time, because the PCBs are stored in fat and they degrade very slowly, the PCB levels in the organisms increases. So, when the larger animals or the higher predators eat these smaller animals lower in the food chain, the PCBs similarly will accumulate and increase in concentration, resulting in higher concentrations over time than in the smaller prey species. So essentially as you’re moving up the food chain, the PCB concentrations increase. So by the time you get to the top of the food chain, and like for example something like dolphins or top predator fish that prey on smaller fish, they have the potential for higher PCB concentrations.

In many parts of the United States, there’s advisories and restrictions on the amount of fish that people should eat from contaminated waterways. And this is really an effort to keep us safe as PCBs have been determined to be probable carcinogenic contaminants to humans. You should know that it’s still safe to have fish as part of your diet, but it’s good to be mindful of the recommendations.

HOST: And to build on this more, what are some of the impacts to fish and marine life from this chemical?

LISA DIPINTO: Well, there’ve been many laboratory and field studies that have shown potentially harmful effects from PCBs on things like fish and birds and mammals and other wildlife. Some of these effects include impaired reproductive, endocrine and immune system functions, we’re finding increased lesions and tumors on fish, and sometimes death or mortality.

For example, some of the research I’ve done in the past has looked at the reproductive effects of PCBs on little sediment-dwelling crustaceans or little shrimp-like guys that live in the mud that are called copepods. They’re really cute. Our studies indicate that sediments contaminated with PCBs affect the reproductive capacity of these little guys and they weren’t able to produce as many offspring as those that were living in uncontaminated sediments. So what, people say – who cares about whether or not copepods can reproduce, but really it has implications up the food chain, as they’re a really important source of food for the juvenile fish that come into the marshes to feed. And further these little copepods can be indicators of potential effects on other guys that are living in the mud that are exposed to PCBs and other contaminants that also serve as important prey species. 

Similarly, there’ve been studies with various species of fish across the country both endangered and non-endangered that indicate that PCBs can affect things like their immune systems and when they’re exposed to PCBs it makes them more susceptible to diseases that fish that live in uncontaminated areas would be able to fight off so putting them at greater risk. 

HOST: Lisa, earlier you mentioned that these chemicals can be found all over the world. Why is it that PCBs can be found in such remote areas if they were developed more for industrial applications?

LISA DIPINTO: Well Kate, that’s a good question and the persistence and the transport of PCBs, is a big part of the issue. The modes of transport of PCBs are complicated, and they can be moved by air, by water, and by sediments. As I mentioned, PCBs don’t dissolve in water and they don’t degrade easily so they’re going to be persistent. PCBs can get vaporized from water or off of tiny particles and then attach themselves to particulates in the air for example like dust. And depending on the particle size they can get transported varying distances, sometimes great distances, by the prevailing winds and then re-deposited on land or in water by particle sedimentation out of the air from rainfall or snowfall that washes these particles out.

PCBs that get into the waterways can also, because they’re hydrophobic, like to attach themselves to the fine particles in the water and then they get transported varying distances from the tides or the currents, or maybe they’ll settle out to the bottom where they may persist a long time in the sediments, they can get buried by other sediments, or they can even get carried around with the movement of bottom sediments through the features of bottom sediment currents. So all these transport mechanisms contribute to PCBs greater distribution all over the world. 

HOST: Has the level or amount of PCBs in the environment increased, decreased, or remained the same in the last 30 years?

LISA DIPINTO: Given the complicated transport mechanisms I described earlier, it’s kind of difficult to say across the USA as a whole. But overall, as we address more and more of these PCB-contaminated waste sites and work with the Environmental Protection Agency and our trustee partners at the state, federal, and tribal levels to remove PCBs from the environment, we’ve been successful in reducing the overall amount of PCBs that are posing a threat to the resources at the sites we’re involved with. 

HOST: Lisa, with all of these impacts and this consistent transport of PCBs almost 30 years again after its ban, I imagine cleanup is something that many are still focused on. What is involved in cleanup efforts to remove PCBs from the environment?

LISA DIPINTO: Well, there’s a lot of issues with removal of PCBs from the environment. For the areas where we know that PCBs exist in the sediments, some of the main issues are whether it would be better to dredge and remove these contaminated sediments from the waterways and dispose of them in a properly designed and maintained hazardous waste storage facility that would prevent the PCBs from re-entering the environment and affecting animals and humans. Or is it safer to allow the sediments just to remain in place and you can cover them up with clean sediments and allow them to naturally biodegrade by bacteria over time. Or perhaps you could consider placing a cap or a barrier over the contaminated sediments in the environment in place to prevent them from re-entering the environment and exposing organisms. Obviously there are environmental, human health, and financial concerns from all sides.

HOST: OK, so there are many options for cleanup and it’s probably decided on a case-by-case basis.


HOST: Lisa, what is the role of the National Ocean Service in PCB research?

LISA DIPINTO: There are many offices in the National Ocean Service, and really NOAA for that fact, that are involved in the research of chemical contaminants. In my office, the Office of Response and Restoration which is part of the National Ocean Service, we focus on PCB research that can be applied to specific site assessments on both the cleanup side and the damage assessment side. However we’ve found that much of our research has broader applications, and we’ve developed some projects and products that are used more widely. For example, our watershed-based projects provide a comprehensive evaluation of PCB contamination on a watershed level along with a suite of other contaminants. And they’re these cool mapping projects that resource managers can access online or the public can access online to get a sense of where the particular contaminants are in a particular watershed.

We’ve also developed and published sediment guidelines that help determine whether a certain amount of toxic chemical, such as PCB in the environment, is likely to harm the ecosystem. We’ve also as part of our work conducted a number of site-specific toxicity studies that contribute to the overall understanding of how PCBs affect things like sediment-dwelling organisms and fish

HOST: Lisa, what is the role of NOAA, and specifically your office, in cleanup efforts of PCBs?

LISA DIPINTO: Our Office of Response and Restoration works to protect and restore coastal resources that have been injured by contaminants associated with things like hazardous waste sites and oil spills. The waste site work is of particular relevance to our discussions today as many of these waste sites have PCB-contamination problems. NOAA is a trustee for coastal resources on behalf of the public. So things like marine and estuarine fish, marine mammals like whales and dolphins, and the habitats that support these kinds of resources such as marshes, wetlands, coastal streams, tidally-influenced rivers; are all considered to be NOAA’s trust resources. And then we work with other trustee agencies which include federal and state agencies and tribes to mitigate and restore for adverse effects of contaminants in the environment to these kinds of resources.

On the cleanup side, through our work with the Environmental Protection Agency, we help to ensure that the site cleanups are as protective to NOAA’s trust resources as possible. By ensuring good cleanups on the front end, we feel like we can minimize the residual injuries that might persist longer term as a result of any contamination that’s left behind as a result of the cleanup.   

We also are involved in Natural Resource Damage Assessments, where we work in partnership with our federal, state, and tribal co-trustees to conduct environmental assessments and these are designed to determine the magnitude, the type, and the extent of environmental injuries to our resources that have been impacted by contamination such as PCBs. We then, as part of this Natural Resource Damage Assessment process determine what type of and how much restoration is needed to compensate the public for their loss of resources that’s due to the contamination. So our overall goal through this damage assessment process is to get restoration projects implemented that are going to compensate the public for their lost resources. 

HOST:  These damage assessments and restoration claims sound like they can get pretty complicated and rather expensive. Does the public pay for these? 

LISA DIPINTO:  Well Kate, that’s one of the neat things about our program. We have statutory authority to pursue these natural resource damage claims under a number of environmental laws. So we are seeking compensation, usually cooperatively but sometimes through litigation, from the companies that are responsible for releasing the contaminants into the environment. And part of the compensation to the public, in addition to paying for or implementing the restoration projects, is paying the trustees, like NOAA, for the costs that are associated with developing the claim. So the public’s really getting a good deal through our damage assessment work. 

HOST: Lisa, are there any examples that you can share with us today on the impacts of these efforts to date? How has this cleanup helped local communities?

LISA DIPINTO: Well, we have been and are currently involved with a number of PCB-contaminated waste sites on all coasts including the Great Lakes and all the regions of the U.S. One example I can give to illustrate what we do and to highlight how we help the communities is our Housatonic River site, which originated in Pittsfield, Massachusetts from a General Electric facility. There are PCBs contaminating the Housatonic River from Massachusetts down into Connecticut and at this site there are fishing advisories all along the river that are due to the presence of PCB contamination in the rivers, sediments, soils, and in the groundwater.

And NOAA has been working with the United States Fish and Wildlife Service, the Connecticut Department of Environmental Protection who are our co-trustee agencies to develop a comprehensive settlement with General Electric that includes river remediation that’s under way now – that’s cleaning up the river from the PCB contamination – and we’ve developed plans that are out for public review for restoration projects that will compensate the public for their natural resource losses. General Electric has paid over $15 million in natural resource damages that will be available for restoration projects in both Massachusetts and Connecticut. And that’s just an example; we’ve got other sites across the United States where we’ve worked to ensure the cleanup gets conducted to the maximum extent possible and that restoration will be conducted to bring back clean fish, clean habitats, and environmental restoration that’s going to compensate the public for their losses.

HOST: Thanks Lisa. Do you have any final closing words for our listeners today?

LISA DIPINTO: Well, first I wanted to just thank you for providing me the opportunity to talk about PCBs and what we’re doing to address some of the environmental issues associated with them. I feel really proud of what our program does and I’m glad to have the opportunity to share it with a larger audience than just the world I work in.

Some of the things I think are worth remembering about PCBs is that even after 30 years of being banned, they remain an environmental concern for humans and wildlife – we’re still finding them in the environment, they’re persistent, and we’re still seeing fish advisories that result from high PCB levels in the fish in many of our waterways.

And I hope that we’ll be able to continue our work with our partner agencies and with industry to cleanup or contain these PCB-contaminated sediments in our waterways in order to reduce the PCB levels in fish and other animals and thereby reduce risks to humans and wildlife, and to restore the public’s resources. 

HOST: Thank you Lisa for joining us on today’s episode of Diving Deeper and talking more about PCBs and what these mean in our everyday lives. To learn more about PCBs and similar restoration projects and cleanup efforts by the Office of Response and Restoration, please visit

That’s all for this week’s show. Please tune in on July 1st for our next episode on the dead zone.