The Dolphin Defender
The Effects of PCBs

orca whale

Wild dolphins face numerous threats, from hungry sharks to the entangling nets of fishing boats. But scientists have only recently begun to fully recognize another threat: chemical pollution.

Around the globe, researchers have found potentially unhealthy quantities of industrial chemicals in dolphins’ tissue and in mother dolphins’ milk. As NATURE’s The Dolphin Defender shows, one group of contaminants is of special concern: polychlorinated biphenyls, or PCBs.

More than 200 kinds of PCBs have been used as flame retardants and electrical insulators in products ranging from cereal boxes to plastics. Although they were banned in the United States and many other nations in the late 1970s, PCBs continue to leak into the oceans from river sediments and other sources. The chemicals enter into the food chain and ultimately into fish, which dolphins eat. Researchers with the National Institute of Standards and Technology in Charleston, South Carolina, say that dolphin blubber carries some of the highest PCB concentrations found in any wild animal.

Although it is difficult to link PCBs to specific health problems, dolphin researchers have found some troubling trends. One is that female dolphins with high levels of PCBs appear to have lower pregnancy rates than less-contaminated females. That may be because PCBs interfere with the reproductive process.

Another finding of concern is that heavily contaminated female dolphins that do get pregnant often lose their first calves. That may be because the mother dolphin “burns” blubber to make milk. The PCBs and other compounds stored in the blubber become part of the milk and are transferred to the calf. The chemicals may harm the baby dolphin’s immune system, making it less able to fight off infections from viruses and bacteria.

Scientists have also found that PCB-contaminated male dolphins don’t develop sexually. Even more alarming, research shows PCB similarly affects other members of the dolphin family, such as orcas. As The Dolphin Defender shows, the orca population in Puget Sound, off Seattle, Washington has dwindled in the past 20 years. The high mortality rate and undeveloped reproduction systems were attributed to the high PCB levels in the orcas’ tissues.

Researchers are still trying to verify such links. They are now conducting several long-term studies of dolphin populations around the world. PCBs aren’t the only target; pesticides and other industrial chemicals that wash into the ocean are also being measured and analyzed. Eventually, conservationists hope the studies will lead to a better understanding of this invisible threat to dolphin survival, which will then lead to possible solutions.

  • K. Black

    Yet another sad commentary on our species and its lack of intellect, wisdom and compassion! But, as long as a few individuals got a profit from the sales of chemicals.

  • Jay

    This was painful to watch. Between the slaughter of the Dolphins on Solomon island to the PCB’s in the Puget sound orca tissue, its disgusting how humans are destroying this planet. “… Every mammal on this planet instinctively develops a natural equilibrium with its surrounding environment, but you humans do not. You move to an area and you multiply, and multiply until every natural resource is consumed. The only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer of this planet.” Agent Smith- The Matrix

  • Maggie

    I was deeply saddened to see this being a lover of whales and dolphins my whole life. Thank you for making me aware of the tragedy happening right off our own coasts. What can we do to help?

  • madoline

    hey i love dolphins alot so bring me a picture

  • SpectreWriter

    I recall some Balugas at the St. Lawrence Seaway which had their skin sloughing off some years ago. It was attributed to toxins being put into the waterway from the manufacturing of PVC.

    We have decades of history, proof that we’re messing with their environment and ours. All the time there are people expressing dismay and claiming to have been unaware… and still it continues — on and on, more and different ways of abusing every day. But do you still buy “dolphin-safe” tuna? The ONLY tuna that is truly safe is Albacore, but the same company sells the other types as well. Even salmon (tastes almost the same when prepared with mayo and is better for you)is often sold and packaged by the same folks who put out so-called “dolphin-safe” tuna. It’s inexcusable to kill thousands of them every year for the sake of a cheaper can of tuna.

    Sea Shepherd is out there, has been for years. Rick O’Grady, Ocean Preservation Society, Bluevoice… all in the trenches.

    What will you do? Will you stop buying tuna? Will you stop going to parks that keep dolphins in captivity? Will you tell others the ugly truth about all of this?

    Please, do all you can… and don’t stop. What is happening is a change in our collective social consciousness. When there are no people going to those parks, the billions of dollars will go away and the dolphins will be released, never to be captured and kept captive again. When we stop buying cheap tuna, they will stop sending out the boats after it. Isn’t paying a dollar or so for a can of Albacore instead of 60 cents for “light” tuna worth thousands of dolphins’ lives?

    Time is always running out, for those dolphins in captivity now, and those who will be caught up in the days and months and years to come. Don’t wait. Make the changes within yourself, and talk to others as well. I look forward to a day when dolphin-dangerous products are looked upon with scorn and trying to buy them is met with disgust. WE are the only ones who can make this happen. There are billions of dollars on the line each year. Those corporations aren’t going to give up that money without a fight.

    Do what you can. Do all you can. Please, do it now! Keep on doing it until no dolphin on this planet is held captive, and we learn to coexist harmoniously with the rest of the sentients and other life-forms on this planet. No act or gesture is too small. Everything helps. Thank you!


  • JT

    EDITOR: Please correct that to Ric O’Barry. I was in the moment, thinking ahead of my fingers. Feel free to add other groups to that list as well? Thanks!

  • Max Fury

    As I write this it is June 11th and there is a massive oil leak devastating the Gulf of Mexico. The long term effects of the oil in the gulf as unknown as when the oil leak will finally be stopped.

    I came across this site as I was researching PCB’s for an upcoming information release. The news I have read has painted a rather grim picture. Though the production of PCB’s has been stopped in the United States for over 40 years, the increase of PCB’s in the environment has steadily increased. PCBs is a man-made product, a synthetic that does not occur naturally in nature, so it’s presence in the environment can only be attributed to the release of this product into the environment. That PCB’s are accumulating in species at ever increasing rates can only mean that PCBs are still to this day leeching out into water supplies from wherever they have been dumped and making there way to our oceans where they are ingested by organism and start the process of climbing the food chain. Because PCBs do not break down easily, their presence in our environment and in all living organisms will only escalate. To what level is unknown.

    A previous information release was on “Hydraulic Fracturing”, a way of opening reservoirs of natural gas and oil that can be drawn from deep underground. This form of “drilling” has now caused drinking water in certain small cities across the United States to become undrinkable. Hydraulic Fracturing pumps an unknown “fluid” deep underground to cause the fracturing of substrate strata. Since different strata will disperse differently under pressure, the direction the fluid will travel and how far it will travel is unknown. Since Hydraulic Fracturing is exempt from the “Safe Water Act” the continued use of Hydraulic Fracturing goes on unabated. The increased use of hydraulic fracturing has prompted more speculation about its environmental dangers. A 2008 investigation of benzene contamination in Colorado and Wyoming led some EPA officials to suggest hydraulic fracturing as a culprit. The accepted make up of the fracturing fluid by the government and Natural gas companies is that it is 99.5% water, and the rest natural ingredients. Separate determinations say it is made up chemicals include toxins, known carcinogens and heavy metals which may have polluted the ground water near fracking sites in Pennsylvania and Colorado. The longterm effects of fracturing fluid in the environment is unknown. There will be no way to clean up fluid pumped underground if it is determined to be an environmental health hazard.

    Like PCBs, leaking oil, and fracturing fluid, the long term damage to our ecosystem may be widespread, and unreversible.

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