News: OnEarth Magazine

by Michael A. Rivlin

Frank S. Balthis

ourism and souvenir trinkets have despoiled Bar Harbor, on Maine's Mount Desert Island. But one spring morning I find myself in a deserted and apparently pristine cove on the seaward side of the island, protected by money and the Nature Conservancy on the shore and by isolation in the water. The cove has the vaguely Pleistocene look of a Scottish firth, and I expect a serpentine dinosaur neck to shoot up from the water at any moment-only instead of Nessie it's a colony of noisy, inquisitive, and extremely appealing harbor seals. Bobbing heads and bushy whiskers surround our rubber Zodiac, the seals fearless in their medium, their round, black, mournful eyes looking me over, and when they dive back down my eyes follow them under as I try to imagine their watery world. No question, I'm a creature of the coast.

So is my host, Susan Shaw, director of the Marine Environmental Research Institute (MERI), which over the previous three days held a conference in Bar Harbor to discuss the impacts of the pollutants known as endocrine disruptors on seals and other marine wildlife. Shaw, fifty-seven, is a bony woman with a narrow face, long neck, and thin lips, whom I watched during the conference trying nervously to impress the celebrated scientists she'd invited. But today she is transformed into a carefree teenager, her toes curling over the edges of her sandals in excitement as she pushes our Zodiac to full throttle, at home amid the waters and creatures to which she has devoted her career in public health.

Shaw is intentionally a long way from her northwest Texas birthplace. "As soon as I got to the ocean, I just felt better," she tells me. "About everything. I don't like cows. I don't like that whole thing." Her voice still has a dusty Great Plains resonance, and her body appears permanently sun-dried. But now, when she looks out on the horizon she doesn't see cattle but harbor seals -- barking, growling, yipping, like seaworthy coyotes.

Pupping season has just concluded in this cove, which is inhabited by about 150 of the 16,000 seals that populate the mid-coast area of Maine. On the sun-drenched granite ledges uncovered by low tide are groups of adults and pups, their coats spotted, mottled, and splotched in shades of light gray, tan, reddish brown, and blond, many of them stretched out full-length on their sides like prone Botero sculptures. The pups sunning themselves on their warm rocks are about the size of golden retrievers lying on hearth rugs, and the seals bobbing in the water around us, their domed heads with square muzzles and dark eyes emerged to periscope height, look like nothing so much as earless dogs. When one's gaze appears to meet mine, my instinct is to return the greeting and pat it on the head. Anyone who tells you he or she was initially drawn to study marine mammals for reasons other than an attraction to charismatic, endearing animals is a liar.

Susan Shaw left the laboratory and went to sea, where her research confirmed that the type of chemicals that endangered the bald eagle had made their way into seal populations. Ken Woisard

Also out on the water with Shaw and me are two graduate students, helping with her research, and Corine Koopman-Esseboom, a Dutch pediatrician who has studied the effects of perhaps the best-known endocrine disruptors -- polychlorinated biphenyls (PCBs) -- on infants in the Netherlands. The convergence of more than a hundred MDs, public health scientists, and animal biologists at Shaw's conference was striking, but it made sense. Seals and other marine mammals, poisoned by chemicals produced by people, are sometimes hunted and eaten by other people. The human mothers, like the seal mothers, give their fetuses a chemical bath in their wombs. They both pass contaminants along in their breast milk; their babies are both smudged with chemical fingerprints. And so, throughout the field of endocrine disruptors, a thriving, multidisciplinary collaboration is drawing together scientists who study people and those who study animals.

Like most of us, Shaw has erected stelae along the arc of her life, and on three different occasions, with as little variation as if she were reading off a stone inscription, she tells me the story of how the harbor seals first spoke to her. She was a doctoral student at Columbia University's School of Public Health when, in the spring of 1988, just six months into her dissertation research, she realized that the early protease inhibitor HIV-AIDS treatment study she was working on was not the right path. "In any kind of research there are many, many things that can go wrong," says Shaw, "and it seemed like in that project everything was going wrong." She was also frustrated by the project's single, narrow focus. And by the work, which chained her to a lab bench, no interactions with anyone or anything.

After calling a halt to her research, Shaw went up to a summer house near Mount Desert Island to stare out at the sea and think about a new dissertation topic. One day, she opened the local paper and began reading about thousands of dead harbor seals in the Baltic-North Sea area and how the problem might have been caused by PCBs. Shaw's background was in immunology and environmental toxicology, and she was already enchanted by the seals that crowded her field of view. The story moved her.

"I kept thinking about it the whole summer," she tells me. "There were pictures of these dead seals on a beach. And I started thinking, If that's the hypothesis, that chemicals are involved in this extreme population event, what are the levels in animals here? If we are actually wiping out these big mammals because of things we're doing -- actually watching their bodies float up on the shore -- it's a horrible scenario."

Marine biologist Peter Ross tags a nursing harbor seal for easy identification. Young mammals can be exposed to high levels of contaminants in their mothers' milk. Bruce Obee

Although Shaw was surrounded by seals in 1988, there was not much of a rescue network in place on the East Coast to provide her with stranded seals to study. So she headed to Sausalito, California, which offered an active stranding center that rehabilitated beached marine mammals, as well as experienced field biologists to team up with at nearby schools and research institutes. The regional seal population was stable, but more pups were being stranded and the number of infections had been rising. Shaw suspected endocrine disruptors.

There are more than a hundred synthetic chemicals known to be capable of interfering with the hormones that choreograph the growth and operation of critical systems of the body. The external molecular designs of these chemicals resemble those of natural hormones; because they can interact with hormones and their receptors, they can carry false messages or block or scramble the correct messages. Young, still-growing animals are the most susceptible to damage from these misdirections. And an organism in its earliest days in the womb -- when it is still being transformed from a raw mass of cells into a functioning creature of organs and limbs -- is exquisitely sensitive to even minute exposures. During this time, endocrine disruptors can cause profound, lifelong effects on the skeleton, brain, and endocrine and immune systems. In some cases, they can leave an animal prone to growth and development abnormalities, such as misconfigured sexual organs. In others, they may disrupt the body's ability to produce antibodies or T-cells, making it vulnerable to infections.

Shaw's arrival in Sausalito marked an abrupt change in the nature of her research. For the first time, she started applying her talents in organizing, fundraising, and communicating -- she's a former filmmaker and photographer -- to her science. Shaw wrote the protocol for a study that required her to coordinate the work of researchers at nine different labs and universities scattered around the country. Her dissertation, published in 1998, confirmed that the stranded Pacific Coast pups, like marine mammals everywhere in the world, were contaminated with DDE (the substance left after DDT breaks down chemically) and PCBs. Shaw also found that the seals with more contaminants in their blubber had signs of immune depression and endocrine disruption -- supporting her suspicion that contaminants had contributed to the strandings.

But the ultimate import of her findings didn't resonate with Shaw until she began writing up their relevance to human health, and came across new studies from Holland. One, co-authored by Koopman-Esseboom, measured the same immunological effects in infants that Shaw had studied in seals. It showed that even at very low contaminant levels, comparable to those Shaw found in seal pups stranded on the beach, the immune systems of human babies had been diminished. "They were finding the same thing in children that I found in these seals," she says now. "It was just shocking to me."

xamples of endocrine disruptors at work in the world's industrialized lakes, rivers, and estuaries, where waste pipes still pour and contaminants collect in alarming concentrations, are numerous and notorious. There's the famous sexual confusion of alligators in Florida's Lake Apopka, where young male gators have been found with abnormally high levels of estrogen and abnormally small penises. Beluga whales in the St. Lawrence Estuary, plagued by high levels of PCBs, are afflicted with pneumonia, bacterial infections, gastric ulcers, and high rates of cancer. The killer whales of Puget Sound have been called the most polluted mammals on earth.

But what about the seas, the open ocean, and along coastlines, where dolphins, whales, and seals live? As yet, the scientific community has no single answer. To a great extent, the answer may depend on local conditions. And, because of the nature of endocrine disruptors, those conditions vary widely around the world.

The most troubling endocrine disruptors are in the class of chemicals labeled persistent organic pollutants or POPs -- "persistent" because they don't easily decompose, and once loose in the environment they last a long time. The vast majority of POPs are industrial chemicals, pesticides, herbicides, or manufacturing byproducts. Most were banned long ago in the industrialized world, though they are still present in contaminated soil and water. But until very recently, developing nations continued to use them with abandon. And around the world there are stores of unused POPs -- the UN recently estimated that half a million tons are in the developing world alone -- many in rotting barrels and warehouses from which they are inexorably leaking. So POPs are now ubiquitous. They have spread to the most remote spots on earth, contaminating places thousands of miles from any site where they were ever manufactured or used.

Scientists fear that the immune systems of even seemingly healthy seal populations, like the one near Bar Harbor, Maine, may be compromised by POPs, making seals vulnerable to sudden epidemics.

Each chemical follows a slightly different path through the environment. The most volatile, such as the group of agricultural pesticides called hexachlorocyclohexanes, evaporate from water and soils and disperse into the atmosphere -- where they rise invisibly until they're swept up by global air currents. Often, they are carried to distant northern latitudes. There they condense in the cooler temperatures, falling to the ground or into the ocean when it rains or snows. By one estimate, a slug of a highly volatile chemical can get from India to the Arctic in just five days. And although sunlight, warmth, and other natural effects can eventually degrade even POPs into less harmful substances, at ground level or undersea in the cold of the Arctic this process takes place with excruciating slowness. Chemicals that might survive for only a few days after being used in the tropics may last a year or more if they reach a colder climate. Hexachlorocyclohexane levels in the Canadian north can be as much as a hundred times greater than in the tropics.

Nature also concentrates POPs through the process known as bioaccumulation. In seawater, the chemicals are so highly diluted that they are harmless. But POPs, by definition, are lipophilic; that is, their molecular structure causes them to grip onto the fatty tissue of animals. What the great volumes of the seas dilute, invertebrates, then fish, and then each larger creature in turn concentrates, retaining the contaminants of every smaller creature it consumes. The mathematics of this phenomenon, called biomagnification, are staggering. A killer whale at the top of the food chain retains in its body contaminants that may have been distilled 10 million times.

To add to the problem, cetaceans, and to a lesser extent seals, have an unusually low capacity to degrade POPs in their bodies. Yet these are precisely the animals that are the major natural food sources for peoples in the northern Arctic. It is as if nature and the chemical industry had conspired to concentrate endocrine disruptors into tightly packed, tasty containers, and deliver them to the shores of the one place on earth where humans are likely to consume them.

fter Shaw returned to Maine and completed her doctorate, she began wondering once again about the seals she saw from her back porch. She had organized MERI to help coordinate and fund her Pacific Coast research. Now she planned a new study that would draw on its resources. It was while Shaw was telling me about her search for a less lab-confined dissertation topic that her intern walked in with the first stranded seal pup carcass for testing.

To all appearances, Maine's harbor seals are thriving. In fact, seal populations along the eastern seaboard have been burgeoning since the Marine Mammal Protection Act was passed in 1972. So the possibility exists that Shaw is headed down a blind alley -- that there are no detectable endocrine disruption problems in her seals, and her study will merely provide baseline data on contaminant levels in western Atlantic seals.

But population-wide effects of POPs are not always obvious, or easy to untangle from other factors. Animal populations rise and fall naturally. It can be difficult to say whether small dips in a population are the product of lower reproductive rates and slightly diminished immune systems -- or just the ordinary stress of trying to find food and survive in the wild.

The elusive quality of these effects has created a rift in the scientific community. Some of the more dubious regard the evidence for population-wide harm as not just equivocal but positively chimerical. Others, convinced that the problem is real, are wary of being accused that they're doing careless science or, as Ross Norstrom of the Canadian Wildlife Service puts it, acting like the scientific version of "left-of-center greenies."

When I ask him about the skeptical note in the paper he presented at the Bar Harbor workshop, David St. Aubin, director of research and veterinary sciences at Mystic Aquarium in Connecticut, acknowledges that I heard correctly. "I was maybe trying to infuse some balance into the discussion," he says. "I'm certainly in agreement that exposure to these chemicals is not a good thing. But I think it may be oversimplifying to suggest that every inflection in mortality is a direct result of contaminants."

Seal populations off Maine are burgeoning. But, asks one scientist, "If a population is growing, is that going to be our only way of measuring its health?" Frank S. Balthis

St. Aubin acknowledges that he is on the cautious side of a continuum that, at times, is more like a chasm. Most Bar Harbor participants expressed an ardent belief that marine mammals are contaminated with endocrine-disrupting chemicals at levels that at least have the potential to lower birth rates and alter growth and development. They also concurred with the growing sentiment that in marine mammals it is the weakening of the immune system that is the most common, most pernicious threat. In a consensus statement to appear in the December issue of Environmental Health Perspectives, he conference speakers said: "At present, the weight of evidence suggests that the contaminant-endocrine system link is no longer a hypothesis, but constitutes a real health hazard to wildlife and humans."

n late March, I drive out to the marine mammal stranding center at Riverhead, New York, to have a look at some seals in extremis. The facility's main building is an outsized utilitarian construction that looks like an aircraft hangar. Even in the sea turtle area, which is filled with the grinding hum of motors circulating water, I can hear muffled whoops and yelps, the sort of racket I'm used to at my vet's office. After passing the room where antibiotic capsules are stuffed into herring and mackerel -- and after dunking our feet into a tub of disinfectant to prevent the spread of disease from one animal to the next -- we enter the cavernous seal room. Giant metal and plastic tubs of all sizes are spaced evenly across the floor. Each one holds a seal, most of them holding their heads up and staring at us warily.

It's peak season at the stranding center, when seals from further north are moving south in search of food and territories, and with forty-two animals -- the most it has ever seen -- the facility has surpassed its carrying capacity. Seals waiting for tubs are lined up in cages along the wall. "At this point," says Kim Durham, the rescue program director, "we're only picking up critical animals."

The patients at Riverhead arrive malnourished, dehydrated, overcome by heavy parasite infestations. Some are now clearly on the road to recovery, moving around as vigorously as they can in a few inches of water in the high-walled tubs. Others lie listless, their tubs filled with discolored feces, a sign of intestinal distress. Durham's seals may, or may not, be immune-compromised. She'll provide samples to Shaw for analysis. But the fact that there are many different species, from different points of origin, leads Durham to look to more natural causes for this year's high stranding rate.

It is, in any case, a minor blip compared with some events of the past. During the late 1970s, an influenza virus killed 450 harbor seals off Cape Cod. In 1987, morbillivirus killed about half the inshore migrant population of bottlenose dolphins from New Jersey to Florida. The bodies contained high levels of PCBs, DDT, and other immunosuppressants. During the Baltic-North Sea die-off that changed the course of Shaw's life, almost 20,000 harbor seals died of morbillivirus.

Peter Ross, then a Canadian graduate student who had studied the devastating effects of environmental contaminants on cormorants in the Great Lakes, was also reading accounts of the Baltic-North Sea catastrophe in 1988. "The virologists figured there was a virus at the root of it," he remembers. "I had a different background, and figured, Well, there might be a virus responsible, but contaminants are making them vulnerable." Ross flew to Europe's largest stranding center, in Pieterburen, the Netherlands, to see for himself.

What he found horrified him. "The workers were just being overwhelmed by the numbers of animals being brought in, by car, truck, helicopter, everything, arriving as I stood there. Lots of animals coming in dead. Lots of animals coming in taking their last gasps. These animals were coughing, sneezing, they had pus around the eyes, they had open sores around the gums, skin ulcerations, diarrhea.

"The people were just exhausted, working seven days a week, and often eighteen hours a day. It was a little bit like a battle zone. And there was this perception that the North Sea was collapsing, that the North Sea ecosystem was dying. That's how scary it was. It wasn't just seals, but also, What are they telling us about the environment when they're dying like this?"

Ross went on to make his name in the world of contaminants research. He took part in a study in which he fed uncontaminated young harbor seals either PCB- and dioxin-laden herring from the Baltic Sea, or relatively contaminant-free herring from the Atlantic. In a single year, white blood cell function in the seals fed Baltic herring was diminished by 30 to 50 percent.

The Inuit people, like this mother, face a tough choice between a sugary, fat-laden western diet and their traditional one, in which marine mammals play an important role. Ottmar Bierwagen

But what about the seals of the Maine coast -- whose populations are not dying off, but robust? I ask Ross, now at Canada's Institute of Ocean Sciences and among the most respected experts on marine mammal contaminants, whether Shaw may be wasting her time. But he points out that a seemingly healthy population can nevertheless be immune-compromised, and vulnerable. "You can certainly conceive of a population that is growing and that seems to be doing okay," Ross says, "and all of a sudden a new virus comes in that they haven't seen before. And if they're healthy and their immune system's working properly, that might be reflected by a common-cold sort of response. Whereas if their immune system isn't working properly, you might get mortalities -- something like the Spanish flu in 1918." That is precisely what Ross and other scientists think happened in 1988.

In all probability, Maine waters are not as polluted as the North Sea's. According to Richard F. Addison, head of contaminants science at Ross's lab, concentrations of contaminants along the eastern seaboard have been falling rapidly and are likely twenty to thirty times lower than those in the North Sea at the time of the die-off.

However, almost every scientist I spoke with had the same admonition: Don't make assumptions. The seals of the northwestern Atlantic and the waters in which they swim have never been studied intensively before. Moreover, these waters have seen dramatic contaminant events in the past -- notably, the collapse of Maine's marine bald eagle population as a result of DDT. And there are still significant sources of pollution in the region, such as a PCB-contaminated former naval base just north of Shaw's study area.

Adds Ross, "If a population is growing, is that going to be our only way of measuring its health? Are we going to be happy if there's a seemingly healthy population but they've got malformation or developmental abnormalities? Because if we're weakening a population -- if we're affecting their evolution or their adaptability or lack thereof -- then we certainly aren't doing them very much good."

Or, as Louis Joseph Gillette, Jr. of Lake Apopka alligator fame told the Bar Harbor workshop: "You don't just have to kill things to have long-term consequences."

n no ecosystem on earth are people closer to animals than the Arctic, where approximately 150,000 Inuit live in parts of Alaska, Canada, Greenland, and Russia. And as scientists have discovered, when we poisoned the creatures of the oceans, we also poisoned ourselves; for many Inuit literally depend for their survival on meat and blubber from narwhals, belugas, walrus, and seals, as well as fish.

In the mid-1980s, Eric Dewailly, a Quebec community health worker, began looking into POP levels in Arctic Inuit. What happened next was a scenario that has recurred often in the study of environmental contaminants: A scientist goes into a remote and presumably pristine region in search of unsullied physiologies, takes a few samples, and his jaw drops. Dewailly found that Inuit mothers had five times the amount of PCBs in their breast milk as women further south. On Baffin Island, the Inuit who eat the most marine mammal meat consume chlordane at levels up to twenty times the recommended maximum allowance. A sugar cube-sized piece of muktuk -- the skin and surface fat from the beluga -- contains the accepted maximum weekly limit of PCBs. In a week, some Inuit eat a hundred times that amount.

What are the health repercussions? A famous 1985 study of Great Lakes Mohawks by Sandra and Joseph Jacobson found memory and language deficits among children whose mothers ate the most PCB-contaminated fish during pregnancy. At age eleven, the children had lower IQs, poorer memory, and difficulty learning to read. But the effects are often described by other scientists as "subtle." And Dewailly says he cannot yet tell whether the Inuit children's mental development has been impaired.

However, Dewailly has less reserve about discussing the immunosuppressive effects. The Inuit babies he studied developed twenty times more infectious diseases during their first year than babies in southern Quebec. Infants with the highest exposure to POPs were almost twice as likely as unexposed children to develop acute inner-ear infections. As a result, nearly one in four Inuit teenagers have long-term partial hearing loss.

But Dewailly is a pragmatic man, and he is transported to a very different place from that of most scientists who study endocrine disruptors. In evaluating his findings, he must perform an excruciating calculus -- a risk-benefit analysis that accounts for the fact that all the contaminant-soaked traditional Inuit food offers a vitamin-packed, stupendously healthy diet, full of protein, vitamin A, selenium, and the fatty acids that may be responsible for the Inuit's very low rates of cancer and almost complete absence of heart disease. And the alternative, Dewailly points out, is processed, nutrient-poor food imported from southern Canada, high in sugar and saturated fats. "Most of it is junk food," Dewailly tells me. "If all the population shifts to a western diet, they will die from diabetes and heart disease."

hen I speak with Shaw on the phone this spring, she says she now knows that in the summer, the seals she is studying eat mostly hake. Hair samples revealed that the animals have substantial mercury levels, which she'd expected. Also high lead levels, which were a surprise. Blood samples are being tested for endocrine disruption and immune system function.

And Shaw herself has been learning more about the hands-on rigors of wildlife biology. During a day spent at the Riverhead stranding center restraining seals so vets could take the tissue samples now being analyzed in her lab, she was nearly clawed and bitten by an adult gray that backed her up against a wall. The species, says Shaw, is "absolutely vicious."

But the experience has not dulled Shaw's sense of mission, or of kinship, at least with the harbor seals. "Humans are not so unlike seals," she tells me. "They're close biologically. The endocrine system is similar. The organs are similar. And we are also wild animals." And, she might have added, we both live at the top of and at the mercy of the long, contaminated marine food chain.

That's karma. In the end, it always catches up with us.

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OnEarth. Fall 2001
Copyright 2001 by the Natural Resources Defense Council

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