Immune-Altering Pollution: It's Headline News
Air Date: Week of June 7, 1996
Steve Curwood speaks with Marla Cone, an environmental reporter at the Los Angeles Times about her recent articles on links between animal die-offs and human immune system disorders, and what many scientists believe is causing problems throughout the animal kingdom: persistent synthetic chemical compounds.
CURWOOD: This is Living on Earth. I'm Steve Curwood. Over the past few years there has been an ominous trend. Marine mammals have been dying off in large numbers. Dozens of beluga whales in the St. Lawrence River, 1,000 dolphins in the Mediterranean, half of Europe's harbor seals. At the same time researchers have noticed immune disorders in people, leading at times to widespread illness. The link between these trends, according to more and more scientists, is persistent toxic chemicals in the environment. Over the past few years, we've reported on the association between these chemicals and the disruption of reproductive and neurological functioning, as well as immune responses. Now there's harder evidence that pollution is causing animals and people to succumb to diseases that they might otherwise fight off. Los Angeles Times environmental writer Marla Cone has interviewed dozens of researchers and reviewed hundreds of scientific reports on the subject. She joins us now from the NPR studios in Los Angeles. Hi, Marla.
CONE: Hello, Steve.
CURWOOD: Tell me, why are scientists thinking now that immune disorders and pollution might be connected?
CONE: Well, scientists say it's a question of not whether this is happening, it's to what degree. There have been some massive die-offs among wild animals throughout the world, especially marine mammals that feed in contaminated water. And when scientists started exploring what was happening here they originally thought it was natural causes. They found viruses and bacteria in these animals. But when they explored a little further, they also found that the animals that died also had high levels of PCBs in their tissues and other contaminants, too, but mostly PCBs. And they found a correlation between those. Animals that survived epidemics had much lower levels of these contaminants in their tissues.
CURWOOD: And this had affected their immune systems.
CONE: Right. What it did is, it apparently suppressed the animals' immune cells. They couldn't produce the T-cells, the B-cells, the natural killer cells, those lines of defense against viruses and bacteria and infections.
CURWOOD: And we're talking, this is in response to chemicals like what? Dioxin, PCBs?
CONE: PCBs, DDT, all the organochlorines, as well as some metals and hydrocarbon type chemicals.
CURWOOD: Now there's a study involving seals in the Netherlands that shows a pretty strong link here between pollution and immune disorders. I wonder if you could discuss that for us.
CONE: This was a fascinating study, and it was a landmark one that all the scientists draw attention to. Because what they did is, they took 2 sets of seals that were taken from the wild. One set was fed fairly uncontaminated fish from the Atlantic and Europe while the other was fed highly contaminated fish, contaminated with PCBs, from the Baltic Sea. And at the end of this, what they found is that the seals that were fed the most contaminated fish from the Baltic had severe immune suppression. They lost 25 to 35% of their immune ability.
CURWOOD: How does that compare to something like AIDS?
CONE: In AIDS, in a severe case, you would have fatal complications from a 50% suppression. So we're talking about seals that were fed for only 2 years, which is short, much shorter than the life span of these animals. Yet they had suppression that would mirror what happens with people with AIDS. And these seals were fed natural fish, I mean, that they normally would feed on. And perhaps the most alarming thing to the scientists is that these were also fish that were sold in commercial markets. People in Europe eat these very same herring.
CURWOOD: What about people and pollution? Are immune systems fairly similar to these animals, and so we have a similar risk?
CONE: All animals, and that includes humans, have the same basic immune cells. So we're all facing similar risk. It all depends of course to what our exposure is. And everybody says that certain animals might be more sensitive to pollutants than humans, but nobody really knows at this point.
CURWOOD: Now there have been some looks at humans, for example, the Inuit have been studied, right?
CONE: The Inuit people who live in northern Quebec are living in a very highly contaminated environment, which surprises a lot of people. That's because the pollution seems to wind up there. It blows up there in the air and through the water. And they're winding up, the women especially are winding up with such high amounts of contamination in their blood and their tissues that they pass it on to their infants. And these infants are born with highly suppressed immune cells, and they wind up with a high rate of diseases, especially chronic ear infections which lead to hearing loss, and meningitis and pneumonia.
CURWOOD: What about the rest of us who don't live in the Arctic? What about the world's general population? Are we at risk of suppressed immune systems?
CONE: Experts say that everybody on this planet is immuno-suppressed, and that's because we all contain certain amounts of these compounds in our tissues. This doesn't mean that people are dropping dead. What it means is that people aren't as healthy as they would be, and experts tell me that perhaps the general population has lost 5% of its immunity. Now that might sound like a minor degree of immune suppression, but that's worldwide, that's chronic, that's not just a transient loss of immunity like you'd get from a stressful day at the office.
CURWOOD: So that means that we get sicker more often and stay sicker longer?
CONE: Yes, that's exactly what scientists say it means.
CURWOOD: Marla Cone is an environmental writer for the Los Angeles Times. Thanks for joining us, Marla.
CONE: Thanks, Steve.
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