Air Date: Week of January 5, 2001
CURWOOD: Stunted sexual development in alligators. Egg proteins produced by male fish. These are examples of the effects of hormone disrupting chemicals in our environment. Most research has focused on pollutants that mimic or interfere with estrogens, the female hormones. But now for the first time, scientists have identified an environmental androgen. Androgens are chemicals that work as male sex hormones. Janet Raloff covered the story for "Science News" and joins me now. Hi, Janet.
RALOFF: Hi, Steve.
CURWOOD: Janet, set the scene for us now on this research. Let's say we were to go down to Florida, to the Fen Halloway stream, where the substance was first identified. What will we see?
RALOFF: You'd see a beautiful, shady stream. The only thing that might catch your attention is it's a bit stinky. It has a bit of a chemical smell. But not too out of the ordinary for some of the swampy streams in the area. The most notable thing is that the water is the color of espresso coffee. You put your hand under the water and you probably won't even see it. Visibility is about an inch or two.
CURWOOD: Wow. And this is because?
RALOFF: It turns out this was right downstream of a pulp and paper mill. And this particular mill uses so much of the water from the stream that at times 100 percent of the lower Fen Halloway is effluent from the pulp and paper mill. So we're dealing with basically straight paper mill wastes.
CURWOOD: Who can live in this kind of place?
RALOFF: Well, the scientists who were down there suspected nothing could live in there. But they dipped in their nets and they found lots of little fish. Mostly something that's called mosquito fish. These are tiny fish that you can find all over the southeast. They get their name because they eat mosquitoes. If they look hard enough, they can find some other fish, too. It's not a real broad range of fish. But there are things that live in there, and they actually seem to like it.
CURWOOD: How did they know that they had found fish that had their hormones affected?
RALOFF: Every single fish seemed to look like a male. Males have different fins than females. They have, on the bottom side of the fish there's a long, elongated anal fin, which is used in copulation. It's called the gonopodium. And all of these fish seem to have it. And that just didn't make sense, that every single fish was a male. And then they realized that one of the fish they caught had a black spot on it, and that black spot usually connotes a female that's pregnant. Sure enough, there were more like that, and they realized that many of these male-looking fish were actually pregnant females. And they looked some more, and over the next basically 20-something years, they've been showing that there are lots of males and females, but all of the fish look like males.
CURWOOD: So, what exactly is causing these kinds of changes in the fish?
RALOFF: It turns out, after much probing, that there seems to be a series of androgens, or male sex hormones, in the water. The primary one that they found is something called androstenedione. It's better known as andro. It's the thing that Mark McGuire used to sort of boost up his muscle tone and that sort of thing when he was on his home run hitting streak.
CURWOOD: So this isn't actually a hormone mimic. It's the actual hormone itself that's in the water.
RALOFF: It's the real thing. Only in this case it doesn't come out of a bottle.
CURWOOD: How would something like this get into the water from a paper mill?
RALOFF: Well, it doesn't directly get into the water from the paper mill. The paper mill is putting out some other compound, probably a cholesterol-like substance that's from its bark. And in the water, and probably in the sediment, there are bacteria that convert this plant sterol into androstenedione. So, you actually have the activity of bacteria in the water that are making this hormone out of some kind of ordinary pulp mill waste.
CURWOOD: Now, aside from making girl fish look like boy fish, what other effects do you get from androstenedione?
RALOFF: There are behavioral changes. The females, for example, try to mate with other females. They seem to recognize a masculinized female across the stream from them as looking like a real female. They don't seem to recognize that they themselves are females. So there is this inappropriate sexual behavior. In addition, while they are fertile, they produce far fewer babies than would ordinarily be the case. The males are far smaller than usual, extremely stunted. And the females, at least in some related species that are in the same rivers, are turning amazingly aggressive. In fact, one scientist who'd studied them described them as little sharks. He put, like, a little paper into a beaker with these fish in it and they'd chomp holes right through the paper.
CURWOOD: Janet, you've covered this issue of hormone disruptors, endocrine disruptors, for a number of years. What do you see here as the wider implications of discovering andro and these other androgens in a body of water?
RALOFF: Well, the first thing is that nobody knew they were there. They didn't even know to look. And if they're there, you've got to wonder, what other things have we been missing over the years? The second thing is, you've got very hardy fish that have survived in this water, but in more dilute concentrations other fish and aquatic life might also survive. And what kinds of subtle effects might you see in them? Because hormones tend to have pretty similar effects on all vertebrates, including humans. But I think maybe one of the most interesting things that it makes you think about is that what these fish are being impacted by are not the paper mill wastes directly, but by something that's been transformed by bacteria. So in other words, these ordinary microbes in the water and sediment are playing an active role in changing the pollutants to which we're exposed and the effects that it'll have.
CURWOOD: Janet Raloff is senior editor at Science News. Her article, "Macho Waters," appears in the January sixth issue of Science News. Thanks for filling us in, Janet.
RALOFF: Thank you, Steve.
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CURWOOD: Just ahead: What to do when noisy neighbors keep you up at night, and those neighbors may be the world's noisiest frogs. Stay tuned to Living on Earth.
Now this environmental technology update with Cynthia Graber.
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