Steroids and hormones used to treat livestock are passing through the animals and into the environment. Science News senior editor Janet Raloff discusses concerns that they may be damaging the development of fish and other animals.
CURWOOD: For decades, the North American livestock industry has used growth- promoting hormones and steroids to increase meat production. Concerns have centered primarily around whether enough residues remained in the meat to be harmful to humans. But, until recently, no one has examined how much of these chemicals pass through the animal and get into the environment. Now, scientists and regulators are becoming concerned that what the animals excrete may have a significant impact on the ecosystem.
Here to talk about this is Janet Raloff, senior editor of Science News. Hi, Janet.
RALOFF: Hi, Steve.
CURWOOD: Janet, tell me, what's the problem with the hormones used to treat livestock animals?
RALOFF: Well, from the farmers' point of view, there aren't a lot of problems. They are actually quite good. These are reproductive hormones that essentially re-program beef cattle, for example, into taking more of the energy than their food and turning it into muscle or meat, than into other activities, such as making babies. From an environmental perspective, however, you've got to remember that these hormones are very potent chemicals. Biologically, hormones are probably the most potent agents known. Now, ordinarily when the body produces them, it produces them at a certain time to produce a certain function--maybe to put you to sleep or to tell a developing embryo to grow a certain way and become a male versus a female.
But when these things end up littering the environment, they can be exposing critters throughout the environment, at any time, sort of willy-nilly, and causing them to turn on or off certain biological activities inappropriately.
CURWOOD: Janet, how compelling is the evidence that the use of hormones in livestock does create a problem this way, being excreted into the environment?
RALOFF: Well, there's no longer any doubt that animals do excrete large amounts--at least 10% of what they're administered. There also have been some very recent studies, both in the laboratory, but even more in some environmental studies downstream, of livestock operations in Nebraska that show that fish exposed to these compounds, basically their development can be derailed. Some of the males end up looking a little bit feminized, some of the females are ending up with masculine features. Sometimes the young fish in some of these studies have ended up producing egg yolk protein, first stage in egg production, long before they were ever supposed to do it. It would be sort of the equivalent, in human terms, of a toddler producing eggs.
So, they clearly can have an effect. The question is how broadly they're polluting the environment right now, and nobody has done those pervasive studies to find out.
CURWOOD: I have to ask you, why has it taken so long for science to become concerned about this?
RALOFF: Good question, and I think that was probably because the initial concern about them was safety, both to livestock and to people who might eat meat from treated animals. And in fact, I would suspect that if they found this stuff getting into the environment, back 20 or 30 years ago, the big concern was that farmers would be ending up paying for a drug that they didn't use, not that it was going to be harmful to the environment.
Now, there have been a few sort of insightful researchers even 30 years ago that started worrying about this, but their concerns became sort of overshadowed as this whole laundry list of new chemicals with hormone like properties--some of them pesticides or drugs or plasticizers--came under the horizon and people recognized that they had these endocrine disruption or hormone like properties.
Ironically, these livestock steroids are not hormone-like agents. They're the real thing, and they're sometimes 100 to 1,000 times more potent than the endocrine interrupters people have been worried about.
CURWOOD: So, where is all this headed? What needs to change here, to respond to this concern?
RALOFF: Well, in the past, livestock wastes have not been taken probably as seriously as human wastes. When you get a big community of people, you wouldn't let all of their urine and feces enter the environment untouched; you actually put them through waste treatment plants. The same isn't being done for livestock, even though you can have huge communities, large herds of animals producing huge amounts of wastes, and this stuff is allowed to pretty much enter the environment as is. I think that in the future that's going to have to change.
CURWOOD: How is animal waste treated now?
RALOFF: For the most part, cattle waste would be held in large filtration ponds, basically, lagoons of waste, and they'll just be left there for the solids to settle out and the liquids will slowly filter through the soil and into ground water or surface water. What you'd like to do is potentially even compost them. New USDA studies, done for an entirely different reason, were looking at what happens when you compost chicken waste, for example, and it turns out that all livestock naturally produce estrogens and testosterone and other steroids in their waste. They thought, is there some way you can naturally encourage the degradation? So, they put them in compost heaps and after four months, the hormones in those wastes were down to almost negligible levels. It's reasonable to think that you might be able to do the same thing on a regular basis with feedlot wastes as well.
CURWOOD: Janet Raloff's article on animal waste appeared this month in Science News. Thanks, Janet.
RALOFF: My pleasure, Steve.
[MUSIC: "Who Let 'Dem Cows Out?" Weird Al Yankovich]
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