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Out of the frying pan: Sludge fertilizer as the antidote to lead poisoning
For a second, there, I thought I was reading The Onion. No such luck.
In separate studies in Baltimore and St. Louis, government-funded researchers spread sludge fertilizer on lawns and vacant lots in poor, black neighborhoods to see whether the fertilizer would inhibit lead poisoning in children. In case you need a refresher (who doesn't now and then), sludge is what's left over at the waste treatment plant -- a semisolid mess made up mostly of human waste, with a few goldfish and anything else we've flushed down the drain. It's likely to contain heavy metals, antibiotics, lots of that stuff that's ending up in our water, and who knows what else. Recent studies show that earthworms in sludge fertilizer absorb all kinds of chemicals.
The idea behind the project is that iron and phosphorous in the sludge can chemically bind lead, preventing it from being bioavailable to children (or other animals) who eat the soil.
Go ahead. Read that last paragraph again.
Do they actually mean to say that soil amended with sludge fertilizer is safe to eat?
I applaud the researchers' attempt to find a low-cost way of mitigating lead exposure. I really do. But the government has been trying to find an economically beneficial way of disposing of human waste for the past 30 years, and it seems to be getting a bit out of hand. That these studies were carried out in poor black neighborhoods and, according to the AP story, there's no evidence that the subjects had follow-up medical exams, makes the whole endeavor a little smelly.
Photo by hufse.
Comments
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Posted by: John Fink | April 15, 2008 4:32 PM
I encourage you to read the original study (which I would be happy to send you if you email me). I think the ABC/AP journalists are taking advantage of American scientific illiteracy and our country's unfortunate history of screwing over the poor and minorities to push a sensationalist piece that seems to reflect reality very poorly. I actually read the original scientific article (and blogged about it over at http://bio-rocks.blogspot.com). Before it ever reaches lawns (or the store, this product is commercially available), it is composted for 45 days and then pasteurized (which is how we make milk safe to drink). The substance they used is actually an organic compost fertilizer and not "sludge", as the article claims. As part of the study, the researchers measured the amount of toxic chemicals (actually: trace amounts of lead, zinc, and other substances found naturally in soil) in the compost fertilizer (which turns out to be extremely below the EPA's safe limits, and also negligible compared to what was already in the soil).
One reason I wish more journals were open-access is that the media couldn't exploit people who don't have access to the original research and make false claims. What we have here is an environmentally-friendly, organic way to deal with human waste, that has been on the market for many years. These journalists make it seem like the scientists poured raw sewage on poor people's lawns. They did not.
Posted by: Sarah Werning | April 15, 2008 6:08 PM
Wow, thanks for your comment, Sarah. You make some good points, specifically in relation to pathogens and the composting/pasteurization process.
On the other hand, pasteurization doesn't get rid of all of the other chemicals that come along with human waste -- the cleaning and personal care products that go down the drain, the triclosan, the pharmaceuticals, the hormone disruptors... Did the researchers measure amounts of those sorts of things in the fertilizer, too? Other studies show that they're there, and I wouldn't call spreading that on lawns (or gardens, eesh) a safe or organic way to get rid of human waste.
I guess I just wish they'd do more testing on the effects of sludge fertilizer itself before they start trying to use it to solve other problems, y'know?
Posted by: Amanda | April 16, 2008 10:02 AM
Thank you for the informative article. I had no idea, for instance, that the US government has been trying to find ways to dispose of human waste. No idea. As you placed it into context, suddenly now I realize the alternative motive the government has for engaging in this sort of research. Thanks again for doing the legwork on this topic!
Posted by: Curious Reader | April 29, 2008 4:15 PM
They are using the sludge in our area. I don't know all the pros and cons of it. I do know they won't put it out if it is going to rain because of runoff. If it goes into tanks it will kill the fish. I do know you can smell it for miles around. I do know our cows eat the grass and it does get into well water. I do know I don't want it anywhere near me I don't care if they do say it's safe.
Posted by: Jaime | April 29, 2008 4:17 PM
Why don't the researchers test it on in their own neighborhood?
Posted by: Jill | April 30, 2008 2:21 PM