Keeping Sludge Away from Your Seedlings Is Harder than You Think

Some common brands of compost contain a potentially toxic material misleadingly labeled as "biosolids."

By Jill Richardson

Spring is so close we can almost taste it. If you’re a gardener, you’ve already counted how many weeks until the last frost, ordered your seeds, and perhaps even began starting your seedlings indoors.

And if you’re like some gardeners, once it’s warm enough, you’ll take them outside and plant them in sewage sludge.

Yes, that’s right. I said sewage sludge.

“I would never do that!” you might think, with a disgusted look on your face. But would you? How would you know?

I tried an experiment a few years ago. I went to a few local Home Depots and asked the gardening staff about several Kellogg brand “compost” products, all of which contained sewage sludge from Los Angeles County. “Does this contain sewage sludge?” I asked. They swore up and down that it didn’t.

They probably even thought they were telling the truth. After all, the ingredient lists on the bags said they contained “compost.” Not stated: They contained composted sewage sludge.

How does the sludge make it into the gardening aisle at your local store?

The story started long ago when we began mixing together all of our waste — including industrial waste — with water and disposing of it through the sewer to sewage treatment plants. They do their best to separate the water from everything else. The “everything else” is the sludge I mentioned. Then they have to get rid of it.

Cities used to just dump the sludge in the ocean, but — it turned out — that was bad for the fish.

Unfortunately, responsible and sanitary disposal of sludge can be expensive.

The solution? Call it fertilizer and put it on farmland. (Over the years, this has been a popular way to deal with industrial waste. Some of the first pesticides were arsenic-based waste products from the dye industry.)

But how would industry get Americans to accept using sewage sludge on farms and even in gardens? Step one: rename it. The Water Environment Federation lobby and PR group actually held a contest. Entries included “bioslurp,” “the end product,” “geoslime,” and “hu-doo.” The winner was “biosolids.”

The Environmental Protection Agency took it a step further. They gave out a $300,000 grant to the main lobby group for the sewage treatment industry to “educate the public” about the “benefits of sludge.” And they codified the term biosolids into law.

If you unwittingly get a bag of sludge at your local garden store, it will contain Class A Biosolids. Both the government and the manufacturer will assure you that it’s highly regulated. And it is — sort of.

Out of the thousands of toxic chemicals that are found in that sludge, they strictly regulate exactly 10 heavy metals and two pathogens.

And it’s nice that they regulate lead, mercury, and Salmonella. But you’re still left with everything else: flame retardants, nanoparticles, pharmaceuticals, endocrine disruptors like triclosan, cancer-causing dioxins, and a long list of other nasties you don’t want in your garden. Or in your body.

The public relations efforts to convince us that sludge is good for our gardens can be quite powerful. So much so that it even fooled Eliza Barclay of NPR’s program The Salt. When I wrote her to give her the facts, she replied that the sludge-as-fertilizer scheme is actually a program to “recycle precious nutrients.”

Right. But — as I wrote back to her — would you eat a salad laced with toxic chemicals just because it’s full of nutrients too?

If you’re with me on this one, you can avoid food grown in sewage sludge by eating organic or buying gardening materials that are listed by the Organic Materials Review Institute.

OtherWords columnist Jill Richardson is the author of Recipe for America: Why Our Food System Is Broken and What We Can Do to Fix It. OtherWords.org