This obstruction to truly organic gardening occurs because sludge companies are allowed to take the sludge left behind in wastewater treatment plants, bag it, and sell it as an organic amendment found in garden centers and big-box stores, unbeknownst to many organic gardeners. This is a real problem, considering the sludge is chock-full of pharmaceuticals, heavy metals, industrial waste, and gender-bending, hormone-disrupting chemicals—all of the nonsense organic-minded souls are trying to avoid in the first place.
Problems associated with sewage sludge aren't limited to bagged compost, either. Many farms in the United States fertilize with human sewage sludge, an application process that causes fumes and dangerous dust to linger in neighboring communities. A 2013 study from University of North Carolina researchers found that residents living near fields doused with liquefied or human sewage sludge cake stayed indoors instead of spending time outside their homes or going out to socialize with family and friends, thanks to offensive odors.
What may come as a surprise to those hunkering down inside in sludge zones is that previous studies found people living near sewage sludge-treated fields experienced headaches, skin rashes, breathing and stomach distress, and other health problems.
Whether you live near a sludge field or not, you can help keep the dangerous material out of your garden with a little persistence. For now, unless you make your own compost, it's best to be skeptical about bagged organic soil amendments. For instance, avoid compost that lists "biosolids" as an ingredient—that's a friendlier-sounding word for human sewage sludge. Compost should be crumbly, dark, and earthy smelling, not heavy and caked together with an ammonia or sewer smell.
Products on the Organic Materials Review Institute list do not contain sewage sludge because these products are allowed in organics. A search for "compost" on the OMRI database includes sludge-free soil products from Organic Mechanics and dozens of other suppliers.
For more specific tips on how to choose sewage-sludge-free compost, read How to Buy Compost. To learn how to build your own composting system at home, check out Organic Gardening magazine's How to Build a Compost Pile.