Sewage sludge can contain disease-causing microbes, synthetic chemicals and heavy metals that can cause acute and chronic disease. Many of these contaminants can persist in soil for centuries and can enter the food system through crops grown on sludge-treated land, as well as animals that graze on contaminated land.

Consumers should choose foods produced without sludge and avoid the use of sewage-based fertilizer products in home gardens, says a guide, entitledSmart Guide on Sludge Use in Food Production, from the Institute for Agriculture and Trade Policy (IATP).

Currently there is no labeling requirement for food produced on land treated with sewage sludge, and consumers may find it difficult to know if they are using a sludge-based fertilizer product. Given the risk factors, sludge usage should not be allowed on agricultural land or home gardens.

The EPA has set minimum standards for sludge contaminant content and application, but these standards include no restrictions on synthetic chemical content, weak limits on heavy metals and inadequate protections for pathogen content. The EPA’s oversight has come under heavy criticism following a February 2008 11th Circuit Court ruling in which “the fairness and objectivity of the EPA’s opinions with respect to the sludge land application program” was called into question. The judge found evidence that “extraordinary steps” have been taken by senior officials “to quash scientific dissent, and any questioning of the EPA’s biosolids program.”

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