Health and Environmental Risks of Sludge Use in Food Production

by Ben Lilliston, 10/14/08 • Consumers should choose foods produced without sludge and avoid use of sewage sludge-based fertilizer products in home gardens, concludes a new guide by the Institute for Agriculture and Trade Policy (IATP).

Think Forward is a blog written by staff of the Institute for Agriculture and Trade Policy covering sustainability as it intersects with food, rural development, international trade, the environment and public health. The Institute for Agriculture and Trade Policy promotes resilient family farms, rural communities and ecosystems around the world through research and education, science and technology, and advocacy.

Sewage sludge can contain disease-causing microbes, synthetic chemicals, and heavy metals that can cause acute and chronic disease, finds the “Smart Guide on Sludge Use in Food Production” by IATP’s Marie Kulick. 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 through food animals that graze on sludge-treated land.

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. IATP developed the “Smart Guide” and companion resources to help consumers make informed food and fertilizer choices.

“Given the high contaminant content of sludge, it makes no sense to allow the use of sludge on agricultural land or home gardens,” says Kulick. “This practice poses an unnecessary health risk, particularly when there are safer alternatives available.”

The Environmental Protection Agency (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.” Many states have adopted tougher heavy metal standards and better management practices for sludge, but still fall short of what is needed to assure safety of sludge use in food production, both on the farm and at home.

You can listen to an interview with Marie Kulick, as well as download IATP’s Smart Guide on Sludge Use in Food Production, a chart outlining the potential health effects of some of the more persistent synthetic chemicals found in sludge and a list of sludge-based fertilizer products marketed for home use at: www.iatp.org.

The Institute for Agriculture and Trade Policy works locally and globally at the intersection of policy and practice to ensure fair and sustainable food, farm and trade systems.