Friday, April 15, 2011

Are Biosolids Safe?

At a recent industry-sponsored biosolids conference Deborah Koons Garcia castigated the EPA-approved practice of turning sewage sludge into fertilizer.

The waste-treatment community would like us to accept this practice.  Critics charge that the Environmental Protection Agency (EPA) has turned a blind eye to the industry’s desire to pass off toxic material as a safe fertilizer.  Could this be?  Let’s find out.

According to an EPA web page
  • ·         The risk assessment for the Federal Part 503 rule that governs the land application of biosolids took nearly ten years to complete and had extensive rigorous review and comment.
  • ·         Only biosolids that meet the most stringent standards spelled out in the Federal and state rules can be approved for use as a fertilizer. Now, through a Voluntary Environmental Management System, being developed for biosolids (EMS) by the National Biosolids Partnership (NBP), community-friendly practices will also be followed.
  • ·         Although cities decide how best to manage their biosolids, the U.S. Environmental Protection Agency (EPA) is obligated and continues to provide the public with educational information, based on the best science, about the safe recycling and disposal of biosolids.
In other words, the EPA has chosen not to regulate the production of biosolids from sewage waste.  Rather, this agency has positioned itself only to provide information to the public.

But does this really confirm critics’ charges that the EPA is capitulating to businesses that might be more concerned with profit than with human health?  Why don’t we compare the science behind the policy to make up our minds.

In a 2003 press release
the EPA announced its decision not to regulate the dioxin content of land-applied sewage sludge.  In other words, the EPA claims that its analysis of the data on sewage-born dioxins allows it to conclude that the dioxins in the sludge pose a negligible risk of increasing human cancer rates.

This, however, is not the last word on the toxicity of sewage sludge.  A Wikipedia article on sludge
contains references to studies that suggest that at least some sludge is anything but benign.  According to the article, one study published in 2002
documents numerous instances of pathology among 48 people living near a site where sludge residues were applied.  For instance, about one quarter of this population suffered from Staphylococcus aureus infections, with two deaths noted.  (Curiously, the lead author of this published study was an employee of the EPA.  Did anyone say, “Suppressed results?)

Another study cited in the Wikipedia article
presents evidence for concern.  According to the authors of this study residents near another site where sewage biosolids were applied reported a variety symptoms or maladies at statistically significant levels.  These included abdominal bloating, jaundice, skins ulcers, bronchitis and giardiasis.

This is not to say that human excrement should not be converted into fertilizer.  A number of sources suggest that human wastes can successfully boost agricultural productivity.  For example, one article summarizes a grass roots pilot project for bacterial decomposition of human waste.
According to Nancy Klehm, the brainchild behind the project, feces can be converted into high quality fertilizer—if it is collected directly from the human beings producing it.  On the other hand, trying to convert sewage sludge into something safe has the inherent disadvantage that sewage collects and concentrates many additional toxic by-products.  These include toxic metals, pharmaceutical compounds, insecticides, industrial wastes and pollution runoff from urban roads.

Finally, I’d like to ponder this question.  You mean the EPA is not the impartial entity I believed it to be?  If I can’t trust the EPA, who can I trust?  WHO, indeed!

The World Health Organization recognized that human wasted could be an essential component of agricultural nutrients in many areas of the planet.  Therefore, this organization published the results of its studies as a guideline document for people to practice safe production of “humanure”.  Here is that document:
By the way, that is only the Executive Summary.  If you want the full document, use this link:

So there it is.  From bio-mess to biomass.

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