Sewer sludge not safe for crops

By Christianne Carin

President Barack Obama has shown his willingness to jump on “teachable moments,” events that at first seem small or local but can act as a springboard to look at larger issues. Obama has one of these moments right in his own backyard, literally, with the discovery that his organic vegetable garden contains high amounts of lead. Tests for other harmful chemicals are underway.

The story first broke in mid-June when tests showed elevated levels of lead in the garden. The levels were 93 parts per million, slightly under the U.S. Environmental Protection Agency’s 100 ppm danger level, which, to be fair, is common in urban areas from the settling of a hundred years of vehicle exhausts. In fact, many urban gardens have levels that exceed the EPA’s limits.

What’s of more danger are the tens of thousands of chemical compounds that are found in treated sludge — including hundreds of different prescription and over-the-counter drugs that we flush down our drains, cleaners and soaps — from home and industrial and processing wastes that use our sewers for disposal. Sludge is the end result of “treating” human and all other wastes entering our sewers, mainly by decomposition during storage, aeration and filtration in order to turn it into material for reintroduction back into the environment.

This year, U.S. farmers will fertilize their lands with 45 million wet tons of processed sludge coming from municipal and county sewage plants across the nation. The sludge is used by farmers for fertilizer on crops that make their way directly or indirectly to our kitchen tables. The cities are more than happy to find a place for their sludge other than already overcrowded landfills.

In 1993, the EPA supported the disposal of sludge on farmland, through regulation and set limits on pathogens present. At the time, the government and sludge producers found a seemingly perfect symbiotic relationship to spread sludge on farmland including a massive PR campaign that quieted dissenting voices. Even spreading sludge on then-President Bill Clinton’s White House lawn was part of that campaign.

But this sludge may not be as safe as we think.

In February 2008 a federal court ruled that Georgia farmer Andy McElmurray was entitled to Agriculture Department “prevented planting” subsidies because of contamination of his farm by sewage sludge. Judge Anthony Alaimo found that the sludge was responsible for killing hundreds of dairy cattle and contaminating the milk supplies in several states. The U.S. District Court concluded that the evidence showed “McElmurray’s land is contaminated and unfit for growing food-chain crops” and that “the evidence of contamination on the McElmurray’s land was substantial.”

Among those now wary of using sludge on farms are food suppliers H.J. Heinz and Del Monte, both of which do not accept vegetables grown using sludge as fertilizer. The U.S. Department of Agriculture’s cutting-edge National Organic Program doesn’t allow organic farmers to use sludge.

Currently, there is a way to treat sludge that makes it safer for use in many situations. By heating sludge to over 800 degrees Fahrenheit all pathogens and many chemical compounds are rendered inert and the sludge is safe to use in nonfood crops (such as cotton and biofuels), land repair, golf courses and turf applications.

President Obama has made food safety a priority for his administration, and this teachable moment compels us to find a suitable and safe way to manage our sewage even if it means radically changing how we think about it. It’s time for policy makers and legislators to take a serious look at the dangers of using sludge on farms.

Christianne Carin, CEO of EarthRenew, Inc., is writing a book about the politics of manure.