Growing our food with sewage

One fifth of the world’s food is now grown in urban areas and for half of the urban fields the only source of water is untreated city sewage. Thus, according to a recent study from the International Water Management Institute (IWMI), one tenth of the world’s food is now grown using raw sewage.

Sewage abroad

Raw sewage brings heavy metals, pathogenic bacteria, and worms. But the water is necessary for the plants, and the sewage contains nitrates and phosphates, which promote plant growth. In many areas the use of city sewage has become necessary to prevent starvation. This is just one reminder of the consequences of our unjust global economic system and of the interconnections among water supplies, waste treatment, agriculture, the environment, and economic development.

Sewage at home

But the issues about sewage and agriculture are not confined to crowded cities in developing countries. In most of Europe and North America, about half of the sewage sludge is now spread on farmland, but after treatment that breaks down most of the complex organic molecules and kills most of the pathogens. A major contribution of US industry and the Environmental Protection Agency, has been to promote the term “biosolids,” for the treated stuff, which sounds much better than “sewage,” “sludge,” or “shit.” But despite the name change, we know little about the health and environmental effects of using it.

A report in 2002 from the National Academy of Sciences says that unsafe pathogens and chemicals remain in biosolids. No epidemiological studies have been done to show whether spreading them on land is safe for agriculture workers, nearby residents, or food consumers. In short, we don’t know whether we’re better off than the 10% getting the raw stuff.

Experimental sewage

Meanwhile, biosolid experiments are underway. Could sludge be a fix for hazardous lead paint by lowering the the rate at which lead enters the bloodstream and circulates to organs and tissues? A study asking that was conducted recently on a vacant lot in East St. Louis next to an elementary school. The 300 students were black and almost entirely from low-income families. It’s not clear how the residents could make informed decisions about participating in the study, given the NAS report that no studies have ever been done on its safety.

Where is the public?

Issues such as this never get mentioned in political campaigns, and rarely make the mainstream news. They’re unpleasant to think about, and solutions might require changes in lifestyle or large expense. Most of us are so confused that we can’t even frame the questions. Nevertheless, these issues deserve more attention as part of the world we’re making for ourselves and our children.

Writing in 1927, John Dewey (in The Public and Its Problems) noted that “The public is so confused and eclipsed that it cannot even use the organs through which it is supposed to mediate political action and polity.” In contrast to Walter Lippman, who argued for a knowledgeable elite to address complex problems, Dewey saw full participation in civic life as essential:

We have the physical tools of communication as never before. [But] the thoughts and aspirations congruous with them are not communicated, and hence are not common. Without such communication the public will remain shadowy and formless, seeking spasmodically for itself, but seizing and holding its shadow rather than its substance. Till the Great Society is converted into a Great Community, the Public will remain in eclipse.

I doubt that sewage will become the rallying call for the Great Community, but Dewey was annoyingly vague about what that call might be. What’s clear is that we need to find better ways to create the kind of democracy in which people really participate and which addresses the most basic problems we all face.

See also:

World’s farmers turn to raw sewage for irrigation – health (New Scientist)

Sludge tested as lead-poisoning fix (AP)

Sewage Sludge Standards Need New Scientific Basis (NAS)

2 thoughts on “Growing our food with sewage

  1. Pingback: Bookmarks about Sewage

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