Escherichia coli—usually abbreviated as E. coli—is one of the most common “gut flora” in mammals. It is a species of bacteria that flourishes in the lower intestines ; in the course of a day, a typical human being will excrete anywhere from 100 billion to 10 trillion E. coli. Though you can occasionally find it growing in other areas—along the edges of hot springs, for example—it’s almost entirely native to the mammalian digestive tract. While harmless (and even crucial to proper digestion) in its normal habitat, when introduced to other parts of the body, E. coli can cause disease. When it’s introduced in food, it can often cause food poisoning very similar to dysentery. Of course, its presence in food makes the genesis of such poisoning quite clear: your food is covered in shit.

A lovely, appetizing thought, of course, given the current E. coli outbreak. While some might be tempted to believe that its incidence at Taco Bell restaurants simply means that fast food employees are careless washing their hands, the evidence makes it abundantly clear that the problem is much more systemic than that. The contaminated vegetables—scallions and white onions have both been implicated—were traced to a single storage facility supplied by Ready Pac, a California producer with offices in Irwindale (near Los Angeles), and at least some farms in the Salinas Valley.¹ Steve Dickstein, marketing vice president for Ready Pac, identified the region where they were grown only as “California.”²

More recently, a midwestern chain—Taco John’s—has suffered the same fate. While the cause in that incident has not yet been tracked down, a clear pattern is emerging. Earlier in the year, it wasn’t fast food, but bagged spinach that spread E. coli.

In both cases, the ultimate source of the outbreak was California, though the food was consumed in the northeast and the midwest. Specifically, “America’s salad bowl,” the Salinas Valley. This is hardly surprising, after all; more than half the country’s spinach, and an overwhelming percentage of other salad greens are grown in this single central California valley. This isn’t new for Salinas, either; this is the ninth time since 1995 that a national E. coli outbreak has come out of the Salinas Valley.

So why is so much of the food coming out of the Salinas Valley covered in shit?

The ultimate answer is precisely because the valley produces so much of the country’s food. California grows not only produce but livestock as well, and E. coli lives not only in human digestive tracts, but other mammals, as well.

Cows don’t have the luxury of hand-washing. When they are cramped into pens, ankle-deep in the manure of hundreds to thousands of cows, E. coli tends to spread. Bacteria can splash up on udders and get into milk; or get into intestines and contaminate meat during the slaughtering process; or pass through the cow in manure and ultimately end up on crops directly as fertilizer or indirectly by leaching into the water supply.³

Salinas Valley suffers from both problems. The concentration of the country’s agricultural output also concentrates a great deal of its ecological impact. The result is that the water used to irrigate the majority of the country’s salad greens in the Salinas Valley is incredibly thick with fecal contamination—or to put it more bluntly, it’s full of cow shit. When that water is supplied to the fields, it gets into the crops, and the result is an E. coli outbreak.

In the wake of the E. Coli outbreak that resulted in the destruction of spinach crops in California’s Salinas Valley it appears that the bacterium is so pervasive that almost every waterway in the valley is in violation of national standards. An environmental scientist at the Central Coast Regional Water Quality Control Board in California has stated that many of the water sources coming into the Salinas Valley watershed have generic E. coli and may carry the E. coli strain linked to the spinach food poisonings.⁴

We should recognize this for what it is. This is not a question of washing vegetables or even the unhealthy nature of fast food. The E. coli is being absorbed right into the vegetables in their irrigation water. This is the price we pay for intense, concentrated, industrial agriculture.

At work are the perverse forces of economic markets, not the forces of nature. The U.S. food production system has been fined-tuned to maximize profits for a small group of farmers, often corporations, holding vast acres of land.

Spinach from small, local farms could very well be contaminated with E. coli O157:H7. It simply wouldn’t spread to other states, or to other cities for that matter. Health authorities would be able to identify the source of the bad E. coli within hours. And tons of safe spinach sold around the country wouldn’t need to be recalled “just in case,” as is the case now.

Small-scale farming inherently means fewer hands and fewer opportunities for contamination—bacterial, viral or parasitic—from field to fork. So while the small, local guys aren’t immune to the kind of contamination problems that plague the big guys, the odds are in their favor.⁵

Concentrated agriculture not only increases contamination, but it also means that one problem in one part of the country will infect everyone. The 1,500-mile salad has huge implications not only for energy, but for our health, as well. If you can’t stay on the paleo diet, the 100 mile diet is a good way to go, too (or do both!).

The industrial agricultural system is the only thing that can ramp up to feed 6.5 billion people, but it can’t do it well—to do so, even temporarily, it must compromise the health and well-being of us all, and undercuts its own foundations. We shouldn’t kid ourselves: eating locally will never work in such an overpopulated world. But by the same token, neither will anything else.