Americans eat approximately 7 billion hot dogs between Memorial Day and Labor Day — 150 million of which will be consumed on July 4.

The vast majority of the hot dogs eaten today will be made from pigs that come from eastern North Carolina, where a quiet battle has been waged for years between massive factory hog farms and surrounding rural communities.

The battle is being fought over pig shit.

A hog produces three times as much of the stuff as a human. According to the North Carolina Department of Agriculture, there are about 7.7 million hogs and pigs in the state. So all of those future hot dogs produce more than 40 million gallons of shit… every single day. And factory farms don't really know how to dispose of it.

The current popular method is to gather the untreated waste in vast open-air cesspools called lagoons, which can measure thousands of square feet and hold millions of gallons of the toxic sludge. When these lagoons fill up or overflow, it's common practice to pump out the waste and spray it in a fine mist across nearby open spaces. (Yes, that's really what happens.) The mist soaks the fields and pollutes the air.

When accumulated in vast amounts, pig shit becomes highly toxic, emitting potentially deadly gases such as ammonia, hydrogen sulfide, and methane. In addition, the byproduct of factory farming is often not just feces, but also pretty much anything that ends up on a slaughterhouse floor — urine, blood, and flesh.

The toxicity of the substance is hinted at by the color of the lagoons, which are an unnatural-looking pink.

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The smell that comes off these lagoons permeates the surrounding area, powerful to the point of destruction and overwhelming from miles away. The lagoons are often located in residential communities, and not surprisingly, residents are not happy about it.

Steve Wing is an epidemiologist at the University of North Carolina and has studied the public health effects of these waste lagoons. "You're seeing acute symptoms, like mucus membrane respiratory issues, in these surrounding communities," Wing told VICE News. "Spraying this waste causes air pollution, which causes asthma for people living nearby, especially in children."

According to a study conducted by Wing, more than half the people who live within two miles of an industrial pig farm reported that they were unable to go outside or open their windows because of the noxious odor. Other documented results of the toxic fecal spray include severe nausea, fainting, seizures, brain damage, and pregnancy complications.

A toxic hog waste lagoon in eastern North Carolina. Photo via Wikimedia

What's more, lagoons tend to overflow when it rains, meaning the toxic sludge seeps into the ground and contaminates the drinking water of surrounding communities.

Lagoons have been known to burst when they overflow, dumping their contents into the nearest body of water. In 1999, a lagoon spilled 1.5 million gallons into the Cape Fear River. But the biggest hog waste lagoon spill occurred in 1995, when an eight-acre lagoon burst and spilled more than 25 million gallons of shit into a nearby river. The spill killed 10 million fish and destroyed miles of coastline.

Rick Dove used to be a river keeper in North Carolina's Neuse River and a commercial fisherman, but he was forced to stop fishing after the pork farming industry killed off most of the fish in the surrounding waters.

"When you fly above these cesspools and look down, you see they're literally right next to neighborhoods and people's houses," Dove said. "These communities are completely surrounded by these cesspools. People used to enjoy going outside, sit on their back porch, but they can no longer do that. The area is inundated by flies and you never know when the stench is going to hit you."

'When you have a really large presence of factory farms, like in North Carolina, they exert a huge amount of political pressure on state legislature or state politics.'

The cesspools are almost always located in disadvantaged and low-income communities, where people don't have the resources to fight back against the factory farms. Wing has called this "environmental racism."

"Low income communities and communities of color is the path of least resistance," Wing said. "If [the companies] are able to exploit them, that's where they'll go."

Another outspoken critics of the pork companies in North Carolina is Don Webb, who used to be a hog farmer himself. He stopped in the early 1990s after his neighbors began complaining of the stench coming from his operation. He has since devoted much his time to fighting factory pig farming.

"They don't put [the lagoons] by the country clubs, they put them out where the poor people live," he told VICE News. "You think you could build one of these factory farms near a golf course? Absolutely not. The spray system is the cheapest, most primitive way of getting rid of the waste. I've been in the hog business, and I know how it stinks."

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Smithfield Foods, which was recently acquired by the Chinese corporation Shuanghui International Holdings Ltd., is by the far the biggest and most notorious hog producer in North Carolina.

Last year, almost 600 residents of eastern North Carolina sued Smithfield Foods for their waste-management practices, arguing that they presented a public health hazard. But the case has been sitting in a "mediation process" since then.

In a similar case in January of this year, environmental groups in North Carolina filed an intent to sue the owners of a hog farm for discharging toxic waste into their groundwater in violation of the Clean Water Act. The owner of the farm in question is Wendell H. Murphy Jr, a major political donor in the state and the son of an influential former state lawmaker and billionaire, Wendell Murphy. A lawsuit still hasn't been filed.

"When you have a really large presence of factory farms, like in North Carolina, they exert a huge amount of political pressure on state legislature or state politics," said Patty Lovera, a spokeswoman for Food and Water Watch, an NGO that monitors consumer food safety. "The EPA has always struggled with taking on agriculture issues such as these because there is just not much political will to do so."

When VICE News asked Smithfield Foods about the various lawsuits, a spokeswoman declined to comment, saying it was company policy not to speak about open litigation. She also declined to comment on its waste management techniques, and instead directed any inquires toward the company's FAQ.

"Our companies have invested millions of dollars over the past 15 years to evaluate different manure management technologies and will continue to monitor emerging technologies," the FAQ reads. "A few years ago, we sponsored research… that analyzed 18 different treatment technologies; the researchers concluded — and we agreed — that anaerobic lagoons are the best technology for Murphy-Brown's existing North Carolina farms today."

This infuriates Don Webb. "Everyone else in the country is eating pork, but we're the only ones paying the price," he said. "They're letting our homes, our families, and our communities stink up with urine and feces.

"I truly think it would be more difficult to prosecute a hog farmer than a murderer in North Carolina."

Follow Olivia Becker on Twitter: @obecker928