Scientists Find DNA Proof of Swine Feces in North Carolina Homes

In Duplin County, North Carolina, there is a pollutant that hangs in the air, the water and the soil. It tumbles in the breeze and into homes through open windows, settling as a thin film of dust on their kitchen tables. It gloops together in masses of sludge in the surface water that feeds their creeks and streams. The fresh, nostalgic smell of seawater along the county coast has dissipated, replaced by a permanent foul smell from nearby swine factory farms, similar to that of a decomposing body, residents say. Policymakers have long ignored their complaints but new research from Johns Hopkins University publishing soon could finally show scientific evidence of pollution that officials can’t ignore.

It wasn’t always this way, says Devon Hall, who grew up in Duplin County. Over the past few decades, Hall tells Sentient that he has witnessed the rapid expansion of swine factory farms in the region. Now, hogs generate 10 billion gallons of waste across the state annually, so much so that their pollution can be seen from space. Neighbors not only deal with the pungent smell that emanates from these farms, but are also more at risk of adverse health effects from pollution. Constant exposure to pig waste can lead to lung problems, brain damage and an increased risk of bacterial infections.

Hall, who co-founded Rural Empowerment Association for Community Help (REACH) says interactions with policymakers and industry are fraught. “Has anyone died?” was one county commissioner’s response to residents presenting their concerns, Hall recalls. “That was a bit cold because that’s what you’re asking for? You want body bags until you believe us? Take some stock in the science,” he says.

Air pollution from Duplin County farms is linked to 98 premature deaths annually, according to The Washington Post’s reporting. Across the U.S., food production results in 15,900 air quality–related deaths, mainly from fertilizer application and livestock waste. Yet a key gap remains in proving pollution exposure and, consequently, harm in Duplin County. Christopher Heaney, associate professor at John Hopkins Bloomberg School of Public Health, has been working to close that gap and develop a new tool in collaboration with residents that can be used to identify when air pollution comes from pig waste.

Researchers Develop New Tool to Identify Pollution

Using microbial source tracking, Heaney identified a specific bacterial gene sequence called “Pig-2-Bac” that is unique to pig fecal waste. That means that if this bacteria is detected, there is no way the feces could be from a cow, a bird, a human or any other sort of wild animal — which is important, considering the pushback from industry and politicians.

Although a 2017 report by a former EPA and USDA employee found hog feces DNA particles had reached residents homes, this work goes further. Hall and Heaney developed a diagnostic tool that shows this particular harmful bacteria “Pig-2-Bac” has not only reached residents’ doorsteps but actually gotten inside their homes, too.

“If there’s Pig-2-Bac detected on that swab, on that sample that came from the inside of your house, we know that shouldn’t be, plain and simple. I don’t have hogs inside my house,” Hall tells Sentient. “Most of us don’t have hogs even on our properties…So we know it’s airborne, and that’s how it’s getting into the house.”

Using a specialized Q-tip, Hall and other residents swab the inside and outside of their homes for the pig dust before Heaney analyzes the sample in the lab to measure both the frequency and quantity of this pig sequence. After examining over 1,400 samples from roughly 300 households, they found the highest concentration of fecal waste in neighbors who lived close to or worked in the industrial farms.

“It’s not just an indicator of swine fecal filth, which has incredible implications for people’s dignity, their overall health, the ability to live with the absence of a nuisance,” Heaney says, but it’s “also within the context of antimicrobial resistance, which represents important health implications for the neighbors.” The presence of Pig-2-Bac was strongly associated with antimicrobial resistant Staphylococcus aureus strains — of concern, considering the growing prevalence of superbug diseases while new antibiotic treatments remain scarce.

New Research Builds on Decades of Citizen Science

Science and community collaboration have long gone hand-in-hand in Duplin County to identify pollution sources. The epidemiological effort was largely led by Steve Wing, a former researcher at the University of North Carolina Chapel Hill and Heaney’s former mentor, who studied how agricultural industries were emitting harmful chemicals like hydrogen sulfides that were disproportionately affecting Black residents and residents of color. But Heaney says industry and officials often dismissed their research and community grievances as nothing more than a malodor, rather that evidence of real health impacts.

Heaney has continued Wing’s legacy of digging into pollution exposures in Duplin by working in collaboration with residents like Hall.

One poignant example of their work was finding evidence of fecal contamination in surface water and drinking water. Duplin County officials again dismissed it, saying there was no proof that contamination is coming from industry farmed pigs, it could just be from wild animals, Heaney says.

“I remember hearing this and saying, ‘oh my, this is just such a challenging dynamic for the communities,’” Heaney tells Sentient. The writing was on the wall, he says — there are over “2,000 permitted swine concentrated feeding operations, each with approximately having a football field-sized lagoon containing fecal and urine waste,” and laboratory-based evidence of impaired water quality, but it still wasn’t enough to implicate the industrial hog operations in their eyes.

Heaney was undeterred, deciding to zero in on specific markers like Pig-2-Bac that would unequivocally link these hog operations to the ongoing contamination issues in Duplin County.

Duplin’s Factory Farming Mainly Affects Communities of Color

Industrial hog operations in Duplin County spray pig fecal matter into the air via massive sprinklers, raining down upon locals. Such facilities and their waste (stored in open cesspools) are disproportionately concentrated in Black, Latino and Native American communities — creating a long-standing legacy of environmental racism.

A 2023 study found that the largest CAFOs in Duplin were located where more than 56 percent of residents were people of color, and that exposures to associated chemicals were 66 percent higher for households where members spoke poor English, and 13 percent higher for low-income households. CAFO stands for Concentrated Animal Feeding Operation; these are more commonly called factory farms or industrial livestock operations.

Beyond the more obvious physical health impacts, living adjacent to pollutant-heavy and smelly industries brings a mental toll, too. The World Health Organization defines health as not merely the absence of disease, but the ability to achieve a full state of physical, social and emotional well-being. Research indicates that people who live near factory farms have higher risks of respiratory problems and mental health issues.

In North Carolina, hurricanes regularly wreak havoc and breach manure lagoons, causing them to contaminate local waterways. Beyond that, CAFO owners have also illegally drained their lagoons prior to hurricanes by spraying the waste into the air, posing a serious public health problem for locals.

Multiple groups have worked to prove environmental racism in court cases, the most recent of which REACH is involved in, along with the environmental law organization Earth Justice. Their complaint aims to change the exemption for industrial farms in reporting their air emissions to the Environmental Protection Agency.

“​​I’ve never advocated to put anyone out of business. We’ve learned there’s superior cleaning technology that’s better for the environment, better for human health. So implement it, don’t tell me that it’s not economically feasible. The [industry] not wanting to change the same method of disposing of swine waste tells me that they really don’t care,” Hall says.

Gathering Evidence to Strengthen Future Lawsuits

North Carolina’s laws limit the ability of residents to put forth nuisance lawsuits against the state’s agricultural industry — the bulk of which belongs to Chinese-owned Smithfield Foods. “I think that was shameful on their part, not just because they passed those bills, but because the industry belonged to another country.” Hall says. “I know there’s politics involved, but at the same time, when you hinder your state regulatory agencies from doing their work and it’s proven that these facilities, the way they’re operating, are harming people — then I’m not sure what to say about our North Carolina assembly.”

Environmental justice lawyers say the data gleaned from Heaney’s diagnostic tool will bolster evidence for filing future complaints against agricultural polluters. The EPA is due to revise its Clean Air Act standards, which will require factory farms to monitor and report their emissions. It’s unclear if this will actually happen under the leadership of Lee Zeldin, who plans to deregulate the agency. A recent Senate vote also limited regulation of air pollutants from industries.

Duplin County is used to the pushback from politicians and industry, but will continue to fight for clean air and water, Hall says. “It is tiresome. It does take a psychological toll on us. But at the same time, what do you do exactly? I can’t just sit down and do nothing, because I still live here. Because I’m not planning to pack up and move. This is home to me.”