Hogs are enclosed in a barn at a concentrated animal feeding operation. (Photo: Environmental Protection Agency)

In the nation's top livestock-producing states, people living next to large-scale livestock operations often complain of odors, asthma, and hordes of flies. These concentrated animal feeding operations, or CAFOs, produce more than 1.1 billion tons of manure a year, but are subject to limited federal oversight, so their neighbors have turned to nuisance lawsuits to fight back. In North Carolina, a jury awarded the neighbors of Smithfield Foods' hogs farms $474 million in damages last year, the Winston-Salem Journal reports.

According to a report from the Food and Environment Reporting Network, agribusiness leaders don't want this kind of payout to happen again: With the support of state farm bureaus, more states are expanding laws that restrict who can sue a CAFO, and for how much. West Virginia and Oklahoma passed bills in March and April; lawmakers in Utah, Nebraska, and Georgia are considering similar proposals.

Here's what the research says about this approach.

Making It Harder for Low-Income People to Sue

All 50 states already have some form of these "right-to-farm" laws, which protect agriculture operations from lawsuits and zoning restrictions. As researchers write in the Journal of Rural Studies, the laws were originally billed as necessary protection for family farms, but as agriculture became increasingly consolidated, the laws moved to "collapse nuisance protections," shielding large corporations from public attacks.

These laws make it difficult for low-income people to sue, since about one-third of states require the plaintiffs to pay the agriculture operations' legal fees if the CAFOs win. Several states' proposed expansions would also cut down on punitive damages, like the kind paid out in North Carolina. This could exacerbate existing disparities: In North Carolina, studies have shown that the burden falls on the state's low-income African-American residents, who tend to live in counties with greater concentrations of hog waste and are saddled with lingering health risks from polluted water and air.

Excluding Neighbors Who Still Suffer Health Risks

In West Virginia and Utah, the new expansions would exclude anyone who lives outside a half-mile radius of a CAFO from bringing a nuisance lawsuit. But as a large body of research shows, the environmental and health effects of these operations extend miles beyond their borders.

Living next to CAFOs has been shown to pose a host of health risks, from the constant noise to the contamination of water wells on neighbors' private property. Runoff is a persistent problem, sending hormones and nitrates into lakes, rivers, and reservoirs nearby—hardly respecting a half-mile radius.

CAFOs also emit air pollutants, including ammonia, methane, and particulate matter, at much higher rates than small agriculture operations. One 2006 study found that children at middle schools within three miles of CAFOs in North Carolina had a higher prevalence of asthma symptoms.

And as the National Association of Local Boards of Health outlined in a 2010 report, odors from a CAFO can be smelled up to six miles away, carried on the air from the anaerobic reaction within the lagoons of hog and chicken waste. It's not just the stench: These odors have been linked to mental-health issues, including post-traumatic stress disorder, and can destroy neighbors' livelihoods. "Homes are no longer an extension of or a means for enjoying the outdoors," wrote researchers in a 2007 paper on CAFOs. "Rather, homes become a barrier against the outdoors that must be escaped."