Leafy greens contaminated with deadly microbial pathogens pose a serious threat to U.S. consumers. Lawsuits against growers and processors over the past two decades have forced the industry to pay tens of millions of dollars in compensation to outbreak victims and to implement extensive food safety measures. Unfortunately, these efforts have fallen short because they fail to address an important root cause of the problem.

Mounting evidence suggests that the escape of manure from nearby cattle operations into agricultural water sources and growing fields is a significant source of contamination. However, the beef and dairy industries have successfully blocked efforts to strengthen environmental regulations aimed at eliminating the discharge of manure. Additionally, cattle operators have refused to adopt voluntary measures, such as animal vaccination and antimicrobial feed supplements, that would reduce the presence of pathogens in manure.

As a legal scholar who studies how civil liability incentivizes companies to improve food safety, I believe that bringing nuisance lawsuits against cattle operators for the escape of manure would complement existing environmental regulations and motivate feedlot owners and dairy farmers to vaccinate their herds and use antimicrobial feed supplements. 

Regulating growers and processors is not enough
Contaminated leafy greens cause an estimated 2.3 million cases of acute gastroenteritis annually, generating $5.2 billion in healthcare costs. Investigations have identified the escape of manure from nearby cattle operations as the likely source of contamination in some of the most severe outbreaks.

Pathogens in cattle feces reach crops through multiple pathways. Rainwater runoff and flooding can carry manure from grazing lands and feedlots into irrigation canals or directly onto fields. Manure stored in lagoons may seep into groundwater, contaminating wells used for irrigation. Windborne dust from dried manure can settle on crops, while flies, birds, rodents, and other animals can transport pathogens between cattle operations and produce fields. Farm equipment and field workers sometimes inadvertently spread contamination by carrying manure on tires and footwear.

Although the cattle industry contributes significantly to the contamination of leafy greens, the responsibility for addressing the problem has fallen almost entirely on growers and processors. They are subject to stringent regulations and demanding industry standards designed to mitigate microbial contamination at both preharvest and postharvest stages. Growers must test water and organic fertilizers, establish buffer zones and barriers to around their fields, and train workers in hygiene and sanitation. Processors, meanwhile, employ chlorinated washes, ozone treatment, irradiation, ultraviolet or blue light exposure, and cold plasma applications to decontaminate produce. They also use refrigeration to inhibit pathogen growth.

Unfortunately, these costly efforts have not put an end to recurrent foodborne illness outbreaks traced back to contaminated leafy greens.

Instead of trying to mitigate the effects of contaminated manure migrating into growing fields and processing plants, an alternative approach would be to prevent the escape of manure from cattle operations in the first place. This is wher environmental regulations enter the picture.

Gaps in existing environmental regulations
The U.S. Environmental Protection Agency’s National Pollutant Discharge Elimination System (NPDES) requires facilities that release pollutants into U.S. waters to obtain permits and adhere to minimum waste management standards. State regulators enforce a variety of additional measures for cattle operations, such as monitoring water quality and mandating dust control practices to limit airborne contamination from manure.

However, the NPDES permitting regime has significant gaps. For one, the program does not regulate runoff from cattle grazing in pastures and rangelands, and stormwater runoff from fields treated with manure is largely exempt. Additionally, water quality monitoring is limited by a lack of scientific consensus regarding what to test for and how to test for it, as well as by the wide variability of pathogen survival based on the organism and environmental conditions. Moreover, in some states, animal feeding operations are required to obtain and comply with the terms of a permit only if they have previously discharged pollutants. 

Trade associations representing the beef and dairy industries have successfully resisted attempts to fill in these gaps in the NPDES regulations. Consequently, manure from feedlots and dairy farms continues to be a source of microbial contamination in agricultural water.

The promise of cattle vaccination and feed supplements
Aside from preventing manure discharge, another strategy for protecting leafy greens is to eliminate pathogens within the manure. Field trials have demonstrated that vaccination dramatically reduces the number of cattle that shed pathogenic E. coli in their manure and decreases the concentration of harmful fecal bacterial in the manure of cattle that still do. In addition, studies have shown that supplementing feed with probiotics or various foods with natural antimicrobial effects—such as orange peel, cottonseed, and seaweed—reduces the shedding of pathogenic bacteria in manure.

None of this is to say that vaccination or feed supplements will entirely eliminate foodborne illness outbreaks caused by contaminated leafy greens. Neither vaccination nor feed supplements can completely eradicate the presence of harmful microbial pathogens in cattle manure. Moreover, cattle are not the only source of microbial pathogens that contaminate crops. Outbreak investigations indicate that birds and other wild animals may contaminate agricultural water sources or intrude into fields. 

Nevertheless, reducing fecal shedding by cattle would complement current efforts by growers and processors to mitigate contamination in the pre- and post-harvest stages of production. Additionally, insofar as cattle and surrounding wildlife serve as sources of infection for each other, addressing infection among cattle might also reduce the prevalence of infection among birds and other wild animals.

Resistance among cattle operators and dairy farmers
Regrettably, cattle operators have shown little interest in adopting pathogen-reduction measures due to a lack of economic incentives. Vaccination and feed supplementation add costs without benefiting cattle health or profitability. Since many fecal pathogens like E. coli O157 are harmless to cattle, ranchers, feedlot operators, and dairy farmers rely on downstream processing methods such as steam pasteurization of beef carcasses and milk pasteurization to eliminate microbial threats to consumers, reducing their motivation to intervene earlier.

Moreover, industry groups have consistently opposed mandatory vaccination, arguing that scientific research on efficacy remains inconclusive. Although vaccines have been commercially available since 2009, trade associations and major beef producers continue to resist regulatory efforts to require their use, citing concerns about cost and the lack of direct benefits to cattle operations.

Using nuisance law to motivate reform
Nuisance lawsuits against cattle operations for the escape of contaminated manure would incentivize ranchers, feedlot operators, and dairy farmers to pay for vaccinations and feed additives. 

The discharge of manure containing harmful pathogens into nearby agricultural water sources and growing fields and its subsequent contamination of the food supply constitutes both a public and a private nuisance. A public nuisance is broadly defined as unreasonable interference with a right common to the general public. This includes any activity—such as pollution of water sources by animal waste —t hat is harmful to health and interferes with the enjoyment of life or property of a large number of people. A private nuisance is a non-trespassory invasion that affects another person’s ability to use and enjoy their land.

The legal remedies for successful nuisance claims include the award of monetary compensation and injunctions to abate (i.e., eliminate) the nuisance. Nuisance litigation against cattle operators for the discharge of contaminated manure could result in court injunctions to abate the nuisance, which might include measures to prevent manure discharge beyond NPDES requirements, as well as mandatory cattle vaccination and feed supplementation. More broadly, the prospect of legal liability for foodborne illness outbreaks could provide cattle operators with an economic incentive to adopt such measures preemptively without anyone actually having to file a lawsuit.

The role of civil litigation in advancing food safety
The U.S. food safety system relies on three essential pillars. The most visible pillar is  government regulation at the federal, state, and local levels. A second, no less important pillar, is industry standards and the extensive private food safety auditing infrastructure of that enforces them. The third pillar is the civil liability system, which provides powerful economic incentives for companies to ensure that the food they produce is safe.

The Trump administration’s efforts to reduce government regulation — especially in the area of environmental protection — makes is highly unlikely that Congress or the EPA will eliminate the gaps in the NPDES standards governing the discharge of manure from cattle operations. Moreover, neither the beef nor the dairy industries show any sign of voluntarily adopting cattle vaccination or feed supplementation. Civil liability is the one remaining pillar for addressing the devastating impact that recurring foodborne illness outbreaks from contaminated leafy greens continue to have on consumers, growers, and processors. 

For more than two decades, leafy green growers and processors have worked hard to implement one of the most extensive and demanding programs of private standards in the food industry — the California and Arizona leafy green marketing agreements — and the industry has collaborated with university researchers and government agencies to support the development of the federal government’s produce safety regulations. 

Now it is time for the beef and dairy industries to do their part, and nuisance lawsuits would be an effective way to encourage them to do so.

This article is adapted from Timothy D. Lytton, Using Nuisance Law to Advance Food Safety, published in the Denver Law Review and available on SSRN.