Researchers have documented health problems in veterinarians and other people working in buildings where as many as 17,000 pigs are housed; however, less is known about the impact concentrated livestock operations have on the health of the people who live nearby.
More research and cooperation between the livestock industry and public health community are essential to solving these problems, said Dr. Kelley J. Donham, director of the University of Iowa's Center for Agricultural Safety and Health, during his session "Environmental concerns with concentrated livestock production: so what is new," July 22 at the AVMA Annual Convention.
Many veterinarians and other people who work at such operations develop severe respiratory problems from exposure to dust that contains endotoxins, glucans, and microbes, Dr. Donham said. To mitigate these risks, he and his colleagues urge those people to wear respirators. Hearing loss is another common problem, and wearing ear protection and avoiding barns during the loudest times—such as feeding, can prevent it. He suggested that veterinary schools teach students about the importance of using protective equipment and how to use it properly.
Women working in barns face unique risks, particularly during pregnancy, he said. Exposure to carbon monoxide or accidental inoculations with veterinary drugs can result in abortion.
The health effects of concentrated livestock production facilities on people in the surrounding community are not as well understood.
"There have not been a lot of studies in this area," Dr. Donham said.
Some studies have found abnormally high rates of depression and anxiety, respiratory ailments similar to those experienced by farm workers, and high rates of gastrointestinal problems in the communities surrounding concentrated livestock facilities. Dr. Donham cautioned, however, that these studies do not necessarily prove a causative relationship.
Additionally, antimicrobials and antimicrobial-resistant microbes have been found in hog dust at concentrated livestock operations. "There is some evidence that people in the barns or the neighboring community may be exposed to antibiotics and antibiotic-resistant microbes in the dust," Dr. Donham said.
University of Iowa studies have shown that hydrogen sulfate concentrations may exceed accepted amounts near concentrated livestock operations, whereas ammonia concentrations were rarely exceeded. Endotoxin and microbe concentrations were also a concern near these operations, but whether they are a biohazard is unknown.
Less-concentrated housing arrangements, such as hoop structures, may also create biohazards, according to the University of Iowa studies. The studies found increased amounts of ammonia, endotoxin, and microbes in the immediate vicinity of hoop structures.
Dr. Donham said that discussions about the public health impact of concentrated livestock operations can be emotionally charged, and public health officials and producers look to science for answers.
"Everyone says, 'We must have a science-based approach.' But the question arises, whose science?" Dr. Donham explained that public health experts and industry officials have divergent viewpoints that must be reconciled.
"It's like two entirely different cultures coming together," he said.
Public health experts aim to protect the public, including vulnerable subgroups. They also are focusing on prevention when they conduct risk assessment—they are not waiting for a body count, he said. They rely on the weight of the scientific evidence, even if the data are not complete. Industry officials are looking for more-definitive evidence.
Veterinarians have a large role in addressing public health problems created by concentrated livestock operations, Dr. Donham said. They should be aware of the problems and take measures to protect their own health and the health of their clients. They also should be able to assess environmental conditions in the barns and make changes as needed.
Dr. Donham urged industry officials to be proactive about these public health concerns and inform their producers and communities about these issues.
Researchers need to stand firm in the face of pressure from industry groups and provide the best science they can, he said. He also suggested that researchers find solutions to the problems, and not merely create lists of problems.