by Tamara Scully
The University of Nebraska Medical Center recently held its 10th Annual Agricultural Health and Safety Course virtually. Aimed at medical and safety professionals, registrants participated over several days, gaining a solid understanding of myriad health and safety issues which impact those working in agriculture.
A session on general environmental concerns in agriculture, presented by Dr. Risto Rautiainen, provided an overview of agricultural practices in the U.S. Air and water contamination concerns, which arise from various agricultural practices, along with the associated human health impact, was discussed.
The majority of farming in America relies on high input, medium precision practices at this time, Rautiainen said. High synthetic input farming causes more health concerns than lower input systems. Precision application of fertilizers, precision use of irrigation, reducing equipment passes in fields and utilizing reduced tillage can all lessen the impact of farming practices. Air, soil and water contaminants, including chemicals, pathogenic microbes from manure, greenhouse gas (GHG) emissions from equipment and concentrated animal feeding operations and nitrogen, phosphorous and trace mineral excesses can all arise from ag practices.
Breathing in dangerous particulate matter, having chemicals spilled on your skin, ingesting pathogens in contaminated food or drinking water or soil can all cause illness. There are also cumulative effects of repeated exposure to low level environmental hazards.
Infectious diseases caused by microbes are a concern in agriculture. Parasites are also common. These can be spread to humans directly by touch or via bodily fluids, or indirectly by animal or insect vectors, water, air or soil. Keeping these pathogens out of the environment is a priority to protect human health.
“There’s a lot of different bacteria that can be in the agricultural environment, and viruses that are common in rural and agricultural environments,” Rautiainen said.
Chemical concerns include water and soil contamination from fertilizer applications. Nutrient management is needed to reduce the adverse effects of excess nitrogen, phosphorous or trace minerals. When nutrient levels in soils are excessive, runoff and leaching move the excess into waterways. This not only wastes expensive inputs, it also causes pollution and health concerns.
Precision application of inputs, and proper timing of application, can mitigate issues. Proper land management, including cover crops, reduced tillage, riparian buffers, buffer strips, irrigation management and wetlands restoration, can all mitigate environmental concerns.
“Leaving land without any vegetation is always prone to erosion,” he said.
Agriculture can also add other pollutants to the environment. Veterinary pharmaceuticals, antibiotics, pesticides, GHGs and pathogens can all be introduced into the environment. In addition to finding their way into water or soils, they contaminate air as well.
These “can all potentially become aerosolized, and become a health concern,” Rautiainen said.
GHGs, a major source of air pollution, can come from agriculture. In the U.S., agricultural sources of GHGs amount to a mere 10% of the total overall. Agriculture does, however, have the potential to mitigate vast amounts of carbon. Putting animals on pasture can capture more carbon and offset the GHGs the animals emit.
“Agriculture is in a major position to take a lot of carbon out of the air,” he said. “Agriculture and growing green everything is really beneficial.”
Aside from GHG emissions, manure itself is a major air, soil and water contaminant. But there are methods of decreasing the dangers from land application of manure. Direct injection, rather than spraying or spreading manure, can reduce odors and runoffs as much as 90%. Tilling manure into soil is also beneficial, preventing runoff, as is never applying manure to frozen ground. Biogas systems remove methane from manure, transforming it into energy. Manure storage covers and roofs also decrease contaminant concerns.
Other sources of air pollution in agricultural areas include unpaved roads. Proper maintenance can decrease dust. Finding opportunities to decrease fire and smoke generation, modifying equipment to enhance combustion and creating wind barriers to stop the spread of pollutants over open spaces are other means of reducing air pollution.
Skin rashes, difficulty breathing, central nervous system damage, irritation of the eyes, nose and throat and increased risk of cancer are some health effects of exposure to agricultural chemicals. Death can also occur if exposure is severe. Pesticides and herbicides are commonly used in many farming systems.
“Insecticides are something to worry about,” he said. “If it kills an insect, what does it do to a person?”
Never store chemicals in containers other than the ones they came in, particularly if they’re not properly labeled or previously held food items. Keep the chemicals securely stored, and dispose of outdated or excess chemicals via community hazardous waste collection.
Concentrated animal feeding operations are another environmental hazard. These operations accumulate an abundance of manure, GHGs, dust, odors, pests, pathogens, chemicals and pharmaceuticals in one area.
Particulate matter from CAFOs can contain bioactive materials. When combined with GHGs, the concerns are amplified, having synergistic effects. Odor is a primary concern too.
“Odor can be a combination of over 200 different chemical compounds, and it is something we need to worry about how to minimize,” Rautiainen said.
Nutrient management plans, setback requirements, windbreaks and other measures can have some impact. However, the concerns go beyond the immediate pollution risk.
Long-term exposure to low levels of contaminants has not been well researched, and human health impacts are not well understood. Stress from exposure to noxious odors, loss of property value, quality of life issues and concerns about negative health outcomes can all take a toll on health and well being. Psychosocial aspects of living in a community with CAFOs present are an extra-toxic mechanism of concern.
Agriculture does cause environmental contamination. But there are many routes of reducing the impacts on air, soil and water or direct exposure to pathogens or chemicals. Mitigating these risks is in everyone’s best interest.
“You can make some changes to something that is better for the environment,” Rautiainen advised.