Sustainable Agriculture Literature Review - Boulder County

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10.1 Food Safety
Animal Waste
Animal wastes, when concentrated, can present significant problems during handling,
use, and disposal, posing both health and environmental risks. A variety of different
viruses can be present in animal fecal wastes and manures. Exposure of humans to
these disease-causing pathogens of animal origin can occur via occupational exposure,
water, food, air, or soil. 763 Generally, direct animal-to-human transmission via animal
wastes is not as high a risk as bacterial transmission through the food supply. However,
animal-to-animal transmission or herd-to-herd transmission of viruses is a concern. 764
Manure can contain high concentrations of pathogens, which can affect both animal and
human health. 765, 766 Manure runoff from livestock operations into water supplies has
been associated with a number of health concerns including Salmonella and
Cryptosporidium outbreaks, and dangerous levels of nitrates - potentially fatal to
infants. 767 Manure runoff from livestock operations is among the suspected causes of
outbreaks of Pfiesteria piscicida in a number of states, causing human health effects
including acute short-term memory loss, cognitive impairment, asthma like symptoms,
liver and kidney dysfunction, blurred vision, and vomiting. 768
In concentrated amounts, or when improperly handled, manure can present health risks
to humans, but when used as part of an integrated system like pastoral production,
wastes can be used as an important input. For example, animal wastes could be treated
through composting to create a crop fertilizer that no longer harbors pathogens, and that,
when applied at appropriate rates and times with methods that minimize nutrient
leaching, can help to reduce pollution and health risks. Additionally, this closing of the
nutrient cycle decreases dependence on synthetic fertilizer production and is more
efficient when animal and crop production are combined locally. 769 For more information
on animal fertilizers, see the section on manure in 5.4 Soil Amendments.
Antimicrobials in Animal Agriculture
In the U.S., food animals are often exposed to antimicrobials to treat and prevent
infectious disease or to promote growth. Many of these antimicrobials closely resemble,
or are identical to, the drugs used by the human population. 770 About 70 percent of all of
the U.S. antimicrobials produced are fed to animals to help promote growth and treat
disease. 771
The high volume and frequent use of antimicrobials in animal agriculture has greatly
increased the development of drug resistant strains of disease, causing several
outbreaks of heavily drug resistant diseases. 772 The National Research Council and
Institute of Medicine found that there is a strong link between the use of antimicrobials in
food animals and the development of bacterial resistance to these drugs and human
diseases. Despite increased bacterial resistance, they found that the incidence of such
diseases is very low. 773 The World Health Organization has called for the reduced use of
antimicrobials in animal agriculture, as a number of resistant diseases are able to pass
to humans through the food chain, particularly strains of Salmonella, Campylobacter,
Enterococci, and E. coli. 774
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