IATP Hog Report - Institute for Agriculture and Trade Policy

Section 3
Liquid manure also contains bacterial and viral pathogens, parasites, weed
seeds, and even antibiotics, disinfectants, and insecticides, when these are
present on the farm. 11 The spread of many classic human diseases, such as
cholera, typhoid fever, or dysentery, has been controlled by improvements
in personal hygiene and the use of sewage and water treatment processes
that separate humans from their waste. 12 In areas of the world where these
improvements have not been made, or where treatment systems are
inefficient, these diseases are endemic. Several hundred diseases are
transmitted from animal to animal, and more than 150 of them can be
passed from animals to human beings. 13 The pathogens and parasites
causing most of these diseases are excreted by the affected animals. 14
Animals on factory farms are highly stressed by their surroundings.
Stressed animals excrete more pathogens in their feces than animals that
are not under stress. 15 Pathogens such as salmonellae can even be present
in the feces of animals that appear to be clinically healthy. Antibiotics
used routinely at subtherapeutic levels in the diet of hogs suppress
outbreaks of some bacterial diseases but do not kill all the pathogens that
may be present. The pathogens that survive and are excreted are those that
become resistant to the antibiotics during their stay in the gut. 16 Unlike the
composting or heating that takes place naturally in stored manure from
animal housing when ample straw bedding is used, manure stored
anaerobically in liquid form never reaches the temperatures necessary to
kill pathogens, parasites, and weed seeds.
When liquid hog manure is spread or sprayed onto pastureland, cattle,
other livestock, and wildlife grazing there can accidentally ingest
pathogens and parasite eggs from the manure, endangering their health. 17
Yet, a number of large hog factories spray or irrigate cattle grazing areas
with liquid manure effluent. Although pathogens may die of attrition
during liquid manure storage if the storage is kept undisturbed for a month
or more, it requires the farm to have a second storage basin or facility to
accept fresh manure a fresh source of pathogens daily while the first is
standing still. Few, if any, factory farms have a second manure storage
facility for this purpose.
Although it is very hazardous, 18,19 , 20 on some factory farms, human
wastes may be channeled to the storage lagoons. 21 Residents living near
hog factories have witnessed dead hogs floating in open-air lagoons. 22
In 1988, an expert panel convened by the World Health Organization
identified liquid manure spreading as a critical pathway by which
salmonellae and other pathogens are spread to the natural environment. 23
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