|
Photographs
showing sewage overflows, flooded fields, "manure
burn", dead pigs on roadway, etc
The environmental problems associated with the Hog Industry
are numerous. The following provides a brief overview of some
of the issues.
Pathogens
A large
variety of bacteria, viruses, protozoa, and parasitic worms can be
transferred from hogs to people. They may be ingested via
contaminated drinking water, or inhaled as aerosols carried by wind
when manure is sprayed on fields.
The US Agriculture Dept.
has cautioned that many swine pathogens can be spread on farms by
rodents and cats. Some examples:
Yersinia is a bacterium that
causes severe gastrointestinal illness. Japan has identified
Yersinia in imported Canadian pork. In Denmark, pork has been
reported to be the only source of human infection in that country.
Has been demonstrated in hog manure in Quebec.
Streptococcus
suis: a meningitis that can infect hog workers
E. coli: some
varieties can result in grave illness or even death
Listeria
monocytogenes: a meningitis that can be lethal
Brucella: in
1992 there was an outbreak of brucellosis among the workers in a
North Carolina pork processing plant
Bacillus anthracis:
there was an outbreak of anthrax in 1989 at a pig farm in north
Wales
Pfiesteria: outbreaks have occurred in various places
around the world associated with intensive swine
confinement
Salmonella: pigs now harbor many
antibiotic-resistant strains. In Germany 20% of human cases have
been shown to originate from swine.
Toxoplasma gondii: an
intracellular parasite that is particularly hazardous to pregnant
women A 1991-92 study found that 8.6% of Canadian market-age pigs
were infected with this organism
Cryptosporidium: a protozoan
that has already been found in some water supplies in Manitoba. This
organism is resistant to chlorination, and causes a severe
gastrointestinal illness.
Ascaris: a large (30 cm) roundworm
that lives in the intestine. One female worm produces 2 million
eggs/day. Eggs can remain viable in water and soil for many
months.
Trichinella spiralis is a small roundworm that may be
found in cysts in pork meat. Eating undercooked pork may result in
trichinosis in humans, and can be fatal. According to the Centers
for Disease Control and Prevention in the U.S. 80% of trichinosis
cases were due to pork consumption.
Taenia solium is a
tapeworm that is readily transferable to humans.
Many
kinds of viruses and other infectious agents: e.g. swine
influenza: the Journal of Occupational Medicine reported an
occupational hazard for pork producers, veterinarians and meat plant
employees
In North Carolina, Texas, Minnesota and Iowa there
have been outbreaks of influenza-A viruses that were very similar to
human genetic strains.
Swine hepatitis-E virus has been shown
to be transferable to humans.
The British Medical Journal
reported that BSE (mad cow disease) can be present in pigs as well
as cows
Drug and vaccine residues
A
variety of antibiotics, vaccines and hormones are used because
disease can spread extremely quickly in the crowded conditions of
the barns Disease can cause disastrous economic losses. e.g. in 1997
in the Netherlands, hog plague required the destruction of hundreds
of thousands of pigs and the disinfection of 60,000 transport
vehicles Medication may be administered in feed, water or
injected
The massive use of antibiotics contributes to the
emergence of new antibiotic-resistant strains of disease organisms A
1998 study reported in the journal Microbial Drug Resistance showed
that “E. coli from swine may represent a considerable reservoir of
antibiotic resistance genes”.
Unlike people, who take
antibiotics only when they are already sick, in intensive livestock
operations the drugs are given routinely at rates of 100-1000x the
rates for people
There is considerable concern about residues
of antibiotics in pork. Some (e.g. Sulfamethazine) are carcinogenic
Antibiotic residues may be high enough in meat that sensitive
individuals may get an allergic reaction on consuming the
meat
Hog farmers that use medicated feed have been shown to
harbor a higher proportion of antibiotic resistance than the general
population
Compounds that speed growth of swine, e.g. porcine
somatotropin and beta-agonists increase the leanness of meat and
reduce the amount of feed needed. Some studies suggest that hormone
residues in meat may affect young consumers
The European Union
has banned the use of hormones in meat, no longer permits
the
importation of hormone-treated meat
The drug residues
are also present in the manure and can gain access to
water
Ochratoxin A is a fungal toxin that can originate from
contaminated grain and has been demonstrated in Canadian pork
products. It Is carcinogenic and suppresses the immune system, and
causes kidney damage.
Air pollution
Odor reduces quality of life and decreases
property values
On many days people can’t go outdoors and may be
unable to sell their property
Methane from manure
contributes to greenhouse gases. At present, methane from all
sources is responsible for 12-20% of greenhouse
warming.
Hydrogen sulphide gas causes people to feel
ill, headaches, breathing difficulties as well as experiencing
increased reaction time and mood changes
Ammonia
volatilizes readily into the air from lagoons and manure spread on
fields. Studies have found that ammonia in the air contributes to
acid rain
Phosphine gas may arise when fresh swine
manure ferments in the absence of oxygen
Water pollution
Nitrate in the waste gains easy access to surface
and ground water. Nitrate in drinking water may cause
methemoglobinemia, a condition where blood can no longer carry
oxygen effectively. Infants are at greatest risk.
Chronic
consumption of nitrate in drinking water may be associated with
greater risk of stomach cancer
Some studies have implicated
nitrate exposure in increased rate of birth defects, particularly
spina bifida
Ammonia is extremely soluble in water. It
is toxic to animals, fish are very sensitive. Promotes growth of
bacteria in water systems
Phosphorus tends to leach
easily from fields where manure has been spread because the nutrient
proportion in manure does not match the needs of crops, therefore
phosphorus tends to be in excess
In surface water phosphorus
and nitrogen feed the growth of noxious algae that impact on the
fisheries and tourism industries
Bluegreen algae may create
blooms to the extent that the water may become toxic to people,
livestock and wildlife. Water containing a bluegreen algal bloom is
unsuitable for swimming because the toxins cause skin irritation and
there is the danger of swallowing some water
Heavy metals
Manure contains a variety of heavy metals and salts, for example
zinc, copper, cadmium, nickel, cobalt, lead, boron, selenium
These metals are present in the feed because some, such as copper,
enhance swine growth Much of them are excreted and end up in the
manure
Repeated application of manure to the same soils causes accumulation
of these elements
Detergents and disinfectants from barn washing
Carcass disposal
Unscrupulous operators may dispose of dead pigs in an environmentally
unsafe manner, or pigs may end up in local landfills
Hazards to hog industry workers
Up to 25% of workers in Manitoba’s meat packing plants suffer
a work-related injury or illness
People who work in barns are suscepitble to organic dust toxic
syndrome from breathing hog dust
Suffer chronic respiratory illnesses such as cough and asthma.
There is a direct correlation between severity of symptoms and
number of hours worked in the barn. Young barn workers are most
susceptible to lung damage
Suffer allergic reactions to endotoxins from airborne bacteria
in the barns Chronic exposure to endotoxins is associated with
liver damage and bowel diseases. Dust masks have little
effect because particles are very small
Hearing loss. The scream of a sow can exceed 100 decibels
go
to home page
|