top of page

When Manure is Not Manure

Understanding What is In CAFO Hog Sewage

There is a reason why hog manure from Concentrated Animal Feeding Operations (CAFOs) smells so bad and can make people sick. It’s a toxic soup of 300+ noxious gases, pathogens, hormones, nitrates, and more. 1, 2

Over 34 million gallons of hog waste will be applied to Jefferson County cropland in 2015.3 Termed “manure” or euphemistically “nutrients” by the pork industry, much of what is contained in this raw, untreated sewage is anything but a nutrient.

Manure vs. Sewage

Hog manure decomposes differently in natural conditions than it does in confinement pits or lagoons. Waste products from pasture-raised hogs fully break down in the presence of oxygen and soil organisms when deposited on open ground. Livestock walking on pastureland also works the manure into the soil, naturally fertilizing and enriching cropland with a rich organic layer.

On the other hand, CAFO sewage decomposes without oxygen, often putrefying for six to 12 months at a time, in pits or lagoons that can hold 500,000 to a million gallons or more at any one time. This putrefaction changes the chemical composition of the manure into a toxic brew which is potentially harmful to human health and the environment. The odor associated with anaerobically decomposing hog sewage is miles apart from naturally decomposing manure from pasture-raised livestock.4

These are some of the toxins that scientific research identifies in putrefied, untreated hog waste: 5, 6

  • 160+ Harmful Gases – including hydrogen sulfide, ammonia, methane, and carbon monoxide. These gases generate the infamous stench associated with hog factories.

  • Infectious Bacteria including E. coli, Salmonella, Campylobacter jejuni, Yersinia enterocolitica, and more.

  • Antibiotic-resistant Bacteria such as Methicillin Resistant Staphylococcus aureus (MRSA)

  • Parasites such as Giardia lamblia, Cryptosporidium parvum, and Helminthes (worms)

  • Viruses including Rotavirus and Norovirus

  • Antimicrobials – both antibiotics and vaccines

  • Hormones including estrogens, androgens, and progestogens

  • Heavy Metals including zinc, arsenic, and copper

  • Nitrate and Phosphates 


Raw waste products from humans go through a rigorous purification process in expensive treatment facilities in order to protect public health.

Raw sewage from hogs does not.

A hog produces at least three times the amount of waste as a person – often more. The 34 million gallons of hog sewage in Jefferson County equates to human waste produced by 216,000 people – a city the size of Des Moines.7

Do you want to live in a county that would allow untreated sewage from Des Moines to be directly applied to land? Why is it acceptable in the case of hogs?


Health Impacts of Untreated Hog Sewage

Putrefying CAFO waste causes a wide range of health problems, from respiratory issues to the growth of antibiotic resistant bacteria. Environmentally induced asthma, wheezing, headaches, nausea and vomiting, runny eyes, and confusion are among the many symptoms people experience living near CAFOs.8

Living near a CAFO or next to a field receiving raw, untreated hog sewage may increase your risk of contracting MRSA. This potentially fatal antibiotic-resistant infection is hard to treat, often requiring several rounds of antibiotics. It frequently presents as a skin infection but can migrate internally, where is poses the greatest threat to health.

A 2014 University of Iowa study found people living within a mile of a large confinement (2500 or more hogs) had nearly a three times chance of carrying community acquired MRSA.9 People who carry the bacteria have a greater chance of contracting it.Community acquired MRSA is a transmission of the infection that takes place outside of a hospital setting.

In a 2013 study, researchers from Johns Hopkins School of Public Health found that 11% of community acquired MRSA and soft tissue infections in individuals could be attributed to living next to fields with applied manure.10 A significant portion of MRSA cases linked to hospitals may originate with people who acquire MRSA from a CAFO and are then treated in hospitals.

Of particular concern to parents, young infants and children are experiencing a higher incidence of community acquired MRSA, according to a 2013 Center for Diseases Control study. Researchers found a 10% increase in children over a five-year period with children between 3 to 90 days experiencing more MRSA than older infants and children. 11

MRSA now causes more fatalities in the US than HIV/AIDS every year. Individuals with compromised immune systems are most at risk for fatal outcomes. 12

Water Quality Impacts Are Bad, Too

Spills and runoff from hog waste application are all too common, fouling public and private waterways and wells. In 2013 alone, Iowa saw a 65% jump in the number of manure spills from the previous year, according to Iowa Department of Natural Resources (DNR) statistics. 13

Between 2003 to 2013, at least 534 manure spills took place across Iowa, dumping untold gallons of untreated hog sewage into Iowa’s waters. Iowa has some of the worst waters in the nation, with 642 impairments affecting 480 water bodies according to 2012 EPA figures. 14

Toxins from hog waste can find its way into Iowa waterways even when the waste is applied according to DNR regulations. Much of Iowa’s cropland is under laid with tile drainage systems, shallow pipes that collect water percolating through the soil and divert it to nearby waterways. Water in the tile drains can take contaminants from the applied manure to the waterways.

Hog waste in Iowa waterways has consequences. Pollution of drinking water, disease outbreaks from waterborne pathogens, the rise of antibiotic-resistant bacteria, and more are all linked to untreated hog waste. 2

Aquatic life is also damaged by manure contamination. Fish kills are common. Recent studies also point out that hormones in waterways disrupt aquatic reproduction and health. 2

Learn What You Can Do




  1. Effect of Anaerobic Dairy Manure Co-Digestion And Effluent Solid Separation on Volatile Fatty Acids During Manure Storage. Purdue University, 2013.

  2. Literature Review of Contaminants in Livestock and Poultry Manure and Implications for Water Quality. United States Environmental Protection Agency. July 2013

  3. Iowa Department of Natural Resources Manure Management Plans for Jefferson County CAFOs, 2015 figures.

  4. Thicke, Francis. A New Vision for Iowa Food and Agriculture. Chapter 9. 2010.

  5. Putting Meat on the Table: Industrial Farm Animal Production in America. Pew Charitable Trusts and Johns Hopkins Bloomberg School of Public Health. 2008.

  6. Human versus Animals – Comparison of Waste Properties. Ridgetown College, University of Guelph, Ontario, Canada. July 4, 2001.

  7. “Symptomatic effects of exposure to dilute air samples from swine confinement atmosphere on healthy human subjects.” Environmental. Health Perspectives. v.113:567-576.

  8. “Intensive Livestock Operations, Health, and Quality of Life Among Eastern North Carolina Residents.” Environmental Health Perspectives, v. 108(3):233-238, 2000.

  9. Residential Proximity to Large Number of Swine in Feeding Operations Is Associated with Increased Risk of Methicillin-Resistant Staphylococcus aureus Colonization at Time of Hospital Admission in Rural Iowa Veterans. University of Iowa, Iowa City Veterans Affairs, and Kent State University, Infection Control and Hospital Epidemiology. February 2014.

  10. National Burden of Invasive Methicillin-Resistant Staphylococcus aureus Infections, United States. Centers for Disease Control and Prevention and twelve other research organizations, 2011.

  11. Trends in Invasive Methicillin-Resistant Staphylococcus aureus Infections. Pediatrics. September 23, 2013.

  12. The Journal of the American Medical Association. October 17, 2007; vol 298: pp 1763-1771.

  13. "Iowa Manure Spills Jump 65% in 2013." Des Moines Register. February 4, 2014.

  14. Iowa's 2012 Integrated Report: Category 5: EPA-Approved Section 303(d) impaired waters. Iowa Department of Natural Resources. April 25, 2013.  

bottom of page