Environmental scientists and social activists are starting to argue that caged animal feeding operations (CAFOs) are harmful to the environment in several ways. CAFOs are the result of 10,000 years of human progress resulting from the transition from a hunter/gatherer society to an agrarian society. The transition from a hunter/gatherer society to an agrarian society contributed to the creation of large cities, resulting in population growth, for example Mesopotamia. As time passed and countries started to become more populated, especially the United States, a greater demand for food had to be met due to the growing population. It got to the point where there were so many people that small family farms couldn't meet the demand of the growing population. The advent of new technologies such as the automobile, refrigerator, food processing, and preservation provided entrepreneurs with a way to start new businesses that allowed for the large-scale production, distribution, and centralized retailing of food both meat and vegetable based. The result is CAFOs. CAFOs are beneficial as they can provide a low-cost source of meat, milk and eggs through efficient methods of animal feeding and housing, as well as boost the local economy by providing jobs. Unfortunately, the negative aspects of CAFOs greatly outweigh the benefits. The most pressing problem associated with CAFOs stems from the amount of manure/waste they produce. The manure resulting from CAFOs contains a panoply of potential contaminants. Manure is full of plant nutrients like nitrogen and phosphorus, pathogens like E.coli, growth hormones, antibiotics, chemicals used as additives in manure or to clean equipment, animal blood, silage... half the paper.. ....urkholder, J., Libra, B., Weyer, P., Heathcote, S., Kolpin, D., Thorne, P., et al. (2007). Impacts of waste from concentrated animal feeding operations on water quality. Environmental Health Perspectives, 11(2), 308–312. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1817674/pdf/ehp0115-000308.pdfHribar, Carrie, MA. Understanding concentrated animal feeding operations and their impacts on communities. Ed. Mark Schultz, MD. http://www.cdc.gov/nceh/ehs/docs/understanding_cafos_nalboh.pdf. National Association of Local Health Authorities, n.d. Web. December 14, 2013. .Sigurdarson, S. T. & Kline, J. N. (2006). School proximity to concentrated animal feeding operations and prevalence of asthma in students. Chest, 129, 1486–1491. Retrieved from http://chestjournal.chestpubs.org/content/129/6/1486.full.pdf