Chapter 5. Animal Agriculture: Our Health and Our Environment

Even if we could, no matter how unlikely, contain the pathogens running amok among factory farms, we are still faced with a much larger problem. This is because there are just too many animals being produced for food: animals grown for meat and dairy products account for 20 per cent of the world’s terrestrial animal biomass. To sustain this massive production requires unprecedented quantities of water, energy, land, pesticides and feed crops (crops fed to farmed animals). In exchange for all these depleted resources, we get polluted water, air and land, and perhaps one of the most significant climate transformations in human history.

In September 1999, Hurricane Floyd hit the eastern part of North Carolina, acting as a catalyst for the environmental disaster that followed. As many as 50 animal waste lagoons, some of them several acres in size, filled with floodwaters and overflowed. This manure flowed into the surrounding wetlands and groundwater aquifers, resulting in massive contamination and pollution of drinking water. In addition to multi-antibiotic-resistant fecal bacteria and antibiotics, excess levels of nitrogen nutrients were discovered in the groundwater near some of the farms following the flooding. North Carolina is the second largest pig producer in the USA; pig production in that state alone exploded in the 1990s, growing from 2.6 million pigs in 1988 to almost 10 million today, most of them confined to factory farms. The aftermath of Hurricane Floyd highlighted the disturbing environmental implications of industrial animal agriculture.

In the USA, animal agriculture is responsible for 32 and 33 per cent, respectively, of the nitrogen and phosphorus loads found in freshwater sources. The problem with these nutrients is that, like manure, there are too much of them. The application of manure to cropland and leakage from manure lagoons cause nitrogen, phosphorus and other nutrients to run off agricultural land and into waterways. Excess nutrient loading of waterways causes eutrophication, or overfertilization, leading to loss of oxygen, algal blooms and massive die-offs of fish and other animal populations. Most marine algae are harmless. However, the growth of several toxic species of algae is boosted by nutrient supersaturation. These species produce potent neurotoxins that can be transferred through the food web, where they adversely affect and kill fish, birds, marine mammals and humans that either directly come in contact with or consume them.

One harmful species, Pfiesteria, is believed to be the cause of massive fish kills along the eastern shore of the USA. It produces a potent neurotoxin and an epidermal toxin that have been linked to significant neurological illness and skin lesions in humans. Additionally, nitrogen in manure and liquid waste can contaminate drinking water. These nitrates, which are associated with human health risks, have been identified by the US Environmental Protection Agency (EPA) as the most widespread agricultural contaminant in drinking water wells. Elevated nitrate levels in water can cause severe methemoglobinemia (‘blue baby syndrome’), particularly in infants. This is a frequently fatal condition in which the blood has a reduced capacity to carry oxygen.

Excess nitrates and eutrophication render water unfit for drinking. Compounding the eutrophication of our waterways, animal agriculture also consumes 70 per cent of the freshwater supply and is among the most damaging industries to the earth’s increasingly scarce water resources, contributing significantly to water pollution. According to the EPA, agriculture, is ‘the leading contributor to identified water quality impairments in the nation’s rivers and streams, lakes, ponds, and reservoirs’. In excess of 129,000 miles of streams and rivers and more than 3.2 million acres of lakes have been impaired as a result of agriculture, a significant part due to animal waste and factory farms. The primary pollutants associated with animal waste are nutrients (particularly nitrogen and phosphorus), organic matter, solids and odorous/volatile compounds.

Animal waste also contains pesticides, hormones and, of course, pathogens and antibacterials. Pollutants in animal waste can impact water supplies through several possible pathways, including surface runoff, erosion, spills, direct discharge to surface waters and leaching into soil and groundwater. Atmospheric transport is another major pathway by which nitrogen and other pollutants are deposited back to the land and waterways. More than 80 per cent of ammonia emissions in Europe are generated by animal agriculture. Factory farm waste emits a number of pollutants of concern to human health, including heavy metals, volatile gases, methane, nitrous oxide and hydrogen sulphide.