Other than risks from eating animal products, are there hazards merely from working with animals? The answer is yes. Dairy farmers, veterinarians, and meat handlers have significantly increased rates of a number of serious diseases, as listed in Figure 24: Diseases Associated with the Handling of Animals.132
Although farmers have exposure to pesticides and chemicals, many of the research articles focus on the possibility of exposure to cancer-inducing viruses as being a factor.133
Often the settings in which animals are raised are so unhealthful that humans working in those situations are more susceptible to illness. Specific categories of livestock workers are also exposed to unique risks. For example, because pigs are usually raised in enclosed "factory houses," hog farmers may develop a variety of respiratory ailments from their work in these closed buildings. Studies show that nearly half of those working in such enclosed buildings (pig or chicken) complain of bronchitis, asthma-like conditions, inflamed sinuses, or flu-like illnesses.134, 135 This has been attributed to breathing dust and gasses from pig feces and urine. Confined employees in poultry farms have similar respiratory problems.136
Perhaps the area of greatest occupational concern relates to those who work in slaughterhouses and meat packing plants. A recent study looked at some 10,000 of such individuals over a period of nine years.137 The results revealed an excess risk of all cancers combined. A number of specific cancers were also increased. These included: cancer of the lung, cancer of the mouth and throat (buccal cavity and pharynx), and cancers of the esophagus (the swallowing tube), colon, bladder, kidney, and bone. The increases in risk were often impressive. Hodgkin's disease deaths were increased six-fold, mortality from other lymphomas was tripled, and leukemia deaths were more than doubled. The investigators raised the question as to whether such increases could be related to exposure to BLV and other cancer-inducing viruses. Their research leaves us with serious concerns about the possibility of occupational risk to such workers.
A More Complete List of Human Diseases Contracted from Animals
The information in this chapter has provided appreciable evidence regarding the serious nature of disease in animals and the risk to humans. However, I have only touched the surface of an extremely broad subject. Dozens more pages could have been included that deal with the toxicologic and infectious diseases that are increased by eating animal products or having contact with animals. If I were making a more complete list of animal-related conditions that affect humans, it would include all of those listed in Figure 25: Other Diseases and Conditions Associated with Eating Animal Products or Exposure to Animals.138
