Production of beef, poultry, pork and other meats tripled between 1980 and 2010 and will likely double again by 2050. This ever increasing meat consumption in a world of more than 7 billion people is already taking a staggering toll on wildlife, habitat, water resources, air quality and the climate.
The increase in meat and dairy products is only achieved with artificial insemination of cattle. The production of milk, cheese and meat is inextricably linked. Cows are constantly re-impregnated after the birth of the calves by artificial insemination, so that their milk will never stop flowing. The cow must give birth to as many calves as possible for milk, cheese and meat. Female calves grow up to be dairy cows, bulls go to the meat industry. As a result, carcinogenic viruses are now found in cattle and in the meat and dairy industry. Harmful viruses such as Avian (poultry) leukemia virus (ALV) and Bovine (cattle) leukemia virus (BLV) are found in raw egg proteins and meat products. Harmful leukemia viruses from cattle and poultry have spread to animal carers, employees in the meat and poultry industry and consumers (Johnson 2010, Blair 1982).
risks in the meat industry
An increased mortality of brain tumors has been observed in veterinary surgeons (Blair A). Veterinarians and Artificial Insemination assistants do a lot of internal research on cows. Transmission via the uterus and the birth canal during labor, of bovine leukemia virus (BLV) plays a crucial role in the spread and persistence of BLV infection in cattle (Mekata H). In their work, veterinarians and AI staff come into contact with bovine leukemia virus, a carcinogenic virus. Bovine leukemia is an economically important infection of dairy cattle worldwide, caused by bovine leukemia virus (BLV). The presence of infections in Canadian dairy herds is high and is still increasing. Seventy percent of the herds were identified as BLV positive (one or more positive animals).
Nekouei O, VanLeeuwen J, Sanchez J, Kelton D, Tiwari A, Keefe G Herd-level risk factors for infection with bovine leukemia virus in Canadian dairy herds. Prev Vet Med. 2015; 119 (3-4)
The deaths of 5,016 veterinarians were examined and compared with those of the general American population. The mortality rates were significantly increased from malignant lymphomas and leukemia, colon, brain and skin. Less mortality was found for stomach and lung cancer.
Blair A, Hayes HM Jr. (1982) Mortality patterns among US veterinarians, 1947-1977: an expanded study. Int J Epidemiol. 1982 Dec;11(4):391-7.
Increased risk of esophageal, colon, brain and pancreatic cancer and melanoma in veterinarians in Sweden could not be explained by the socio-economic status of this profession. Occupational exposures to carcinogenic viruses in livestock are potential sources.
Travier N, Gridley G, Blair A, Dosemeci M, Boffetta P. (2003) Cancer incidence among male Swedish veterinarians and other workers of the veterinary industry: a record-linkage study. Cancer Causes Control. 2003 (6):587-93.
Employee risks in the poultry industry
Carcinogenic viruses are found and cause tumors in chickens and turkeys. A number are carriers and diffusers of these infectious viruses. Virus has been shown in chicken products and eggs, so exposure to humans is universal and almost unavoidable. These viruses are not very contagious, but still have the ability to infect and transform human cells. Antibodies against avian leukemia sarcoma viruses (ALSV) and reticulo endothelial viruses (REV) have been found in blood sera of workers in poultry slaughterhouses.Mortality from cancer has been studied in 20,132 workers in poultry slaughterhouses and processing plants, a group with the highest human exposure to these viruses. The mortality rate among poultry workers has been compared with that of the American population as a whole. Substantially increased risks were observed in poultry workers as a whole or in subgroups, for different cancers: cancer of the mouth and pharynx; pancreas; trachea / bronchus / lung; brain; cervix; lymphocytic leukemia; monocytic leukemia; and tumors of the blood-forming and lymphatic systems. This study provides evidence that a group of people with high exposure to carcinogenic viruses, occurring in poultry, are at a higher risk of death from a number of cancers. Antibodies have been shown in the blood of these workers against avian leukemia viruses (ALV) and reticulo endothelial viruses (REV).
Metayer C, Johnson ES, Rice JC (1998) Nested case-control study of tumors of the hemopoietic and lymphatic systems among workers in the meat industry. Am J Epidemiol 147(8):727-38
Johnson ES, Ndetan H, Lo KM (2010) Cancer mortality in poultry slaughtering / processing plant workers belonging a union pension fund. Environ Res 110(6):588-94 https://www.ncbi.nlm.nih.gov/pubmed/20541185
Brain cancer is more common in poultry farmers involved in killing chickens. The killing of chickens was accompanied by an almost 6-fold increase in the risk of brain cancer. Workers in poultry slaughterhouses and processing plants often process thousands of chickens daily, come into contact with poultry meat, organs and blood and run the risk of injuries that form a route for viruses and other microbial substances to enter the body. They also work for longer periods in confined spaces, which increases the risk of inhaling microbes. Viruses that are known to cause cancer in poultry can be responsible for the increased incidence of cancer in poultry farmers killing chickens.
Gandhi S, Felini MJ, Nidetan H, Cardarelli K, Jadhav S, Faramawi M, Johnson ES (2014) A pilot case cohort study of brain cancer in poultry and control workers. Nutr Cancer. https://www.ncbi.nlm.nih.gov/pubmed/24564367
Professor ES Johnson, an epidemiologist at the University of Fort Worth Texas, has published more than 30 articles in scientific journals about increased cancer risks for employees in the meat industry, many of which are specifically for poultry farmers. To definitively link the cancer risk to occupational exposure, he has developed and patented the only test to date that can detect the presence of carcinogenic viruses in the genome of tumor cells of workers with these cancers.