Pets and adult leukemia

Update of cancer and non-cancer mortality in the Missouri poultry cohort

BACKGROUND

workers in poultry slaughtering and processing plants have one of the highest human exposures to transmissible agents that cause cancer and other diseases in chickens and turkeys, and also have other occupational carcinogenic exposures. The general population is also exposed to these transmissible agents.

METHODS

we investigated mortality in workers who belong to a poultry union in Missouri, and estimated standardized mortality ratios.

RESULTS

significantly increased mortality was observed for some leukemias, benign neoplasms, thyroid diseases, bacterial infections, and schizophrenic disorders. The risk of breast cancer and several non-cancer conditions was significantly depressed.

CONCLUSION

the findings add to the growing evidence suggesting that workers occupationally exposed to transmissible agents and carcinogens in the poultry industry, are at increased risk of dying from certain chronic diseases, including cancer.

Cancer in veterinarians

OBJECTIVES

Veterinarians come into contact with several potentially carcinogenic exposures in the course of their occupation. These exposures include radiation, anaesthetic gases, pesticides (particularly insecticides), and zoonotic organisms. This review aims to summarise what is known about the carcinogenic risks in this profession.

METHODS

The levels of exposure to potential carcinogens in the veterinary profession are examined and evidence is reviewed for carcinogenesis of these substances in humans at doses similar to those experienced by veterinarians. The few published studies of cancer in veterinarians are also summarised.

RESULTS

Veterinarians have considerable potential for exposure to several known and potential carcinogens. Risks may be posed by work in clinics with poorly maintained x ray equipment, by use of insecticides, and from contact with carcinogenic zoonotic organisms. The few studies available suggest that veterinarians have increased mortality from lymphohaematopoietic cancers, melanoma, and possibly colon cancer.

CONCLUSIONS

The exposures examined in this review are not unique to the veterinary profession, and, as a consequence, information gathered on the carcinogenic risks of these exposures has implications for many other occupations such as veterinary nurses, animal handlers, and some farmers, as well as dentists, radiographers, and anaesthetists.

On the need to assess cancer risk in populations environmentally and occupationally exposed to virus and chemical agents in developing countries

Evidence exists that exposure to poultry oncogenic viruses may produce elevated cancer mortality in human populations, particularly excesses of cancer of lung and excesses of cancer of lymphopoietic tissues. To date, this potential risk is unknown in populations from the developing countries. This paper suggests the need to assess cancer risk in populations of developing countries with reported environmental exposure to chicken meat products and eggs; the need to assess risk of cancer in populations inoculated with vaccines from infected chicken embryos; and the need to assess risk of cancer in occupational populations highly exposed to poultry oncogenic viruses, and with potential concurrent exposure to chemical agents known or suspected to be carcinogens.

A case-control study of myelodysplastic syndromes among Japanese men and women

To determine the risk factors of the myelodysplastic syndromes (MDS) we conducted a case-control study in Japan. One hundred and sixteen MDS patients were diagnosed from 1 September to 31 October 1992 and from 1 August to 31 October 1993 in the 32 hospitals enrolled in the idiopathic Disorders of Hematopoietic Organs Research Committee. Age, sex, and hospital-matched controls were selected for each case. Information on cigarette smoking and drinking habits, hair dye use, history of keeping pet animals, and occupational exposures to organic solvents, lead and radiation was obtained from self-administered questionnaires. Conditional logistic regression was applied to this individually matched case-control study and odds ratios (ORs) were computed to estimate association between each exposure variable and risk of MDS. Alcohol drinking was associated with increased risk of MDS (OR = 2.15; 95% confidence interval = 1.12-4.16) and there was a significant trend in risk with increasing amounts of ethanol consumed per week (P < 0.05). We also found elevated ORs for cigarette smokers (OR = 1.80), users of hair dye products (OR = 1.77), and workers exposed to organic solvents (OR = 1.50), although these ratios were not statistically significant. Exposure to pet animals was not associated with risk of MDS. The association observed between alcohol drinking and MDS was still eminent even after adjusted with other variables of cigarette smoking, hair dye use and occupational exposure to organic solvents, and the dose-response relationship was also confirmed.

Occupational exposure to poultry and prevalence of antibodies against Marek's disease virus and avian leukosis retroviruses

OBJECTIVES

To compare the prevalence of antibodies against Marek's disease herpes virus (MDV) and against avian leukosis viruses type C (ALV) in groups of workers exposed to poultry and in unexposed groups.

METHODS

Antibodies directed against avian viral proteins were detected by enzyme linked immunosorbent assay in 549 subjects. Exposure to chickens was high in two subgroups: farmers on intensive chicken farms and workers at chicken slaughterhouses. One subgroup, traditional farmers on dairy or pig farms with poultry, had moderate exposure to poultry. Another subgroup, farmers and slaughterhouse workers on quail farms, had high exposure to quails. Three subgroups were not exposed to chickens: farmers on dairy or pig farms without poultry, workers at cattle slaughterhouses, and white collar workers. Also, MDV antibodies were tested after serum sample adsorption with chicken antigens in 134 serum samples.

RESULTS

The prevalence of antibodies against MDV was significantly higher in the exposed subgroups than in unexposed groups (odds ratio (OR) 6.17; 95% confidence interval (95% CI) 3.91-9.75). No association was found between seroprevalence and age. However, higher prevalence was found among women and was related to duration of exposure to chickens. The concentration of antibodies from a few subjects remained very high after adsorption. Significant differences between the men and women were found for the prevalence of antibodies for ALV but were not related to exposure to chickens.

CONCLUSIONS

The prevalence of antibodies against MDV was significantly higher among workers exposed to chickens and was related to sex and duration of exposure. The higher prevalence of antibodies against avian oncogenic viruses found among women compared with men may be induced by differences in exposure or by genetic factors. The meaning of these high titres could be related to the presence of MDV in humans. Because the involvement of animal oncogenic viruses in human cancer is indicated by epidemiological and some experimental studies, the integration of viral DNA in human cells needs to be investigated.

Cancer and other causes of death among U.S. veterinarians, 1966-1977

Causes of death among 1,551 white male veterinarians identified from obituary listings in the Journal of the American Veterinary Medical Association were compared to an expected distribution based on the general US population. The proportion of deaths was significantly high for particular neoplasms, especially leukemia and Hodgkin's disease, and cancers of the brain and skin. Although socioeconomic and methodologic factors may be involved, the excesses were primarily among veterinarians in clinical practice, raising the possibility that specific occupational exposures may be carcinogenic. Mortality was also relatively high for motor vehicle accidents, suicides and asthma, but low for lung cancer and other diseases of the respiratory system.