Cancer mortality in workers employed in cattle, pigs, and sheep slaughtering and processing plants

No evidence of bovine leukemia virus proviral DNA and antibodies in human specimens from Japan

Background

The potential risk and association of bovine leukemia virus (BLV) with human remains controversial as it has been reported to be both positive and negative in human breast cancer and blood samples. Therefore, establishing the presence of BLV in comprehensive human clinical samples in different geographical locations is essential.

Result

In this study, we examined the presence of BLV proviral DNA in human blood and breast cancer tissue specimens from Japan. PCR analysis of BLV provirus in 97 Japanese human blood samples and 23 breast cancer tissues showed negative result for all samples tested using long-fragment PCR and highly-sensitive short-fragment PCR amplification. No IgG and IgM antibodies were detected in any of the 97 human serum samples using BLV gp51 and p24 indirect ELISA test. Western blot analysis also showed negative result for IgG and IgM antibodies in all tested human serum samples.

Conclusion

Our results indicate that Japanese human specimens including 97 human blood, 23 breast cancer tissues, and 97 serum samples were negative for BLV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12977-022-00592-6.

Spatial interaction between breast cancer and environmental pollution in the Monterrey Metropolitan Area

This research examines the spatial structure of a sample of breast cancer (BC) cases and their spatial interaction with contaminated areas in the Monterrey Metropolitan Area (MMA). By applying spatial statistical techniques that treat the space as a continuum, degrees of spatial concentration were determined for the different study groups, highlighting their concentration pattern. The results indicate that 65 percent of the BC sample had exposure to more than 56 points of PM10. Likewise, spatial clusters of BC cases of up to 39 cases were identified within a radius of 3.5 km, interacting spatially with environmental contamination sources, particularly with refineries, food processing plants, cement, and metals. This study can serve as a platform for other clinical research by identifying geographic clusters that can help focus health policy efforts.

Absence of bovine leukemia virus proviral DNA in Japanese human blood cell lines and human cancer cell lines

Bovine leukemia virus (BLV) infects cattle worldwide and causes B-cell lymphoma in cattle. BLV has been identified in human breast and lung cancer and in blood, but the association of BLV and human cancer is controversial. In this study, we investigated the existence of BLV in 145 Japanese human blood cell lines and 54 human cancer cell lines, using a new highly sensitive PCR assay that can amplify even one copy of BLV using LTR primers different from those in previous studies on BLV provirus in breast cancer. All samples were found negative for BLV provirus, suggesting that BLV is unlikely to infect humans.

Expression of p53 protein, Jaagsiekte sheep retrovirus matrix protein, and surfactant protein in the lungs of sheep with pulmonary adenomatosis

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring cancer in sheep that is caused by the Jaagsiekte sheep retrovirus (JSRV). Because the pathologic and epidemiologic features of OPA are similar to those of bronchoalveolar carcinoma in humans, OPA is considered a useful animal model for pulmonary carcinogenesis. In this study, 3,512 lungs from various breeds of sheep were collected and macroscopically examined. OPA was identified in 30 sheep, and samples of these animals were further examined by histologic, immunohistochemical (p53 protein, surfactant protein A [SP-A], proliferating cell nuclear antigen [PCNA], JSRV matrix protein [MA]), and PCR methods. Papillary or acinar adenocarcinomas were detected microscopically in the affected areas. Immunoreactivity for p53 PAb240 was detected in 13 sheep, whereas p53 DO-1 was not detected in any of the OPA animals. PCNA immunoreactivity was recorded in 27 animals. SP-A and JSRV MA protein was immunopositive in all 30. JSRV proviral DNA was detected by PCR analysis in all of the lung samples collected from OPA animals. In addition, the pulmonary SP-A levels were increased in tumor cells. The results of this study suggest that PCNA and p53 protein expression may be useful indicators in monitoring malignancy of pulmonary tumors.

Non-cancer mortality in workers in the meat and delicatessen departments of supermarkets (1950-2006)

We studied non-cancer mortality in 10,701 workers in the meat and delicatessen departments of supermarkets because they have increased exposure to a variety of microorganisms that infect and cause disease in food animals such as cattle, pigs, sheep, and poultry, to which subjects in the general population are also exposed, albeit to a lesser degree. These workers were also exposed to fumes from the wrapping machine. Standardized mortality ratios were estimated in the cohort as a whole and in race/sex subgroups, using the US population for comparison. Study subjects were followed up from January 1950 to December 2006. Significantly increased deaths from diabetes, ischemic heart disease, pulmonary embolism, chronic bronchitis, peritonitis, intracranial and intraspinal abscess, other bacterial diseases, and significantly decreased deaths from diffuse diseases of connective tissue, functional diseases of the heart, intracerebral hemorrhage, occlusion/stenosis of the precerebral and cerebral arteries, and various types of accidents were observed in certain race/sex subgroups or in the cohort as a whole. The observed increased risks of several infectious conditions suggest that the increased occupational exposure to microorganisms may be responsible for at least some of the observed excess deaths, while exposure to fumes may also contribute to the excess of chronic bronchitis. The findings are important not only for supermarket workers and other workers in the meat and poultry industries, but also because the general population is exposed to these microorganisms found in food animals and their products. Nested case-control studies within cohorts that include both workers in supermarkets and other sectors of the meat and poultry industries, are now needed to examine specific risks from occupational exposures while adequately controlling for confounding factors, so that the role of these infectious agents in the occurrence of these diseases in workers and in general population subjects can be adequately assessed.

Cancer mortality in the meat and delicatessen departments of supermarkets (1950-2006)

Meat cutters and meat wrappers in the meat department of supermarkets are exposed to oncogenic viruses present in raw meat from cattle, pigs, sheep, and poultry, and their products (unpasteurized milk and raw eggs). Up to the mid 1970s, meat wrappers were also exposed to carcinogens present in fumes emitted from the machine used to wrap meat. Because of this we studied cancer mortality in a cohort of 10,701 workers in the meat and delicatessen departments of supermarkets, and we report here the findings after the third follow-up. Standardized mortality ratios (SMR) were estimated in the cohort as a whole and in race/sex subgroups, using the US population for comparison. Study subjects were followed up from January 1950 to December 2006. Significantly increased SMRs of 1.3 (95% CI, 1.2-1.5), and 2.7 (95% CI, 1.2-5.3) were recorded for cancers of the lung, and tonsils/oropharynx, respectively, in the entire cohort, affecting nearly all race/sex subgroups. SMRs of 4.6 (95% CI, 1.0-13.6) for cancer of the floor of the mouth, and 2.8 (95% CI, 1.3-5.3) for cancer of the gall bladder and biliary tract were recorded only in White male meatcutters. Significantly decreased SMRs were observed for a few cancers. It is not known if the observed excess of cancers is a result of occupational exposures. However, substantial evidence points to fumes from the wrapping machine as a possible candidate for explaining the excess in female meat wrappers. Nested case-control studies that can examine risks from occupational exposures in greater detail, and adequately control for confounding factors are now needed, to permit specifically investigate the role of the oncogenic viruses, fumes and non-occupational risk factors in the occurrence of these cancers. The findings are important, not only occupationally but also because the general population may also experience these exposures, albeit to a lesser degree.

Lack of evidence that avian oncogenic viruses are infectious for humans: a review

Chickens may be infected with three different oncogenic viruses: avian leukosis virus (ALV), reticuloendotheliosis virus (REV), and Marek's disease herpesvirus (MDV). Several epidemiological studies have suggested a link between these viruses and different types of cancer in people working in poultry processing plants and with multiple sclerosis. In this article, we analyze the epidemiological evidence that these viruses are causative agents for human cancer, followed by description of the relevant key characteristics of ALV, REV, and MDV. Finally, we discuss the biological evidence or lack thereof that avian tumor viruses are involved in the etiology of human cancer and multiple sclerosis (MS). The recent primary epidemiologic articles that we reviewed as examples were only hypothesis-generating studies examining massive numbers of risk factors for associations with various imprecise, non-viral-specific outcomes. The studies lacked precise evidence of exposure to the relevant viruses and the statistical methods failed to adjust for the large risks of false-positive claims. ALV subgroups A-D and J have been eradicated in the United States from the pure lines down to the parent stocks by the breeder companies, which have greatly reduced the incidence of infection in layer flocks and broilers. As a consequence, potential exposure of humans to these viruses has greatly diminished. Infection of humans working in processing plants with ALV-A and ALV-B is unlikely, because broilers are generally resistant to infection with these two subgroups. Moreover, these viruses enter cells by specific receptors present on chicken, but not on mammalian, cells. Infection of mammalian cell cultures or animals with ALV-A, ALV-B, and ALV-J has not been reported. Moreover, humans vaccinated with exogenous or endogenous ALV-contaminated vaccines against yellow fever, measles, and mumps did not become antibody- or virus-positive for ALV. The risks for human infection with REV are similarly limited. First of all, REV also has been eradicated from pure lines down to parent stock by breeder companies in the United States. Broilers can still become infected with REV through infection with fowl pox virus containing REV. However, there is no indication that REV can infect human cells. Low levels of antibodies to ALV and REV in human sera have been reported by a few groups. Absorption of sera with chicken antigens reduced the antibody titers, and there was no clear association with contacts with poultry. Possible cross-reactions with human endogenous or exogenous retroviruses were not considered in these publications. MDV is typically associated with infection of chickens, and almost all experimental data show that MDV cannot infect mammalian cells or animals, including nonhuman primates. One study reports the presence of MDV gD DNA in human sera, but this finding could not be confirmed by another group. A Medline search of the term "gene expression in human cancers" was negative for publications with avian retroviruses or MDV. In conclusion, there is no indication that avian oncogenic viruses are involved in human cancer or MS or even able to infect and replicate in humans.

Contact with ruminants is associated with esophageal squamous cell carcinoma risk

The etiology of esophageal squamous cell carcinoma (ESCC) in the high risk area of northern Iran is only partially known. We aimed to investigate prolonged animal contact as a risk factor for ESCC in this population. From 2003 to 2007, we administered a validated questionnaire to 300 ESCC cases and 571 randomly selected controls matched for neighborhood of residence, age (±2 years) and sex. Questions on lifelong exposure to equines, ruminants, canines, and poultry, including duration and level of contact, were asked in a face-to-face interviews. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) adjusted for potential confounders. A total of 94.7% of cases and 68.7% of controls reported lifelong history of contact with ruminants. After controlling for potential confounders, contact with ruminants was associated with an eightfold increase (95% CI: 3.92-14.86) in risk of ESCC, and increments in duration of contact raised the risk estimates in a dose-dependent manner. Contact with equines and poultry did not significantly change associated OR for ESCC risk and contact with ruminants. OR (95% CI) for contact with canines was 1.99 (1.35-2.93) which after exclusion of contact with ruminants was not significant (OR for contact only with canine: 3.18, 95% CI: 0.73-13.17). These results add to the evidence that contact with ruminants may increase the risk of ESCC.

Jaagsiekte sheep retrovirus detected in human lung cancer tissue arrays

Background

Adenocarcinoma is the most common type of non-small cell lung cancer and is frequently observed in non-smoking patients. Adenocarcinoma in-situ (formerly referred to as bronchioloalveolar carcinoma) is a subset of lung adenocarcinoma characterized by growth along alveolar septae without evidence of stromal, vascular, or pleural invasion, that disproportionately affects never-smokers, women, and Asians. Adenocarcinoma in-situ is morphologically and histologically similar to a contagious lung neoplasm of sheep called ovine pulmonary adenocarcinoma (OPA). OPA is caused by infection with the exogenous betaretrovirus, jaagsiekte sheep retrovirus (JSRV), whose envelope protein (Env) is a potent oncogene. Several studies have reported that a proportion of human lung adenocarcinomas are immunopositive for an antigen related to the Gag protein of JSRV, however other groups have been unable to verify these observations by PCR.

Methods

Here we examine human lung cancer tissue arrays (TA) for evidence of JSRV Env protein and DNA by immunohistochemical staining and PCR, respectively.

Results

Our results reveal that a subset of human lung cancers express an antigen that reacts with a JSRV Env-specific monoclonal antibody in immunohistochemistry and that exogenous JSRV-like env and gag sequences can be amplified from TA tumor samples, albeit inefficiently.

Conclusions

While a causative role has not been established, these data suggest that a JSRV-like virus might infect humans. With next generation sequencing approaches, a JSRV-like virus in human lung cancers may be identified which could have profound implications for prevention, diagnosis and therapy.

[Biosafety of working in cold storage units: from the profit margin to the safety margin]

The cold storage unit and meat production industry has made Brazil one of the leading suppliers and exporters of products of animal origin. The rapid expansion of the market has led to a rise in competitiveness from a capitalist standpoint, and in this respect corporate profit often leads to the need to adapt human actions to new functions in order to reduce costs and maximize production. These routine activities involve repetitive work, multi-tasking, long hours and operating machines with the use of sharp cutting tools, which is why the work is conducted wearing protective gear. Among the main hazards present, biological risks are the most important due to direct exposure to internal organs, blood, fecal matter, urine and placental or fetal fluids from slaughtered animals that may be infected with pathogens of zoonotic origin. This paper discusses the risks to which slaughterhouse-cold storage unit professionals are exposed, conducting a thorough bibliographical review of the literature that takes into consideration the conceptual framework of Biosafety, which contributes to improve the safety and health conditions of these workers.

Occupation and risk of lymphoid and myeloid leukaemia in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVES

Established risk factors for leukaemia do not explain the majority of leukaemia cases. Previous studies have suggested the importance of occupation and related exposures in leukaemogenesis. We evaluated possible associations between job title and selected hazardous agents and leukaemia in the European Prospective Investigation into Cancer and Nutrition.

METHODS

The mean follow-up time for 241 465 subjects was 11.20 years (SD 2.42 years). During the follow-up period, 477 incident cases of myeloid and lymphoid leukaemia occurred. Data on 52 occupations considered a priori to be at high risk of developing cancer were collected through standardised questionnaires. Occupational exposures were estimated by linking the reported occupations to a job exposure matrix. Cox proportional hazard models were used to explore the association between occupation and related exposures and risk of leukaemia.

RESULTS

The risk of lymphoid leukaemia significantly increased for working in chemical laboratories (HR 8.35, 95% CI 1.58 to 44.24), while the risk of myeloid leukaemia increased for working in the shoe or other leather goods industry (HR 2.54, 95% CI 1.28 to 5.06). Exposure-specific analyses showed a non-significant increased risk of myeloid leukaemias for exposure to benzene (HR 1.15, 95% CI 0.75 to 1.40; HR=1.60, 95% CI 0.95 to 2.69 for the low and high exposure categories, respectively). This association was present both for acute and chronic myeloid leukaemia at high exposure levels. However, numbers were too small to reach statistical significance.

CONCLUSIONS

Our findings suggest a possible role of occupational exposures in the development of both lymphoid and myeloid leukaemia. Exposure to benzene seemed to be associated with both acute and chronic myeloid leukaemia.

A cohort mortality study of workers in a soup manufacturing plant

There has been no study of disease risk or exposures in workers in soup manufacturing plants. These workers may have hazardous exposures to biological and chemical cancer-causing agents at the workplace. The authors report here on mortality in 1,779 workers from a plant in Baltimore, Maryland. Standardized mortality ratios (SMRs) were estimated using the US population for comparison. Significantly increased mortality was observed for cancer of the floor of the mouth, colon cancer, epilepsy, and chronic nephritis in certain groups. Significantly decreased SMRs were observed for some causes. The findings are important, given the complete absence of data on this occupational group. It is not known whether the associations observed are related to occupational or nonoccupational exposures, or due to chance. The findings do, however, indicate that further studies of this occupational group are warranted.

Mortality in workers employed in pig abattoirs and processing plants

OBJECTIVE

workers in slaughterhouses and processing plants that handle pigs, and pork butchers/meatcutters have been little studied for health risks associated with employment, in spite of the fact that they are potentially exposed to oncogenic and non-oncogenic transmissible agents and chemical carcinogens at work. We report here on an update of mortality in 510 workers employed in abattoirs and processing plants that almost exclusively handled pigs and pork products.

METHODS

standardized mortality ratios (SMRs) were estimated for the cohort as a whole, and in subgroups defined by race and sex, using the corresponding US general population mortality rates for comparison. Study subjects were followed up from January 1950 to December 2006, during which time 45% of them died.

RESULTS

mortality was significantly increased overall in the cohort. A statistically significant excess of deaths was observed for colon and lung cancers in the entire cohort, SMR=2.7 (95% CI, 1.2-5.1), SMR=1.8 (95% CI, 1.1-2.7), respectively. Significant SMRs in the cohort as a whole were also observed for senile and pre-senile psychotic conditions (SMR=5.1, 95% CI, 1.4-13.1), and pneumonia (SMR=2.6, 95% CI, 1.3-4.8). An observed excess of subarachnoid hemorrhage was seen mainly in whites (SMR=10.1, 95% CI, 1.2-36.3). There was a suggestion of an excess of deaths from ischemic heart disease also, but the elevated SMR was confined to men and was not statistically significant.

CONCLUSION

this study confirms the excess occurrence of lung and colon cancers, and stroke previously reported in this occupational group. New findings are the excess of risk for senile and pre-senile psychotic conditions and pneumonia, which together with the excess of colon cancer appear specific for pig/pork workers, as they were not evident in much larger studies of workers in abattoirs and processing plants handling cattle and sheep. However, caution should be exercised in interpreting these findings, since some of them could have occurred by chance, resulting from our examination of a large number of causes of death in multiple study subgroups. For the moment, the significance of these findings remains unknown until they are confirmed in larger studies of adequate statistical power. Studies that will take into account possible occupational and non-occupational confounding factors are needed.