A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents.

BACKGROUND: We conducted a population-based case-control study in Montreal, Canada, to explore associations between hundreds of occupational circumstances and several cancer sites, including colon. METHODS: We interviewed 497 male patients with a pathologically confirmed diagnosis of colon cancer, 1514 controls with cancers at other sites, and 533 population-based controls. Detailed job histories and relevant potential confounding variables were obtained, and the job histories were translated by a team of chemists and industrial hygienists into a history of occupational exposures. RESULTS: We found that there was reasonable evidence of associations for men employed in nine industry groups (adjusted odds ranging from 1.1 to 1.6 per a 10-year increase in duration of employment), and in 12 job groups (OR varying from 1.1 to 1.7). In addition, we found evidence of increased risks by increasing level of exposures to 21 occupational agents, including polystyrene (OR for "substantial" exposure (OR(subst)) = 10.7), polyurethanes (OR(subst) = 8.4), coke dust (OR(subst) = 5.6), mineral oils (OR(subst) = 3.3), polyacrylates (OR(subst) = 2.8), cellulose nitrate (OR(subst) = 2.6), alkyds (OR(subst) = 2.5), inorganic insulation dust (OR(subst) = 2.3), plastic dusts (OR(subst) = 2.3), asbestos (OR(subst) = 2.1), mineral wool fibers (OR(subst) = 2.1), glass fibers (OR(subst) = 2.0), iron oxides (OR(subst) = 1.9), aliphatic ketones (OR(subst) = 1.9), benzene (OR(subst) = 1.9), xylene (OR(subst) = 1.9), inorganic acid solutions (OR(subst) = 1.8), waxes, polishes (OR(subst) = 1.8), mononuclear aromatic hydrocarbons (OR(subst) = 1.6), toluene (OR(subst) = 1.6), and diesel engine emissions (OR(subst) = 1.5). Not all of these effects are independent because some exposures occurred contemporaneously with others or because they referred to a group of substances. CONCLUSIONS: We have uncovered a number of occupational associations with colon cancer. For most of these agents, there are no published data to support or refute our observations. As there are few accepted risk factors for colon cancer, we suggest that new occupational and toxicologic studies be undertaken focusing on the more prevalent substances reported herein.

Evaluation of the potential promoting effect of 60 Hz magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in female F344 rats.

The present study investigated the possible effect of 60 Hz magnetic fields (MFs) as promoters of neurogenic tumors initiated transplacentally by a chemical carcinogen, N-ethyl-N-nitrosourea (ENU). In a preliminary study, 5 mg of ENU was shown to induce 30 to 40% neurogenic tumors in F344 rats offspring after 420 days of observation. In the present study, 400 female rats were divided into eight different groups (50 animals/group) and exposed in utero (on day 18 of gestation) to a single intravenous dose of either Saline (Group I), or ENU, 5 mg/kg (Group II to VIII). Dams in group II were given no further treatment while dams in Groups III to VII were exposed to 5 different intensities of MFs forty eight hours later. Animals in group III were sham exposed (<0.02 microT) while groups IV to VII were exposed to 2, 20, 200, and 2000 microT, respectively. Dams in Group VIII were injected intraperitoneally with 12-O-tetradecanoylphrobol-13-acetate (TPA; 10 micrograms/kg) from day 19 until delivery, and then their female offspring continued to be injected every 15 days, starting at day 14 after birth until sacrifice (positive controls). Accordingly, this study included three different types of controls: Internal controls (Groups II and III) and positive control (Group VIII). Body weight, mortality and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund or sacrificed at termination of the study. Histopathological evaluation was done for all brains, spinal cords, cranial nerves, major organs (lungs, liver, spleen, kidneys, pituitary, thyroid and adrenals) and all gross lesions observed during necropsy. All clinical observations and pathological evaluations were conducted under "blinded" conditions. The findings from this ENU/MFs promotion study clearly demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs had no effect on the survival of female F344 rats or on the number of animals bearing neurogenic tumors. These results suggest that MFs have no promoting effect on neurogenic tumors in the female F344 rats exposed transplacentally to ENU.

Epidemiology of acquisition and clearance of cervical human papillomavirus infection in women from a high-risk area for cervical cancer.

Acquisition and clearance of cervical human papillomavirus (HPV) infection were analyzed among 1425 low-income women attending a maternal and child health program in São Paulo, Brazil. Specimens collected every 4 months were tested by a polymerase chain reaction protocol (MY09/11). In all, 357 subjects were positive at least once. There were 1.3% new infections per month, with 38% cumulative positivity after 18 months. Of 177 positive subjects at enrollment, only 35% remained infected after 12 months. The monthly clearance rate was higher for nononcogenic types (12.2%; 95% confidence interval [CI], 9.6-15.4) than for oncogenic HPV infections (9.5%; 95% CI, 7.5-11.9). Median retention times were 8.1 months (95% CI, 7.8-8.3) for oncogenic types and 4.8 months (95% CI, 3.9-5.6) for nononcogenic HPV infections. The mean infection durations were 8.2 and 13.5 months for nononcogenic and oncogenic types, respectively. Although a woman's age did not affect mean duration for oncogenic types (13-14 months), nononcogenic-type infections lasted longer (10. 2 months) among younger (<35 years old) than in older women (5.6 months).

Risks of developing cancer relative to living near a municipal solid waste landfill site in Montreal, Quebec, Canada.

In this study, we sought to determine whether men who lived near the Miron Quarry municipal solid waste landfill site in Montreal, Quebec, Canada, were at higher risk for developing cancer than individuals who lived at more remote locations. Subjects were selected from a previously completed population-based, interview, cancer case-control study of men who lived in metropolitan Montreal. Thirteen sites of cancer (n = 2 928 subjects) and a population-based control group (n = 417) were analyzed. We used the exact street address at the time of diagnosis to classify subjects by geographic zones and distance from the site. We used unconditional logistic regression to estimate odds ratios (ORs) and associated 95% confidence intervals (CIs) for each site of cancer, adjusted for key covariates. In the exposure zone nearest to the site, elevated risks were found for cancers of the pancreas (adjusted OR = 1.4 [95% CI = 0.8, 2.6]); liver (OR = 1.8 [95% CI = 0.8, 4.3]); and prostate (OR = 1.5 [95% CI = 1.0, 2.1]). A high risk was also found for pancreatic cancer (OR = 1.7 [95% CI = 0.9, 3.5]) and the non-Hodgkin's lymphomas (OR = 1.5 [95% CI = 0.8, 2.6]) in a subexposure zone approximately downwind from the site. We used distance from the site as another exposure metric, and higher-than-expected risks were found for pancreatic cancer (OR for living within 1.25 km of the site [OR<1.25km] = 2.2 [95% CI = 1.0, 4.6]); liver cancer (OR<1.5km = 2.1 [95% CI = 0.8, 5.3]); kidney cancer (OR<2 km = 1.4 [95% CI = 0.9, 2.3]); and the non-Hodgkin's lymphomas (OR<1km = 2.0 [95% CI = 1.0, 4.0]). Data from this study and from a previous investigation at the same site suggest that men who lived near this landfill site may have been-and may continue to be-at excess risk of cancers of the liver, kidney, pancreas, and non-Hodgkin's lymphomas.

Associations between several sites of cancer and occupational exposure to benzene, toluene, xylene, and styrene: results of a case-control study in Montreal.

BACKGROUND: Except for the leukemogenic effects of benzene, there is inadequate or sparse evidence on the carcinogenicity of the most common monocyclic aromatic hydrocarbons. The purpose of this study was to generate hypotheses on associations between exposure to benzene, toluene, xylene, and styrene and various common types of cancer. METHODS: In the context of a population-based case-control study carried out in Montreal, 3,730 cancer patients (15 types of cancers, not including leukemia) and 533 population controls were interviewed, and their job histories were translated by a team of experts into occupational exposures, including benzene, toluene, xylene, and styrene. In the present analysis, exposure to these substances was compared between each case series and a control group pooling selected cancer patients and population controls, using logistic regression analysis. RESULTS: Exposure levels were low for most exposed subjects, and there was a high correlation between exposure to benzene, toluene and xylene. For most sites of cancer there was no evidence of excess risk due to these substances. However, limited evidence of increased risk was found for the following associations: esophagus-toluene, colon-xylene, rectum-toluene, rectum-xylene and rectum-styrene. CONCLUSIONS: These latter observations warrant further investigation.

Evaluation of the potential carcinogenicity of 60 Hz linear sinusoidal continuous-wave magnetic fields in Fischer F344 rats.

Electric and magnetic fields (EMFs) associated with the production, transmission, and use of electricity are ubiquitous in industrialized societies. These fields are predominantly of low frequency (50/60 Hz) and are generally of low intensity. Review of the epidemiological evidence shows that the association between exposure to EMFs and cancer is weak and inconsistent, and generally fails to show a dose-response relationship. Moreover, in view of the methodological problems of these epidemiological studies, animal and laboratory studies are urgently needed to determine whether EMFs could be initiators and/or promoters of cancers. The objective of the present study was to determine whether chronic exposure to 60 Hz linear (single axis) sinusoidal, continuous-wave magnetic fields (MFs) of different intensities might increase the risk of leukemia and solid tumor development in rodents born and raised under these fields. Five groups of 50 female F344 rats were exposed for 20 h/day to 60 Hz MFs at intensities of <0.02 (sham controls), 2, 20, 200, and 2000 microT. Full body exposure to the different fields was administered for 104 wk starting from the prenatal period (2 days before birth) and continuing during lactation and weaning until late adult life. Body weight, survival, and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund, or were killed at termination of the study. To preserve and demonstrate the absence of any experimental bias, all clinical observations and pathological evaluations were conducted under "blinded" conditions. Fifty organs and tissues were evaluated in each animal, with special attention to the incidence of mononuclear cell leukemia, brain tumors, and mammary tumors. The findings from this chronic carcinogenicity study demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs did not affect animal survival, solid tumor, or mononuclear cell leukemia development in female F344 rats. No statistically significant, consistent, positive dose-related trends with the number of tumor-bearing animals per study group could be attributed to MF exposure.

High rates of HIV infection among injection drug users participating in needle exchange programs in Montreal: results of a cohort study.

Needle exchange programs (NEPs) are designed to prevent human immunodeficiency virus (HIV) transmission among injection drug users. Although most studies report beneficial effects in terms of behavior modification, a direct assessment of the effectiveness of NEPs in preventing HIV infection has been lacking. A cohort study was conducted to assess the association between risk behaviors and HIV seroprevalence and seroincidence among injection drug users in Montreal, Canada. The association between NEP use and HIV infection was examined in three risk assessment scenarios using intensive covariate adjustment for empirical confounders: a cross-sectional analysis of NEP use at entry as a determinant of seroprevalence, a cohort analysis of NEP use at entry as a predictor of subsequent seroconversion, and a nested case-control analysis of NEP participation during follow-up as a predictor of seroconversion. From September 1988 to January 1995, 1,599 subjects were enrolled with a baseline seroprevalence of 10.7%. The mean follow-up period was 21.7 months. The adjusted odds ratio for HIV seroprevalence in injection drug users reporting recent NEP use was 2.2 (95% confidence interval 1.5-3.2). In the cohort study, there were 89 incident cases of HIV infection with a cumulative probability of HIV seroconversion of 33% for NEP users and 13% for nonusers (p < 0.0001). In the nested case-control study, consistent NEP use was associated with HIV seroconversion during follow-up (odds ratio = 10.5, 95% confidence interval 2.7-41.0). Risk elevations for HIV infection associated with NEP attendance were substantial and consistent in all three risk assessment scenarios in our cohort of injection drug users, despite extensive adjustment for confounders. In summary, in Montreal, NEP users appear to have higher seroconversion rates then NEP nonusers.

Are the apparent effects of cigarette smoking on lung and bladder cancers due to uncontrolled confounding by occupational exposures?

It has been suggested that the well known associations between smoking and cancer may in part reflect inadequately controlled confounding due to occupational exposures. The purpose of the present analysis is to describe the association between cigarette smoking and both lung and bladder cancers, taking into account the potential confounding effects of over 300 covariates, most of which represent occupational exposures. A population-based case-control study was undertaken in Montreal to investigate the associations between a large variety of environmental and occupational exposures, on the one hand, and several types of cancer, on the other. Interviews were carried out with male incident cases of several sites of cancer, including 857 lung cancers and 484 bladder cancers. A group of non-smoking-related cancers, comprising 1,707 interviewed subjects, was used as one control group. Additionally, 533 population controls were interviewed and constituted a second control group. Interview information included detailed lifetime smoking histories, job histories, and other potential confounders. Each job history was reviewed by a team of experts who translated it into a history of occupational exposures. These occupational exposures, as well as nonoccupational covariates, were treated as potential confounders in the analysis of cigarette smoking effects. Regardless of whether population controls or cancer controls were used, the odds ratio (OR) between smoking and lung cancer (ranging from 12 to 16 for ever vs never smokers) was not materially affected by adjustment for occupational exposures. The odds ratios for bladder cancer (ranging from 2 to 3) were also unaffected by confounding due to occupational exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

Sensitivity to "atypical" mycobacteria in high school children in two community health departments.

To evaluate the prevalence of atypical mycobacteria infections in our population, a study was done among students of secondary fifth grade (15-19 years of age) in the community health departments of Maisonneuve-Rosemont in Montreal and of Sherbrooke. The tuberculin used was the RT-23 2 T.U. with Tween 80 and the sensitins prepared by the Statens Serum Institute of Copenhagen from Mycobacterium intracellulare (Battey) and from Mycobacterium kansasii. Each student had a tuberculin test on one arm and a sensitin test on the other. The sensitins were randomly allocated. Depending on how the prevalence is calculated, the Mycobacterium intracellulare infection varies from 3 to 20% in Montreal and from 0 to 9.6% in Sherbrooke. The Mycobacterium kansasii infection is much less important in both regions. All reactions to those atypical mycobacteria are in the range of tuberculin reactions of 0 to 9 mm. In our population which is weakly infected with atypical mycobacteria, the level of positivity of tuberculin reactions to 2 T.U. RT-23 or 5 T.U. P.P.D. would give a more realistic evaluation of M. tuberculosis infection if it was fixed at 5 mm than at 10 mm as it is now.

Translocation (1;5)(q23;q33) in adult acute non-lymphocytic leukemia.

Chromosome banding studies carried out on bone marrow cells from a 57-year-old white caucasian male with an M1 acute non-lymphocytic leukemia (ANLL) revealed an unbalanced translocation involving chromosomes 1 and 5 [der(5)t(1;5)(q23;q33)] as part of complex abnormalities in 76% of the cells analyzed. This chromosomal abnormality is the first to be reported in an adult patient with acute non-lymphocytic leukemia. A review of previous reports on translocations involving the juxtaposition of the 1q23----qter DNA segment to other chromosomes suggests that this new translocation may be specifically involved with abnormal myeloid proliferation.

Immune response to an Actinobacillus pleuropneumoniae vaccine in swine.

Piglets vaccinated with an inactivated tetravalent vaccine (Pleurovac 4) against Actinobacillus pleuropneumoniae serotypes 1, 2, 5 and 7, produced circulating antibodies after a first intramuscular injection and showed an anamnestic reaction after a second. The rise in antibody levels in vaccinated piglets was statistically significant when compared with those of the control group. The administration of 1 or 2 mL of vaccine did not lead to significantly different antibody levels. The specificity of the immune response is demonstrated by an increase in titer to all four serotypes in pigs given the tetravalent vaccine, but an increase in titer to only two serotypes in pigs given a bivalent vaccine (Pleurovac).

Associations between several sites of cancer and nine organic dusts: results from an hypothesis-generating case-control study in Montreal, 1979-1983.

A multi-cancer site, multi-factor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with over 2,000 subjects. All incident cases of 19 sites of cancer in males aged 35-70 and resident in Montreal were eligible. The interview was designed to obtain detailed lifetime job histories, and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed as a case series, controls were selected from among the other cancer sites in the study. This report concerns the associations between sites of cancer for which there were over 100 cases processed (stomach; colorectal, also analyzed by subsites; lung; prostate; bladder; kidney; non-Hodgkin's lymphoma) and nine organic dusts (wood; paper; grain; flour; fabrics; cotton; wool; synthetics; fur). All site-exposure combinations were investigated. The ones that provided the most interesting leads were lung-wood dust (odds ratio (OR) = 1.5), stomach-wood dust (OR = 1.5), colorectal-synthetic fiber (OR = 1.5), bladder-synthetic fiber (OR = 1.8), non-Hodgkin's lymphoma-cotton dust (OR = 1.9), colon-grain dust (OR = 2.6), prostate-grain dust (OR = 2.2), and prostate-paper dust (OR = 2.0). Only the associations with wood dust, synthetic fibers and cotton dust showed some evidence of "dose-response" with duration of exposure. Because it is such a common exposure and appears to increase lung and stomach cancer risks, wood dust may be responsible for a great deal of occupational cancer.

A case of pulmonary alveolar proteinosis complicating chronic myelogenous leukemia. A peculiar pathologic aspect of busulfan lung?

A 34-year-old woman with typical chronic myelogenous leukemia was treated with daily busulfan (total dose, 1600 mg approximately) from July 1978 to June 1981. In February 1981, she noticed a progressive deterioration of her clinical status, characterized by increasing dyspnea and productive cough. In July 1981, an open lung biopsy revealed pulmonary alveolar proteinosis. The patient died of progressive respiratory failure in August 1981. The association between chronic myelogenous leukemia and pulmonary alveolar proteinosis is briefly reviewed. The report discusses the possible etiologic role of busulfan therapy in the development of pulmonary alveolar proteinosis.