Cause-specific mortality among Rhode Island jewelry workers

Trichloroethylene-induced alterations in DNA methylation were enriched in polycomb protein binding sites in effector/memory CD4+ T cells

Exposure to industrial solvent and water pollutant trichloroethylene (TCE) can promote autoimmunity, and expand effector/memory (CD62L) CD4+ T cells. In order to better understand etiology reduced representation bisulfite sequencing was used to study how a 40-week exposure to TCE in drinking water altered methylation of ∼337 770 CpG sites across the entire genome of effector/memory CD4+ T cells from MRL+/+ mice. Regardless of TCE exposure, 62% of CpG sites in autosomal chromosomes were hypomethylated (0-15% methylation), and 25% were hypermethylated (85-100% methylation). In contrast, only 6% of the CpGs on the X chromosome were hypomethylated, and 51% had mid-range methylation levels. In terms of TCE impact, TCE altered (≥ 10%) the methylation of 233 CpG sites in effector/memory CD4+ T cells. Approximately 31.7% of these differentially methylated sites occurred in regions known to bind one or more Polycomb group (PcG) proteins, namely Ezh2, Suz12, Mtf2 or Jarid2. In comparison, only 23.3% of CpG sites not differentially methylated by TCE were found in PcG protein binding regions. Transcriptomics revealed that TCE altered the expression of ∼560 genes in the same effector/memory CD4+ T cells. At least 80% of the immune genes altered by TCE had binding sites for PcG proteins flanking their transcription start site, or were regulated by other transcription factors that were in turn ordered by PcG proteins at their own transcription start site. Thus, PcG proteins, and the differential methylation of their binding sites, may represent a new mechanism by which TCE could alter the function of effector/memory CD4+ T cells.

Exposure Cessation During Adulthood Did Not Prevent Immunotoxicity Caused by Developmental Exposure to Low-Level Trichloroethylene in Drinking Water

Exposure to the water pollutant trichloroethylene (TCE) can promote autoimmunity in both humans and rodents. Using a mouse model we have shown that chronic adult exposure to TCE at 500 μg/ml in drinking water generates autoimmune hepatitis in female MRL+/+ mice. There is increasing evidence that developmental exposure to certain chemicals can be more toxic than adult exposure. This study was designed to test whether exposure to a much lower level of TCE (0.05 μg/ml) during gestation, lactation, and early life generated autoimmunity similar to that found following adult exposure to higher concentrations of TCE. When female MRL+/+ mice were examined at postnatal day (PND) 259 we found that developmental/early life exposure [gestational day 0 to PND 154] to TCE at a concentration 10 000 fold lower than that shown to be effective for adult exposure triggered autoimmune hepatitis. This effect was observed despite exposure cessation at PND 154. In concordance with the liver pathology, female MRL+/+ exposed during development and early life to TCE (0.05 or 500 μg/ml) generated a range of antiliver antibodies detected by Western blotting. Expression of proinflammatory cytokines by CD4+ T cells was also similarly observed at PND 259 in the TCE-exposed mice regardless of concentration. Thus, exposure to TCE at approximately environmental levels from gestational day 0 to PND 154 generated tissue pathology and CD4+ T cell alterations that required higher concentrations if exposure was limited to adulthood. TCE exposure cessation at PND 154 did not prevent the immunotoxicity.

Chronic exposure to trichloroethylene increases DNA methylation of the Ifng promoter in CD4+ T cells

CD4+ T cells in female MRL+/+ mice exposed to solvent and water pollutant trichloroethylene (TCE) skew toward effector/memory CD4+ T cells, and demonstrate seemingly non-monotonic alterations in IFN-γ production. In the current study we examined the mechanism for this immunotoxicity using effector/memory and naïve CD4+ T cells isolated every 6 weeks during a 40 week exposure to TCE (0.5mg/ml in drinking water). A time-dependent effect of TCE exposure on both Ifng gene expression and IFN-γ protein production was observed in effector/memory CD4+ T cells, with an increase after 22 weeks of exposure and a decrease after 40 weeks of exposure. No such effect of TCE was observed in naïve CD4+ T cells. A cumulative increase in DNA methylation in the CpG sites of the promoter of the Ifng gene was observed in effector/memory, but not naïve, CD4+ T cells over time. Also unique to the Ifng promoter was an increase in methylation variance in effector/memory compared to naïve CD4+ T cells. Taken together, the CpG sites of the Ifng promoter in effector/memory CD4+ T cells were especially sensitive to the effects of TCE exposure, which may help explain the regulatory effect of the chemical on this gene.

Chronic exposure to water pollutant trichloroethylene increased epigenetic drift in CD4(+) T cells

AIM

Autoimmune disease and CD4(+) T-cell alterations are induced in mice exposed to the water pollutant trichloroethylene (TCE). We examined here whether TCE altered gene-specific DNA methylation in CD4(+) T cells as a possible mechanism of immunotoxicity.

MATERIALS & METHODS

Naive and effector/memory CD4(+) T cells from mice exposed to TCE (0.5 mg/ml in drinking water) for 40 weeks were examined by bisulfite next-generation DNA sequencing.

RESULTS

A probabilistic model calculated from multiple genes showed that TCE decreased methylation control in CD4(+) T cells. Data from individual genes fitted to a quadratic regression model showed that TCE increased gene-specific methylation variance in both CD4 subsets.

CONCLUSION

TCE increased epigenetic drift of specific CpG sites in CD4(+) T cells.

Modeling toxicodynamic effects of trichloroethylene on liver in mouse model of autoimmune hepatitis

Chronic exposure to industrial solvent and water pollutant trichloroethylene (TCE) in female MRL+/+mice generates disease similar to human autoimmune hepatitis. The current study was initiated to investigate why TCE-induced autoimmunity targeted the liver. Compared to other tissues the liver has an unusually robust capacity for repair and regeneration. This investigation examined both time-dependent and dose-dependent effects of TCE on hepatoprotective and pro-inflammatory events in liver and macrophages from female MRL+/+mice. After a 12-week exposure to TCE in drinking water a dose-dependent decrease in macrophage production of IL-6 at both the transcriptional and protein level was observed. A longitudinal study similarly showed that TCE inhibited macrophage IL-6 production. In terms of the liver, TCE had little effect on expression of pro-inflammatory genes (Tnfa, Saa2 or Cscl1) until the end of the 40-week exposure. Instead, TCE suppressed hepatic expression of genes involved in IL-6 signaling (Il6r, gp130, and Egr1). Linear regression analysis confirmed liver histopathology in the TCE-treated mice correlated with decreased expression of Il6r. A toxicodynamic model was developed to estimate the effects of TCE on IL-6 signaling and liver pathology under different levels of exposure and rates of repair. This study underlined the importance of longitudinal studies in mechanistic evaluations of immuntoxicants. It showed that later-occurring liver pathology caused by TCE was associated with early suppression of hepatoprotection rather than an increase in conventional pro-inflammatory events. This information was used to create a novel toxicodynamic model of IL-6-mediated TCE-induced liver inflammation.

Differential immunotoxicity induced by two different windows of developmental trichloroethylene exposure

Developmental exposure to environmental toxicants may induce immune system alterations that contribute to adult stage autoimmune disease. We have shown that continuous exposure of MRL+/+ mice to trichloroethylene (TCE) from gestational day (GD) 0 to postnatal day (PND) 49 alters several aspects of CD4(+) T cell function. This window of exposure corresponds to conception-adolescence/young adulthood in humans. More narrowly defining the window of TCE developmental exposure causes immunotoxicity that would establish the stage at which avoidance and/or intervention would be most effective. The current study divided continuous TCE exposure into two separate windows, namely, gestation only (GD0 to birth (PND0)) and early-life only (PND0-PND49). The mice were examined for specific alterations in CD4(+) T cell function at PND49. One potentially long-lasting effect of developmental exposure, alterations in retrotransposon expression indicative of epigenetic alterations, was found in peripheral CD4(+) T cells from both sets of developmentally exposed mice. Interestingly, certain other effects, such as alterations in thymus cellularity, were only found in mice exposed to TCE during gestation. In contrast, expansion of memory/activation cell subset of peripheral CD4(+) T cells were only found in mice exposed to TCE during early life. Different windows of developmental TCE exposure can have different functional consequences.

Epigenetic alterations may regulate temporary reversal of CD4(+) T cell activation caused by trichloroethylene exposure

Previous studies have shown that short-term (4 weeks) or chronic (32 weeks) exposure to trichloroethylene (TCE) in drinking water of female MRL+/+ mice generated CD4(+) T cells that secreted increased levels of interferon (IFN)-γ and expressed an activated (CD44(hi)CD62L(lo)) phenotype. In contrast, the current study of subchronic TCE exposure showed that midway in the disease process both of these parameters of CD4(+) T cell activation were reversed. This phase of the disease process may represent an attempt by the body to counteract the inflammatory effects of TCE. The decrease in CD4(+) T cell production of IFN-γ following subchronic TCE exposure could not be attributed to skewing toward a Th2 or Th17 phenotype or to an increase in Treg cells. Instead, the suppression corresponded to alterations in markers used to assess DNA methylation, namely increased expression of retrotransposons Iap (intracisternal A particle) and Muerv (murine endogenous retrovirus). Also observed was an increase in the expression of Dnmt1 (DNA methyltransferase-1) and decreased expression of several genes known to be downregulated by DNA methylation, namely Ifng, Il2, and Cdkn1a. CD4(+) T cells from a second study in which MRL+/+ mice were treated for 17 weeks with TCE showed a similar increase in Iap and decrease in Cdkn1a. In addition, DNA collected from the CD4(+) T cells in the second study showed TCE-decreased global DNA methylation. Thus, these results described the biphasic nature of TCE-induced alterations in CD4(+) T cell function and suggested that these changes represented potentially reversible alterations in epigenetic processes.

Coexposure to mercury increases immunotoxicity of trichloroethylene

We have shown previously that chronic (32 weeks) exposure to occupationally relevant concentrations of the environmental pollutant trichloroethylene (TCE) induced autoimmune hepatitis (AIH) in autoimmune-prone MRL+/+ mice. In real-life, individuals are never exposed to only one chemical such as TCE. However, very little is known about the effects of chemical mixtures on the immune system. The current study examined whether coexposure to another known immunotoxicant, mercuric chloride (HgCl(2)), altered TCE-induced AIH. Female MRL+/+ mice were treated for only 8 weeks with TCE (9.9 or 186.9 mg/kg/day in drinking water) and/or HgCl(2) (260 μg/kg/day, sc). Unlike mice exposed to either TCE or HgCl(2) alone, mice exposed to both toxicants for 8 weeks developed significant liver pathology commensurate with early stages of AIH. Disease development in the coexposed mice was accompanied by a unique pattern of anti-liver and anti-brain antibodies that recognized, among others, a protein of approximately 90 kDa. Subsequent immunoblotting showed that sera from the coexposed mice contained antibodies specific for heat shock proteins, a chaperone protein targeted by antibodies in patients with AIH. Thus, although TCE can promote autoimmune disease following chronic exposure, a shorter exposure to a binary mixture of TCE and HgCl(2) accelerated disease development. Coexposure to TCE and HgCl(2) also generated a unique liver-specific antibody response not found in mice exposed to a single toxicant. This finding stresses the importance of including mixtures in assessments of chemical immunotoxicity.

Xenobiotic exposure and autoimmune hepatitis

Although genetics contributes to the development of autoimmune diseases, it is clear that "environmental" factors are also required. These factors are thought to encompass exposure to certain drugs and environmental pollutants. This paper examines the mechanisms that normally maintain immune unresponsiveness in the liver and discusses how exposure to certain xenobiotics such as trichloroethylene may disrupt those mechanisms and promote autoimmune hepatitis.

Delineating liver events in trichloroethylene-induced autoimmune hepatitis

Exposure to the environmental pollutant trichloroethylene (TCE) has been linked to autoimmune disease development in humans. Chronic (32-week) low-level exposure to TCE has been shown to promote autoimmune hepatitis in association with CD4(+) T cell activation in autoimmune-prone MRL+/+ mice. MRL+/+ mice are usually thought of as a model of systemic lupus rather than an organ-specific disease such as autoimmune hepatitis. Consequently, the present study examined gene expression and metabolites to delineate the liver events that skewed the autoimmune response toward that organ in TCE-treated mice. Female MRL+/+ mice were treated with 0.5 mg/mL TCE in their drinking water. The results showed that TCE-induced autoimmune hepatitis could be detected in as little as 26 weeks. TCE exposure also generated a time-dependent increase in the number of antibodies specific for liver proteins. The gene expression correlated with the metabolite analysis to show that TCE upregulated the methionine/homocysteine pathway in the liver after 26 weeks of exposure. The results also showed that TCE exposure altered the expression of selective hepatic genes associated with immunity and inflammation. On the basis of these results, future mechanistic studies will focus on how alterations in genes associated with immunity and inflammation, in conjunction with protein alterations in the liver, promote liver immunogenicity in TCE-treated MRL+/+ mice.

A meta-analysis of occupational trichloroethylene exposure and liver cancer

OBJECTIVE

Findings from epidemiologic studies of trichloroethylene (TCE) exposure and liver cancer have been inconsistent. To quantitatively evaluate this association and to examine sources of heterogeneity, we conducted a meta-analysis of occupational studies of TCE exposure and liver/biliary tract cancer.

METHODS

We identified 14 occupational cohort studies of TCE exposed workers and one case-control study that met our inclusion criteria. Nine studies specifically identified TCE as a workplace exposure, and were classified as Group I cohort studies. Subcohorts of workers, identified within eight of these studies as more likely exposed to TCE than the total cohort, were analyzed separately.

RESULTS

The combined liver/biliary cancer summary relative risk estimate (SRRE) for all studies was 1.08 (95% CI 0.91-1.29; heterogeneity (H)-P-value=0.12). For the total study populations in the Group I cohorts, the SRRE was 1.14 (95% CI 0.93-1.39; H-P-value=0.05) and for the subcohorts, the SRRE was 1.30 (95% CI 1.09-1.55). Within this subcohort analysis, the association for the European studies of workers from various industries (SRRE=1.38; based on four studies) was higher than the association for the US studies of aerospace and aircraft workers (SRRE=0.97, based on four studies).

CONCLUSION

Although positive associations were observed for some analyses, results were inconsistent across occupational groups (aerospace/aircraft vs. other industries combined), study location, and incidence versus mortality endpoints. In addition, exposure-response trends were not observed consistently across studies. Interpretation is also limited by the potential impact of uncontrolled confounding by other occupational or lifestyle exposures such as smoking or alcohol consumption. Given these limitations, the currently available epidemiologic data are not sufficient to support a causal relation between occupational TCE exposure and liver/biliary cancer.

Multiple myeloma: A review of the epidemiologic literature

Multiple myeloma, a neoplasm of plasma cells, accounts for approximately approximately 15% of lymphatohematopoietic cancers (LHC) and 2% of all cancers in the US. Incidence rates increase with age, particularly after age 40, and are higher in men, particularly African American men. The etiology is unknown with no established lifestyle, occupational or environmental risk factors. Although several factors have been implicated as potentially etiologic, findings are inconsistent. We reviewed epidemiologic studies that evaluated lifestyle, dietary, occupational and environmental factors; immune function, family history and genetic factors; and the hypothesized precursor, monoclonal gammopathies of undetermined significance (MGUS). Because multiple myeloma is an uncommon disease, etiologic assessments can be difficult because of small numbers of cases in occupational cohort studies, and few subjects reporting exposure to specific agents in case-control studies. Elevated risks have been reported consistently among persons with a positive family history of LHC. A few studies have reported a relationship between obesity and multiple myeloma, and this may be a promising area of research. Factors underlying higher incidence rates of multiple myeloma in African Americans are not understood. The progression from MGUS to multiple myeloma has been reported in several studies; however, there are no established risk factors for MGUS. To improve our understanding of the causes of multiple myeloma, future research efforts should seek the causes of MGUS. More research is also needed on the genetic factors of multiple myeloma, given the strong familial clustering of the disease.

Occupational silica exposure and risk of various diseases: an analysis using death certificates from 27 states of the United States

BACKGROUND

Although crystalline silica exposure is associated with silicosis, lung cancer, pulmonary tuberculosis, and chronic obstructive pulmonary disease (COPD), there is less support for an association with autoimmune disease, and renal disease.

METHODS

Using data from the US National Occupational Mortality Surveillance (NOMS) system, a matched case-control design was employed to examine each of several diseases (including silicosis, lung cancer, stomach cancer, oesophageal cancer, COPD, pulmonary tuberculosis, sarcoidosis, systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, and various types of renal disease). Cases were subjects whose death certificate mentioned the disease of interest. A separate control group for each of the diseases of interest was selected from among subjects whose death certificate did not mention the disease of interest or any of several diseases reported to be associated with crystalline silica exposure. Subjects were assigned into a qualitative crystalline silica exposure category based on the industry/occupation pairing found on their death certificate. We also investigated whether silicotics had a higher risk of disease compared to those without silicosis.

RESULTS

Those postulated to have had detectable crystalline silica exposure had a significantly increased risk for silicosis, COPD, pulmonary tuberculosis, and rheumatoid arthritis. In addition, a significant trend of increasing risk with increasing silica exposure was observed for these same conditions and for lung cancer. Those postulated to have had the greatest crystalline silica exposure had a significantly increased risk for silicosis, lung cancer, COPD, and pulmonary tuberculosis only. Finally, those with silicosis had a significantly increased risk for COPD, pulmonary tuberculosis, and rheumatoid arthritis.

CONCLUSIONS

This study corroborates the association between crystalline silica exposure and silicosis, lung cancer, COPD, and pulmonary tuberculosis. In addition, support is provided for an association between crystalline silica exposure and rheumatoid arthritis.

Mortality in dry-cleaning workers: an update

BACKGROUND

A cohort of 1,708 dry-cleaning workers identified from union records was exposed to perchloroethylene (PCE), a known animal carcinogen and probable human carcinogen, for at least 1 year before 1960. Many workers also had exposure to Stoddard solvent, a petroleum-based dry-cleaning solvent.

METHODS

Vital status was updated through 1996 and life table analyses conducted.

RESULTS

The cohort had excess cancer mortality (271 deaths, standardized mortality ratio [SMR] 1.25, 95% confidence interval [CI] 1.11-1.41). Elevated SMRs for tongue, bladder, esophagus, intestine, lung, and cervical cancer, pneumonia, and diseases of the stomach and duodenum were statistically significant.

CONCLUSION

The current study confirms findings of prior updates and other studies that dry-cleaning workers have excess cancer mortality at several sites. Although important lifestyle and socioeconomic risk factors exist for both cervical and esophageal cancer mortality, excesses of these sites in the PCE only subcohort and among workers with longer duration of PCE exposure suggest an association with PCE exposure.

Trichloroethylene and cancer: epidemiologic evidence

Trichloroethylene is an organic chemical that has been used in dry cleaning, for metal degreasing, and as a solvent for oils and resins. It has been shown to cause liver and kidney cancer in experimental animals. This article reviews over 80 published papers and letters on the cancer epidemiology of people exposed to trichloroethylene. Evidence of excess cancer incidence among occupational cohorts with the most rigorous exposure assessment is found for kidney cancer (relative risk [RR] = 1.7, 95% confidence interval [CI] 1.1-2.7), liver cancer (RR = 1.9, 95% CI(1.0-3.4), and non-Hodgkin's lymphoma (RR = 1.5, 95% CI 0.9-2.3) as well as for cervical cancer, Hodgkin's disease, and multiple myeloma. However, since few studies isolate trichloroethylene exposure, results are likely confounded by exposure to other solvents and other risk factors. Although we believe that solvent exposure causes cancer in humans and that trichloroethylene likely is one of the active agents, we recommend further study to better specify the specific agents that confer this risk and to estimate the magnitude of that risk.

Occupational risk factors for female breast cancer: a review

OBJECTIVES

Although progress has been made in identifying personal risk factors and in improving treatment for female breast cancer, incidence rates continue to increase. With women now occupying a sizable fraction of the workforce, it is worth inquiring whether there are occupational risk factors for breast cancer. This is a review of occupational studies on female breast cancer.

METHODS

Suitable reports and published articles with associations of female breast cancer and occupation were identified from technical reports, by searching the MEDLINE bibliographic data base, and by reviewing each paper on cancer that was published in 20 major journals during the period from about 1971-94.

RESULTS

A total of 115 studies were identified; 19 studies relied exclusively on data collected for administrative purposes, and there were four incident case-control studies and 92 cohort studies. Although data for individual industries, occupations, and exposures were sparse, there was limited evidence of an association with employment in the pharmaceutical industry and among cosmetologists and beauticians. Associations were also found for chemists and occupations with possible exposure to extremely low frequency electromagnetic fields, but potential methodological weaknesses preclude drawing any definite conclusions. There was little support for increased risks among textiles workers, dry cleaning workers, and nuclear industry workers.

CONCLUSIONS

Few high quality occupational studies directed specifically toward women have been carried out to allow the unambiguous identification of occupational risk factors for breast cancer. It is suggested that investigations that account for non-occupational risk factors and that assess exposure in a more detailed way be carried out. One strategy already suggested is to conduct population based, case-control studies in which subjects are interviewed about their occupational histories and exposure to chemical and physical agents which are then attributed from the job descriptions by a team of experts. These studies can then be supplemented when necessary with cohort studies of specific populations.

Trichloroethylene--a review of the literature from a health effects perspective

This report reviews the literature on the impact of exposure to trichloroethylene (TCE) on human health. Special emphasis is given to the health effects reported in excess of national norms by participants in the TCE Subregistry of the Volatile Organic Compounds Registry of the National Exposure Registries--persons with documented exposure to TCE through drinking and use of contaminated water. The health effects reported in excess by some or all of the sex and age groups studied were speech and hearing impairments, effects of stroke, liver problems, anemia and other blood disorders, diabetes, kidney disease, urinary tract disorders, and skin rashes.

Asbestos-induced lung injury among Danish jewelry workers

Asbestos has been used extensively in a variety of occupations. In the jewelry industry, inadequate hygiene practices may often go unrecognized with resultant exposure to hazardous amounts of asbestos. We report on four retired jewelers. Two of these had both pleural and parenchymal changes. One had isolated pleural plaques and the final patient showed only parenchymal infiltrates. Their work involved hand cutting asbestos plates used for protection during soldering. In the soldering process asbestos fibers were then blown into the workroom air as the plates broke down. In addition, at the end of each work day the workroom floor was swept, with subsequent airborne asbestos dust distribution. Any patient with pleural plaques or interstitial lung disease should be questioned about potential sources of asbestos exposure in the past, regardless of present employment status.

Occupation and stomach cancer in a cohort of Swedish men

Using the Cancer-Environment Registry of Sweden, which links the 1960 census information on employment with cancer incidence data from 1961-1979, we conducted a systematic, population-based assessment of stomach cancer incidence by industry and occupation for men in Sweden. Nearly 17,000 stomach cancer cases were diagnosed during the 19 years of follow-up. Stomach cancer incidence was elevated among miners and quarrymen, farmers and fishermen, and craftsmen and production workers. Men who held white collar jobs, including professional and technical, administrative and management, clerical, and sales jobs, had a reduction in stomach cancer incidence. Examination of specific jobs revealed generally elevated rates of stomach cancer among men who may be exposed to dusty work environments, such as quarry workers, stone cutters, circular and plane operators, construction workers, crane operators, heavy laborers, and shop and construction metal workers. These occupational associations mostly were observed for stomach cancers of noncardia origin, and no significant associations were found with cardia cancers. We had no information on dietary or other potential confounding factors and cannot make inferences about the role of occupation per se, but the current findings support those of earlier investigations and add to the evidence of a small but significant occupational role in stomach carcinogenesis.

Cancer mortality among jewelry workers

Mortality was investigated for the years 1950-1980 for 1,009 male members of a New York jewelry workers union, and for the years 1984-1989 among 919 men and 605 women identified as jewelry workers on death certificates from 24 states. Malignant neoplasms were excessive for male union members (proportional mortality ratio [PMR] = 1.17; 95% confidence interval [CI]: 1.02-1.33) and female jeweler deaths from the 24 states (PMR = 1.24; 95% CI: 1.07-1.42). Deaths due to nonmalignant causes were not unusual, except for excesses, in union males, of the circulatory system (PMR = 1.10; 95% CI: 1.02-1.19), including arteriosclerotic heart disease (PMR = 1.25; 95% CI: 1.14-1.37) and rheumatic heart disease (PMR = 3.02; 95% CI: 1.94-4.50). Cancers of the digestive tract were proportionally elevated among union males (proportional cancer mortality rate [PMR] = 1.13; 95% CI: 0.89-1.41) and among deaths from the 24 states (PCMR = 1.22; 95% CI: 1.01-1.47). For the 24 states, excesses for digestive cancer were found for both males (PCMR = 1.19; 95% CI: 0.90-1.54) and females (PCMR = 1.26; 95% CI: 0.96-1.62). Regarding specific sites in the digestive tract, colon cancer excesses were found in union males (PCMR = 1.53: 95% CI: 1.05-2.15), and for men (PCMR = 1.27; 95% CI: 0.82-1.88) and women (PCMR = 1.36; 95% CI: 0.92-3.27) in 24 states.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for gastric carcinoma in coal miners

This study aimed to determine the prevalence of dyspeptic symptoms and premalignant gastric lesions in coal miners and sex matched population control subjects. Retired coal miners and men from the general population in north Nottinghamshire were sent a dyspepsia questionnaire to fill in, and those with upper gastrointestinal symptoms were invited for gastroscopy and biopsy. A total of 1272 men from the general population and 2099 retired coal miners aged 50-75 years took part in the study. Some 977 of 1272 (76.8%) control subjects and 1715 of 2099 (81.7%) miners replied to the questionnaire. A total of 308 of 977 (31.5%) controls and 620 of 1715 (36.2%) miners were positive for at least one symptom. There was a highly significant difference between the numbers of surface mine and underground workers who reported dyspeptic symptoms (66 of 300 (22%) v 425 of 1083 (32.2%) of p < 0.0001). Histology showed that significantly more miners than controls had acute on chronic gastritis (22 v 11%; p = 0.01) and intestinal metaplasia (23 v 8%; p = < 0.0001). Coal miners may be a suitable group for gastric premalignancy screening using an upper gastrointestinal symptom questionnaire and upper gastrointestinal endoscopy.

Malignant mesothelioma in the jewelry industry

We conducted a clinical, environmental, pathologic, and mineral lung burden investigation of a 61-year-old man with malignant mesothelioma. For 35 years, up until three weeks prior to pneumonectomy, the patient made asbestos soldering forms at a costume jewelry production facility. Only chrysotile asbestos was used at the plant during the last decade of the patient's employment, and recent environmental sampling of the work-place identified no other asbestos fiber type. Anticipating that the patient would add to the very small number of cases of mesothelioma attributable solely to chrysotile, we found instead that the patient's lung tissue contained large numbers of both coated and uncoated amosite asbestos fibers but, surprisingly, no chrysotile. We subsequently learned that a distributor of both chrysotile and amosite supplied the company during the first 25 years the patient was fabricating soldering forms. The findings underscore the futility of estimating environmental exposure to chrysotile on the basis of fiber counts in lung tissue. Although we previously described non-neoplastic asbestos-related disease among patients engaged in similar work, this case, to the best of our knowledge, represents the first report of mesothelioma in the commercial jewelry industry. As such, it prompted us to initiate a public health campaign to replace asbestos soldering forms in this industry with readily available, safer alternatives.

Occupational risk factors for gastric cancer in Shanghai, China

Occupational data for over 13,000 incident stomach cancer cases reported to the Shanghai Cancer Registry between 1980 and 1984 were compared with 1982 census employment information to calculate standardized incidence ratios for stomach cancer in the Shanghai urban area. Several occupations were found to have statistically significantly increased risks for stomach cancer, most notably grain farming and several jobs involving potential for exposure to metal, wood, and other dusts and to fossil fuel combustion products. Because of the large numbers involved and consistency of associations, the findings raise hypotheses regarding occupational exposures that warrant further investigation.

Cause-specific mortality among male textile workers in Rhode Island

Cause-specific mortality patterns among male textile workers in Rhode Island who died during the period 1968-1978 were examined using the proportionate mortality ratio (PMR) method. Textile worker decedents were identified by the usual occupation and industry statements on Rhode Island death certificates. A statistically significant PMR elevation was observed for nonmalignant respiratory disease (NMRD) among male textile workers (PMR = 110; Observed deaths [Obs] = 433; 95% confidence interval (CI) = 102-120). The PMRs for NMRD by specific textile occupation and by type of textile manufacturing generally exhibited the pattern expected for work-related mortality owing to textile dust exposure. High PMRs were observed among carding, lapping, and combing operatives, the decedents who probably had the highest dust exposure (PMR = 166; Obs = 24; CI = 114-243), and among operatives most likely to have worked in cotton manufacturing (PMR = 137; Obs = 47; CI = 104-179). This is the first report of excess mortality from NMRD among male textile workers in the United States. This finding is consistent with previous evidence that exposure to cotton dust can cause disabling chronic lung disease. Also noteworthy were statistically significant elevated PMRs for cancers of the rectum and esophagus among decedents who had been engaged in textile dyeing and finishing. Owing to the lack of direct information about occupational exposures and smoking habits of the decedents and uncertainties in classifying decedents by type of textile manufacturing, this investigation should be viewed as being exploratory in nature.