Historical cohort investigation of spontaneous abortion in the semiconductor health study: Epidemiologic methods and analyses of risk in fabrication overall and in fabrication work groups

The risk of spontaneous abortion (SAB) in the semiconductor industry was examined in a historical cohort study of pregnancies at 14 companies. We identified Female employees who had worked for at least 6 months and whose ages ranged from 18 to 44 years during the 1986–1989 study period. Using company records, we included all fabrication-room (fab) employees and an Approximately equal number of nonfabrication (non-fab) employees, for a total sample of 7,269. Telephone interviews with 6,088 women (84%) identified 904 eligible pregnancies and 113 SABs. Exposure classification was based on questionnaire and industrial hygiene assessments of tasks the women performed during the first trimester of pregnancy. Using logistic regression to control for age, smoking, ethnicity, education, income, year of pregnancy, and stress, we found a higher risk of SAB in fab employees than in nonfab employees (15.0% of fab pregnancies ended in SAB vs. 10.4% of nonfab pregnancies, adjusted relative risk [RR] = 1.43, 95% CI = 0.95-2.09). Analysis of fab work groups showed that the highest relative risk was in MAsking employees (17.5% SAB rate, adjusted RR = 1.78, 95% CI = 1.17-2.62 in comparison with nonfab employees). Within MAsking, the highest risk was found in etching-related process employees (22.2% SAB rate, adjusted RR = 2.08, 95% CI = 1.27-3.19 in comparison to nonfab employees)     

Association of spontaneous abortion and other reproductive effects with work in the semiconductor industry

This study tested the hypothesis that fabrication room (fab) work in the silicon-based semiconductor industry is associated with an increased risk of spontaneous abortion (SAB). The study was conducted nationwide at 14 companies representing a spectrum of large to small manufacturers. A small increase in risk of SAB was observed among fab workers compared with nonfabrication room (nonfab) workers in two cohorts, historical (adjusted RR = 1.43, 95% confidence interval [CI] 0.95–2.09) and prospective (adjusted RR = 1.25, 95% CI = 0.63–1.76). Analysis of specific fab exposures in the historical cohort showed a consistent, dose-response association of SAB with photoresist and developer solvents, whose major component was ethylene-based glycol ethers. The consistency of our findings and the toxicological data for these agents suggest that this is a causal association. Independent associations of SAB with self-reported stress and with etching fluorides were observed and require further research. No significant decrease in fertility was observed among men or women working in fabs, but reduced fecundability was suggested for some women fab workers.     

Prospective monitoring of early fetal loss and clinical spontaneous abortion among female semiconductor workers

Women who work in silicon wafer fabrication rooms (fabs) have been reported to have an increased risk of spontaneous abortion (SAB). Although previous studies have included only clinically recognized SABs, more than two-thirds of SABs MAy be clinically unrecognized. To determine whether fab work is associated with SAB, we recruited 152 fab and 251 nonfab workers, who collected urine samples for a 6-month period. Samples were analyzed by immunoradiometric assay for the presence of human chorionic gonadotropin to detect early fetal losses. Approximately 63% of fab and 46% of nonfab pregnancies ended in SAB [adjusted relative risk (RR) = 1.25; 95% confidence interval (CI) = 0.63-1.76]. Similar RR were seen for women who worked in dopant and thin-film processes (adjusted RR = 1.30; 95% CI = 0.51-1.96) or in MAsking (adjusted RR = 1.30; 95% CI = 0.59-1.84). The four pregnancies among women who worked with ethylene-based glycol ethers ended in SAB.     

Exposure to a nutrition supplementation intervention in early childhood and risk factors for cardiovascular disease in adulthood: evidence from Guatemala

To study the role of nutrition in the association of birth size and childhood growth with development of cardiovascular disease, the authors in 2002-2004 surveyed 665 men and 790 women aged 25-42 years who had been exposed as children to a community-randomized nutrition supplementation intervention in four villages in eastern Guatemala. Exposure was associated with a lower fasting glucose level (7.0 mg/dl, 95% confidence interval (CI): 0.5, 13.5) for exposure at ages 36-72 months; lower systolic blood pressure (3.0 mmHg, 95% CI: 0.4, 5.6) for exposure at ages 24-60 months; and a lower triglyceride level (sex-adjusted; 22.2 mg/dl, 95% CI: 0.4, 44.1) and higher high density lipoprotein cholesterol level (males only; 4.7 mg/dl, 95% CI: 1.5, 7.9) for exposure prior to age 36 months. Improved nutrition at any age prior to 7 years was not associated with diastolic blood pressure, total or low density lipoprotein cholesterol level, or prevalence of the metabolic syndrome. Interventions designed to address nutrient deficiencies and ameliorate stunting that are targeted at pregnant women and young children are unlikely to increase cardiovascular disease risk later in life and may instead lower the risk.     

Radiographic osteoarthrosis in the acromioclavicular joint resulting from manual work or exposure to vibration.

The hypothesis that manual work and exposure to vibration are antecedents to the development of osteoarthrosis was assessed employing a cross sectional study design. The frequency of osteoarthrosis in the acromioclavicular joint was studied in three groups of workers in the construction industry. Two groups were manual workers (54 bricklayers and 55 rock blasters); the third group consisted of 98 foremen. The radiographic appearance of the right and left acromioclavicular joints was classified into one of five grades of osteoarthrosis. A protocol was developed to assess exposure on the basis of job title, years of manual work, total weight lifted during working life, and total hours of exposure to vibrating tools. Odds ratios for job titles (manual worker v foreman) and for years of manual work as indicators of exposure were of similar magnitude of around 2.5. Construction workers who had lifted more than 709 tonnes had an increased risk of developing severe osteoarthrosis of the right acromioclavicular joint, odds ratio: 2.62 (95% confidence interval (95% CI), 1.13-6.06). The odds ratio for the left side was 7.67 (95% CI, 2.76-21.34). In the analysis of vibration exposure, workers who had been highly exposed to vibration had an odds ratio of 1.99 (95% CI, 1.00-3.92) on the right side and 2.20 (95% CI, 1.07-4.56) on the left. This effect almost disappeared after simultaneous adjustment for manual work. Occupational and ergonomic factors, such as the sum of lifted tonnes during working life, job title, and the sum of years of manual work seem to be risk factors for osteoarthrosis of the acromioclavicular joint, whereas vibration alone was a weaker risk factor.     

Radiographic osteoarthrosis in the acromioclavicular joint resulting from manual work or exposure to vibration.

The hypothesis that manual work and exposure to vibration are antecedents to the development of osteoarthrosis was assessed employing a cross sectional study design. The frequency of osteoarthrosis in the acromioclavicular joint was studied in three groups of workers in the construction industry. Two groups were manual workers (54 bricklayers and 55 rock blasters); the third group consisted of 98 foremen. The radiographic appearance of the right and left acromioclavicular joints was classified into one of five grades of osteoarthrosis. A protocol was developed to assess exposure on the basis of job title, years of manual work, total weight lifted during working life, and total hours of exposure to vibrating tools. Odds ratios for job titles (manual worker v foreman) and for years of manual work as indicators of exposure were of similar magnitude of around 2.5. Construction workers who had lifted more than 709 tonnes had an increased risk of developing severe osteoarthrosis of the right acromioclavicular joint, odds ratio: 2.62 (95% confidence interval (95% CI), 1.13-6.06). The odds ratio for the left side was 7.67 (95% CI, 2.76-21.34). In the analysis of vibration exposure, workers who had been highly exposed to vibration had an odds ratio of 1.99 (95% CI, 1.00-3.92) on the right side and 2.20 (95% CI, 1.07-4.56) on the left. This effect almost disappeared after simultaneous adjustment for manual work. Occupational and ergonomic factors, such as the sum of lifted tonnes during working life, job title, and the sum of years of manual work seem to be risk factors for osteoarthrosis of the acromioclavicular joint, whereas vibration alone was a weaker risk factor.     

Risk factors for kidney cancer in New South Wales. IV. Occupation.

In a population based case-control study of kidney cancer in New South Wales, data from structured interviews with 489 cases of renal cell cancer (RCC), 147 cases of renal pelvic cancer (CaRP), and 523 controls from the electoral roles were obtained about employment in certain industries or occupations, and exposure to particular chemicals chosen because of suspected associations with kidney cancer. A low level of education increased the risk for CaRP but not RCC. After adjustment for known risk factors, exposure to asbestos significantly increased the risk for RCC (relative risk (RR) = 1.62; 95% confidence interval (95% CI) 1.04-2.53). Working in the dry cleaning industry had a stronger link with CaRP (RR = 4.68; 95% CI 1.32-16.56) than with RCC (RR = 2.49; 95% CI 0.97-6.35). Working in the iron and steel industry doubled the risk for CaRP (RR = 2.13; 95% CI 1.04-4.39) whereas employment in the petroleum refining industry had a non-significant association with CaRP (RR = 2.60; 95% CI 0.88-7.63) and none with RCC.     

Prediction model to identify patients with Staphylococcus aureus bacteremia at risk for methicillin resistance.

OBJECTIVES: To identify institution-specific risk factors for MRSA bacteremia and develop an objective mechanism to estimate the probability of methicillin resistance in a given patient with Staphylococcus aureus bacteremia (SAB). DESIGN: A cohort study was performed to identify institution-specific risk factors for MRSA. Logistic regression was used to model the likelihood of MRSA. A stepwise approach was employed to derive a parsimonious model. The MRSA prediction tool was developed from the final model. SETTING: A 279-bed, level 1 trauma center. PATIENTS: Between January 1, 1999, and June 30, 2001, 494 patients with clinically significant episodes of SAB were identified. RESULTS: The MRSA rate was 45.5%. Of 18 characteristics included in the logistic regression, the only independent features for MRSA were prior antibiotic exposure (OR, 9.2; CI95, 4.8 to 17.9), hospital onset (OR, 3.0; CI95, 1.9 to 4.9), history of hospitalization (OR, 2.5; CI95, 1.5 to 3.8), and presence of decubitus ulcers (OR, 2.5; CI95, 1.2 to 4.9). The prediction tool was derived from the final model, which was shown to accurately reflect the actual MRSA distribution in the cohort. CONCLUSION: Through multivariate modeling techniques, we were able to identify the most important determinants of MRSA at our institution and develop a tool to predict the probability of methicillin resistance in a patient with SAB. This knowledge can be used to guide empiric antibiotic selection. In the era of antibiotic resistance, such tools are essential to prevent indiscriminate antibiotic use and preserve the longevity of current antimicrobials.     

Are childhood socio-economic circumstances related to coronary heart disease risk? Findings from a population-based study of older men

BACKGROUND: The independent influence of childhood social circumstances on health in later life remains uncertain. We examined the extent to which childhood socio-economic circumstances are related to the risk of coronary heart disease (CHD) in older British men, taking account of adult social class and behavioural risk factors. METHODS: A socio-economically representative sample of 5552 British men (52-74 years) with retrospective assessment of childhood socio-economic circumstances (father's occupation and childhood household amenities) who were followed up for CHD (fatal and non-fatal) for 12 years. RESULTS: Men whose childhood social class was manual had an increased hazard ratio (HR) 1.34 (95% CI 1.11-1.63)-this effect was diminished when adjusted for adult social class and adult behavioural risk factors (cigarette smoking, alcohol, physical activity and body weight) (HR 1.19; 95% CI 0.97-1.46). Men whose family did not own a car in their childhood were at increased CHD risk even after adjustments for adult social class and behaviours (HR 1.35, 95% CI 1.04-1.75). Men with combined exposure to both childhood and adult manual social class had the highest risk of CHD (HR 1.51; 95% CI 1.19-1.91); this was substantially reduced by adjustment for adult behavioural risk factors (adjusted HR 1.28; 95% CI 0.99-1.65). CONCLUSIONS: Less affluent socio-economic conditions in childhood may have a modest persisting influence on risk of CHD in later life.     

Mortality of copper cadmium alloy workers with special reference to lung cancer and non-malignant diseases of the respiratory system, 1946-92.

OBJECTIVES--To identify and quantify any relations between occupational exposure to cadmium oxide fume and mortalities from lung cancer and from chronic non-malignant diseases of the respiratory system. METHODS--The mortality experience of 347 copper cadmium alloy workers, 624 workers employed in the vicinity of copper cadmium alloy work (vicinity workers), and 521 iron and brass foundry workers (all men) was investigated for the period 1946-92. All subjects were first employed in these types of work in the period 1922-78 and for a minimum period of one year at one of two participating factories. Two analytical approaches were used, indirect standardisation and Poisson regression. RESULTS--Compared with the general population of England and Wales, mortality from lung cancer among copper cadmium alloy workers was close to expectation (observed deaths 18, expected deaths 17.8, standardised mortality ratio (SMR) 101, 95% confidence interval (95% CI) 60 to 159). A significant excess was shown for lung cancer among vicinity workers but not among iron and brass foundry workers (vicinity workers: observed 55, expected 34.3, SMR 160, 95% CI 121 to 209, P < 0.01; iron and brass foundry workers: observed 19, expected 17.8, SMR 107, 95% CI 64 to 167). Increased SMRs for non-malignant diseases of the respiratory system were shown for each of the three groups (alloy workers: observed 54, expected 23.5, SMR 230, 95% CI 172 to 300, P < 0.001; vicinity workers: observed 71, expected 43.0, SMR 165, 95% CI 129 to 208, P < 0.001; iron and brass foundry workers: observed 34, expected 17.1, SMR 199, 95% CI 137 to 278, P < 0.01). Work histories of the copper cadmium alloy workers were combined with independent assessments of cadmium exposures over time to develop individual estimates of cumulative exposure to cadmium; this being a time dependent variable. Poisson regression was used to investigate risks of lung cancer and risks of chronic non-malignant diseases of the respiratory system in relation to three levels of cumulative cadmium exposure (< 1600, 1600-4799, > or = 4800 micrograms.m-3.y). After adjustment for age, year of starting alloy work, factory, and time from starting alloy work, there was a significant positive trend (P < 0.01) between cumulative exposure to cadmium and risks of mortality from chronic non-malignant diseases of the respiratory system. Relative to a risk of unity for the lowest exposure category, risks were 4.54 (95% CI 1.96 to 10.51) for the middle exposure category and 4.74 (95% CI 1.81 to 12.43) for the highest exposure category. There was a non-significant negative trend between cumulative cadmium exposure and risks of mortality from lung cancer. Relative to a risk of unity for the lowest exposure category, risks were 0.85 (95% CI 0.27 to 2.68) for the middle exposure category and 0.81 (95% CI 0.18 to 3.73) for the highest exposure category. Similar findings were obtained when adjustment was made for age only. CONCLUSIONS--The findings are consistent with the hypothesis that exposure to cadmium oxide fume increases risks of mortality from chronic non-malignant diseases of the respiratory system. The findings do not support the hypothesis that exposure to cadmium oxide fume increases risks of mortality for lung cancer.     

Association of DDT with spontaneous abortion: a case-control study

PURPOSE: Spontaneous abortion (SAB), the most common adverse pregnancy outcome, affects approximately 15% of clinically recognized pregnancies. Except for advanced maternal age and smoking, there are not well-established risk factors for SAB. Animal models associate increased fetal resorption or abortion with exposure to the pesticide dichlorodiphenyl trichloroethane (DDT), but epidemiologic investigations of DDT and SAB are inconsistent. We undertook a pilot investigation of the hypothesized association of DDT with SAB. METHODS: Participants in this case-control study were selected from a longitudinal study of reproductive effects of rotating shifts among female Chinese textile workers who were married, ages 22-34, nulliparous without history of SAB or infertility, and planning pregnancy. From 412 pregnancies, 42 of which ended in SAB, 15 SAB cases and 15 full-term controls were randomly selected and phlebotomized. Serum was analyzed for p,p'-DDT, o,p'-DDT, their metabolites (DDE and DDD), and other organochlorines including polychlorinated biphenyls. RESULTS: Cases and controls were nonsmokers and did not differ in age (mean 25 years), body mass index (BMI), passive smoke exposure, or workplace exposures. Cases had significantly (p < 0.05) higher serum levels of p,p'-DDE (22 vs.12 ng/g) and o,p'-DDE (0.09 vs. 0.05 ng/g) than controls. After adjustment for age and BMI, each ng/g serum increase in p,p'-DDE was associated with a 1.13 (CI, 1.02-1.26) increased odds of SAB. With adjustment of serum DDE levels for excretion via breastfeeding, DDE-associated increased odds of SAB remained significant with up to 7% declines in maternal serum DDE levels for each month of breastfeeding. CONCLUSIONS: A potential increased risk of SAB is associated with maternal serum DDE levels.     

Lyme disease in outdoor workers: risk factors, preventive measures, and tick removal methods

A statewide cross-sectional study of risk factors for seropositivity for antibody to Borrelia burgdorferi in outdoor workers in New Jersey was performed in September and October 1988. The crude odds ratio associated with exposure to ticks on the primary state job was 2.2 (95% confidence interval (CI) 0.7-9.0). After adjustment for multiple confounding variables with logistic regression, the adjusted occupational tick exposure odds ratio was 5.1 (95% CI 1.1-23.6). Additional analyses revealed that any use of insect repellent or antibiotics may have decreased the risk of Lyme disease in these workers (adjusted odds ratios for not using insect repellent or antibiotics were 2.0 (95% CI 1.0-4.0) and 2.3 (95% CI 0.8-6.7), respectively). These data suggest that Lyme disease is a hazard of outdoor work and that increased recognition of this fact will be necessary to prevent Lyme disease in these workers.     

Occupational exposures and head and neck cancers among Swedish construction workers

OBJECTIVES: Occupational exposures in the construction industry may increase the risk of head and neck cancers, although the epidemiologic evidence is limited by problems of low study power and inadequate adjustment for tobacco use. In an attempt to address this issue, the relationship between selected occupational exposures and head and neck cancer risk was investigated using data from a large cohort of Swedish construction workers. METHODS: Altogether 510 squamous cell carcinomas of the head and neck (171 in the oral cavity, 112 in the pharynx, 227 in the larynx) were identified during 1971-2001 among 307 799 male workers in the Swedish construction industry. Exposure to diesel exhaust, asbestos, organic solvents, metal dust, asphalt, wood dust, stone dust, mineral wool, and cement dust was assessed using a semi-quantitative job-exposure matrix. Rate ratios (RR) and 95% confidence intervals (95% CI) were calculated for head and neck cancers in relation to occupational exposure, using Poisson regression with adjustment for age and smoking status. RESULTS: Asbestos exposure was related to an increased laryngeal cancer incidence (RR 1.9, 95% CI 1.2-3.1). Excesses of pharyngeal cancer were observed among workers exposed to cement dust (RR 1.9, 95% CI 1.2-3.1). No occupational exposures were associated with oral cavity cancer. These findings did not materially change upon additional adjustment for cigarette pack-years. CONCLUSIONS: These findings offer further evidence that asbestos increases the risk of laryngeal cancer. The observation of a positive association between cement dust exposure and pharyngeal cancer warrants further investigation.     

Critical windows of exposure to household pesticides and risk of childhood leukemia

The potential etiologic role of household pesticide exposures was examined in the Northern California Childhood Leukemia Study. A total of 162 patients (0-14 years old) with newly diagnosed leukemia were rapidly ascertained during 1995-1999, and 162 matched control subjects were randomly selected from the birth registry. The use of professional pest control services at any time from 1 year before birth to 3 years after was associated with a significantly increased risk of childhood leukemia [odds ratio (OR) = 2.8; 95% confidence interval (CI), 1.4-5.7], and the exposure during year 2 was associated with the highest risk (OR = 3.6; 95% CI, 1.6-8.3). The ORs for exposure to insecticides during the 3 months before pregnancy, pregnancy, and years 1, 2, and 3 were 1.8 (95% CI, 1.1-3.1), 2.1 (95% CI, 1.3-3.5), 1.7 (95% CI, 1.0-2.9), 1.6 (95% CI, 1.0-2.7), and 1.2 (95% CI, 0.7-2.1), respectively. Insecticide exposures early in life appear to be more significant than later exposures, and the highest risk was observed for exposure during pregnancy. Additionally, more frequent exposure to insecticides was associated with a higher risk. In contrast to insecticides, the association between herbicides and leukemia was weak and nonsignificant. Pesticides were also grouped based on where they were applied. Exposure to indoor pesticides was associated with an increased risk, whereas no significant association was observed for exposure to outdoor pesticides. The findings suggest that exposure to household pesticides is associated with an elevated risk of childhood leukemia and further indicate the importance of the timing and location of exposure.     

Lung cancer mortality in a cohort of workers employed at a cadmium recovery plant in the United States: an analysis with detailed job histories.

OBJECTIVES: To identify and measure any relations between occupational exposure to cadmium compounds (oxide, sulphide, and sulphate) and the risk of mortality from lung cancer. METHODS: The mortality experience of 571 male production workers from a cadmium recovery facility in the United States was investigated for the period 1940-82. All study subjects were first employed in the period 1926-69; they had all been employed for at least six months between 1 January 1940 and 31 December 1969. Newly abstracted detailed job histories for the period 1926-76 were combined with assessments of exposures to cadmium over time to develop individual estimates of cumulative exposure to cadmium (total exposure and exposures received both in the presence and absence of "high" exposures to arsenic trioxide). Poisson regression was used to investigate risks of mortality from lung cancer in relation to four concentrations of cumulative exposure to cadmium (< 400, 400-999, 1000-1999, > 2000 mg.m-3.days). RESULTS: After adjustment for age attained, year of hire, and Hispanic ethnicity, there was a significant positive trend (P < 0.05) between cumulative exposure to cadmium and risks of mortality from lung cancer. Relative to a risk of unity for the lowest exposure category (first level), risks were 2.30 (95% confidence interval (95% CI) 0.72 to 7.36), 2.83 (95% CI 0.75 to 10.72), and 3.88 (95% CI 1.04 to 14.46) for the second, third, and fourth categories, respectively. Similar findings were obtained after adjustment for age only. Trends were more pronounced when employment histories were lagged first by 10 years and then by 20 years. A separate analysis examined the independent effects of exposure to cadmium received in the presence of high exposures to arsenic trioxide (mainly cadmium oxide) and exposures to cadmium received without such exposure to arsenic (mainly cadmium sulphide and cadmium sulphate). A significant trend for a risk of lung cancer was found only for exposures to cadmium received in the presence of arsenic trioxide. CONCLUSIONS: Hypotheses which are consistent with the study findings include: (a) cadmium oxide in the presence of arsenic trioxide is a human lung carcinogen, (b) cadmium oxide and arsenic trioxide are human lung carcinogens and cadmium sulphate and cadmium sulphide are not (or they are less potent carcinogens), or (c) arsenic trioxide is a human lung carcinogen and cadmium oxide, cadmium sulphate, and cadmium sulphide are not. There were only 21 deaths from lung cancer available for this analysis and it is impossible to gauge which, if any, of these hypotheses are correct.     

Exposure to organic solvents and adverse pregnancy outcome

In a large case-control study (n = 1,926) of spontaneous abortion (SAB), exposure to solvents was ascertained by a telephone interview that asked about occupational use of 18 specific solvents or products, as well as an open-ended "other" solvent category. The adjusted odds ratio for use of any solvent was 1.1 (0.8, 1.5). Solvents for which at least a doubled crude risk of SAB was found included perchlorethylene (OR = 4.7, 95% CI = 1.1, 21.1), trichloroethylene (OR = 3.1, CI = 0.9, 10.4), and paint thinners (OR = 2.3, CI = 1.0, 5.1). Comparing exposure greater than 10 hours per week versus less did not show consistent dose-response effects. By solvent class, an association was seen with aliphatic solvents (adjusted OR = 1.8, 95% CI = 1.1, 3.0), but there was no dose-response effect by hours of use. Household use of solvent-containing products was generally not strongly associated with SAB, nor did it appear to confound the association seen with occupational use. From this and other studies, occupational exposure to at least some solvents appears associated with SAB. The associations of solvent exposure and fetal growth among liveborn offspring of controls was also examined.     

Exposure to benzene and risk of leukemia among shoe factory workers

OBJECTIVES: The study attempted to add years of follow-up to an earlier study describing excess leukemia among workers exposed to benzene-based glues in a shoe-factory and to conduct a quantitative exposure assessment of the exposure to benzene and the risk of leukemia. METHODS: The cohort comprised 1687 persons with complete work histories, at work on 1 January 1950, and followed through 31 December 1999. For each subject, time-specific cumulative exposure (ppm-years) was calculated as the sum of the products of job-specific concentrations of benzene (ppm) and the duration (years) for each job. Standardized mortality ratios (SMR) were estimated using national and regional rates specific for gender, age, and period. RESULTS: The cumulative exposure ranged from 0 to >500 ppm-years. The SMR values for all hematolymphopoietic malignancies and leukemia for the men and women combined were elevated in all but the lowest exposure category. Leukemia risk was significantly elevated in the highest exposure category and the most evident among the men. The SMR values for the men were 1.4 [95% confidence interval (95% CI) 0.2-5.0], 3.7 (95% CI 0.1-20.6), 3.0 (95% CI 0.4-10.9), and 7.0 (95% CI 1.9-18.0) for benzene, the cumulative exposure equaling <40, 40-99, 100-199, and >200 ppm-years, respectively. CONCLUSIONS: The results indicate that leukemia mortality is associated with exposure to benzene in this factory and that the risk increases with increasing cumulative exposure. The relevance of these findings for estimating risk at much lower levels is limited because of the small study size.     

Sugarcane farming,occupational solvent exposures,and the risk of oral cancer in Puerto Rico

The work history information from a population-based case-control study conducted in Puerto Rico was analyzed using a job exposure matrix to investigate the relationship between occupational exposures and cancers of the oral cavity or pharynx. After adjustment for age, alcohol, smoking, and residence in a logistic model, the risk for cancer of the oral cavity, but not the pharynx, was significantly elevated among farm workers in the sugarcane industry (OR = 4.4, 95% CI = 1.4-13.6). An exposure-response trend was seen for cumulative exposure to solvents, with an OR = 3.2 (95% CI = 0.8-12.6) in the highest exposure category. The overall contribution to the risk of cancer of the oral cavity or pharynx associated with occupational exposures in Puerto Rico appears to be small, however, the elevated risks were seen among sugarcane farmers and subjects with high cumulative exposure to solvents.     

Occupation and cancer of the oral cavity or oropharynx in Turin, Italy

In a population-based case-referent study, the occupational experience of 86 men with oral or oropharyngeal cancer and 373 referents was analyzed with respect to employment in 41 occupations and 40 industries, as well as to exposure to 16 chemicals, as estimated via a job-exposure matrix. Among the occupations and industries at higher risk were machinery operator (odds ratio [OR] 2.0; 95% confidence interval [95% CI] 1.0-4.0), plumber (OR 5.0, 95% CI 1.2-21.5), building industry (OR 2.5; 95% CI 1.3-4.5), textile industry (OR 2.5; 95% CI 0.6-4.6), and electricity production (OR 2.8; 95% CI 0.7-12.1). All the OR estimates were adjusted for age, education, area of birth, tobacco smoking, and alcohol consumption. An association between formaldehyde exposure and oral cancer was suggested (OR for any exposure 1.6, 95% CI 0.9-2.8; OR for probable or definite exposure 1.8, 95% CI 0.6-5.5). No other chemical included in the matrix showed any risk pattern. The evidence of an association between formaldehyde exposure and oral or oropharyngeal cancer is strengthened by the results of this study.     

Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany

BACKGROUND: To investigate the association between lung cancer and occupational exposure to man-made vitreous fibers (MMVF), a pooled analysis of two case-control studies was conducted in the years 1988-1994. METHODS: The case series consisted of 3498 males who were histologically or cytologically verified primary lung cancer cases. 3541 male population controls were drawn at random from the general population and matched to cases by sex, age, and place of residence. To examine the relationship between MMVF and lung cancer we asked all study subjects who worked for at least 6 months as construction and installation workers whether they ever installed or removed insulations and what kind of insulation material they used. RESULTS: Some 304 (8.7%) cases and 170 (4.8%) controls reported to have insulated with glass wool or mineral wool mats. Coded as ever/never exposed, the odds ratio was 1.48 (95% CI: 1.17-1.88), adjusted for smoking and asbestos. To be sure to exclude any confounding effect of asbestos, we tried to identify those cases and controls who insulated with glass wool or mineral wool mats only and never reported any asbestos exposure. For this group we calculated an odds ratio of 1.56 (95% CI: 0.92-2.65), after adjustment for smoking. An elevated risk was also estimated on the basis of an expert rating which was done for a subgroup of cases and controls. Ever exposure to MMVF (but not to asbestos) in this subgroup yielded an odds ratio of 1.30 (95% CI: 0.82-2.07). CONCLUSIONS: Our study provides some indication for an excess risk of man-made vitreous fibers. This result also persists after adjustment for smoking and asbestos.