Lifetime cumulative exposure to rubber dust, fumes and N-nitrosamines and non-cancer mortality: a 49-year follow-up of UK rubber factory workers.

OBJECTIVES: To examine associations between occupational exposures to rubber dust, rubber fumes and N-nitrosamines and non-cancer mortality. METHODS: A cohort of 36 441 males aged 35+ years employed in British rubber factories was followed-up to 2015 (94% deceased). Competing risk survival analysis was used to assess risks of dying from non-cancer diseases (respiratory, urinary, cerebrovascular, circulatory and digestive diseases). Occupational exposures to rubber dust, rubber fumes, N-nitrosamines were derived based on a population-specific quantitative job-exposure matrix which in-turn was based on measurements in the EU-EXASRUB database. RESULTS: Exposure-response associations of increased risk with increasing exposure were found for N-nitrosomorpholine with mortality from circulatory diseases (subdistribution hazard ratio (SHR) 1.17; 95% CI 1.12 to 1.23), ischaemic heart disease (IHD) (SHR 1.19; 95% CI 1.13 to 1.26), cerebrovascular disease (SHR 1.19; 95% CI 1.07 to 1.32) and exposures to N-nitrosodimethylamine with respiratory disease mortality (SHR 1.41; 95% CI 1.30 to 1.53). Increased risks for mortality from circulatory disease, IHD and digestive diseases were found with higher levels of exposures to rubber dust, rubber fumes and N-nitrosamines sum, without an exposure-dependent manner. No associations were observed between rubber dust, rubber fumes and N-nitrosamines exposures with mortality from asthma, urinary disease, bronchitis, emphysema, liver disease and some digestive diseases. CONCLUSIONS: In a cohort of rubber factory workers with 49 years of follow-up, increased risk for mortality from circulatory, cerebrovascular, respiratory and digestive diseases were found to be associated with cumulative occupational exposures to specific agents.

Cancer mortality in an international cohort of reinforced plastics workers exposed to styrene: a reanalysis.

OBJECTIVE: To investigate the carcinogenicity of styrene by reanalysing data from a previous international cohort study of workers in the reinforced plastics industry. METHODS: Mortality from cancers of prior interest was analysed with more detailed consideration of exposure-response relations and an updated classification of leukaemias and lymphomas in data from a previous international cohort study of 37 021 reinforced plastics workers exposed to airborne styrene. RESULTS: Increased mortality from non-Hodgkin's lymphoma (NHL) was associated with the mean level of exposure to styrene in air (relative risk (RR) 2.31, 95% CI 1.29 to 4.12 per 100 ppm), but not with cumulative styrene exposure. Similar associations with mean exposure were observed for the oesophagus (RR 2.44, 95% CI 1.11 to 5.36 per 100 ppm) and pancreas (RR 1.89, 95% CI 1.17 to 3.09). Oesophageal cancer mortality was also associated with cumulative styrene exposure lagged 20 years (RR 1.16, 95% CI 1.03 to 1.31). No other cancer, including lung cancer, was associated with any indicator of styrene exposure. CONCLUSION: This reanalysis does not substantially change the conclusions of the original study with respect to NHL or lung cancer but new evidence concerning cancers of the oesophagus and pancreas merits further investigation.

Non-malignant respiratory disease among workers in the rubber manufacturing industry: A systematic review and meta-analysis.

BACKGROUND: Non-malignant respiratory disease (NMRD) cases have occurred among rubber manufacturing workers. We examined exposure to rubber manufacturing emissions as a risk factor for NMRD. METHODS: From a systematic literature review, we identified case reports and assessed cross-sectional and mortality studies for strength of evidence of positive association (strong, intermediate, non-significant positive association, none) between exposure to rubber manufacturing emissions and NMRD-related morbidity and mortality, and conducted two meta-analyses. RESULTS: We analyzed 62 articles. We identified 11 cases of NMRD. Nine (30%) of 30 cross-sectional studies and one (4%) of 26 mortality studies had strong evidence. The summary odds ratio and SMR for the cross-sectional and mortality meta-analyses were 3.83 (95% confidence interval [CI], 2.28-6.51) and 0.90 (95%CI, 0.82-0.99), respectively. CONCLUSION: Available evidence supports rubber manufacturing emissions as a potential risk factor for NMRD-related morbidity. Further investigations with longer follow-up periods and inclusion of short-tenured workers could further define risks for NMRD and identify prevention strategies.

British rubber and cable industry cohort: 49-year mortality follow-up.

BACKGROUND: The International Agency for Research on Cancer (IARC) has determined there is sufficient evidence that working in the rubber manufacturing industry increases the risk of cancers of the stomach, lung, bladder and leukaemia and lymphoma. OBJECTIVES: To examine mortality patterns of a prospective cohort of men from the rubber and cable manufacturing industries in Great Britain. METHODS: SMRs were calculated for males aged 35+ years at start of follow-up in 1967-2015 using the population of England and Wales as the external comparator. Tests for homogeneity and trends in SMRs were also completed. RESULTS: For all causes, all malignant neoplasms, non-malignant respiratory diseases and circulatory diseases, SMRs were significantly elevated, and also particularly for cancers of the stomach (SMR=1.26,95% CI 1.18 to 1.36), lung (1.25,95% CI 1.21 to 1.29) and bladder (1.16,95% CI 1.05 to 1.28). However, the observed deaths for leukaemia, non-Hodgkin's lymphoma (NHL) and multiple myeloma were as expected. Bladder cancer risks were elevated only in workers exposed to antioxidants containing 1-naphthylamine and 2-naphthylamine. CONCLUSIONS: This study provides evidence of excess risks in the rubber industry for some non-cancer diseases and supports IARC's conclusions in relation to risks for cancers of the bladder, lung and stomach, but not for leukaemia, NHL or multiple myeloma.

Quantitative estimated exposure to vinyl chloride and risk of angiosarcoma of the liver and hepatocellular cancer in the US industry-wide vinyl chloride cohort: mortality update through 2013.

OBJECTIVE: To evaluate mortality risks of angiosarcoma of the liver (ASL), primary hepatocellular carcinoma (HCC) and other cancers among 9951 men employed between 1942 and 1972 at 35 US vinyl chloride (VC) or polyvinyl chloride plants followed for mortality through 31 December 2013. METHODS: SMR and time-dependent Cox proportional hazards analyses were used to evaluate mortality risks by cumulative VC exposure. RESULTS: Liver cancer mortality was elevated (SMR=2.87, 95% CI 2.40 to 3.40), and ASL and HCC were strongly associated with cumulative VC exposure ≥865 parts per million-years (ppm-years) (ASL: HR=36.3, 95% CI 13.1 to 100.5; and HCC: HR=5.3, 95% CI 1.6 to 17.7 for ≥2271 ppm-years). Excess deaths due to connective and soft tissue cancers (SMR=2.43, 95% CI 1.48 to 3.75), mesothelioma (SMR=2.29, 95% CI 1.18 to 4.00) and explosions (SMR=3.43, 95% CI 1.25 to 7.47) were seen. Mortalities due to melanoma, brain cancer, lung cancer and non-Hodgkin's lymphoma were not increased or associated with VC exposure. CONCLUSION: The association between VC and ASL first reported in this cohort 44 years ago persisted and was strongest among workers most highly exposed. VC exposure also was associated with HCC mortality, although it remains possible that misdiagnosis of early ASLs influenced findings.

[Mortality study in a cohort of workers employed in the hot working processing of plastics and rubber]. / Studio di mortalità in una coorte di esposti nella lavorazione a caldo di materie plastiche e gomma.

OBJECTIVES: to study mortality rates among workers in companies manufacturing thermoplastic and rubber articles (excluding tyres). DESIGN: cohort study. SETTING AND PARTICIPANTS: the cohort includes 4,543 workers employed up to 2000 in 131 companies in the Province of Bologna (Emilia-Romagna Region, Northern Italy) exposed to emissions from hot processing of plastics (3,937) and rubber (606). MAIN OUTCOME MEASURES: general- and cause-specific Standardized Mortality Rates (SMR), with 95% confidence intervals; entire reference population resides in the Emilia-Romagna Region. RESULTS: excess mortality for all causes (116 Obs; SMR: 1.20; 95%CI 1.00-1.44) and for lung cancer (18 Obs; SMR: 1.67; 95%CI 1.05-2.65) in men of the rubber factories. Increased mortality rates for oesophageal cancers in women (3 Obs; SMR: 5.41; 95%CI 1.74-16.8) and in men (6 Obs; SMR: 2.16; 95%CI 0.97-4.81), for malignant tumours of pancreas (16 Obs; SMR: 1.65; 95%CI 1.01- 2.70), rectum (11 Obs; SMR: 2.17; 95%CI 1.20-3.92) and kidney (11 Obs; SMR: 1.98; 95%CI 1.10-3.58) in men occupied in plastic processing. CONCLUSION: in this study, we observed an excess of mortality rates for lung cancer in men of rubber factories and for malignant tumours of the digestive tract, pancreas, and kidney in workers employed in the production of plastic articles. Nevertheless, these results must be interpreted with caution, because exposures to non-occupational risk factors, like tobacco smoke or other occupational exposures outside the companies concerned, are not known. The results suggest to continue epidemiological surveillance.

Mortality among styrene-exposed workers in the reinforced plastic boatbuilding industry.

BACKGROUND: We updated mortality through 2011 for 5203 boat-building workers potentially exposed to styrene, and analysed mortality among 1678 employed a year or more between 1959 and 1978. The a priori hypotheses: excess leukaemia and lymphoma would be found. METHODS: Standardised mortality ratios (SMRs) and 95% CIs and standardised rate ratios (SRRs) used Washington State rates and a person-years analysis programme, LTAS.NET. The SRR analysis compared outcomes among tertiles of estimated cumulative potential styrene exposure. RESULTS: Overall, 598 deaths (SMR=0.96, CI 0.89 to 1.04) included excess lung (SMR=1.23, CI 0.95 to 1.56) and ovarian cancer (SMR 3.08, CI 1.00 to 7.19), and chronic obstructive pulmonary disease (COPD) (SMR=1.15, CI 0.81 to 1.58). Among 580 workers with potential high-styrene exposure, COPD mortality increased 2-fold (SMR=2.02, CI 1.08 to 3.46). CONCLUSIONS: COPD was more pronounced among those with potential high-styrene exposure. However, no outcome was related to estimated cumulative styrene exposure, and there was no change when latency was taken into account. We found no excess leukaemia or lymphoma mortality. As in most occupational cohort studies, lack of information on lifestyle factors or other employment was a substantial limitation although we excluded from the analyses those (n=3525) who worked <1 year. Unanticipated excess ovarian cancer mortality could be a chance finding. Comparing subcohorts with potential high-styrene and low-styrene exposure, COPD mortality SRR was elevated while lung cancer SRR was not, suggesting that smoking was not the only cause for excess COPD mortality.

Mortality among workers exposed to toluene diisocyanate in the US polyurethane foam industry: Update and exposure-response analyses.

BACKGROUND: Mortality among 4,545 toluene diisocyante (TDI)-exposed workers was updated through 2011. The primary outcome of interest was lung cancer. METHODS: Life table analyses, including internal analyses by exposure duration and cumulative TDI exposure, were conducted. RESULTS: Compared with the US population, all cause and all cancer mortality was increased. Lung cancer mortality was increased but was not associated with exposure duration or cumulative TDI exposure. In post hoc analyses, lung cancer mortality was associated with employment duration in finishing jobs, but not in finishing jobs involving cutting polyurethane foam. CONCLUSIONS: Dermal exposure, in contrast to inhalational exposure, to TDI is expected to be greater in finishing jobs and may play a role in the observed increase in lung cancer mortality. Limitations include the lack of smoking data, uncertainty in the exposure estimates, and exposure estimates that reflected inhalational exposure only. Am. J. Ind. Med. 59:630-643, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Cause-specific mortality in Finnish ferrochromium and stainless steel production workers.

BACKGROUND: Although stainless steel has been produced for more than a hundred years, exposure-related mortality data for production workers are limited. AIMS: To describe cause-specific mortality in Finnish ferrochromium and stainless steel workers. METHODS: We studied Finnish stainless steel production chain workers employed between 1967 and 2004, from chromite mining to cold rolling of stainless steel, divided into sub-cohorts by production units with specific exposure patterns. We obtained causes of death for the years 1971-2012 from Statistics Finland. We calculated standardized mortality ratios (SMRs) as ratios of observed and expected numbers of deaths based on population mortality rates of the same region. RESULTS: Among 8088 workers studied, overall mortality was significantly decreased (SMR 0.77; 95% confidence interval [CI] 0.70-0.84), largely due to low mortality from diseases of the circulatory system (SMR 0.71; 95% CI 0.61-0.81). In chromite mine, stainless steel melting shop and metallurgical laboratory workers, the SMR for circulatory disease was below 0.4 (SMR 0.33; 95% CI 0.07-0.95, SMR 0.22; 95% CI 0.05-0.65 and SMR 0.16; 95% CI 0.00-0.90, respectively). Mortality from accidents (SMR 0.84; 95% CI 0.67-1.04) and suicides (SMR 0.72; 95% CI 0.56-0.91) was also lower than in the reference population. CONCLUSIONS: Working in the Finnish ferrochromium and stainless steel industry appears not to be associated with increased mortality.

Risk of cancer in workers exposed to styrene at eight British companies making glass-reinforced plastics.

OBJECTIVES: To provide further information on the risks of lymphohaematopoietic (LH) and other cancers associated with styrene. METHODS: We extended follow-up to December 2012 for 7970 workers at eight companies in England which used styrene in the manufacture of glass-reinforced plastics. Mortality was compared with that for England and Wales by the person-years method, and summarised by SMRs with 95% CIs. A supplementary nested case-control analysis compared styrene exposures, lagged by 5 years, in 122 incident or fatal cases of LH cancer and 1138 matched controls. RESULTS: A total of 3121 cohort members had died (2022 since the last follow-up). No elevation of mortality was observed for LH cancer, either in the full cohort (62 deaths, SMR 0.90, 95% CI 0.69 to 1.15), or in those with more than background exposure to styrene (38 deaths, SMR 0.82, 95% CI 0.58 to 1.14). Nor did the case-control analysis suggest any association with LH cancer. In comparison with background exposure, the OR for non-Hodgkin's lymphoma/chronic lymphocytic leukaemia in workers with high exposure (estimated 8-h time-weighted average of 40-100 ppm) for ≥1 year was 0.54 (95% CI 0.23 to 1.27). Mortality from lung cancer was significantly elevated, and risk increased progressively across exposure categories, with an SMR of 1.44 (95% CI 1.10 to 1.86) in workers highly exposed for ≥1 year. CONCLUSIONS: We found no evidence that styrene causes LH cancer. An association with lung cancer is not consistently supported by other studies. It may have been confounded by smoking, but would be worth checking further.

Cancer mortality among Brazilian dentists.

BACKGROUND: Previous studies have variably shown excess risks of elected cancers among dentists. METHODS: National Brazilian mortality data were used to obtain mortality patterns among dentists between 1996 and 2004. Cancer mortality odds ratios (MORs) and cancer proportional mortality ratios for all cancer sites were calculated, using the general population and physicians and lawyers as comparison groups. RESULTS: Female dentists from both age strata showed higher risks for breast, colon-rectum, lung, brain, and non-Hodgkin lymphoma. Compared to physicians and lawyers, higher MOR estimates were observed for brain cancer among female dentists 20-49 yr. Among male dentists, higher cancer mortality was found for colon-rectum, pancreas, lung, melanoma, and non-Hodgkin lymphoma. Higher risk estimates for liver, prostate, bladder, brain, multiple myeloma and leukemia were observed among 50-79 yr old male dentists. DISCUSSION: If confirmed, these results indicate the need for limiting occupational exposures among dentists in addition to establishing screening programs to achieve early detection of selected malignant tumors.

Chernobyl cleanup workers from Estonia: follow-up for cancer incidence and mortality.

This study examined cancer incidence (1986-2008) and mortality (1986-2011) among the Estonian Chernobyl cleanup workers in comparison with the Estonian male population. The cohort of 4810 men was followed through nationwide population, mortality and cancer registries. Cancer and death risks were measured by standardised incidence ratio (SIR) and standardised mortality ratio (SMR), respectively. Poisson regression was used to analyse the effects of year of arrival, duration of stay and time since return on cancer and death risks. The SIR for all cancers was 1.06 with 95% confidence interval 0.93-1.20 (232 cases). Elevated risks were found for cancers of the pharynx, the oesophagus and the joint category of alcohol-related sites. No clear evidence of an increased risk of thyroid cancer, leukaemia or radiation-related cancer sites combined was apparent. The SMR for all causes of death was 1.02 with 95% confidence interval 0.96-1.08 (1018 deaths). Excess mortality was observed for mouth and pharynx cancer, alcohol-related cancer sites together and suicide. Duration of stay rather than year of arrival was associated with increased mortality. Twenty-six years of follow-up of this cohort indicates no definite health effects attributable to radiation, but the elevated suicide risk has persisted.

Cohort study of workers employed in an Italian tire manufacturing plant, 1962-2004.

PURPOSE: To investigate mortality and bladder cancer incidence among workers of a tire manufacturing plant where antioxidants severely contaminated by beta-naphthylamine were never used. METHODS: Mortality follow-up was performed of 9,501 workers first hired between 1962 when the plant started operations and 2000. Person-years of observation from 1962 to 2004, expected deaths, and standardized mortality ratios (SMR) were calculated. Follow-up for bladder cancer incidence from 1988 to 2003 was carried out, and standardized incidence ratios (SIR) were calculated. Multivariable (Poisson) analyses of bladder cancer incidence and mortality by duration of employment (DOE) and time since first employment (TSFE) were performed. RESULTS: Among men, SMRs were significantly reduced for all causes, all cancers, lung cancer, cardiovascular, and ischemic heart diseases. Bladder cancer mortality and leukemia mortality were close to expectation but increased with TSFE. Seventy-two incident cases of bladder cancer were observed (SIR = 1.15; 95 % confidence interval 0.90-1.44), and multivariable analysis suggested a possible increase in rate ratios with DOE. Among women, mortality was close to expectation, but the limited number of observed deaths prevented detailed analyses. CONCLUSIONS: No significant cancer excess was observed. A suggestion of increased risks of bladder cancer and leukemias after extended TSFE was present in men, deserving consideration as exposure to carcinogens possibly occurred early in plant operation. Furthermore, this cohort of workers is still relatively young and less than 10 % have died. There was, thus, limited power to detect small increases in risk at rare cancer sites. Further epidemiological surveillance of this cohort is planned.

Mortality among dentists in Taiwan, 1985-2009.

BACKGROUND/PURPOSE: Controversy exists in the literature regarding whether dentists with multiple occupational exposures suffer from premature mortality. A cohort mortality study was conducted to evaluate the survival outcome and determine if potential exposure to harmful agents leads to premature mortality among dentists. METHODS: Using the Life Table Analysis System, we calculated standardized mortality ratios (SMRs) for a cohort of 11,700 dentists affiliated with the Taiwan Dental Association. These dentists were followed from 1985-2009. Reference rates were derived from cause-, gender-, and age-specific mortality rates of the general population of Taiwan and 18,664 Taiwanese internists, who were considered to be more socioeconomically proximal to dentists. A Cox proportional hazard model was also constructed to determine multiple risk factors associated with mortality. RESULTS: Compared with the general population, dentists in Taiwan consistently demonstrated reduced from all-cause mortality. However, compared with internists, significant and excess mortality were observed in dentists for overall mortality (SMR=1.13; 95% confidence interval [CI]=1.00-1.26), drowning (SMR=6.62; 95% CI=2.15-15.45), and heart diseases (SMR=1.66; 95% CI=1.22-2.21). After adjusting for other risk factors, the Cox model showed an increased hazard ratio of 1.17 (95% CI=1.01-1.37) for dentists. CONCLUSION: Taiwanese dentists demonstrated significant elevated SMRs for overall causes, drowning, and heart diseases. Careful precaution should be taken to reduce these trends. Future studies are also needed for in-depth exploration of the mechanisms regarding how professional stress and exposure contribute to the increased risk of mortality in Taiwanese dentists.

Mortality from liver cancer and leukaemia among polyvinyl chloride workers in Taiwan: an updated study.

OBJECTIVES: To investigate types of cancer caused by occupational exposure to vinyl chloride monomer (VCM) and the temporal mortality trends of these cancers in workers from polyvinyl chloride (PVC) manufacturing factories in Taiwan, with follow-up of the cohort extended by 15 years, from 1980 to 2007. Methods A retrospective cohort study of workers from six PVC factories in Taiwan was conducted. 3336 male PVC workers were enrolled and further linked with the National Mortality Registry and National Household Registry databases. Standardised mortality ratios (SMR) with 95% CIs were calculated and compared to the general Taiwanese male population. Cause-specific mortality between two study periods, 1980-1997 and 1998-2007, was compared. Six-year moving averages of the SMRs were calculated to examine mortality trends. RESULTS: Liver cancer mortality increased during 1989-1994 (SMR 1.90, 95% CI 1.01 to 3.25), reached a peak during 1991-1996 (SMR 2.31, 95% CI 1.39 to 3.61) and became non-significant during 1994-1999 (SMR 1.42, 95% CI 0.80 to 2.34). Leukaemia mortality significantly increased during 1984-1989 (SMR 6.06, 95% CI 1.24 to 17.53), reached a peak during 1985-1990 (SMR 7.56, 95% CI 2.06 to 19.35) and became non-significant during 1991-1996 (SMR 3.24, 95% CI 0.39 to 11.69). The mortality trend for haemolymphopoietic cancer showed a similar pattern to that of leukaemia. CONCLUSIONS: VCM may increase the risk of liver cancer and leukaemia. When VCM exposure was controlled at worksites, mortality from these cancers returned to background levels.

Update of a cohort mortality study of workers exposed to methylene chloride employed at a plant producing cellulose triacetate film base.

PURPOSE: To update the mortality experience of employees of a factory that produced cellulose triacetate film base at Brantham in the United Kingdom and generate information on the effects of exposure to methylene chloride, in particular, mortality from cardiovascular disease and cancers of the lung, liver and biliary tract, pancreas and brain. METHODS: All 1,785 male employees with a record of employment at the film factory in 1946-1988 were followed through 2006, including 1,473 subjects exposed to methylene chloride on average for 9 years at a concentration of 19 ppm (8 h time-weighted average). RESULTS: A total of 559 deaths occurred during the follow-up period. In the subcohort of workers exposed to methylene chloride, substantially reduced mortalities compared with national and local rates were found for all causes, all cancers, and all the principal cancer sites of interest except for brain cancer. There was a small excess of brain cancer deaths (8 observed and 4.4 expected), but no evidence of an association with exposure to methylene chloride. Lung cancer mortality was significantly reduced in exposed workers, even compared to the low mortality rate in the local population (SMR 55). In contrast, mortality from ischaemic heart disease in exposed workers was slightly increased compared with local rates (SMR 102), but was lower in active employees (SMR 94; local rates), where a direct effect of exposure to methylene chloride should be concentrated. CONCLUSIONS: The study provided no indication that employment at the plant, or exposure to methylene chloride, had adversely affected the mortalities of workers.

1,3-Butadiene, styrene and selected outcomes among synthetic rubber polymer workers: Updated exposure-response analyses.

OBJECTIVE: - To evaluate exposure-response relationships between 1,3-butadiene and styrene and selected diseases among synthetic rubber polymer workers. METHODS: - 21,087 workers (16,579 men; 4508 women) were followed from 1943 through 2009 to determine mortality outcomes. Cox regression models estimated rate ratios (RRs) and 95% confidence intervals (CIs) by quartile of cumulative exposure to butadiene or styrene and exposure-response trends for cancers of the bladder, lung, kidney, esophagus and pancreas, and for all nonmalignant respiratory disease (NMRD), chronic obstructive pulmonary disease (COPD) and pneumonia. RESULTS: - Bladder cancer RRs were 2.13 (95% CI = 1.03 to 4.41) and 1.64 (95% CI = 0.76 to 3.54) in the highest quartiles of cumulative exposure to butadiene and styrene, respectively, and exposure-response trends were positive for both monomers (butadiene, trend p = 0.001; styrene, trend p = 0.004). Further analyses indicated that the exposure-response effect of each monomer on bladder cancer was demonstrated clearly only in the subgroup with high cumulative exposure (at or above the median) to the other monomer. Lung cancer was not associated with either monomer among men. Among women, lung cancer RRs were above 1.0 in each quartile of cumulative exposure to each monomer, but exposure-response was not seen for either monomer. Male workers had COPD RRs slightly above 1.0 in each quartile of cumulative exposure to each monomer, but there was no evidence of exposure-response among the exposed. Monomer exposure was not consistently associated with COPD in women or with the other cancer outcomes. CONCLUSIONS: - This study found a positive exposure-response relationship between monomer exposures and bladder cancer. The independent effects of butadiene and styrene on this cancer could not be delineated. In some analyses, monomer exposure was associated with lung cancer in women and with COPD in men, but inconsistent exposure-response trends and divergent results by sex do not support a causal interpretation of the isolated positive associations.

Mortality from malignant diseases-update of the Baltimore union poultry cohort.

We previously studied mortality up to 1989 in 2,639 members of a local union who had ever worked in poultry slaughtering and processing plants, because they were exposed to oncogenic viruses present in poultry. In this report, cancer mortality was updated to the year 2003 for 2,580 of the 2,639 subjects who worked exclusively in poultry plants. Mortality in poultry workers was compared with that in the US general population through the estimation of proportional mortality and standardized mortality ratios separately for each race/sex group and for the whole cohort. Compared to the US general population, an excess of cancers of the buccal and nasal cavities and pharynx (base of the tongue, palate and other unspecified mouth, tonsil and oropharynx, nasal cavity/middle ear/accessory sinus), esophagus, recto-sigmoid/rectum/anus, liver and intrabiliary system, myelofibrosis, lymphoid leukemia and multiple myeloma was observed in particular subgroups or in the entire poultry cohort. We hypothesize that oncogenic viruses present in poultry, and exposure to fumes, are candidates for an etiologic role to explain the excess occurrence of at least some of these cancers in the poultry workers. Larger studies which can control for confounding factors are urgently needed to determine the significance of these findings.

Fractional polynomials and model selection in generalized estimating equations analysis, with an application to a longitudinal epidemiologic study in Australia.

In epidemiologic studies, researchers often need to establish a nonlinear exposure-response relation between a continuous risk factor and a health outcome. Furthermore, periodic interviews are often conducted to take repeated measurements from an individual. The authors proposed to use fractional polynomial models to jointly analyze the effects of 2 continuous risk factors on a health outcome. This method was applied to an analysis of the effects of age and cumulative fluoride exposure on forced vital capacity in a longitudinal study of lung function carried out among aluminum workers in Australia (1995-2003). Generalized estimating equations and the quasi-likelihood under the independence model criterion were used. The authors found that the second-degree fractional polynomial models for age and fluoride fitted the data best. The best model for age was robust across different models for fluoride, and the best model for fluoride was also robust. No evidence was found to suggest that the effects of smoking and cumulative fluoride exposure on change in forced vital capacity over time were significant. The trend 1 model, which included the unexposed persons in the analysis of trend in forced vital capacity over tertiles of fluoride exposure, did not fit the data well, and caution should be exercised when this method is used.

Lung cancer mortality and iron oxide exposure in a French steel-producing factory.

OBJECTIVE: To study the possible association between iron oxide exposures and lung cancer risk among workers in a French carbon steel-producing factory. METHODS: 16 742 males and 959 females ever employed for at least 1 year between 1959 and 1997 were followed up for mortality from January 1968 to December 1998. Causes of death were ascertained from death certificates. Job histories and smoking habits were available for 99.7% and 72.3% of subjects, respectively. Occupational exposures were assessed by a factory-specific job-exposure matrix (JEM) validated with atmospheric measurements. Standardised mortality ratios (SMRs) were computed using local death rates (external references). Poisson regressions were used to estimate the relative risks (RRs) for occupational exposures (internal references), adjusted on potential confounding factors. RESULTS: Among males, observed mortality was lower than expected for lung cancer compared to the local population (233 deaths, SMR 0.89, 95% CI 0.78 to 1.01) and higher than expected compared to the French population (SMR 1.30, 95% CI 1.15 to 1.48) No lung cancer excess was observed for exposure to iron oxides (RR 0.80, 95% CI 0.55 to 1.17) and no dose-response relationship with intensity, duration of exposure or cumulative index was found. A significant bladder cancer excess was observed among workers exposed to oil mist (RR 2.44, 95% CI 1.06 to 5.60), increasing significantly with intensity, duration of exposure and cumulative index. CONCLUSION: This study did not detect any relationship between exposure to iron oxides and lung cancer mortality. An excess of mortality from bladder cancer was found among workers exposed to oil mist.