Relative burden of lung and pleural cancers from exposure to asbestos: a cross-sectional analysis of occupational mortality in England and Wales.

OBJECTIVES: To explore the extent to which asbestos-exposed jobs vary in the ratio of excess mortality from lung cancer to deaths from pleural cancer. DESIGN: Using data on underlying cause of death and last full-time occupation for 3 688 916 deaths among men aged 20-74 years in England and Wales during 1979-2010, we calculated proportional mortality ratios (PMRs), standardised for age and social class, with all occupations combined as reference. For each of 22 asbestos-exposed job groups with significantly elevated PMRs for pleural cancer, we calculated excess mortality from lung cancer (observed minus expected deaths) and its ratio to number of deaths from pleural cancer. To reduce confounding effects of smoking, we adjusted expected deaths from lung cancer in each job group, according to a formula based on its PMR for chronic obstructive pulmonary disease. SETTING: England and Wales. PARTICIPANTS: 3 688 916 men who died aged 20-74 years during 1979-2010. OUTCOME MEASURES: Ratios of excess mortality from lung cancer to deaths from pleural cancer by job group. RESULTS: Adjusted PMRs for lung cancer were elevated in all but 4 of the 22 asbestos-exposed job groups, but the ratio of excess lung cancer to deaths from pleural cancer varied widely between job groups, being significantly greater than the overall ratio in six, and significantly less in seven. Analysis for 2001-2010, when (because of changes in coding) ascertainment of pleural tumours was more reliable, showed similar variation between job groups, and indicated an overall ratio of 0.28. CONCLUSIONS: Excess lung cancer in asbestos-exposed jobs is not in a simple proportion to deaths from pleural cancer, and the ratio may vary importantly according to intensity of exposure to different types of asbestos and concomitant smoking habits. The current burden of lung cancer from occupational exposure to asbestos in Britain may not be so high as previously thought.

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.

Mesothelioma mortality in Great Britain: how much longer will dockyards dominate?

OBJECTIVES: We aimed to investigate whether there has been a geographic shift in the distribution of mesothelioma deaths in Great Britain given the decline of shipbuilding and progressive exposure regulation. METHODS: We calculated age-adjusted mesothelioma mortality rates and estimated rate ratios for areas with and without a dockyard. We compared spatial autocorrelation statistics (Moran's I) for age-adjusted rates at local authority district level for 2002-2008 and 2009-2015. We measured the mean distance of the deceased's postcode to the nearest dockyard at district level and calculated the association of average distance to dockyard and district mesothelioma mortality using simple linear regression for men, for 2002-2008 and 2009-2015. RESULTS: District age-adjusted male mortality rates fell during 2002-2015 for 80 of 348 districts (23%), rose for 267 (77%) and were unchanged for one district; having one or more dockyards in a district was associated with rates falling (OR=2.43, 95% CI 1.22 to 4.82, p=0.02). The mortality rate ratio for men in districts with a dockyard, compared with those without a dockyard was 1.41 (95% CI 1.35 to 1.48, p<0.05) for 2002-2008 and 1.18 (95% CI 1.13 to 1.23, p<0.05) for 2009-2015. Spatial autocorrelation (measured by Moran's I) decreased from 0.317 (95% CI 0.316 to 0.319, p=0.001) to 0.312 (95% CI 0.310 to 0.314, p=0.001) for men and the coefficient of the association between distance to dockyard and district level age-adjusted male mortality (per million population) from -0.16 (95% CI -0.21 to -0.10, p<0.01) to -0.13 (95% CI -0.18 to -0.07, p<0.01) for men, when comparing 2002-2008 with 2009-2015. CONCLUSION: For most districts age-adjusted mesothelioma mortality rates increased through 2002-2015 but the relative contribution from districts with a dockyard fell. Dockyards remain strongly spatially associated with mesothelioma mortality but the strength of this association appears to be falling and mesothelioma deaths are becoming more dispersed.

The occupations at increased risk of COPD: analysis of lifetime job-histories in the population-based UK Biobank Cohort.

Occupational exposures are important, preventable causes of chronic obstructive pulmonary disease (COPD). Identification of COPD high-risk jobs is key to focus preventive strategies, but a definitive job-list is unavailable.We addressed this issue by evaluating the association of lifetime job-histories and lung function data in the population-based UK Biobank cohort, whose unprecedented sample size allowed analyses restricted to never-smokers to rule out the most important confounder, tobacco smoking. COPD was spirometrically defined as forced expiratory volume in 1 s/forced vital capacity ratio below the lower limit of normal. Lifetime job-histories were collected via OSCAR (Occupations Self-Coding Automatic Recording), a new validated online tool that automatically codes jobs into the UK Standard Occupational Classification v.2000. Prevalence ratios for COPD by employment duration in each job compared to lifetime office workers were estimated using robust Poisson regression adjusted for age, sex, centre and smoking. Only associations confirmed among never-smokers and never-asthmatics were considered reliable.From the 116 375 participants with complete job-histories, 94 551 had acceptable/repeatable spirometry data and smoking information and were included in the analysis. Six occupations showed an increased COPD risk among never-smokers and never-asthmatics; most of these also with positive exposure-response trends. Interesting new findings included sculptors, gardeners and warehouse workers.COPD patients, especially never-smokers, should be asked about their job-history for better disease management. Focussed preventive strategies in COPD high-risk jobs are warranted.

Job-exposure matrix for historical exposures to rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry.

OBJECTIVES: To develop a quantitative historical job-exposure matrix (JEM) for rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry for 1915-2002 to estimate lifetime cumulative exposure (LCE) for a cohort of workers with 49 years follow-up. METHODS: Data from the EU-EXASRUB database-rubber dust (n=4157), rubber fumes (n=3803) and n-Nitrosamines (n=10 115) collected between 1977 and 2002-were modelled using linear mixed-effects models. Sample year, stationary/personal measurement, industry sector and measurement source were included as fixed explanatory variables and factory as random intercept. Model estimates and extrapolations were used to construct a JEM covering all departments in both sectors of the rubber manufacturing industries for the years 1915-2002. JEM-estimates were linked to all cohort members to calculate LCE. Sensitivity analyses related to assumptions about extrapolation of time trends were also conducted. RESULTS: Changes in rubber dust exposures ranged from -6.3 %/year (crude materials/mixing) to -1.0 %/year (curing) and -6.5 %/year (crude materials/mixing) to +0.5 %/year (finishing, assembly and miscellaneous) for rubber fumes. Declines in n-Nitrosamines ranged from -17.9 %/year (curing) to -1.3 %/year (crude materials and mixing). Mean LCEs were 61 mg/m3-years (rubber dust), 15.6 mg/ m3-years (rubber fumes), 2483.2 µg/m3-years (n-Nitrosamines sum score), 18.6 µg/m3-years (N-nitrosodimethylamine) and 15.0 µg/m3-years (N-itrosomorpholine). CONCLUSIONS: All exposures declined over time. Greatest declines in rubber dust and fumes were found in crude materials and mixing and for n-Nitrosamines in curing/vulcanising and preprocessing. This JEM and estimated LCEs will allow for evaluation of exposure-specific excess cancer risks in the British rubber industry.

Lifetime exposure to rubber dusts, fumes and N-nitrosamines and cancer mortality in a cohort of British rubber workers with 49 years follow-up.

OBJECTIVES: To quantitatively evaluate exposure-response associations between occupational exposures to rubber dust, fumes and N-nitrosamines and cancer mortality in the UK rubber industry. METHODS: Competing risk survival analyses were used to examine cancer mortality risk in a cohort of 36 441 males aged 35+ years employed in the British rubber industry in 1967, followed up to 2015 (94% mortality). Exposure measurements are based on a population-specific quantitative job-exposure matrix for rubber dust, rubber fumes and N-nitrosamines from the EU-EXASRUB project. RESULTS: Exposure (lifetime cumulative (LCE))-response associations were found for N-nitrosomorphiline and all cancers (subdistribution HR (SHR) 1.48, 95% CI 1.39 to 1.57) and cancers of the bladder, stomach, multiple myeloma, oesophagus, prostate and pancreas, as well as for N-nitrosodimethylamine and all cancers (SHR 2.08, 95% CI 1.96 to 2.21) and cancers of the bladder, stomach, leukaemia, multiple myeloma, prostate and liver. LCE to the N-nitrosamines sum were associated with increased risks from all cancers (SHR 1.89, 95% CI 1.78 to 2.01) and cancers of the lung, non-Hodgkin's lymphoma and brain. LCE to rubber dust and fumes are associated with increased mortality from all cancers (rubber dust SHR 1.67, 95% CI 1.58 to 1.78; rubber fumes SHR 1.91, 95% CI 1.80 to 2.03) and cancers of the bladder, lung, stomach, leukaemia, multiple myeloma, non-Hodgkin's lymphoma, oesophagus, prostate, pancreas and liver. CONCLUSIONS: Consistent with previous studies, N-nitrosamines exposures are associated with mortality from cancers of the bladder, lung, stomach, leukaemia, multiple myeloma, oesophagus, prostate, pancreas and liver. The long follow-up with nearly complete mortality enabled estimations of lifetime cancer mortality risk from occupational exposures in the rubber industry.

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.

Past and current asbestos exposure and future mesothelioma risks in Britain: The Inhaled Particles Study (TIPS).

Background: Occupational and environmental airborne asbestos concentrations are too low and variable for lifetime exposures to be estimated reliably, and building workers and occupants may suffer higher exposure when asbestos in older buildings is disturbed or removed. Mesothelioma risks from current asbestos exposures are therefore not known. Methods: We interviewed and measured asbestos levels in lung samples from 257 patients treated for pneumothorax and 262 with resected lung cancer, recruited in England and Wales. Average lung burdens in British birth cohorts from 1940 to 1992 were estimated for asbestos-exposed workers and the general population. Results: Regression analysis of British mesothelioma death rates and average lung burdens in birth cohorts born before 1965 suggests a lifetime mesothelioma risk of approximately 0.01% per fibre/mg of amphiboles in the lung. In those born since 1965, the average lung burden is ∼1 fibre/mg among those with no occupational exposure. Conclusions: The average lifetime mesothelioma risk caused by recent environmental asbestos exposure in Britain will be about 1 in 10 000. The risk is an order of magnitude higher in a subgroup of exposed workers and probably in occupants in the most contaminated buildings. Further data are needed to discover whether asbestos still present in buildings, particularly schools, is a persistent or decreasing hazard to workers who disturb it and to the general population, and whether environmental exposure occurs predominantly in childhood or after beginning work. Similar studies are needed in other countries to estimate continuing environmental and occupational mesothelioma hazards worldwide, including the contribution from chrysotile.

Chest physician-reported, work-related, long-latency respiratory disease in Great Britain.

Much of the current burden of long-latency respiratory disease (LLRD) in Great Britain is attributed to historical asbestos exposure. However, continuing exposure to other agents, notably silica, also contributes to disease burden. The aim of this study was to investigate the incidence of work-related LLRD reported by chest physicians in Great Britain, including variations by age, gender, occupation and suspected agent.LLRD incidence and incidence rate ratios by occupation were estimated (1996-2014). Mesothelioma cases by occupation were compared with proportional mortality ratios.Cases were predominantly in men (95%) and 92% of all cases were attributed to asbestos. Annual average incidence rates (males) per 100 000 were: benign pleural disease, 7.1 (95% CI 6.0-8.2); mesothelioma, 5.4 (4.8-6.0); pneumoconiosis, 1.9 (1.7-2.2); lung cancer, 0.8 (0.6-1.0); chronic obstructive pulmonary disease (COPD), 0.3 (0.2-0.4). Occupations with a particularly high incidence of LLRD were miners and quarrymen (COPD), plumbers and gas fitters (asbestosis), and shipyard and dock workers (all other categories). There was a clear concordance between cases of SWORD mesothelioma and proportional mortality ratios by occupation.Occupationally caused LLRD continues to contribute to a significant disease burden. Many cases are attributable to past exposure to agents such as asbestos and silica, but the potential for occupational exposures persists.

Mortality from multiple sclerosis in British military personnel.

BACKGROUND: While analysing trends in occupational mortality in England and Wales, we noticed an unexpectedly elevated proportion of deaths from multiple sclerosis (MS) among men in the armed forces. AIMS: To document and explore possible explanations for the observed excess. METHODS: We analysed data on underlying cause of death and last full-time occupation for 3,688,916 deaths among men aged 20-74 years in England and Wales during 1979-2010, calculating proportional mortality ratios (PMRs) standardised for age. We compared PMRs for MS in the armed forces with those for each main social class, and in selected other occupations. We also compared PMRs for MS with those for motor neurone disease (MND). RESULTS: The overall PMR for MS in the armed forces during 1979-2010 was 243 (95%CI 203-288). The excess was apparent in each of three separate decades of study (PMRs, ranging from 220 to 259), and across the entire age range. PMRs for MS were not elevated to the same extent in comparator occupations, nor in any of the main social classes. There was no parallel increase in PMRs for MND. CONCLUSIONS: These findings suggest that the high proportional mortality from MS in British military personnel is unlikely to have occurred by chance, or as an artefact of the method of investigation. However, the only military cohort study with published results on MS does not support an increased risk. It would be useful to analyse data on MS from other established military cohorts, to check for evidence of a hazard.

Occupational self-coding and automatic recording (OSCAR): a novel web-based tool to collect and code lifetime job histories in large population-based studies.

Objectives The standard approach to the assessment of occupational exposures is through the manual collection and coding of job histories. This method is time-consuming and costly and makes it potentially unfeasible to perform high quality analyses on occupational exposures in large population-based studies. Our aim was to develop a novel, efficient web-based tool to collect and code lifetime job histories in the UK Biobank, a population-based cohort of over 500 000 participants. Methods We developed OSCAR (occupations self-coding automatic recording) based on the hierarchical structure of the UK Standard Occupational Classification (SOC) 2000, which allows individuals to collect and automatically code their lifetime job histories via a simple decision-tree model. Participants were asked to find each of their jobs by selecting appropriate job categories until they identified their job title, which was linked to a hidden 4-digit SOC code. For each occupation a job title in free text was also collected to estimate Cohen's kappa (κ) inter-rater agreement between SOC codes assigned by OSCAR and an expert manual coder. Results OSCAR was administered to 324 653 UK Biobank participants with an existing email address between June and September 2015. Complete 4-digit SOC-coded lifetime job histories were collected for 108 784 participants (response rate: 34%). Agreement between the 4-digit SOC codes assigned by OSCAR and the manual coder for a random sample of 400 job titles was moderately good [κ=0.45, 95% confidence interval (95% CI) 0.42-0.49], and improved when broader job categories were considered (κ=0.64, 95% CI 0.61-0.69 at a 1-digit SOC-code level). Conclusions OSCAR is a novel, efficient, and reasonably reliable web-based tool for collecting and automatically coding lifetime job histories in large population-based studies. Further application in other research projects for external validation purposes is warranted.

Trends in mortality from occupational hazards among men in England and Wales during 1979-2010.

OBJECTIVES: To monitor the impact of health and safety provisions and inform future preventive strategies, we investigated trends in mortality from established occupational hazards in England and Wales. METHODS: We analysed data from death certificates on underlying cause of death and last full-time occupation for 3 688 916 deaths among men aged 20-74 years in England and Wales during 1979-2010 (excluding 1981 when records were incomplete). Proportional mortality ratios (PMRs), standardised for age and social class, were calculated for occupations at risk of specified hazards. Observed and expected numbers of deaths for each hazard were summed across occupations, and the differences summarised as average annual excesses. RESULTS: Excess mortality declined substantially for most hazards. For example, the annual excess of deaths from chronic bronchitis and emphysema fell from 170.7 during 1979-1990 to 36.0 in 2001-2010, and that for deaths from injury and poisoning from 237.0 to 87.5. In many cases, the improvements were associated with falling PMRs (suggesting safer working practices), but they also reflected reductions in the numbers of men employed in more hazardous jobs, and declining mortality from some diseases across the whole population. Notable exceptions to the general improvement were diseases caused by asbestos, especially in some construction trades and sinonasal cancer in woodworkers. CONCLUSIONS: The highest priority for future prevention of work-related fatalities is the minority of occupational disorders for which excess mortality remains static or is increasing, in particular asbestos-related disease among certain occupations in the construction industry and sinonasal cancer in woodworkers.

Pleural mesothelioma and lung cancer risks in relation to occupational history and asbestos lung burden.

BACKGROUND: We have conducted a population-based study of pleural mesothelioma patients with occupational histories and measured asbestos lung burdens in occupationally exposed workers and in the general population. The relationship between lung burden and risk, particularly at environmental exposure levels, will enable future mesothelioma rates in people born after 1965 who never installed asbestos to be predicted from their asbestos lung burdens. METHODS: Following personal interview asbestos fibres longer than 5 µm were counted by transmission electron microscopy in lung samples obtained from 133 patients with mesothelioma and 262 patients with lung cancer. ORs for mesothelioma were converted to lifetime risks. RESULTS: Lifetime mesothelioma risk is approximately 0.02% per 1000 amphibole fibres per gram of dry lung tissue over a more than 100-fold range, from 1 to 4 in the most heavily exposed building workers to less than 1 in 500 in most of the population. The asbestos fibres counted were amosite (75%), crocidolite (18%), other amphiboles (5%) and chrysotile (2%). CONCLUSIONS: The approximate linearity of the dose-response together with lung burden measurements in younger people will provide reasonably reliable predictions of future mesothelioma rates in those born since 1965 whose risks cannot yet be seen in national rates. Burdens in those born more recently will indicate the continuing occupational and environmental hazards under current asbestos control regulations. Our results confirm the major contribution of amosite to UK mesothelioma incidence and the substantial contribution of non-occupational exposure, particularly in women.

Mortality of a cohort of workers in Great Britain with blood lead measurements.

OBJECTIVES: We examined the mortality of a historic cohort of workers in Great Britain with measured blood lead levels (BLLs). METHODS: SMRs were calculated with the population of Great Britain as the external comparator. Trends in mortality with mean and maximum BLLs and assessed lead exposure were examined using Cox regression. RESULTS: Mean follow-up length among the 9122 study participants was 29.2 years and 3466 deaths occurred. For all causes and all malignant neoplasms, the SMRs were statistically significantly raised. For disease groups of a priori interest, the SMR was significantly raised for lung cancer but not for stomach, brain, kidney, bladder or oesophageal cancers. The SMR was not increased for non-malignant kidney disease but was borderline significantly increased for circulatory diseases, for ischaemic heart disease (IHD) and cerebrovascular disease (CVD). No significant trends with exposure were observed for the cancers of interest, but for circulatory diseases and IHD, there was a statistically significant trend for increasing HR with mean and maximum BLLs. CONCLUSIONS: This study found an excess of lung cancer, although the risk was not clearly associated with increasing BLLs. It also found marginally significant excesses of IHD and CVD, the former being related to mean and maximum BLLs. The finding for IHD may have been due to lead, but could also have been due to other dust exposure associated with lead exposure and possibly tobacco smoking. Further work is required to clarify this and the carcinogenicity of lead.

An updated investigation of cancer incidence and mortality at a Scottish semiconductor manufacturing facility with case-control and case-only studies of selected cancers.

OBJECTIVES: An earlier investigation raised concern that some cancer cases might be linked to work at a semiconductor manufacturing plant. The aim of this study was to describe an update of the cancer incidence and mortality of these workers and assess whether workplace exposures contributed to any increased risk of selected cancers. METHODS: Standardised mortality ratios and standardised incidence ratios were calculated for cancer site groups of a priori interest in a cohort previously flagged against the National Health Service Central Register, with follow-up extended to the 2007 for deaths and 2006 for cancer registrations. Cases of female breast cancer, lung and stomach cancer, and male brain cancer, and a random sample of control subjects individually age-matched to the breast cancer cases, were identified from within the cohort dataset and invited to participate via general practitioners. Exposures were estimated using a job exposure matrix developed from a historical hygiene assessment and assigned to job histories obtained from personal interview of subjects (or proxies). RESULTS: Though the findings were uncertain, there were no excesses of mortality or cancer incidence, either overall or for specific cancer sites, suggestive of a workplace effect. Logistic regression analyses comparing 20 cases of breast cancer with 83 matched controls showed no consistent evidence of any relationship with occupational exposures. Assessment of commonalities of workplace exposures among case sets for other cancer types was limited by the small numbers. CONCLUSIONS: These results do not support earlier concerns about occupational cancer risks among this cohort.

Cardiovascular disease mortality among British asbestos workers (1971-2005).

OBJECTIVES: Asbestos is an inflammatory agent, and there is evidence that inflammatory processes are involved in the development of cardiovascular disease. Whether asbestos is a risk factor for cardiovascular disease has not been established. The objective of this study was to investigate cardiovascular disease mortality in a large cohort of workers occupationally exposed to asbestos. METHODS: Cardiovascular disease mortality in a cohort of 98,912 asbestos workers, with median follow-up of 19 years, was analysed. Unadjusted and smoking-adjusted standardised mortality ratios (SMRs) were calculated. The association between indicators of asbestos exposure and mortality was analysed with Poisson regression models, for deaths occurring during the period 1971-2005. RESULTS: Altogether 15,557 deaths from all causes, 1053 deaths from cerebrovascular disease and 4185 deaths from ischaemic heart disease (IHD) occurred during follow-up. There was statistically significant excess mortality from cerebrovascular disease (SMR: men 1.63, women 2.04) and IHD (SMR: men 1.39, women 1.89). Job and birth cohort were associated with the risk of cerebrovascular and IHD mortality in the Poisson regression model including sex, age, smoking status, job, cohort and duration of exposure. For IHD only, duration of exposure was also statistically significant in this model. CONCLUSIONS: Cerebrovascular and IHD mortality was significantly higher among these asbestos workers than in the general population and within the cohort mortality was associated with indicators of asbestos exposure. These findings provide some evidence that occupational exposure to asbestos was associated with cardiovascular disease mortality in this group of workers.

The effect of smoking on the risk of lung cancer mortality for asbestos workers in Great Britain (1971-2005).

OBJECTIVES: Workers in the asbestos industry tend to have high smoking rates compared to the general population. Both asbestos exposure and cigarette smoking are recognized risk factors for lung cancer mortality, but the exact nature of the interaction between the two remains uncertain. The aim of this study was to examine the effect of smoking and smoking cessation among asbestos workers in Great Britain (GB) and investigate the interaction between asbestos exposure and smoking. METHODS: The study population consisted of 98 912 asbestos workers recruited into the GB Asbestos Survey from 1971, followed-up to December 2005. Poisson regression was used to estimate relative risks of lung cancer mortality associated with smoking habits of the asbestos workers and to assess whether these effects differed within various categories of asbestos exposure. The interaction between asbestos exposure and smoking was examined using the Synergy (S) and Multiplicativity (V) indices, which test the hypotheses of additive and multiplicative interaction, respectively. The proportion of lung cancers among smokers attributable to the interaction of asbestos and smoking was also estimated. RESULTS: During 1 780 233 person-years of follow-up, there were 1878 deaths from lung cancer (12% of all deaths). Risk of lung cancer mortality increased with packs smoked per day, smoking duration, and total smoke exposure (pack-years). Asbestos workers who stopped smoking remained at increased risk of lung cancer mortality up to 40 years after smoking cessation compared to asbestos workers who never smoked. The effects of smoking and stopping smoking did not differ by duration of asbestos exposure, main occupation, age at first asbestos exposure, year of first exposure, or latency period. The interaction between asbestos exposure and smoking for asbestos workers was greater than additive [S 1.4, 95% confidence interval (CI) 1.2-1.6], and the multiplicative hypothesis could not be rejected (V 0.9, 95% CI 0.3-2.4). For those asbestos workers who smoked, an estimated 26% (95% CI 14-38%) of lung cancer deaths were attributable to the interaction of asbestos and smoking. CONCLUSIONS: This study emphasizes the importance of smoking prevention and cessation among those who work in the asbestos industry.

Asbestosis and mesothelioma among British asbestos workers (1971-2005).

BACKGROUND: Ascertainment of asbestosis and mesothelioma from underlying cause of death underestimates the burden of these diseases. The aims of this study were to estimate the true frequency of asbestosis and mesothelioma among asbestos workers in Great Britain (GB), and to identify factors associated with the risk of death with these diseases. METHODS: The GB Asbestos Survey was established in 1971 to monitor long-term health outcomes among workers covered by regulations to control asbestos at work. Asbestosis and mesothelioma cases were defined by multiple cause of death, and were ascertained by identifying asbestos workers on the GB Asbestosis and Mesothelioma Registers. Standardized mortality ratios (SMRs) were calculated; the risks of asbestosis and mesothelioma were modeled with Poisson regression analysis. Deaths to the end of 2005 were included. RESULTS: There were 15,557 deaths between 1971 and 2005 among the 98,912 workers. Altogether 477 asbestosis and 649 mesothelioma cases were identified. The SMR for all causes was 1.42, for asbestosis 51.3, and for mesothelioma 13.5. In multiply adjusted analysis, age, sex, job, and birth cohort were significantly associated with asbestosis and mesothelioma. For asbestosis year of first exposure, and for mesothelioma latency, were also statistically significant. CONCLUSIONS: The asbestos workers experienced high mortality from all causes, asbestosis, and mesothelioma. There was some evidence that the risk of asbestosis and mesothelioma was lower in later birth cohorts and among those first occupationally exposed to asbestos more recently. Due to the long latency of both diseases, further follow-up is required to confirm these trends.