Occupational and Environmental Medicine

Published by BMJ Publishing Group
Online ISSN: 1470-7926
Print ISSN: 1351-0711
To examine patterns of cause specific mortality in NHS hospital consultants according to their specialty and to assess these in the context of potential occupational exposures. A historical cohort assembled from Department of Health records with follow up through the NHS Central Register involving 18,358 male and 2168 female NHS hospital consultants employed in England and Wales between 1962 and 1979. Main outcome measures examined were cause specific mortality during 1962-92 in all consultants combined, and separately for 17 specialty groups, with age, sex, and calendar year adjusted standardised mortality ratios (SMRs) for comparison with national rates, and rate ratios (RRs) for comparison with rates in all consultants combined. The 2798 deaths at ages 25 to 74 reported during the 30 year study period were less than half the number expected on the basis of national rates (SMR 48, 95% confidence interval (95% CI) 46 to 49). Low mortality was evident for cardiovascular disease, lung cancer, other diseases related to smoking, and particularly for diabetes (SMR 14, 95% CI 6 to 29). Death rates from accidental poisoning were significantly raised among male consultants (SMR 227, 95% CI 135 to 359), the excess being most apparent in obstetricians and gynaecologists (SMR 934); almost all deaths from accidental poisoning involved prescription drugs. A significantly raised death rate from injury and poisoning among female consultants was due largely to a twofold excess of suicide (SMR 215, 95% CI 93 to 423), the rate for this cause being significantly raised in anaesthetists (SMR 405). Compared with all consultants, significantly raised mortality was found in psychiatrists for all causes combined (RR 1.12), ischaemic heart disease (RR 1.18), and injury and poisoning (RR 1.46); in anaesthetists for cirrhosis (RR 2.22); and in radiologists and radiotherapists for respiratory disease (RR 1.68). There were significant excesses of colon cancer in psychiatrists (RR 1.67, compared with all consultants) and ear, nose, and throat surgeons (RR 2.25); melanoma in anaesthetists (RR 3.33); bladder cancer in general surgeons (RR 2.40); and laryngeal cancer in ophthalmologists (RR 7.63). Lower rates of smoking will have contributed substantially to the low overall death rates found in consultants, but other beneficial health related behaviours, and better access to health care, may have also played a part. The increased risks of accidental poisoning in male consultants, and of suicide in female consultants are of concern, and better preventive measures are needed. The few significant excesses of specific cancers found in certain specialties have no obvious explanation other than chance. A significant excess mortality from cirrhosis in anaesthetists might reflect an occupational hazard and may warrant further investigation.
SMR of all-cause and cause specific mortality within total cohort 
All-cause and cause specific SMR by age, nationality, occupation, and duration of employment 
Construction workers are potentially exposed to many health hazards, including human carcinogens such as asbestos, silica, and other so-called "bystander" exposures from shared work places. The construction industry is also a high risk trade with respect to accidents. A total of 19 943 male employees from the German construction industry who underwent occupational health examinations between 1986 and 1992 were followed up until 1999/2000. A total of 818 deaths occurred during the 10 year follow up (SMR 0.71; 95% CI 0.66 to 0.76). Among those were 299 deaths due to cancer (SMR 0.89; 95% CI 0.79 to 1.00) and 312 deaths due to cardiovascular diseases (SMR 0.59; 95% CI 0.51 to 0.68). Increased risk of mortality was found for non-transport accidents (SMR 1.61; 95% CI 1.15 to 2.27), especially due to falls (SMR 1.87; 95% CI 1.18 to 2.92) and being struck by falling objects (SMR 1.90; 95% CI 0.88 to 3.64). Excess mortality due to non-transport accidents was highest among labourers and young and middle-aged workers. Risk of getting killed by falling objects was especially high for foreign workers (SMR 4.28; 95% CI 1.17 to 11.01) and labourers (SMR 6.01; 95% CI 1.63 to 15.29). Fatal injuries due to falls and being struck by falling objects pose particular health hazards among construction workers. Further efforts are necessary to reduce the number of fatal accidents and should address young and middle-aged, semi-skilled and foreign workers, in particular. The lower than expected cancer mortality deserves careful interpretation and further follow up of the cohort.
The objective of the study is to describe the survey methodology and present initial general findings.1 A ‘representative sample’ was drawn from the last census data available, randomly selecting 167 census segments from all departments in the countries proportional to the respective populations in the departments or provinces. Within each sampling segment, 12 households were … [Full text of this article]
To describe the survey methodology and initial general findings of the first Central American Survey of Working Conditions and Health. A representative sample of 12 024 workers was interviewed at home in Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama. Questionnaire items addressed worker demographics, employment conditions, occupational risk factors and self-perceived health. Overall, self-employment (37%) is the most frequent type of employment, 8% of employees lack a work contract and 74% of the workforce is not covered by social security. These percentages are higher in Guatemala, Honduras and El Salvador, and lower in Costa Rica, Panama and Nicaragua. A third of the workforce works more than 48 h per week, regardless of gender; this is similar across countries. Women and men report frequent or usual exposures to high ambient temperature (16% and 25%, respectively), dangerous tools and machinery (10%, 24%), work on slippery surfaces (10%, 23%), breathing chemicals (12.1%, 18%), handling toxic substances (5%, 12.1%), heavy loads (6%, 20%) and repetitive movements (43%, 49%). Two-thirds of the workforce perceive their health as being good or very good, and slightly more than half reports having good mental health. The survey offers, for the first time, comparable data on the work and health status of workers in the formal and informal economy in the six Spanish-speaking Central American countries, based on representative national samples. This provides a benchmark for future monitoring of employment and working conditions across countries.
Population characteristics
Estimated prevalence of antidepressant purchasers and their 95% CI in relation to year of retirement. Antidepressant purchasers per 100.
Estimated prevalence of hospital treatment for depression and its 95% CI in relation to year of retirement. Hospital treatment for depression per 10 000.
Flowchart of the study population.
Objectives: The effect of retirement on mental health is not well understood. We examined the prevalence of hospital treatment for depression and purchase of antidepressant medication before, during and after retirement in a Danish population sample. We hypothesised that retirement was followed by reduced prevalence of hospital treatment for depression and antidepressant purchase. Methods: Participants were 245,082 Danish workers who retired between 2000 and 2006. Information on retirement, hospital treatment and antidepressant purchases were obtained from Danish national registers. The yearly prevalence of hospital treatment for depression and antidepressant purchases was estimated in relation to the year of retirement from 5 years prior to the retirement year to 5 years after retirement. Using logistic regressions with generalised estimating equations we analysed the trends in prevalence before, during and after the retirement. Results: Two of 1000 participants were hospitalised with depression in the year of their retirement and 63 of 1000 purchased antidepressant medication during the retirement year. The prevalence of hospital treatment for depression increased before and around retirement, followed by a slight decline from 2 years after retirement with the prevalence of hospitalisation dropping from 0.21%(retirement +2 years) to 0.16% (retirement +5 years). For antidepressants, we observed a steady increase in purchases before retirement (retirement -2 years). This increase levelled off in the years around retirement, but continued after retirement (retirement +2 years). Conclusions: Overall, this study did not confirm the hypothesis that retirement is beneficial for mental health measured by hospitalisation with depression and treatment with antidepressants. Although the temporary levelling off of the increase in antidepressant treatment around time of retirement might indicate a beneficial effect, this possible effect was only short-term.
This study was undertaken to clarify the effect of enzymes induced by ethanol consumption on the pharmacokinetics of trichloroethylene (TRI, a highly metabolised substance) and 1,1,1-trichloroethane (1,1,1-TRI, a poorly metabolised substance). Rats maintained on a control liquid diet or a liquid diet containing ethanol (2 g/day/rat) for not less than three weeks were exposed to either TRI (50, 100, 500, and 1000 ppm) or 1,1,1-TRI (50, 100, and 500 ppm) by inhalation for six hours and the concentration of each compound in the blood and the urinary excretion of metabolites (trichloroethanol and trichloroacetic acid) were measured over several hours. Ethanol, which increased the in vitro metabolism of both compounds about fivefold, enhanced the in vivo metabolism of TRI only at high levels of exposure (marginally at 500 and considerably at 1000 ppm), whereas the metabolism of 1,1,1-TRI was enhanced at all concentrations tested. Moreover, there was a definite difference in the effect of induction of enzymes between the two solvents: the enhanced metabolism of TRI in vivo was shown by a decrease in the blood concentration of TRI as well as by an increase in the urinary excretion of its metabolites, whereas that of 1,1,1-TRI was shown by an increase in the urinary excretion of its metabolites alone. These results suggest that the induction of enzymes differentially affects the pharmacokinetics of TRI and 1,1,1-TRI in human occupational exposure: TRI metabolism may be increased only at concentrations much higher than the current occupational exposure limit (mostly 50 ppm), whereas 1,1,1-TRI metabolism may be increased at an exposure similar to occupational exposure.
Effects of exposure to DCE on cell viability, lactate dehydrogenase leakage, and reduced glutathione content of isolated rat hepatocytes 
Distribution of 3H-Na-palmitate (dpm/106 cells)t in homogenate and fractions of control and DCE treated hepatocytes 
1,2-Dichloroethane (DCE) is a volatile liquid readily absorbed through dermal, digestive, or inhalatory routes. After inhalation or oral administration to rats, death occurs within a narrow range of concentrations (six hour LC50 = 5100 mg/m3). Exposure to single high doses of DCE resulted in adverse effects on the central nervous system, liver, kidneys, adrenals, and lungs. The liver showed fatty changes and hepatocellular necrosis with haemorrhage. These injuries are probably related to changes in several cell functions and constituents. Therefore, it was decided to investigate whether DCE was capable of impairing the secretion of hepatocellular lipoglycoproteins acting both at the level of the Golgi apparatus and endoplasmic reticulum. Isolated hepatocytes of Wistar rats were prelabelled with two precursors of lipoglycoproteins 3H-Na-palmitate and 14C-glucosamine, and then exposed to concentrations of DCE from mean (SD) 4.4 (0.03) to 6.5 (0.02) mM for different durations ranging from five to 60 minutes. To measure lipid and sugar bound radioactivity, a preliminary separation of cell homogenate, cytosol, total microsomes, Golgi apparatus, and lipoglycoproteins secreted into cell suspension medium was carried out. After five minutes of exposure, DCE did not induce obvious changes in cell viability or lactic dehydrogenase leakage, but a significant (p < 0.01) depletion of reduced glutathione content was seen (40.10 (4.3) nM/10(6) cells). Furthermore, the cells poisoned by DCE started to show noticeable accumulation of 3H-Na-palmitate in the Golgi apparatus after five minutes (5103 (223) dpm/10(6) cells) and in the microsomes after 15 minutes (85,470 (7190) dpm/10(6) cells). There was a simultaneous significant increase in 14C-glucosamine content in the Golgi apparatus (690 (55) dpm/10(6) cells) and the microsomes (15,975 (2035) dpm/10(6) cells). The specific radioactivity of lipid and sugar moieties incorporated in secreted lipoglycoproteins was already significantly reduced after only five minutes of exposure (480 (57) dpm/10(6) cells for lipids, and 315 (45) dpm/10(6) cells for sugars). Overall, DCE, like other haloalkanes, produces a block of secretion of hepatocellular lipoglycoproteins as early as five minutes after poisoning. The simultaneous percentage increases into Golgi apparatus and microsomes of lipid and sugar bound radioactivity suggest that lipid retention at the sites of processing of lipoglycoproteins would probably play an important part in the early stages of cellular accumulation of fat after exposure to DCE.
Objectives: The present study was conducted to investigate the relationship between occupational chemical exposure and incidence of cholangiocarcinoma among workers in the offset colour proof-printing section of a small printing company in Osaka, Japan. Methods: We identified 51 men who had worked in the proof-printing room, and 11 men who had worked in the front room for at least 1 year between 1991 and 2006. We interviewed them about the chemicals they used, and estimated their levels of exposure to chemicals. We also investigated the medical records of 11 cholangiocarcinoma patients, and calculated the standardised mortality ratio (SMR) from 1991 to 2011. Results: Workers used 1,2-dichloropropane (1,2-DCP) from approximately 1985 to 2006, and dichloromethane (DCM) from approximately 1985 to 1997/1998. Exposure concentrations were estimated to be 100-670 ppm for 1,2-DCP and 80-540 ppm for DCM among the proof-printing workers. All 11 patients were pathologically diagnosed with cholangiocarcinoma. Ages at diagnosis were 25-45 years, and ages at death were 27-46 years among the six deceased individuals. The primary cancer site was the intrahepatic bile duct for five patients, and the extrahepatic bile ducts for six. All patients were exposed to 1,2-DCP for 7-17 years and diagnosed with cholangiocarcinoma 7-20 years after their first exposure. Ten patients were also exposed to DCM for 1-13 years. The SMR for cholangiocarcinoma was 2900 (expected deaths: 0.00204, 95% CI 1100 to 6400) for all workers combined. Conclusions: These findings suggest that 1,2-DCP and/or DCM may cause cholangiocarcinoma in humans.
To investigate the possible effects of occupational exposure to the nematocide cis-1,3-dichloropropene (cis-DCP) on function of the kidney and liver in the starch potato growing region in The Netherlands. The study involved 13 commercial application workers exposed to cis-DCP for 117 days, and 22 matched control workers. The inhalatory exposure of the application workers was estimated from biological monitoring data. All workers collected urine and serum samples before, during, and after the fumigation season for monitoring of variables for kidney and liver function. Renal effect variables were alanine aminopeptidase (AAP), N-acetyl-beta-D-glucosaminidase (NAG), retinol binding protein (RBP), and albumin (ALB) in urine, and beta(2)-microglobulin (beta(2)M-S) and creatinine in serum (Creat-S). Liver variables were alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), gamma-glutamyltranspeptidase (GGT), alkaline phosphatase (ALP), and total bilirubin (TBIL) in serum and the urinary ratio of 6-beta-hydroxycortisol to free cortisol (betaOHC/COR). The geometric mean exposure of the application workers was 2.7 mg/m(3) (8 hour time weighted average (8 hour TWA)); range 0.1-9.5 mg/m(3). No differences were found between the values of the renal effect variables or the liver variables of the exposed group and the control group, except a lower urinary ratio of betaOHC/COR in the exposed group. This was not considered to be related to the exposure to cis-DCP. No dose-effect relations were found between the exposure indices and the effect variables. The present study does not provide evidence that occupational exposure to cis-DCP in the starch potato growing region causes adverse effects on the kidney or liver at 8 hour TWA exposure concentrations below 9.5 mg/m(3) (2 ppm).
A retrospective mortality analysis and prospective morbidity and haematological analyses were performed for Shell Deer Park Manufacturing Complex (DPMC) male employees who worked in jobs with potential exposure to 1,3-butadiene from 1948 to 1989. 614 employees qualified for the mortality study (1948-89), 438 of those were still employed during the period of the morbidity study (1982-9), and 429 of those had haematological data available for analysis. Industrial hygiene data from 1979 to 1992 showed that most butadiene exposures did not exceed 10 ppm (eight-hour time weighted average (8 hour TWA)), and most were below 1 ppm, with an arithmetic mean of 3.5 ppm. 24 deaths occurred during the mortality study period. For all causes of death, the standardised mortality ratio (SMR) was 48 (95% confidence interval (95% CI) = 31-72), and the all cancer SMR was 34 (95% CI = 9-87). There were only two deaths due to lung cancer (SMR 42, 95% CI = 5-151) and none due to lymphohaematopoietic cancer (expected = 1.2). Morbidity (illness absence) events of six days or more for the 438 butadiene employees were compared with the rest of the complex. No cause of morbidity was in excess for this group; the all cause standardised morbidity ratio (SMbR) was 85 (95% CI = 77-93) and the all neoplasms SMbR was 51 (95% CI = 22-100). Haematological results for the 429 with laboratory data were compared with results for the rest of the complex. No significant differences occurred between the two groups and the distributions of results between butadiene and non-butadiene groups were virtually identical. These results suggest that butadiene exposures at concentrations common at DPMC in the past 10-20 years do not pose a health hazard to employees.
Percentage recovery (mean) for HDI and isocyanurate (2500, 10 000, and 40 000 ng) after 0, 10, and 30 minutes on a nitril rubber glove before submersion in DBA solution (dilution series directly added to DBA solution = 100%).  
Overview of urine samples taken in car body repair shops and industrial painting companies
To study inhalation and dermal exposure to hexamethylene diisocyanate (HDI) and its oligomers as well as personal protection equipment (PPE) use during task performance in conjunction with urinary hexamethylene diamine (HDA) in car body repair shop workers and industrial spray painters. Personal task based inhalation samples (n = 95) were collected from six car body repair shops and five industrial painting companies using impingers with di-n-butylamine (DBA) in toluene. In parallel, dermal exposure was assessed using nitril rubber gloves. Gloves were submerged into DBA in toluene after sampling. Analysis for HDI and its oligomers was performed by LC-MS/MS. Urine samples were collected from 55 workers (n = 291) and analysed for HDA by GC-MS. Inhalation exposure was strongly associated with tasks during which aerosolisation occurs. Dermal exposure occurred during tasks that involve direct handling of paint. In car body repair shops associations were found between detectable dermal exposure and glove use (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.09 to 0.57) and inhalation exposure level (OR 1.34, 95% CI 0.97 to 1.84 for a 10-fold increase). HDA in urine could be demonstrated in 36% and 10% of car body repair shop workers and industrial painting company workers respectively. In car body repair shops, the frequency of detectable HDA was significantly elevated at the end of the working day (OR 2.13, 95% CI 1.07 to 4.22 for 3-6 pm v 0-8 am). In both branches HDA was detected in urine of approximately 25% of the spray painters. In addition HDA was detected in urine of a large proportion of non-spray painters in car body repair shops. Although (spray) painting with lacquers containing isocyanate hardeners results in the highest external exposures to HDI and oligomers, workers that do not perform paint related tasks may also receive a considerable internal dose.
Limited data is available about incidence of acute transient symptoms associated with occupational exposure to static magnetic stray fields from MRI scanners. We aimed to assess the incidence of these symptoms among healthcare and research staff working with MRI scanners, and their association with static magnetic field exposure. We performed an observational study among 361 employees of 14 clinical and research MRI facilities in The Netherlands. Each participant completed a diary during one or more work shifts inside and/or outside the MRI facility, reporting work activities and symptoms (from a list of potentially MRI-related symptoms, complemented with unrelated symptoms) experienced during a working day. We analysed 633 diaries. Exposure categories were defined by strength and type of MRI scanner, using non-MRI shifts as the reference category for statistical analysis. Non-MRI shifts originated from MRI staff who also participated on MRI days, as well as CT radiographers who never worked with MRI. Varying per exposure category, symptoms were reported during 16-39% of the MRI work shifts. We observed a positive association between scanner strength and reported symptoms among healthcare and research staff working with closed-bore MRI scanners of 1.5 Tesla (T) and higher (1.5 T OR=1.88; 3.0 T OR=2.14; 7.0 T OR=4.17). This finding was mainly driven by reporting of vertigo and metallic taste. The results suggest an exposure-response association between exposure to strong static magnetic fields (and associated motion-induced time-varying magnetic fields) and reporting of transient symptoms on the same day of exposure. 11-032/C.
Natural rubber latex allergy can cause skin and respiratory symptoms The aim of this study was to evaluate the prevalence and incidence of latex related symptoms and sensitisation among a large group of healthcare workers in Trieste hospitals, followed for three years before and after the introduction of powder-free gloves with low latex release. In the years 1997-99 the authors evaluated 1040 healthcare workers exposed to latex allergen for latex related symptoms and sensitisation by means of a questionnaire, a medical examination, skin prick tests, and IgE specific antibody assay. The second evaluation was carried out in the years 2000-02, subsequent to the changeover to a powder-free environment. Glove related symptoms were seen in 21.8% of the nurses (227), mostly consisting of mild dermatitis: 38 (3.6%) complaining of contact urticaria and 24 (2.3%) of asthma and/or rhinitis. These symptoms were significantly related to skin prick tests positive to latex (OR = 9.70; 95% CI 5.5 to 17) and to personal atopy (OR = 2.29; 95% CI 1.6 to 3.2). Follow up was completed in 960 subjects (92.3%): 19 new subjects (2.4%) complained of itching erythema when using gloves, but none was prick positive to latex. Symptoms significantly improved and in most cases disappeared (p<0.0001). Simple measures such as the avoidance of unnecessary glove use, the use of non-powdered latex gloves by all workers, and use of non-latex gloves by sensitised subjects can stop the progression of latex symptoms and can avoid new cases of sensitisation.
To update and assess mortality from neoplasms to 31 December 1995 among 10 109 men employed in a job exposed to vinyl chloride for at least 1 year between 1942 and 1972 at any of 37 North American factories. Previous analyses indicated associations between employment in vinyl production and increased mortality risk from cancers of the liver and biliary tract, due to increased mortality from angiosarcoma of the liver, and brain cancer. Standardised mortality ratio (SMR) analyses, overall and stratified by several work related variables, were conducted with United States and state reference rates. Cox's proportional hazards models and stratified log rank tests were used to further assess occupational factors. 895 of 3191 deaths (28%) were from malignant neoplasms, 505 since the previous update to the end of 1982. Mortality from all causes showed a deficit (SMR 83, 95% confidence interval (95% CI) 80 to 86), whereas mortality from all cancers combined was similar to state referent rates. Mortality from cancers of the liver and biliary tract was clearly increased (SMR 359, 95% CI 284 to 446). Modest excesses of brain cancer (SMR 142, 95% CI 100 to 197) and cancer of connective and soft tissue (SMR 270, 95% CI 139 to 472) were found. Stratified SMR and Cox's proportional hazard analyses supported associations with age at first exposure, duration of exposure, and year of first exposure for cancers of the liver and soft tissues, but not the brain. Excess mortality risk from cancer of the liver and biliary tract, largely due to angiosarcoma, continues. Risk of mortality from brain cancer has attenuated, but its relation with exposure to vinyl chloride remains unclear. A potentially work related excess of deaths from cancer of connective and soft tissue was found for the first time, but was based on few cancers of assorted histology.
Results of the regression of blood lead versus bone lead for subgroups of exposed subjects 
of the regression of bone lead versus cumulative blood lead index for the diVerent groups 
Tibia lead measurements were performed in a population of 19-29 year old people who had been highly exposed to lead in childhood to find whether lead had persisted in the bone matrix until adulthood. (109)Cd K x ray fluorescence was used to measure the tibia lead concentrations of 262 exposed subjects and 268 age and sex matched controls. Questionnaire data allowed a years of residence index to be calculated for exposed subjects. A cumulative blood lead index was calculated from the time weighted integration of available data of blood lead. The mean (SEM) difference between exposed and control men was 4.51 (0.35) micrograms Pb/g bone mineral, and between exposed and control women was 3.94 (0. 61) micrograms Pb/g bone mineral. Grouped mean bone lead concentrations of exposed subjects were predicted best by age. When exposed and control subjects' data were combined, grouped mean bone lead concentrations were predicted best by cumulative blood lead index. The years of residence index was neither a good predictor of bone lead concentrations for exposed subjects nor for exposed and control subjects combined. Finally, exposed subjects had increased current blood lead concentrations that correlated significantly with bone lead values. Bone lead concentrations of exposed subjects were significantly increased compared with those of control subjects. Lead from exposure in early childhood had persisted in the bone matrix until adulthood. Exposed subjects had increased blood lead concentrations compared with controls. Some of this exposure could be related to ongoing exposure. However, some of the increase in blood lead concentration in adult exposed subjects seemed to be a result of endogenous exposure from increased bone lead stores. The endogenous exposure relation found for men was consistent with reported data, but the relation found for women was significantly lower. Further research is needed to find whether the observed differences are due to sex, or pregnancy and lactation.
Poisson regression is now widely used in epidemiology, but researchers do not always evaluate the potential for bias in this method when the data are overdispersed. This study used simulated data to evaluate sources of overdispersion in public health surveillance data and compare alternative statistical models for analysing such data. If count data are overdispersed, Poisson regression will not correctly estimate the variance. A model called negative binomial 2 (NB2) can correct for overdispersion, and may be preferred for analysis of count data. This paper compared the performance of Poisson and NB2 regression with simulated overdispersed injury surveillance data. Monte Carlo simulation was used to assess the utility of the NB2 regression model as an alternative to Poisson regression for data which had several different sources of overdispersion. Simulated injury surveillance datasets were created in which an important predictor variable was omitted, as well as with an incorrect offset (denominator). The simulations evaluated the ability of Poisson regression and NB2 to correctly estimate the true determinants of injury and their confidence intervals. The NB2 model was effective in reducing overdispersion, but it could not reduce bias in point estimates which resulted from omitting a covariate which was a confounder, nor could it reduce bias from using an incorrect offset. One advantage of NB2 over Poisson for overdispersed data was that the confidence interval for a covariate was considerably wider with the former, providing an indication that the Poisson model did not fit well. When overdispersion is detected in a Poisson regression model, the NB2 model should be fit as an alternative. If there is no longer overdispersion, then the NB2 results may be preferred. However, it is important to remember that NB2 cannot correct for bias from omitted covariates or from using an incorrect offset.
Construction of sum indices for impairment and A&P restrictions 
Sample description and mean disability scores and SD according to covariates (n=4864) 
Objectives: Prevention of disability in the ageing workforce is essential for sustaining economic growth in Europe. In order to provide information on entry points for preventive measures, it is important to better understand sociodemographic, socioeconomic and work-related determinants of disability in older employees. We aimed to test the hypothesis that low socioeconomic position and exposure to a stressful psychosocial work environment at baseline contribute to later disability. We further assumed that the association of socioeconomic position with disability is partly mediated by exposure to adverse working conditions. Methods: We studied longitudinal data from the first two waves of the Survey on Health, Ageing and Retirement in Europe comprising 11 European countries. Sociodemographic, socioeconomic and work-related factors (low control, effort-reward imbalance) and baseline disability of 2665 male and 2209 female employees aged between 50 and 64 years were used to predict disability 2 years later. Following the International Classification of Functioning (ICF), disability was subdivided into the components 'impairment' and 'restriction in activities and participation'. Two multilevel Poisson regressions were fitted to the data. Results: After adjusting for baseline disability and relevant confounding variables, low socioeconomic position and chronic stress at work exerted significant effects on disability scores 2 years later. We found some support for the hypothesis that the association of socioeconomic position with disability is partly mediated by work stress. Conclusions: Investing in reduction of work stress and reducing social inequalities in health functioning are relevant entry points of policies that aim at maintaining work ability in early old age.
To investigate if the preventive measures taken to reduce the occupational exposure to asbestos have resulted in a decreased incidence of pleural mesothelioma in Sweden. The incidence of pleural mesothelioma between 1958 and 1995 for birth cohorts born between 1885 and 1964 was investigated. The cases of pleural mesothelioma were identified through the Swedish Cancer Register. In 1995, around 80 cases of pleural mesothelioma could be attributed to occupational exposure to asbestos. There is an increasing incidence in more recent birth cohorts in men. The incidence was considerably higher in the male cohort born between 1935 and 1944 than in men born earlier. The annual incidence of pleural mesothelioma attributable to occupational exposure to asbestos is today larger than all fatal occupational accidents in Sweden. The first asbestos regulation was adopted in 1964 and in the mid 1970s imports of raw asbestos decreased drastically. Yet there is no obvious indication that the preventive measures have decreased the risk of pleural mesothelioma. The long latency indicates that the effects of preventive measures in the 1970s could first be evaluated around 2005.
Characteristics of workers with lung cancer and controls 
Odds ratios for lung cancer among tin miners by stages of silicosis* 
To evaluate the relation between occupational dust exposure and lung cancer in tin mines. This is an update of a previous study of miners with high exposure to dust at four tin mines in southern China. A nested case-control study of 130 male lung cancer cases and 627 controls was initiated from a cohort study of 7855 subjects employed at least 1 year between 1972 and 1974 in four tin mines in China. Three of the tin mines were in Dachang and one was in Limu. Cumulative total exposure to dust and cumulative exposure to arsenic were calculated for each person based on industrial hygiene records. Measurements of arsenic, polycyclic aromatic hydrocarbons (PAHs), and radon in the work sites were also evaluated. Odds ratios (ORs), standard statistic analysis and logistic regression were used for analyses. Increased risk of lung cancer was related to cumulative exposure to dust, duration of exposure, cumulative exposure to arsenic, and tobacco smoking. The risk ratios for low, medium, and high cumulative exposure to dust were 2.1 (95% confidence interval (95% CI) 1.1 to 3.8), 1.7 (95% CI 0.9 to 3.1), and 2.8 (95% CI 1.6 to 5.0) respectively after adjustment for smoking. The risk for lung cancer among workers with short, medium, and long exposure to dust were 1.9 (95% CI 1.0 to 3.5), 2.3 (95% CI 1.3 to 4.1), and 2.3 (95% CI 1.2 to 4.2) respectively after adjusting for smoking. Several sets of risk factors for lung cancer were compared, and the best predictive model included tobacco smoking (OR=1.6, 95% CI 1.1 to 2.4) and cumulative exposure to arsenic (ORs for different groups from low to high exposure were 2.1 (95% CI 1.1 to 3.9); 2.1 (95% CI 1.1 to 3.9); 1.8 (95% CI 1.0 to 3.6); and 3.6 (95% CI 1.8 5 to 7.3)). No excess of lung cancer was found among silicotic subjects in the Limu tin mine although there was a high prevalence of silicosis. Exposures to radon were low in the four tin mines and no carcinogenic PAHs were detected. These findings provide little support for the hypothesis that respirable crystalline silica induces lung cancer. Ore dust in work sites acts as a carrier, the exposure to arsenic and tobacco smoking play a more important part in carcinogenesis of lung cancer in tin miners. Silicosis seems not to be related to the increased risk of lung cancer.
Because work-related injuries are common and yet the mechanisms through which various types of injuries relate to age, length of service and job remain unknown, this study assessed the role of age, length of service and job in work-related injury. Prospective study of all 164,814 permanently employed male workers at the French national railway company during 1998-2000, based on the company's injury database: 446,120 person-years, 15,195 injuries with working days lost, coded using the company's injury classification, which is derived from that of the French health insurance scheme. We investigated the incidence of 10 types of injury: fall on same level, fall to lower level, handling materials/machine parts during assembly, handling objects, lifting/handling equipment, collision with/by moving objects, collision with/by vehicles, operating machines/equipment, using hand tools and other injuries. Data were analysed using negative binomial regression. Workers aged <25 years were subject to a higher injury risk from handling materials/machine parts during assembly, and collision with/by moving objects or vehicles. Older workers, especially those aged 50-55 years, were subject to a higher risk of fall and injury resulting from lifting/handling materials/equipment/objects or from collision with/by moving objects/vehicles. Using hand tools was a risky task for workers aged <30 or > or =40 years. The relative risk decreased steadily with increasing length of service with the company, from 2.6 for 1 year to 1.0 for > or =30 years, and the slope of the trend is stronger for fall to lower level, lifting/handling materials/equipment and collision with/by moving objects. Younger and older ages and shorter length of service are at risk for various types of injuries. Preventive measures should improve working conditions, especially for younger/older ages, provide knowledge through specific training during the first years in a job and help workers to be more aware of risks associated with their age, years of employment and job.
Comparison of bronchial epithelial expression of IL-5 between the two exposures. Horizontal lines represent medians. 
Quantification of biomarkers in the bronchial epithelium 
Comparison of bronchial epithelial expression of IL-10 between the two exposures. Horizontal lines represent medians. 
Comparison of bronchial epithelial expression of IL-13 between the two exposures. Horizontal lines represent medians. 
Comparison of bronchial epithelial expression of ICAM-1 between the two exposures. Horizontal lines represent medians. 
Repeated daily exposure of healthy human subjects to NO2 induces an acute airway inflammatory response characterised by neutrophil influx in the bronchial mucosa To assess the expression of NF-kappaB, cytokines, and ICAM-1 in the bronchial epithelium. Twelve healthy, young non-smoking volunteers were exposed to 2 ppm of NO2/filtered air (four hours/day) for four successive days on separate occasions. Fibreoptic bronchoscopy was performed one hour after air and final NO2 exposures. Bronchial biopsy specimens were immunostained for NF-kappaB, TNF-alpha, eotaxin, Gro-alpha, GM-CSF, IL-5, -6, -8, -10, -13, and ICAM-1 and their expression was quantified using computerised image analysis. Expression of IL-5, IL-10, IL-13, and ICAM-1 increased following NO2 exposure. Upregulation of the Th2 cytokines suggests that repeated exposure to NO2 has the potential to exert a "pro-allergic" effect on the bronchial epithelium. Upregulation of ICAM-1 highlights an underlying mechanism for leucocyte influx, and could also explain the predisposition to respiratory tract viral infections following NO2 exposure since ICAM-1 is a major receptor for rhino and respiratory syncytial viruses.
Total amount of urinary dialkyl phosphate metabolites recovered from volunteers after an oral dose of chlorpyrifos 
Total amount of urinary dialkylphosphate metabolites and chlorpyrifos recovered from volunteers after a dermal dose of chlorpyrifos 
To determine the kinetics of elimination of urinary dialkylphosphate metabolites after oral and dermally applied doses of the organophosphate pesticide chlorpyrifos to human volunteers and to determine whether these doses affected plasma and erythrocyte cholinesterase activity. Five volunteers ingested 1 mg (2852 nmol) of chlorpyrifos. Blood samples were taken over 24 hours and total void volumes of urine were collected over 100 hours. Four weeks later 28.59 mg (81567 nmol) of chlorpyrifos was administered dermally to each volunteer for 8 hours. Unabsorbed chlorpyrifos was washed from the skin and retained for subsequent measurement. The same blood and urine sampling regime was followed as for the oral administration. Plasma and erythrocyte cholinesterase concentrations were determined for each blood sample. The concentration of two urinary metabolites of chlorpyrifos--diethylphosphate and diethyl-thiophosphate--was determined for each urine sample. The apparent elimination half life of urinary dialkylphosphates after the oral dose was 15.5 hours and after the dermal dose it was 30 hours. Most of the oral dose (mean (range) 93% (55-115%)) and 1% of the applied dermal dose was recovered as urinary metabolites. About half (53%) of the dermal dose was recovered from the skin surface. The absorption rate through the skin, as measured by urinary metabolites was 456 ng/cm2/h. Blood plasma and erythrocyte cholinesterase activity did not fall significantly during either dosing regime. An oral dose of chlorpyrifos was readily absorbed through the skin and almost all of the dose was recovered as urinary dialkylphosphate metabolites. Excretion was delayed compared with the oral dose. Only a small proportion of the applied dose was recovered during the course of the experiment. The best time to collect urine samples for biological monitoring after dermal exposure is before the shift the next day. The amounts of chlorpyrifos used did not depress acetyl cholinesterase activity but could be readily detected as urinary dialkylphosphate metabolites indicating that the urinary assay is a more sensitive indicator of exposure.
Definition of classes of asbestos exposure in the study population
Percentage ofsubjects showing significant retention of asbestos bodies in BAL fluid or lung tissue
Exposure to asbestos was evaluated in 131 patients with pleural malignant mesothelioma in the Paris area between 1986 and 1992 using data from a detailed specific questionnaire and light microscopy analysis of the retention of asbestos bodies in bronchoalveolar lavage fluid or lung tissue. Probable or definite exposure to significant levels of asbestos dust was identified in only 48 (36.6%) subjects, and significant asbestos body counts (above 1 asbestos body/ml in bronchoalveolar lavage fluid or 1000 asbestos bodies/g of dry lung tissue) were found in only 45 (34.3%) subjects. Overall 50 subjects had experienced exposure to only low levels of asbestos or no exposure at all and showed no significant retention of asbestos bodies in the biological sample analysed. Previous studies have shown that light microscopy may be useful in the identification of subjects with previous exposure to asbestos. In this study, apart from cases with obvious exposure to asbestos, a large group of subjects seemed to have a history of exposure or lung retention of asbestos bodies suggestive of very low levels of cumulative exposure, similar to those described in the general population.
Prevalence ofpositive skin prick tests (SPT) to latex and departmental glove consumption 
To determine the prevalence of latex sensitisation among a large group of healthcare workers, study the occupational and non-occupational factors associated with latex allergy, and characterise latex exposure in air and by gloves. All 2062 employees of a general hospital in Hamilton, Ontario, Canada who regularly used latex gloves were invited to participate in a cross sectional survey, representing the baseline phase of a prospective cohort morbidity study. Attempts were made to recruit employees who were diagnosed with latex allergy before the survey. Glove extracts were assayed for antigenic protein, and area and personal air samples were obtained on two occasions (summer and winter) to estimate exposure to airborne latex protein. A questionnaire on medical and occupational information was administered by an interviewer. Skin prick tests were performed with latex reagents, three common inhalants, and six foods. The mean (SD) latex protein concentrations were 324 (227) micrograms/g in powdered surgical gloves and 198 (104) micrograms/g in powdered examination gloves. Personal latex aeroallergen concentrations ranged from 5 to 616 ng/m3. There was a total of 1351 (66%) participants. The prevalence of positive latex skin tests was 12.1% (95% confidence interval (95% CI) 10.3% to 13.9%). This prevalence did not vary by sex, age, hospital, or smoking status but subjects who were latex positive were significantly more likely to be atopic (P < 0.01). Participants who were latex positive were also significantly more likely to have positive skin tests to one or more foods (Mantel-Haenszel odds ratio (OR) adjusted for atopy 12.1, 95% CI 7.6 to 19.6, P < 10(-9)). Work related symptoms were more often reported among latex positive people, and included hives (OR 6.3, 95% CI 3.2 to 12.5), eye symptoms (OR 1.9, 95% CI 1.2 to 2.8), and wheezy or whistling chest (OR 4.7, 95% CI 2.8 to 7.9). The prevalence of latex sensitivity was highest among laboratory workers (16.9%), and nurses and physicians (13.3%). When the glove consumption per healthcare worker for each department was grouped into tertiles, the prevalence of latex skin test positivity was greater in the higher tertiles of glove use for sterile (surgical) gloves (P < 0.005) but not for examination gloves. In this large, cross sectional study of healthcare workers, the prevalence of latex sensitisation was 12.1% (9.5% among all those eligible), and there were significant associations with atopy, positive skin tests to certain foods, work related symptoms, and departmental use of gloves per healthcare worker. This cohort is being followed up prospectively and will be retested to determine the incidence of development of latex sensitivity.
Adjusted models between drinking social norms and heavy drinking, frequent drinking and drinking at work (n = 5338) 
Previous studies on worksite drinking norms showed individually perceived norms were associated with drinking behaviours. To examine whether restrictive drinking social norms shared by workgroup membership are associated with decreased heavy drinking, frequent drinking and drinking at work at the worker level. The sample included 5338 workers with complete data nested in 137 supervisory workgroups from 16 American worksites. Multilevel models were fitted to examine the association between workgroup drinking norms and heavy drinking, frequent drinking and drinking at work. Multivariate adjusted models showed participants working in workgroups in the most discouraging drinking norms quartile were 45% less likely to be heavy drinkers, 54% less likely to be frequent drinkers and 69% less likely to drink at work than their counterparts in the most encouraging quartile. Strong associations between workgroup level restrictive drinking social norms and drinking outcomes suggest public health efforts at reducing drinking and alcohol-related injuries, illnesses and diseases should target social interventions at worksites.
Some characteristics of the cohort of 14 730 male workers in 12 Norwegian ferroalloy plants 
Observed (0) and expected (E) numbers ofdeaths from all causes 1962-90 in 14 730 employees in 12 Norwegian ferroalloy plants 
Observed (0) and expected (E) numbers of deaths 1962-90 in 3086 male furnace workers manufacturing ferromanganese and siliconmanganese by duration of work 
Concern about the health hazards of exposure to workers in the ferroalloy industry has initiated this historical cohort study. The aim was to examine the mortality pattern among male employees in 12 Norwegian ferroalloy plants. All men employed for at least six months who started their first employment during 1933-91 were eligible for the cohort. Deaths observed during 1962-90 were compared with expected figures calculated from national mortalities. Internal comparisons of rates were performed by Poisson regression analysis. The final cohort comprised 14,730 male employees who were observed for 288,886 person-years. Mortality from all causes of death was slightly increased (3390 deaths, standardised mortality ratio (SMR) 1.08, 95% confidence interval (95% CI) 1.04-1.11). Regression analysis of total mortality showed a significant negative trend for the rate ratios with increasing duration of employment. An increased mortality was found among employees in urban plants compared with employees in rural plants (rate ratio (RR) 1.21, 95% CI 1.13-1.29). Excess deaths from cancer (SMR 1.11) and sudden death (SMR 1.47) were found among employees with at least three years of employment. Mortality from accidents, poisonings, and violence was increased among all employees (SMR 1.28). Excess deaths from this cause were however only found for the time after the end of employment in this industry and not during employment (SMR 0.90). The increased mortality from cancer and sudden death could be related to work exposures, at least in subgroups, and these results warrant further studies. The excess deaths from accidents, poisonings, and violence were probably not related to work exposures. The mortality results for short term workers and other information indicate that systematic errors contribute to the increased overall mortality.
A century ago anthrax was a continuing health risk in the town of Kidderminster. The distribution of cases in people and in animals provides an indication of the routes by which spores were disseminated. The response to these cases provides an insight into attitudes to an occupational and environmental risk at the time and can be compared with responses in more recent times. To assess the distribution of anthrax cases associated with the use of contaminated wool and to review the response to them. The area studied was Kidderminster, Worcestershire, England, from 1900 to 1914. Data sources were national records of the Factory Inspectorate and local records from the infirmary, Medical Officer of Health and inquest reports, and county agricultural records, supplemented by contemporary and later review articles. Case reports and summary data were analysed, and discussions and actions taken to improve precautions reviewed. There were 36 cases of anthrax, with five deaths, one of which was the sole case of the internal form of the disease. Cases of cutaneous anthrax were most frequently found in those handling raw wool, but they also occurred in workers at later stages of the spinning process and in people with little or no recorded exposure to contaminated wool. Limited precautionary measures were in place at the start of the study period. Some improvements were made, especially in the treatment of infections, but wool with a high risk of anthrax contamination continued to be used and cases continued to arise. Major changes were made to the disposal of waste and to agricultural practice in contaminated areas to curtail outbreaks in farm animals. The introduction of anthrax as a contaminant of imported wool led not only to cases in the highly exposed groups of workers but also to cases in other members of the population and in farm animals. The measures taken during the study period reduced fatalities from cutaneous anthrax but did not eliminate the disease. Public concern about the cases was muted.
The aim of this study was to calculate the benchmark doses (BMD) and their 95% lower confidence boundary (BMDL) for the threshold number of years of shift work associated with a relative increase in haemoglobin A1c (HbA(1c)), an index of glucose metabolism. A 14-year prospective cohort study was conducted in male workers at a Japanese steel company (n=7104) who had received annual health check-ups between 1991 and 2005. The endpoints were either a 10%, 15%, 20%, 25% or 30% increase in HbA(1c) levels during the observation period, compared to HbA(1c) at entry to the study. The associations between years of shift work and increases in HbA(1c) were investigated using pooled logistic regression, adjusted for age, body mass index, mean arterial pressure, total serum cholesterol, creatinine, alanine aminotransferase, gamma-glutamyl transpeptidase, uric acid, drinking habits, smoking habits and habitual exercise. The BMDL/BMD for years of shift work were calculated using benchmark responses (BMRs) of 5% or 10% and parameters for duration of shift work and other covariates. Assuming a mean age of 53 years in workers aged 50 years or older, the BMDL/BMD for years of shift work with a BMR of 5% were 17.8/23.9 (> or = 15%), 15.7/18.7 (> or = 20%), 18.9/22.7 (> or = 25%) and 25.2/31.7 (> or = 30%). With a BMR of 10%, the respective values were 29.5/39.7 (> or = 15%), 24.3/28.9 (> or = 20%), 27.3/32.7 (> or = 25%) and 34.1/42.9 (> or = 30%). These results suggest that special attention should be paid to middle-aged workers whose years of shift work exceeds these threshold times.
Although smoking causes a variety of diseases and both, a high smoking prevalence and permanent occupational disability are a great burden on the population level, data about the impact of smoking habits on occupational disability are sparse. The objective of this study was to examine the influence of smoking habits on occupational disability among construction workers, an occupational group with particularly high smoking prevalence. The association between smoking and occupational disability was examined during a mean follow-up of 10.8 years in a cohort of 14,483 male construction workers in Württemberg, Germany. The cohort was linked to the regional pension register of the German pension fund to identify workers who were granted a disability pension during the follow-up. HRs (Hazard Ratios) were calculated with non-smokers as reference by the Cox proportional hazards model adjusting for potential confounding factors such as age, nationality, type of occupation, alcohol consumption and body mass index. Overall, 2643 cases of occupational disability were observed, with dorsopathy (21%) being the most common cause. Clear dose-response relationships were seen between smoking and occupational disability due to all causes, as well as occupational disability due to respiratory, cardiovascular and mental diseases, cancer and dorsopathy. Particularly strong associations were seen between heavy smoking (> or =20 cigarettes/day) and occupational disability due to mental and respiratory diseases (HR 3.25, 95% CI 1.93 to 5.46 and HR 3.26, 95% CI 1.69 to 6.27, respectively). Smoking is associated with increased risk of occupational disability among construction workers, in particular occupational disability due to respiratory, cardiovascular and mental diseases, cancer and dorsopathy.
Odds ratios and 95% confidence intervals of shift work compared with day work for increases in total cholesterol 
characteristics of the subjects at their first health examination, grouped according to type of job schedule Job schedule type at entry year 
The widespread adoption of 24 h continuous operations in a number of industries has resulted in an increase in shift work, which may influence lipid metabolism because of disturbed circadian rhythms, broken sleep and lifestyle problems. The objective of the present study was to assess the effect of shift work on serum total cholesterol as an index of lipid metabolism. A 14-year prospective cohort study was conducted in day workers (n = 4079) and alternating shift workers (n = 2807) who received annual health check-ups between 1991 and 2005 in a Japanese steel company. The end-points were either a 20%, 25%, 30%, 35%, 40% or 45% increase in serum total cholesterol during the period of observation, compared with serum total cholesterol at entry to the study. The association between the job schedule type and increase in serum total cholesterol was investigated using multivariate pooled logistic regression analyses. The odds ratios for the effect of shift work were obtained after adjustment for a number of potential confounders. The significant odds ratios of alternating shift work (and 95% confidence intervals) were: >or=20%, 1.16 (1.07 to 1.26); >or=25%, 1.16 (1.05 to 1.28); >or=35%, 1.23 (1.05 to 1.43); >or=40%, 1.30 (1.07 to 1.58); and >or=45%, 1.28 (1.01 to 1.63) for serum total cholesterol. Generally the odds ratios of alternating shift work tended to be higher for stricter cut-points of relative increase in serum total cholesterol level. Our study in male Japanese workers revealed that alternating shift work adversely affected lipid metabolism.
Factors associated with injury in children aged 10-14 years 
Little information exists on injury and factors associated with injury in working youth aged 10-14 years. Most studies do not involve children younger than 15. A cross-sectional anonymous survey was administered to middle school students in five school districts and one large urban school in October 2001. Of the 3189 working middle school students who responded to the survey, the majority were employed in informal job settings, such as working for someone in a home, newspaper delivery, and working on family farms or in family businesses. Overall, 18% of children reported being injured at work. Of those injured, 26% reported that their injury was severe enough to affect their activities for more than three days. Variables that were associated with injury included having a "near-miss" incident at work (AOR 6.61, 95% CI 4.92 to 8.89), having a co-worker injured (AOR 2.65, 95% CI 1.95 to 3.60), and being asked to do something dangerous (AOR 2.25, 95% CI 1.61 to 3.14). Children are working and being injured in jobs that are not covered by existing child labour laws. Injury rates in non-covered occupations are high, warranting review of current laws.
Although sickness absence is a strong predictor of health, whether this association varies by occupational position has rarely been examined. The aim of this study was to investigate overall and diagnosis-specific sickness absence as a predictor of future long-term sub-optimal health by occupational position. This was a prospective occupational cohort study of 15 320 employees (73% men) aged 37-51. Sickness absences (1990-1992), included in 13 diagnostic categories, were examined by occupational position in relation to self-rated health measured annually during 1993-2006. 60% of employees in higher occupational positions and 22% in lower positions had no sickness absence. Conversely, 9.5% of employees in higher positions and 40% in lower positions had over 30 sick-leave days. Repeated-measures logistic regression analyses adjusted for age, sex and chronic disease showed employees with over 30 days absence, compared to those with no absence, had approximately double the risk of sub-optimal health over the 14-year follow-up in all occupational positions. 1-30 days sick-leave was associated with greater odds of sub-optimal health in the high (OR 1.48; 95% CI 1.27 to 1.72) and intermediate (1.29; 1.15 to 1.45) but not lower occupational positions (1.06; 0.82 to 1.38). Differences by occupational position in the association between sickness absence in 13 specific diagnostic categories and sub-optimal health over the ensuing 14 years were limited to stronger associations observed with cancer and mental disorders in the higher occupational positions. The association between sickness absence of more than 30 days over 3 years and future long-term self-rated health appears to differ little by occupational position.
Characteristics of the study population at baseline examination 
Cause of occupational disability by age 
Standardised incidence ratios (SIR) for all-cause disability and disability due to musculoskeletal disorders and accidents by age, nationality, occupation, and duration of employment 
Most industrialised countries have public income maintenance programmes to protect workers in case of disability but studies addressing disability risk of specific professional groups are rare. The objective of this study was to establish a detailed pattern of the nature and extent of occupational disability among construction workers. A cohort study was set up including 14,474 male workers from the construction industry in Württemberg (Germany) aged 25-64 years who underwent occupational health exams between 1986 and 1992. The cohort was linked to the regional pension register of the manual workers' pension insurance institution to identify workers who were granted a disability pension during the 10 year follow up. All-cause and cause specific standardised incidence ratios (SIR) and 95% confidence intervals (CI) were calculated using disability rates from the general workforce and from all blue collar workers in Germany as references. In total, 2247 (16%) members of the cohort were granted a disability pension. Major causes of disability were musculoskeletal (45%) and cardiovascular diseases (19%). In comparison with the general workforce, construction workers experienced a higher risk of disability from cancer (SIR = 1.26; 95% CI 1.08 to 1.47), respiratory diseases (SIR = 1.27; 95% CI 1.03 to 1.55), musculoskeletal diseases (SIR = 2.16; 95% CI 2.03 to 2.30), injuries/poisoning (SIR = 2.52; 95% CI 2.06 to 3.05), and all causes combined (SIR = 1.47; 95% CI 1.41 to 1.53). When compared with the blue collar reference group, increased risks of disability among construction workers were found for musculoskeletal diseases (SIR = 1.53; 95% CI 1.44 to 1.63), injury/poisoning (SIR = 1.83; 95% CI 1.50 to 2.21), and all causes combined (SIR = 1.11; 95% CI 1.07 to 1.16). Musculoskeletal diseases and external causes are major factors limiting the work capability of construction workers and lead to an increased proportion of occupational disability.
To examine possible associations between daily concentrations of urban air pollutants and hospital emergency admissions and mortality due to cardiac and pulmonary disease. A time series study was conducted in the City of Edinburgh, which has a population of about 450,000. Poisson log linear regression models were used to investigate the relation of the daily event rate with daily air pollution concentrations of sulphur dioxide (SO2) and black smoke from 1981 to 1995, and of nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and particulate matter (PM10) from 1992 to 1995. Adjustments were made for seasonal and weekday variation, daily temperature, and wind speed. The most significant findings were positive associations over the period 1981-95 between black smoke as a mean of the previous three days and daily all cause mortality in people aged > or = 65, and respiratory mortality also in this age group (3.9% increase in mortality for a 10 micrograms/m3 increment in black smoke). For hospital emergency admissions between 1992 and 1995 the two most significant findings (p < 0.05) were for cardiovascular admissions of people aged > or = 65 which showed a positive association with PM10 as a mean of the 3 previous days, and a negative association with O3 as a mean of the previous three days. Analyses of outcomes based on linkage with previous cardiorespiratory emergency admissions did not show substantially different results. These data suggest that in the City of Edinburgh, after correction for confounders, there was a small but significant association between concentrations of black smoke and respiratory mortality in the older age group, probably attributable to higher pollution levels in the early part of the study period. There were also generally weak and variable associations between day to day changes in concentrations of urban air pollutants at a single central point and emergency hospital admission rates from cardiac and respiratory disease.
In many places in Europe, the ambient air pollution exceeds the levels considered to be safe for health. The objective of the paper is to review and summarise the methods of assessment of its impact on health, and to indicate the contributions of various research disciplines, particularly environmental epidemiology. The framework for assessment of impact is based on a four stage model: assessment of release of pollutant; assessment of exposure; assessment of the consequence; and risk estimation. Epidemiology is crucial in providing the data for the assessment of consequence. The criteria that determine the use of epidemiological studies for this task include lack of bias, correct control of confounding, and measured estimates of exposure. At present, those criteria are easier to satisfy for studies of short term effects on health than for the delayed consequences of exposure, or exposure accumulated over a prolonged period. Combinations of results from various populations through meta-analysis of existing studies or conducting multicentre studies is often necessary to increase the reliability of the consequence assessment stage. To assess the impact on health systematically helps to focus on actions to limit air pollutants with the greatest impacts on human health and on the most affected populations. This method allows identification of the most pertinent questions which have to be answered by studies on relations between pollution and health and on exposure of populations to air pollutants. Epidemiology has considerable potential to contribute to this research.
The authors had a unique opportunity to study the early impacts of occupational and recreational exposures on the development of noise-induced hearing loss (NIHL) in a cohort of 392 young workers. The objectives of this study were to estimate strength of associations between occupational and recreational exposures and occurrence of early-stage NIHL and to determine the extent to which relationships between specific noise exposures and early-stage NIHL were mitigated through the use of hearing protection. Participants were young adults who agreed to participate in a follow-up of a randomised controlled trial. While the follow-up study was designed to observe long-term effects (up to 16 years) of a hearing conservation intervention for high school students, it also provided opportunity to study the potential aetiology of NIHL in this worker cohort. Study data were collected via exposure history questionnaires and clinical audiometric examinations. Over the 16-year study period, the authors documented changes to hearing acuity that exceeded 15 dB at high frequencies in 42.8% of men and 27.7% of women. Analyses of risk factors for NIHL were limited to men, who comprised 68% of the cohort, and showed that risks increased in association with higher levels of the most common recreational and occupational noise sources, as well as chemical exposures with ototoxic potential. Use of hearing protection and other safety measures, although not universal and sometimes modest, appeared to offer some protection. Early-stage NIHL can be detected in young workers by measuring high-frequency changes in hearing acuity. Hearing conservation programmes should focus on a broader range of exposures, whether in occupational or non-occupational settings. Priority exposures include gunshots, chainsaws, power tools, smoking and potentially some chemical exposures.
regression results (coefficients (b), standard errors (SE), and p values) for log transformed urine mercury and creatinine corrected urine mercury concentrations in women aged 16-49 years for selected characteristics: United States, 1999-2000 
Mercury amalgam dental restorations have been used by dentists since the mid 19th century and issues on safety continue to be periodically debated within the scientific and public health communities. Previous studies have reported a positive association between urine mercury levels and the number of dental amalgams, but this relation has never been described in a nationally representative sample in the United States. Using household interview, dietary interview, dental examination, and laboratory data from the 1999-2000 National Health and Nutrition Examination Survey (NHANES), the association between mercury concentrations and dental restorations was examined in US women of reproductive age. In women of childbearing age, approximately 13% of all posterior dental surfaces were restored with amalgams and the average urinary mercury level in women was low (1.34 microg/l). It is estimated that an increase of 1.8 microg/l in the log transformed values for mercury in urine would occur for each 10 dental surfaces restored with amalgam. Although the findings do not address the important issues of adverse health effects at low thresholds of mercury exposure, they do provide important reference data that should contribute significantly to the ongoing scientific and public health policy debate on the use of dental amalgams in the USA.
To investigate time trends of low back pain (LBP) and concurrent psychological distress in the general population. Every 4 years between 1990 and 2006, a self-administered questionnaire including the General Health Questionnaire (GHQ-12) and a question on LBP were sent to a random sample of the population in the county of Stockholm (response rate 61-69%). All individuals aged 21-64 years in the five samples (n = 1976-26,611) were included in the study. Among women, the prevalence of self-reported LBP rose rather moderately during the 16-year period, from 12.5% to 16.4% (prevalence rate ratio (PRR) 1.31; 95% CI 1.11 to 1.55). The prevalence did not change at all among men (PRR 1.02; 95% CI 0.85 to 1.23). In contrast, the prevalence of LBP with concurrent psychological distress rose more substantially, from 2.6% to 5.9% among women (PRR 2.23; 95% CI 1.53 to 3.24) and from 1.9% to 3.5% among men (PRR 1.82; 95% CI 1.14 to 2.90). The prevalence of both LBP and LBP with concurrent psychological distress seemed to fluctuate somewhat over the period. Between 1990 and 2006, the focus of discussion of the high societal costs for sickness absence and disability pensions gradually shifted from musculoskeletal disorders to psychological well-being. As a result, the general population's awareness and perception of pain and psychological distress may have changed and, in turn, affected individuals' willingness to report these symptoms. Further research is necessary to investigate the impact of cultural changes on subjective symptom reporting.
Three hundred years after his death, it is interesting to speculate how much this doctor from Carpi's talent for clinical innovation and communication still relates to modern occupational medicine. Bernardino Ramazzini insisted that progress in medicine should not focus solely on physiology and clinical questions, but should also cover the health of the population, observing any relations between environmental factors and disease. This approach, while influenced by the Hippocratic doctrine of ‘airs, waters, places’, also refers to the need to test new criteria for observation ‘on the population’, using new tools for processing and interpreting the findings. This surely demonstrates that this scholar from Carpi was very forward-looking indeed! His De Morbis Artificum Diatriba [Diseases of Workers], first published in Modena in 1700, reveals his forward-thinking ideas in its dedication to the Venetian reformers, laying the foundations for the social role of occupational medicine and hygiene, linking workers, business and political institutions. The treatise took at least 10 years to be conceived and written in the last decade of the 17th century. Ramazzini was 67 when he completed it, with more than 40 years of medical practice behind him, and in that very same year, at the peak of his fame, he was recognised by being called to the University of Padua.1 Ramazzini's talent is also clear from his ability to communicate and arouse his readers’ interest, not only within the close circles of medicine but more broadly within the community.2 Like any great communicator in modern times, Ramazzini tells us that the idea of writing …
To extend our knowledge of how exposure to neurotoxic substances during working life affects cognitive functioning in the long term. Does long term occupational exposure to organic solvents lead to aggravated cognitive impairment later in life? A follow up was conducted of floor layers exposed to solvents and their unexposed referents (carpenters) 18 years after the baseline assessment. The pattern of cognitive changes in the two groups was compared, with the same 10 neuropsychological tests from the test battery for investigating functional disorders (TUFF) that were used at baseline. The study included 41 floor layers and 40 carpenters. A medical examination focused on health at the present and during the past 18 years. An extensive exposure assessment made in the initial study included questionnaires, interviews, and measurements. Additional exposure during the follow up period was minor, as explored in interviews at follow up. The entire group of floor layers did not deteriorate significantly more over time than did the carpenters. However, among the oldest subjects (>60 years), only floor layers showed decline in visual memory. Moreover, the most highly exposed floor layers deteriorated significantly more than their referents in visual memory and perceptual speed, and they tended to display larger decrements in motor speed. Significant dose effect relations were found; higher cumulative exposure was associated with decrements in visual episodic memory, perceptual speed and attention, and visuospatial skill. The hypothesis that floor layers would deteriorate more in cognitive performance than their unexposed referents over a period of 18 years was partly supported by the results of this study. The results are consistent with the view that the negative effects of exposure to solvents may interact with the normal aging process, primarily at heavy exposure.
Mortality in the ETO cohort (n = 18 235*) 
Cox regression results for lymphoid cell line tumours* 
Cox regression results for breast cancer mortality* 
To extend mortality follow up from 1987 to 1998 for cohort of 18 235 men and women exposed to ethylene oxide. Standard mortality follow up, life table and Cox regression analysis. There were 2852 deaths, compared with 1177 in the earlier 1987 follow up. There was no overall excess of haematopoietic cancers combined or of non-Hodgkin's lymphoma. However, internal exposure-response analyses found positive trends for haematopoietic cancers which were limited to males (15 year lag). The trend in haematopoietic cancer was driven by lymphoid tumours (non-Hodgkin's lymphoma, myeloma, lymphocytic leukaemia), which also have a positive trend with cumulative exposure for males with a 15 year lag. Haematopoietic cancer trends were somewhat weaker in this analysis than trends in the earlier follow up, and analyses restricted to the post-1987 data did not show any significant positive trends (exposure levels dropped sharply in the early 1980s). Breast cancer did not show any overall excess, although there was an excess in the highest cumulative exposure quartile using a 20 year lag. Internal exposure-response analyses found positive trend for breast cancer using the log of cumulative exposure with a 20 year lag. There was little evidence of any excess cancer mortality for the cohort as a whole, with the exception of bone cancer based on small numbers. Positive exposure-response trends for lymphoid tumours were found for males only. Reasons for the sex specificity of this effect are not known. There was also some evidence of a positive exposure-response for breast cancer mortality.
To identify risk factors for new episodes of sick leave due to neck or back pain. This prospective study comprised an industrial population of 2187 employees who were followed up at 18 months and 3 years after a comprehensive baseline measurement. The potential risk factors comprised physical and psychosocial work factors, health-related and pain-related characteristics and lifestyle and demographic factors. The response rate at both follow-ups was close to 73%. At the 18-month follow-up, 151 participants reported at least one episode of sick-listing due to neck or back pain during the previous year. Risk factors assessed at baseline for sick leave due to neck or back pain at the follow-up were blue-collar work, back pain one or several times during the previous year, 1-99 days of cumulative sickness absence during the previous year (all causes except neck or back pain), uncertainty of one's own working ability in 2 years' time and the experience of few positive challenges at work. After 3 years, 127 participants reported at least one episode of sick leave due to back or neck pain during the year previous to follow-up. The risk factors for this pain-related sick leave were blue-collar work, several earlier episodes of neck pain, no everyday physical activities during leisure time (cleaning, gardening and so on), lower physical functioning and, for blue-collar workers separately, repetitive work procedures. The most consistent risk factors for new episodes of sick leave due to neck or back pain found during both the follow-ups were blue-collar work and several earlier episodes of neck or back pain assessed at baseline. Preventive efforts to decrease sick leave due to neck or back pain may include measures to increase the occurrence of positive challenges at work and to minimise repetitive work procedures. An evidence-based secondary prevention of neck and back pain including advice to stay active is also warranted.
About 7000 tonnes of unleaded petrol were discharged into the English Channel after a tanker collision off Ostend on Saturday 18 January 1997. The petrol evaporated and the vapour plume was carried across the central part of England to Wales, resulting in reports of unidentified odours, and irritation of the eyes, skin, and upper respiratory tract. This work uses this incident to show how marine and atmospheric dispersion modelling together with routine air quality monitoring can assist in identifying hazards to the population at risk from chemical incidents. Public health surveillance and results from environmental sampling were compared with the behaviour of the plume as predicted by computer modelling. The predicted plume path and dispersion were shown to correlate well with the results from surveillance and environmental analysis. There is a need for public health professionals to interact with medical toxicologists, atmospheric and marine scientists and engineers, and other environmental experts in managing events of this nature.
The aim was to determine the prevalence of persistent respiratory symptoms and bronchial hyper-responsiveness due to reactive airways dysfunction syndrome in a population of construction workers at moderate to high risk of developing the syndrome, at an interval of 18 to 24 months after multiple exposures to chlorine gas during renovations to a pulp and paper mill. 71 of 289 exposed workers (25%) were identified on the basis of an exposure and the onset of respiratory symptoms shortly after this event (moderate to high risk). A standardised respiratory questionnaire was first presented, followed by spirometry and a methacholine inhalation test on those whose questionnaire suggested the persistence of respiratory symptoms. 64 of 71 (90%) subjects completed the respiratory questionnaire at the time of the follow up. The questionnaire suggested a persistence of respiratory symptoms in 58 of the 64 workers (91%). Of the 58 subjects, 51 underwent spirometry and assessment of bronchial responsiveness. All of them used bronchodilators as required (not regularly) and four required inhaled anti-inflammatory preparations. Sixteen had bronchial obstruction (forced expiratory volume in one second) (FEV1 < 80% predicted) and 29 showed significant bronchial hyper-responsiveness. Of the subjects (n = 71) who were at moderate to high risk of developing reactive airways dysfunction syndrome after being exposed to chlorine and were seen 18 to 24 months after exposure ended, 58 (82%) still had respiratory symptoms, 16 (23%) had evidence of bronchial obstruction, and 29 (41%) had bronchial hyper-responsiveness.
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Characteristics of the study population 
Garment workers' mortality results (US referent rates); update of cohort to 1998À
To evaluate the mortality experience of 11 039 workers exposed to formaldehyde for three months or more in three garment plants. The mean time weighted average formaldehyde exposure at the plants in the early 1980s was 0.15 ppm but past exposures may have been substantially higher. Vital status was updated through 1998, and life table analyses were conducted. Mortality from all causes (2206 deaths, standardised mortality ratio (SMR) 0.92, 95% CI 0.88 to 0.96) and all cancers (SMR 0.89, 95% CI 0.82 to 0.97) was less than expected based on US mortality rates. A non-significant increase in mortality from myeloid leukaemia (15 deaths, SMR 1.44, 95% CI 0.80 to 2.37) was observed. Mortality from myeloid leukaemia was greatest among workers first exposed in the earliest years when exposures were presumably higher, among workers with 10 or more years of exposure, and among workers with 20 or more years since first exposure. No nasal or nasopharyngeal cancers were observed. Mortality from trachea, bronchus, and lung cancer (147 deaths, SMR 0.98, 95% CI 0.82 to 1.15) was not increased. Multiple cause mortality from leukaemia was increased almost twofold among workers with both 10 or more years of exposure and 20 years or more since first exposure (15 deaths, SMR 1.92, 95% CI 1.08 to 3.17). Multiple cause mortality from myeloid leukaemia among this group of workers was also significantly increased (8 deaths, SMR 2.55, 95% CI 1.10 to 5.03). Results support a possible relation between formaldehyde exposure and myeloid leukaemia mortality. Previous epidemiological studies supporting a relation between formaldehyde exposure and leukaemia mortality have been primarily of formaldehyde exposed professional groups, not formaldehyde exposed industrial workers. Limitations include limited power to detect an excess for rare cancers such as nasal and nasopharyngeal cancers and lack of individual exposure estimates.
To give the observed and expected deaths due to cancer at all separate sites in asbestos workers in east London, and to analyse these for overall effect and exposure-response trend. The mortality experience of a cohort of over 5000 men and women followed up for over 30 years since first exposure to asbestos has been extracted. There was a large excess of deaths due to cancer (537 observed, 222 expected). Most of these were due to cancer of the lung (232 observed, 77 expected) and pleural (52) and peritoneal (48) mesothelioma. The exposure-response trend for all these three causes was highly significant. There was also an excess of cancer of the colon (27 observed, 15 expected) which was significantly related to exposure. There were significant excesses of cancer of the ovary, of the liver, and of the oesophagus but with no consistent relation to exposure. The excess risk of cancer after exposure to asbestos was mainly due to cancer of the lung and mesothelioma. An exposure related excess of cancer of the colon was also detected but the possibility that some of these deaths may have been peritoneal mesotheliomas could not be excluded. There was no consistent evidence of exposure related excesses at any other site.
Between 1940 and 1944 military gas masks with filter pads containing 20% crocidolite were assembled in a Nottingham factory. Records supplied by the late Professor Stephen Jones were of 1154 persons, mainly women, who had worked in the factory during this period; they included many deaths from mesothelioma. A systematic effort was therefore made to establish causes of death for the whole cohort. Of 640 employees with full name and sex recorded, 567 (89%) were traced. Of these, 491 had died, including 65 from mesothelioma, though only 54 were certified as such. After exclusion of these 54, standardised mortality ratios were significantly raised for respiratory cancer (SMR 2.5) and carcinomatosis (SMR 3.2). The pattern of mortality in the remaining 514 employees without full identification was similar, but a low tracing rate (40%) did not justify their further analysis. The first death from mesothelioma was in 1963 (22 years after first exposure) and the last in 1994, whereas a further 5.0 cases would have been expected between 1996 and 2003 (p = 0.0065). These findings in a cohort followed over 60 years after brief exposure to crocidolite confirm a high and specific risk of mesothelioma (28% peritoneal) and perhaps of lung cancer some 20-50 years later. The statistically significant absence of further mesothelioma cases during the past eight years suggests that crocidolite, though durable, is slowly removed.
To re-examine mortality patterns in a cohort of nickel platers with no history of chromium plating. All 284 men first employed by the company in 1945-75 with a minimum employment of three months in the nickel plating department were identified. Workers who had worked in the chromium plating or nickel/chromium plating departments were excluded. Standardised mortality ratios (SMRs), P values, and 95% confidence intervals were calculated. Poisson regression was used to carry out statistical modelling of mortalities within the cohort (internal standard). Four variables were considered to have the potential to influence mortality within the cohort: attained age (age at follow up or age at death), year of starting nickel work, period of follow up (measured from the first period of work with nickel exposure), and duration of exposure to nickel. The only significant difference between observed and expected numbers, when investigated by site of cancer and by broad non-cancer groupings, was that for stomach cancer (observed eight, expected 2.49, SMR 322). The study provides only weak evidence that nickel plating is associated with an excess risk of stomach cancer. This cohort of nickel platers does not seem to have experienced any discernible risk of occupational lung cancer. Other studies of nickel platers rather than nickel/chromium platers would be useful.
Top-cited authors
Jussi Vahtera
  • University of Turku
Alex Burdorf
  • Erasmus MC
Minna Kivimäki
  • University of Eastern Finland
Jens Peter Ellekilde Bonde
  • Bispebjerg Hospital, Copenhagen University
Ken Donaldson
  • The University of Edinburgh