Carolina Bigert

Myocardial infarction among professional drivers.

Background. Professional drivers are at an increased risk of myocardial infarction but the underlying causes for this increased risk are uncertain. Methods. We identified all first events of myocardial infarction among men age 45–70 years in Stockholm County for 1992 and 1993. We selected controls randomly from the population. Response rates of 72% and 71% resulted in 1067 cases and 1482 controls, respectively. We obtained exposure information from questionnaires. We calculated odds ratios (ORs), with and without adjustment for socioeconomic status, tobacco smoking, alcohol drinking, physical inactivity at leisure time, overweight status, diabetes and hypertension. Results. The crude OR among bus drivers was 2.14 (95% confidence interval = 1.34–3.41), among taxi drivers 1.88 (1.19–2.98) and among truck drivers 1.66 (1.22–2.26). Adjustment for potential confounders gave lower ORs: 1.49 (0.90–2.45), 1.34 (0.82–2.19) and 1.10 (0.79–1.53), respectively. Additional adjustment for job strain lowered the ORs only slightly. An exposure-response pattern (by duration of work) was found for bus and taxi drivers. Conclusions. The high risk among bus and taxi drivers was partly explained by unfavorable life-style factors and social factors. The work environment may contribute to their increased risk. Among truck drivers, individual risk factors seemed to explain most of the elevated risk.

Conditions during childhood and adolescence as explanations of social class differences in disability pension among young men

Aims: This study investigates whether conditions present or established in youth and adolescence among young men contribute to the differences in the risk of an early disability pension (DP) among social classes. Methods: The study is based on data from a nationwide survey of the 49,285 Swedish males born between 1949 and 1951 who were conscripted into military service between 1969 and 1970. Data on socioeconomic groups were based on information of occupation and educational level reported in the census of 1975 held by Statistics Sweden. Potential psychosocial and behavioural risk factors were linked to records from the Swedish Social Insurance Board up until 1993. The analyses were based upon those 33,609 conscripts with information on all background variables who reported an occupation and who were not granted a DP in 1975. Results : The strongest social class difference in the distribution of risk indicators was found for low ranking on the psychometric tests and for having been in a remedial class. In the univariate analyses, the highest odds ratios were noted for unskilled manual workers. In the multivariate model, with all the background variables included, the increased risk ratios for lower socioeconomic groups decreased considerably for a DP irrespective of diagnosis, and diminished for a DP with an alcohol-related diagnosis. Conclusion: It is concluded that conditions present or established in youth and adolescence are of major importance to understand the strong social class gradient in disability pensions among young men. It is suggested that the increased risks for skilled and unskilled manual workers compared with non-manual employees might be interpreted according to the concept of unfavourable life careers.

Incidence of lung cancer among subway drivers in Stockholm

BACKGROUND Very high levels of airborne particles have been detected in the subway system in Stockholm. Subway particles are more toxic to DNA in cultured human lung cells than particles from ambient air. METHODS This cohort comprised all men in Stockholm County who were gainfully employed in 1970. They were followed for cancer incidence until 1989. Lung cancer cases were identified from the national cancer register. Subway drivers were identified from the census in 1970. The reference cohort comprised all transport and communication workers in Stockholm. RESULTS There were nine cases of lung cancer among the subway drivers, giving a SIR of 0.82 (95% confidence interval 0.38-1.56). CONCLUSION The lung cancer incidence was not increased among the subway drivers. The study gives some evidence against the hypothesis that subway particles would be more potent in inducing lung cancer than particles in ambient air.

Blood markers of inflammation and coagulation and exposure to airborne particles in employees in the Stockholm underground

Objectives: Although associations have been found between levels of ambient airborne particles and cardiovascular disease (CVD) in the general population, little is known about possible cardiovascular effects from high exposure to particles in underground railway systems. This study investigates risk markers for CVD in employees exposed to particles in the Stockholm underground system. Methods: 79 workers (54 men and 25 women) in the Stockholm underground were investigated between November 2004 and March 2005. All were non-smokers aged 25–50 years. Three exposure groups were delineated: 29 platform workers with high exposure to particles, 29 train drivers with medium exposure and 21 ticket sellers with low exposure (control group). A baseline blood sample was taken after 2 non-working days, and a second sample after 2 working days, for analysis of levels of plasminogen activator inhibitor-1 (PAI-1), high-sensitivity C-reactive protein (hs-CRP), interleukin-6, fibrinogen, von Willebrand factor and factor VII. The study investigated changes in plasma concentrations between sample 1 and sample 2, and differences in average concentrations between the groups. Results: No changes between sample 1 and 2 were found that could be attributed to particle exposure. However, the highly exposed platform workers were found to have higher plasma concentrations of PAI-1 and hs-CRP than the ticket sellers and train drivers. This suggests that particle exposure could have a long-term inflammatory effect. These differences remained for PAI-1 in the comparison between platform workers and ticket sellers after adjusting for body mass index. Conclusions: Employees who were highly exposed to airborne particles in the Stockholm underground tended to have elevated levels of risk markers for CVD relative to employees with low exposure. However, the differences observed cannot definitely be linked to particle exposure as such.

Time trends in the incidence of myocardial infarction among professional drivers in Stockholm 1977–96

Aims: To investigate time trends in the incidence of first myocardial infarction (MI) among bus, taxi, and lorry drivers in Stockholm. Methods: In this population based case-control study, all first events of acute MI among men aged 40–69 in Stockholm County 1977–96 were identified using registers of hospital discharges and deaths. Controls were selected randomly from the general population. National censuses were used for information on occupational titles. A total of 20 364 cases and 136 342 controls were included in the study. Among these, 1183 cases and 6072 controls had worked as drivers. Results: During 1977–84 the MI incidence was higher in all three driver groups than among other manual workers. There was a decline in MI incidence among drivers as well as in the general population during the study period. The decline was greater among drivers than among other manual workers. During 1985–96 the relative risk remained increased compared to other manual workers among taxi and lorry drivers, but not among bus drivers. Conclusions: Despite a reduced MI incidence for professional drivers in recent years, preventive measures to reduce the risk of MI in these occupational groups, and in particular among taxi and lorry drivers, continue to be of importance.

No short-term respiratory effects among particle-exposed employees in the Stockholm subway.

OBJECTIVE Exposure to traffic-related air pollution is associated with adverse respiratory effects, but it is not known whether the high exposure to particles prevailing in the subway system may affect the respiratory system. We investigated airway inflammation and lung function among particle-exposed subway employees. METHODS We studied 81 workers. All participants were non-smokers, aged 25-50 years. Three exposure groups were formed according to particulate matter (PM) levels obtained during an occupational hygienic investigation: 30 platform workers [average PM(2.5) 63 µg/m(3) and DataRAM (MIE Inc, Billerica, Waltham, MA, USA) 182 µg/m(3)], 30 subway drivers (19 µg/m(3) and 33 µg/m(3)), and 21 ticket sellers (10 µg/m(3) and 13 µg/m(3)). We measured the fractional exhaled nitric oxide (FENO) of all workers before and after a workday. We also measured the peak expiratory flow (PEF) and forced expiratory volume in one second (FEV(1)) of platform workers and ticket sellers five times a day over two weeks. We calculated the arithmetic means of PEF and FEV(1) during exposed and unexposed time for every individual. RESULTS There was no significant increase in FENO after work among platform workers, subway drivers or ticket sellers (the means of percentual individual change were -7%, +2% and -4% respectively). The averages of the ratios (exposed to unexposed time) of PEF and FEV(1) were above 1.0 for both ticket sellers (1.016 and 1.002 respectively) and platform workers (1.022 and 1.005). CONCLUSIONS Our observations do not indicate any short-term respiratory effects of particle exposure in the subway among the employees, with respect to airway inflammation or lung function.

Lung cancer among firefighters: Smoking-adjusted risk estimates in a pooled analysis of case-control studies

Objectives: The aim of this study was to explore lung cancer risk among firefighters, with adjustment for smoking. Methods: We used pooled information from the SYNERGY project including 14 case-control studies conducted in Europe, Canada, New Zealand, and China, with lifetime work histories and smoking habits for 14,748 cases of lung cancer and 17,543 controls. We estimated odds ratios by unconditional logistic regression with adjustment for smoking and having ever been employed in a job known to present an excess risk of lung cancer. Results: There was no increased lung cancer risk overall or by specific cell type among firefighters (n = 190), neither before nor after smoking adjustment. We observed no significant exposure-response relationship in terms of work duration. Conclusions: We found no evidence of an excess lung cancer risk related to occupational exposure as a firefighter.

Lung cancer risk among cooks when accounting for tobacco smoking : a pooled analysis of case-control studies from Europe, Canada, New Zealand, and China

Objectives:To investigate the risk of lung cancer among cooks, while controlling for smoking habits. Methods:We used data from the SYNERGY project including pooled information on lifetime work histories and smoking habits from 16 case–control studies conducted in Europe, Canada, New Zealand, and China. Results:Before adjustment for smoking, we observed an increased risk of lung cancer in male cooks, but not in female cooks. After adjusting, there was no increased risk and no significant exposure–response relationship. Nevertheless, subgroup analyses highlighted some possible excess risks of squamous cell carcinoma and small cell carcinoma in female cooks. Conclusions:There is evidence that lung cancer risks among cooks may be confounded by smoking. After adjustment, cooks did not experience an increased risk of lung cancer overall. The subgroup analyses showing some excess risks among female cooks require cautious interpretation.

Chapter 16 – Cardiovascular Disease

There is strong epidemiological and mechanistic evidence for a causal association between exposure to arsenic and lead and development of cardiovascular disease. There is relatively strong but less conclusive evidence for a causal relationship between cadmium and mercury exposure and cardiovascular disease. All of these metals are suspected of inducing pathophysiological changes relevant to atherogenic disorders, including increased oxidative stress, inflammatory response, and coagulation activity. Cardiomyopathy has been associated with excessive intake of arsenic, cobalt, and iron. Deficiency of selenium has been related to dilated cardiomyopathy. Airborne beryllium exposure has been associated with heart disease, including both ischemic heart disease and cor pulmonale. Signs of cor pulmonale have also been observed after cobalt exposure among hard-metal workers. Pulmonary fibrosis with increased blood pressure in the pulmonary circulation is a likely mechanism in the development of cor pulmonale. Ionizing irradiation may explain the suggested relation between uranium exposure and cerebrovascular disease.

An improved method for determining dermal exposure to polycyclic aromatic hydrocarbons

Many workers are occupationally exposed to polycyclic aromatic hydrocarbons (PAHs), which may cause various health problems, and some PAHs are known or suspected carcinogens. PAH exposure is primarily monitored by air sampling, but contamination may also occur through dermal exposure. PAHs adsorbed to the skin can be sampled by tape-stripping, but subsequent extraction of sampling tapes in organic solvent also releases diverse co-eluting substances that are difficult to remove before analysis of the PAHs by gas chromatography/mass spectrometry (GC/MS). The objective of this study was to optimise a procedure for analytical clean-up after extraction of 32 PAHs from tape-strips, by dialysis in organic solvent using semipermeable membranes. With triplicate subsamples, the developed method yields acceptable precision and repeatability for both the 32 PAHs, across the concentration range 10-160 ng per sample, and for a certified reference material (urban dust). The optimized clean-up procedure and GC/MS methodology was used to assess PAHs on skin from the lower part of the ventral side of the wrist and just below the collar bone of three firefighters and seven controls (office workers). Several gaseous and particle-bound PAHs were detected in all samples, including controls. Thus, the optimized procedure using semipermeable membranes for clean-up of tape-strip extracts can be used to assess the dermal exposure of both occupational and general populations to multiple PAHs. The results also show that both gaseous and particle-bound PAHs, including alkylated species, may be present on skin.