Air pollution at the residence of Danish adults, by socio-demographic characteristics, morbidity, and address level characteristics.

BACKGROUND: Exposure to outdoor air pollution is associated with adverse health effects. Previous studies have indicated higher levels of air pollution in socially deprived areas. AIM: To investigate associations between air pollution and socio-demographic variables, comorbidity, stress, and green space at the residence in Denmark. METHODS: We included 2,237,346 persons living in Denmark, aged 35 years or older in 2017. We used the high resolution, multi-scale DEHM/UBM/AirGIS air pollution modelling system to calculate mean concentrations of air pollution with PM2.5, elemental carbon, ultrafine particles and NO2 at residences held the preceding five years. We used nationwide registries to retrieve information about socio-demographic indicators at the individual and neighborhood levels. We used general linear regression models to analyze associations between socio-demographic indicators and air pollution at the residence. RESULTS: Individuals with high SES (income, higher white-collar worker and high educational level) and of non-Danish origin were exposed to higher levels of air pollution than individuals of low SES and of Danish origin, respectively. We found comparable levels of air pollution according to sex, stress events and morbidity. For neighborhood level SES indicators, we found high air pollution levels in neighborhoods with low SES measured as proportion of social housing, sole providers, low income and unemployment. In contrast, we found higher air pollution levels in neighborhoods with higher educational level and a low proportion of manual labor. People living in an apartment and/or with little green space had higher air pollution levels. CONCLUSION: In Denmark, high levels of residential air pollution were associated with higher individual SES and non-Danish origin. For neighborhood-level indicators of SES, no consistent pattern was observed. These results highlight the need for analyzing many different socio-demographic indicators to understand the complex associations between SES and exposure to air pollution.

Socioeconomic differences in the risk of childhood central nervous system tumors in Denmark: a nationwide register-based case-control study.

PURPOSE: Differences in the risk of childhood central nervous system (CNS) tumors by socioeconomic status (SES) may enhance etiologic insights. We conducted a nationwide register-based case-control study to evaluate socioeconomic differences in the risk of childhood CNS tumors in Denmark and examined whether associations varied by different SES measures, time points of assessment, specific tumor types, and age at diagnosis. METHODS: We identified all children born between 1981 and 2013 and diagnosed with a CNS tumor at ages 0-19 years (n = 1,273) from the Danish Cancer Registry and sampled four individually matched controls per case (n = 5,086). We used conditional logistic regression models to estimate associations with individual-level and neighborhood-level socioeconomic measures. RESULTS: We observed elevated risks of ependymoma and embryonal CNS tumors in association with higher parental education (odds ratios (ORs) of 1.6-2.1 for maternal or paternal high education and ependymoma) and higher risk of all tumor types in association with higher maternal income, e.g., OR 1.93; 95% CI 1.05-3.52 for high versus low income for astrocytoma and other gliomas. Associations were often stronger in children diagnosed at ages 5-19 years. We found little evidence for an association with neighborhood SES. CONCLUSION: This large nationwide register study with minimal risk of bias showed that having parents with higher educational level and a mother with higher income was associated with a higher risk of childhood CNS tumors. Bias or under-ascertainment of cases among families with low income or basic education is unlikely to explain our findings.

High-resolution assessment of road traffic noise exposure in Denmark.

Recent studies show associations between transportation noise and various diseases. However, selection bias remains an inherent limitation in many cohort studies. In this study, we aimed to model road traffic noise exposure across the entire Danish population and investigate its distribution in relation to area-level socioeconomic indicators and green space. Based on the Nordic prediction method, we estimated road traffic noise for all Danish residential addresses, in total 2,761,739 addresses, for the years 1995, 2000, 2005, 2010, and 2015 at the most and least exposed façades. Area-level sociodemographic variables encompassing education, income, and unemployment were collected and residential green within a 150 m radius buffer at the address level was estimated using high-resolution national land use classification data. Median levels of noise at both the most and least exposed facades across Denmark increased slightly from 1995 to 2015. Correlations between most and least exposed façades varied based on population density and building type, with the highest correlations between the most and least exposed façades found for semidetached homes and lowest for multistory buildings. Increasing median noise levels were observed across increasing levels of higher education, lower income, and higher unemployment. A decreasing trend in median noise levels with increasing levels of green space was observed. In conclusion, we showed that it is feasible to estimate nationwide, address-specific exposure over a long time-period. Furthermore, the low correlations found between most and least exposed façade for multistory buildings, which characterize metropolitan centers, suggests that the most exposed façade estimation used in most previous studies and predicts exposure at the silent façade relatively poorly.

Associations between residential traffic noise exposure and smoking habits and alcohol consumption-A population-based study.

BACKGROUND: Traffic noise stresses and disturbs sleep. It has been associated with various diseases, and has recently also been associated with lifestyle. Hence, the association between traffic noise and disease could partly operate via a pathway of lifestyle habits, including smoking and alcohol intake. OBJECTIVES: We investigated associations between modelled residential traffic noise and smoking habits and alcohol consumption. METHODS: In a cohort of 57,053 participants, we performed cross-sectional analyses using data from a baseline questionnaire (1993-97), and longitudinal analyses of change between baseline and follow-up (2000-02). Smoking status (never, former, current) and intensity (tobacco, g/day) and alcohol consumption (g/day) was self-reported at baseline and follow-up. Address history from 1987-2002 for all participants were found in national registries, and road traffic and railway noise was modelled 1 and 5 years before enrolment, and from baseline to follow-up. Analyses were performed using logistic and linear regression, and adjusted for demographics, socioeconomic variables, leisure-time sports, and noise from the opposite source (road/railway). RESULTS: Road traffic noise exposure 5 years before baseline was positively associated with alcohol consumption (adjusted difference per 10 dB: 1.38 g/day, 95% confidence interval (CI): 1.10-1.65), smoking intensity (adjusted difference per 10 dB: 0.40 g/day, 95% CI: 0.19-0.61), and odds for being a current vs. never/former smoker at baseline (odds ratio (OR): 1.14; 95% CI: 1.10-1.17). In longitudinal analyses, we found no association between road traffic noise and change in smoking and alcohol habits. Railway noise was not associated with smoking habits and alcohol consumption, neither in cross-sectional nor in longitudinal analyses. CONCLUSION: The study suggests that long-term exposure to residential road traffic is associated with smoking habits and alcohol consumption, albeit only in cross-sectional, but not in longitudinal analyses.

Residential exposure to traffic noise and health-related quality of life--a population-based study.

BACKGROUND: Few studies have investigated the association between objectively measured traffic noise and health-related quality of life. However, as traffic noise has been associated with both cardiovascular disease and diabetes, and health-issues including sleeping problems, annoyance, and stress, it seems plausible that traffic noise is associated with health-related quality of life. METHODS: Between 1999 and 2002, a cohort of 38,964 Danes filled in the short form-36 (SF-36) questionnaire. Residential exposure to road traffic and railway noise was calculated for all historical addresses for 10 years preceding the SF-36, using the Nordic prediction method. Associations between noise exposure and SF-36 summary scales and the eight sub-scales were calculated using general linear models, adjusted for age, sex, socioeconomic status, and lifestyle. RESULTS: Models adjusted for age, sex and socioeconomic factors showed that a 10 dB higher road traffic noise 1 year preceding SF-36 assessment was associated with a 0.14 lower mental component summary (MCS) score (95% confidence interval (CI) -0.26, -0.01). However, further adjustment for lifestyle factors (smoking, alcohol, and waist circumference) attenuated the association: (-0.08 (95% CI: -0.20, 0.04)). Exposure to more than 55 dB of railway noise in the same time period was borderline significantly associated with lower MCS. The physical component summary was not associated with traffic noise. CONCLUSION: The present study suggests a weak association between traffic noise exposure and the mental health component score of SF-36, which may operate through lifestyle. The magnitude of effect was, however, not clinically relevant.

Space-time clusters of breast cancer using residential histories: a Danish case-control study.

BACKGROUND: A large proportion of breast cancer cases are thought related to environmental factors. Identification of specific geographical areas with high risk (clusters) may give clues to potential environmental risk factors. The aim of this study was to investigate whether clusters of breast cancer existed in space and time in Denmark, using 33 years of residential histories. METHODS: We conducted a population-based case-control study of 3138 female cases from the Danish Cancer Registry, diagnosed with breast cancer in 2003 and two independent control groups of 3138 women each, randomly selected from the Civil Registration System. Residential addresses of cases and controls from 1971 to 2003 were collected from the Civil Registration System and geo-coded. Q-statistics were used to identify space-time clusters of breast cancer. All analyses were carried out with both control groups, and for 66% of the study population we also conducted analyses adjusted for individual reproductive factors and area-level socioeconomic indicators. RESULTS: In the crude analyses a cluster in the northern suburbs of Copenhagen was consistently found throughout the study period (1971-2003) with both control groups. When analyses were adjusted for individual reproductive factors and area-level socioeconomic indicators, the cluster area became smaller and less evident. CONCLUSIONS: The breast cancer cluster area that persisted after adjustment might be explained by factors that were not accounted for such as alcohol consumption and use of hormone replacement therapy. However, we cannot exclude environmental pollutants as a contributing cause, but no pollutants specific to this area seem obvious.

Occupational exposures contribute to educational inequalities in lung cancer incidence among men: Evidence from the EPIC prospective cohort study.

The aim of this study is to investigate to what extent occupational exposures may explain socioeconomic inequalities in lung cancer incidence after adjusting for smoking and dietary factors. Analyses were based on a subsample of the European Prospective Investigation into Cancer and Nutrition (EPIC study), a prospective cohort. The analyses included 703 incident lung cancer cases among men in Denmark, the United Kingdom, Germany, Italy, Spain and Greece. The socioeconomic position was measured using the highest level of education. The estimates of relative indices of inequality (RII) were computed with Cox regression models. We first adjusted for smoking (with detailed information on duration and quantity) and dietary factors (fruits and vegetables consumption) and then for occupational exposures. The exposure to three carcinogens [asbestos, heavy metals and polycyclic aromatic hydrocarbons (PAH)] was analyzed. The occupational exposures explained 14% of the socioeconomic inequalities remaining after adjustment for smoking and fruits and vegetables consumption. The inequalities remained nevertheless statistically significant. The RII decreased from 1.87 (95% CI: 1.36-2.56) to 1.75 (1.27-2.41). The decrease was more pronounced when adjusting for asbestos than for heavy metals or PAH. Analyses by birth cohort suggested an effect of occupational exposures among older men, while due to small number of endpoints, no conclusion could be drawn about the role of occupational exposures in educational inequalities among younger men. Our study revealed that the impact of occupational exposures on socioeconomic inequalities in cancer incidence, rarely studied until now, exists while of modest magnitude.

The role of smoking and diet in explaining educational inequalities in lung cancer incidence.

BACKGROUND: Studies in many countries have reported higher lung cancer incidence and mortality in individuals with lower socioeconomic status. METHODS: To investigate the role of smoking in these inequalities, we used data from 391,251 participants in the European Prospective Investigation into Cancer and Nutrition study, a cohort of individuals in 10 European countries. We collected information on smoking (history and quantity), fruit and vegetable consumption, and education through questionnaires at study entry and gathered data on lung cancer incidence for a mean of 8.4 years. Socioeconomic status was defined as the highest attained level of education, and participants were grouped by sex and region of residence (Northern Europe, Germany, or Southern Europe). Relative indices of inequality (RIIs) of lung cancer risk unadjusted and adjusted for smoking were estimated using Cox regression models. Additional analyses were performed by histological type. RESULTS: During the study period, 939 men and 692 women developed lung cancer. Inequalities in lung cancer risk (RII(men) = 3.62, 95% confidence interval [CI] = 2.77 to 4.73, 117 vs 52 per 100,000 person-years for lowest vs highest education level; RII(women) = 2.39, 95% CI = 1.77 to 3.21, 46 vs 25 per 100,000 person-years) decreased after adjustment for smoking but remained statistically significant (RII(men) = 2.29, 95% CI = 1.75 to 3.01; RII(women) = 1.59, 95% CI = 1.18 to 2.13). Large RIIs were observed among men and women in Northern European countries and among men in Germany, but inequalities in lung cancer risk were reverse (RIIs < 1) among women in Southern European countries. Inequalities differed by histological type. Adjustment for smoking reduced inequalities similarly for all histological types and among men and women in all regions. In all analysis, further adjustment for fruit and vegetable consumption did not change the estimates. CONCLUSION: Self-reported smoking consistently explains approximately 50% of the inequalities in lung cancer risk due to differences in education.

Social inequality and incidence of and survival from cancers of the kidney and urinary bladder in a population-based study in Denmark, 1994-2003.

We investigated the effects of socioeconomic, demographic and health-related indicators on the incidence of and survival from cancers of the kidney and urinary bladder diagnosed in Denmark during 1994-2003 with follow-up through 2006 using information from nationwide registers. The analyses were based on data on 2941 patients with kidney cancer and 9471 patients with urinary bladder cancer in a cohort of 3.22 million people born between 1925 and 1973 and aged >or=30 years. Our results indicate that lower socioeconomic position is associated with higher incidences of cancers at both sites in both sexes, whether socioeconomic position is measured as educational level, disposable income, affiliation to the work market, housing tenure or size of dwelling. We also found a moderate pattern of better survival from cancers at both sites in the most advantaged groups, most clearly reflected by the level of education, disposable income and affiliation to the work market.

Lung cancers attributable to environmental tobacco smoke and air pollution in non-smokers in different European countries: a prospective study.

BACKGROUND: Several countries are discussing new legislation on the ban of smoking in public places, and on the acceptable levels of traffic-related air pollutants. It is therefore useful to estimate the burden of disease associated with indoor and outdoor air pollution. METHODS: We have estimated exposure to Environmental Tobacco Smoke (ETS) and to air pollution in never smokers and ex-smokers in a large prospective study in 10 European countries (European Prospective Investigation into Cancer and Nutrition)(N = 520,000). We report estimates of the proportion of lung cancers attributable to ETS and air pollution in this population. RESULTS: The proportion of lung cancers in never- and ex-smokers attributable to ETS was estimated as between 16 and 24%, mainly due to the contribution of work-related exposure. We have also estimated that 5-7% of lung cancers in European never smokers and ex-smokers are attributable to high levels of air pollution, as expressed by NO2 or proximity to heavy traffic roads. NO2 is the expression of a mixture of combustion (traffic-related) particles and gases, and is also related to power plants and waste incinerator emissions. DISCUSSION: We have estimated risks of lung cancer attributable to ETS and traffic-related air pollution in a large prospective study in Europe. Information bias can be ruled out due to the prospective design, and we have thoroughly controlled for potential confounders, including restriction to never smokers and long-term ex-smokers. Concerning traffic-related air pollution, the thresholds for indicators of exposure we have used are rather strict, i.e. they correspond to the high levels of exposure that characterize mainly Southern European countries (levels of NO2 in Denmark and Sweden are closer to 10-20 ug/m3, whereas levels in Italy are around 30 or 40, or higher).Therefore, further reduction in exposure levels below 30 ug/m3 would correspond to additional lung cancer cases prevented, and our estimate of 5-7% is likely to be an underestimate. Overall, our prospective study draws attention to the need for strict legislation concerning the quality of air in Europe.

Socioeconomic status and risk of childhood leukaemia in Denmark.

AIMS: The aim of this study was to assess the influence of socioeconomic status on the risk of childhood leukaemia. METHODS: A matched case-control design was used. The study population comprised all children (0-14 years old) born and reported to the Danish Cancer Registry between 1976 and 1991 for a diagnosis of leukaemia (n=377). Controls were selected from the Central Population Registry and matched by sex, age, and time of birth. Each child was assigned three categories of socioeconomic status, one corresponding to the annual average income in the municipality of residence at the time of birth, another corresponding to that at the time of diagnosis, and, finally, each family was assigned one of five social classes by use of the job titles of the parents. Conditional logistic regression was used to estimate the effect of socioeconomic status on the risk of childhood leukaemia. RESULTS: Children born in low-income municipalities had a significantly increased risk of leukaemia (RR=2.71; 95% CI=1.41-5.21; p=0.003), which was higher among those who received their diagnosis before age five (RR=3.43; 95% CI=1.52-7.74; p=0.003). Neither individual social class nor the socioeconomic status of the residential area at the time of diagnosis was convincingly associated with the risk of childhood leukaemia. CONCLUSIONS: The results suggest that socioeconomic factors associated with community characteristics rather than individual lifestyle are related to the risk of childhood leukaemia and that these factors act early in life.

[Effects on health of particulate air pollution in Denmark--a quantitative assessment]. / Helbredseffekter af partikulaer luftforurening i Danmark--et forsøg på kvantificering.

INTRODUCTION: Ambient air pollution is a risk factor for mortality and morbidity. The aim of this study was to quantify the health effects related to particulate matter (PM10) in Denmark. MATERIALS AND METHODS: We used relative risk estimates in relation to PM10 based on the epidemiological literature. Population exposure to PM10 was calculated. Cases attributable to PM10 were estimated for mortality, cardiovascular and respiratory hospital admissions, chronic bronchitis, acute bronchitis, restricted activity days, and asthma attacks. Moreover, we attempted to estimate health-related gains from equipping all heavy-duty vehicles in Denmark with particle filters. RESULTS: We estimated the average population PM10 exposure to be about 22 micrograms/m3, about one third of which can be attributed to natural (not man-made) PM10. The number of cases per year attributable to the estimated exposure included about 5,000 deaths, about 5,000 hospital admissions, about 5,000 cases of chronic bronchitis, about 17,000 cases of acute bronchitis, about 200,000 asthma attacks, and about three million restricted activity days. The health-related gains from installing particle filters on all heavy-duty vehicles in Denmark are uncertain; the estimates for mortality ranged from 22 to 1,250, depending on the assumptions. DISCUSSION: Although air pollution constitutes only a minor risk factor on the individual level, it seems to be a major public health problem. The particle characteristics responsible for the estimated health effects are not well understood. The ultrafine particle fraction may cause a much greater impact on health than indicated by the mass.

Validation of a job-exposure matrix for assessment of utility worker exposure to magnetic fields.

The aim of this study was to evaluate a 50-Hz electromagnetic field job-exposure matrix used in epidemiological studies of a nationwide cohort of utility workers in Denmark. We compared a job-exposure matrix that distinguished four categories of exposure to 50-Hz time-weighted average (TWA) magnetic fields: low (< 0.1 microT), medium (0.1-0.29 microT), high (0.3-0.99 microT) and very high (> 1.0 microT) of utility company employees with 196 measurements of 8-h exposure for 129 workers in this industry. The 129 workers were selected from the following five main work environments: generation facilities, transmission lines, distribution lines, substations, and other electrically and non-electrically relates jobs. This study shows that the job-exposure matrix can be expected to introduce misclassification mainly between adjacent categories of exposure. Thus, the distribution of measurements of exposure to 50-Hz magnetic fields was similar for workers in the medium and the high exposure matrix categories. But the two extreme categories satisfactorily separate low and very highly exposed workers. The study shows that epidemiological use of this job-exposure matrix might combine the two intermediate categories of exposure. If the sample size in extreme categories provides enough power, a study in which this job-exposure matrix is used should allow detection of a true association between exposure to 50-Hz magnetic field and disease.