Exposure to long-term source-specific transportation noise and incident breast cancer: A pooled study of eight Nordic cohorts

BACKGROUND

Environmental noise is an important environmental exposure that can affect health. An association between transportation noise and breast cancer incidence has been suggested, although current evidence is limited. We investigated the pooled association between long-term exposure to transportation noise and breast cancer incidence.

METHODS

Pooled data from eight Nordic cohorts provided a study population of 111,492 women. Road, railway, and aircraft noise were modelled at residential addresses. Breast cancer incidence (all, estrogen receptor (ER) positive, and ER negative) was derived from cancer registries. Hazard ratios (HR) were estimated using Cox Proportional Hazards Models, adjusting main models for sociodemographic and lifestyle variables together with long-term exposure to air pollution.

RESULTS

A total of 93,859 women were included in the analyses, of whom 5,875 developed breast cancer. The median (5th-95th percentile) 5-year residential road traffic noise was 54.8 (40.0-67.8) dB Lden, and among those exposed, the median railway noise was 51.0 (41.2-65.8) dB Lden. We observed a pooled HR for breast cancer (95 % confidence interval (CI)) of 1.03 (0.99-1.06) per 10 dB increase in 5-year mean exposure to road traffic noise, and 1.03 (95 % CI: 0.96-1.11) for railway noise, after adjustment for lifestyle and sociodemographic covariates. HRs remained unchanged in analyses with further adjustment for PM2.5 and attenuated when adjusted for NO2 (HRs from 1.02 to 1.01), in analyses using the same sample. For aircraft noise, no association was observed. The associations did not vary by ER status for any noise source. In analyses using <60 dB as a cutoff, we found HRs of 1.08 (0.99-1.18) for road traffic and 1.19 (0.95-1.49) for railway noise.

CONCLUSIONS

We found weak associations between road and railway noise and breast cancer risk. More high-quality prospective studies are needed, particularly among those exposed to railway and aircraft noise before conclusions regarding noise as a risk factor for breast cancer can be made.

Long-term exposure to traffic noise and risk of incident colon cancer: A pooled study of eleven Nordic cohorts

Background Colon cancer incidence is rising globally, and factors pertaining to urbanization have been proposed involved in this development. Traffic noise may increase colon cancer risk by causing sleep disturbance and stress, thereby inducing known colon cancer risk-factors, e.g. obesity, diabetes, physical inactivity, and alcohol consumption, but few studies have examined this. Objectives The objective of this study was to investigate the association between traffic noise and colon cancer (all, proximal, distal) in a pooled population of 11 Nordic cohorts, totaling 155,203 persons. Methods We identified residential address history and estimated road, railway, and aircraft noise, as well as air pollution, for all addresses, using similar exposure models across cohorts. Colon cancer cases were identified through national registries. We analyzed data using Cox Proportional Hazards Models, adjusting main models for harmonized sociodemographic and lifestyle data. Results During follow-up (median 18.8 years), 2757 colon cancer cases developed. We found a hazard ratio (HR) of 1.05 (95% confidence interval (CI): 0.99-1.10) per 10-dB higher 5-year mean time-weighted road traffic noise. In sub-type analyses, the association seemed confined to distal colon cancer: HR 1.06 (95% CI: 0.98-1.14). Railway and aircraft noise was not associated with colon cancer, albeit there was some indication in sub-type analyses that railway noise may also be associated with distal colon cancer. In interaction-analyses, the association between road traffic noise and colon cancer was strongest among obese persons and those with high NO₂-exposure. Discussion A prominent study strength is the large population with harmonized data across eleven cohorts, and the complete address-history during follow-up. However, each cohort estimated noise independently, and only at the most exposed façade, which may introduce exposure misclassification. Despite this, the results of this pooled study suggest that traffic noise may be a risk factor for colon cancer, especially of distal origin.

Long-Term Exposure to Transportation Noise and Ischemic Heart Disease: A Pooled Analysis of Nine Scandinavian Cohorts

BACKGROUND

Transportation noise may induce cardiovascular disease, but the public health implications are unclear.

OBJECTIVES

The study aimed to assess exposure-response relationships for different transportation noise sources and ischemic heart disease (IHD), including subtypes.

METHODS

Pooled analyses were performed of nine cohorts from Denmark and Sweden, together including 132,801 subjects. Time-weighted long-term exposure to road, railway, and aircraft noise, as well as air pollution, was estimated based on residential histories. Hazard ratios (HRs) were calculated using Cox proportional hazards models following adjustment for lifestyle and socioeconomic risk factors.

RESULTS

A total of 22,459 incident cases of IHD were identified during follow-up from national patient and mortality registers, including 7,682 cases of myocardial infarction. The adjusted HR for IHD was 1.03 [95% confidence interval (CI) 1.00, 1.05] per 10 dB Lden for both road and railway noise exposure during 5 y prior to the event. Higher risks were indicated for IHD excluding angina pectoris cases, with HRs of 1.06 (95% CI: 1.03, 1.08) and 1.05 (95% CI: 1.01, 1.08) per 10 dB Lden for road and railway noise, respectively. Corresponding HRs for myocardial infarction were 1.02 (95% CI: 0.99, 1.05) and 1.04 (95% CI: 0.99, 1.08). Increased risks were observed for aircraft noise but without clear exposure-response relations. A threshold at around 55 dB Lden was suggested in the exposure-response relation for road traffic noise and IHD.

DISCUSSION

Exposure to road, railway, and aircraft noise in the prior 5 y was associated with an increased risk of IHD, particularly after exclusion of angina pectoris cases, which are less well identified in the registries. https://doi.org/10.1289/EHP10745.

Oophorectomy and rate of dementia: a prospective cohort study

OBJECTIVE

Globally, dementia disproportionally affects women, which is not fully explained by higher female longevity. Oophorectomy at any age leads to the permanent loss of ovarian sex steroids, potentially increasing the risk of dementia. We aimed to investigate the association between oophorectomy and dementia and whether this was conditional on age at oophorectomy, hysterectomy or use of hormone therapy (HT).

METHODS

A prospective study of 24,851 female nurses from the Danish Nurse Cohort. Nurses were followed from age 60 years or entry into the cohort, whichever came last, until date of dementia, death, emigration or end of follow-up (December 31, 2018), whichever came first. Poisson regression models with log-transformed person-years as offset were used to estimate the associations.

RESULTS

During 334,420 person-years of follow-up, 1,238 (5.0%) nurses developed dementia and 1,969 (7.9%)/ 1,016 (4.1%) contributed person-time after bilateral-/unilateral oophorectomy. In adjusted analyses, an 18% higher rate of dementia was observed following bilateral oophorectomy (aRR 1.18: 95% CI, 0.89-1.56) and 13% lower rate (aRR 0.87: 95% CI, 0.59-1.23) following unilateral oophorectomy compared to nurses who retained their ovaries. Similar effects were detected after stratification according to age at oophorectomy. No statistically significant modifying effects of hysterectomy or HT were detected (Pinteraction≥0.60).

CONCLUSIONS

Bilateral, but not unilateral, oophorectomy was associated with an increased rate of incident dementia. We were unable to establish whether this association was conditional on hysterectomy or HT use. Although an increase in dementia after bilateral oophorectomy is biologically plausible, limited statistical power hampers the precision of the estimates.

The long-term association between bilateral oophorectomy and depression: a prospective cohort study

OBJECTIVE

Depression is a leading cause of disability globally and affects more women than men. Ovarian sex steroids are thought to modify depression risk in women and interventions such as bilateral oophorectomy that permanently change the sex steroid milieu may increase the risk of depression. This study aimed to investigate the associations between unilateral and bilateral oophorectomy and depression over a 25-year period (1993-2018) and whether this varied by age at oophorectomy or use of menopausal hormone therapy.

METHODS

Twenty-five thousand one hundred eighty-eight nurses aged ≥45 years from the Danish Nurse Cohort were included. Nurses with depression prior to baseline were excluded. Poisson regression models, with log-transformed person-years as offset, were used to assess the associations between oophorectomy and incident depression. Nurses who retained their ovaries were the reference group.

RESULTS

Compared with nurses with retained ovaries, bilateral oophorectomy was associated with a slightly higher rate of depression (rate ratio [RR], 1.08; 95% confidence interval [CI], 0.95-1.23), but without statistical significance. However, when stratified by age at oophorectomy, compared with nurses with retained ovaries, bilateral oophorectomy at age ≥51 years was associated with higher rates of depression (RR 1.16; 95% CI, 1.00-1.34), but not bilateral oophorectomy at age <51 years (RR 0.86; 95% CI, 0.69-1.07); P value for difference in estimates = 0.02. No association between unilateral oophorectomy and depression was observed.

CONCLUSIONS

In this cohort of Danish female nurses, bilateral oophorectomy at age ≥51 years, but not at younger ages, was associated with a slightly higher rate of depression compared with those who retained their ovaries.

Long-term exposure to road traffic noise and stroke incidence: a Danish Nurse Cohort study

BACKGROUND

Road traffic noise has been linked to increased risk of ischemic heart disease, yet evidence on stroke shows mixed results. We examine the association between long-term exposure to road traffic noise and incidence of stroke, overall and by subtype (ischemic or hemorrhagic), after adjustment for air pollution.

METHODS

Twenty-five thousand six hundred and sixty female nurses from the Danish Nurse Cohort recruited in 1993 or 1999 were followed for stroke-related first-ever hospital contact until December 31st, 2014. Full residential address histories since 1970 were obtained and annual means of road traffic noise (L_den [dB]) and air pollutants (particulate matter with diameter < 2.5 μm and < 10 μm [PM_2.5 and PM₁₀], nitrogen dioxide [NO₂], nitrogen oxides [NOx]) were determined using validated models. Time-varying Cox regression models were used to estimate hazard ratios (HR) (95% confidence intervals [CI]) for the associations of one-, three-, and 23-year running means of L_den preceding stroke (all, ischemic or hemorrhagic), adjusting for stroke risk factors and air pollutants. The World Health Organization and the Danish government's maximum exposure recommendations of 53 and 58 dB, respectively, were explored as potential L_den thresholds.

RESULTS

Of 25,660 nurses, 1237 developed their first stroke (1089 ischemic, 148 hemorrhagic) during 16 years mean follow-up. For associations between a 1-year mean of L_den and overall stroke incidence, the estimated HR (95% CI) in the fully adjusted model was 1.06 (0.98-1.14) per 10 dB, which attenuated to 1.01 (0.93-1.09) and 1.00 (0.91-1.09) in models further adjusted for PM_2.5 or NO₂, respectively. Associations for other exposure periods or separately for ischemic or hemorrhagic stroke were similar. There was no evidence of a threshold association between L_den and stroke.

CONCLUSIONS

Long-term exposure to road traffic noise was suggestively positively associated with the risk of overall stroke, although not after adjusting for air pollution.

The association between general and central obesity and the risks of coronary heart disease in women with and without a familial predisposition to obesity: findings from the Danish Nurse Cohort

Several studies show an increased risk of coronary heart disease (CHD) among people with obesity, but it is largely unknown whether this association also depends on a familial predisposition to obesity. This study examined if associations between Body Mass Index (BMI) or waist circumference (WC) and incident CHD differed among Danish female nurses with and without familial overweight and obesity. Analyses were based on data from the Danish Nurse Cohort (n = 20,701). Self-reported height, weight and self-measured WC were assessed in 1999, as was information on familial overweight/obesity, defined as having one or both parents with overweight/obesity. Information on the development of or death from CHD was collected from nationwide Danish registries in 2015. Analyses were based on Cox proportional hazard regression models adjusted for potential confounding factors. Both BMI and WC were directly associated with CHD risk, but we found no evidence of effect modification from familial predisposition to obesity. Hence a familial predisposition to obesity does not seem to influence the risk of CHD associated with general or central obesity.

Long-Term Exposure to Air Pollution, Road Traffic Noise, and Heart Failure Incidence: The Danish Nurse Cohort

Background We examined the association of long-term exposure to air pollution and road traffic noise with incident heart failure (HF). Methods And Results Using data on female nurses from the Danish Nurse Cohort (aged >44 years), we investigated associations between 3-year mean exposures to air pollution and road traffic noise and incident HF using Cox regression models, adjusting for relevant confounders. Incidence of HF was defined as the first hospital contact (inpatient, outpatient, or emergency) between cohort baseline (1993 or 1999) and December 31, 2014, based on the Danish National Patient Register. Annual mean levels of particulate matter with a diameter <2.5 µm since 1990 and NO₂ and road traffic noise since 1970 were estimated at participants' residences. Of the 22 189 nurses, 484 developed HF. We detected associations with all 3 pollutants, with hazard ratios (HRs) of 1.17 (95% CI, 1.01-1.36), 1.10 (95% CI, 0.99-1.22), and 1.12 (95% CI, 0.99-1.26) per increase of 5.1 µg/m³ in particulate matter with a diameter <2.5 µm, 8.6 µg/m³ in NO₂, and 9.3 dB in road traffic noise, respectively. We observed an enhanced risk of HF incidence for those exposed to high levels of the 3 pollutants; however, the effect modification of coexposure was not statistically significant. Former smokers and nurses with hypertension showed the strongest associations with particulate matter with a diameter <2.5 µm (P_{effect modification}<0.05). Conclusions We found that long-term exposures to air pollution and road traffic noise were independently associated with HF.

Long-Term Exposure to Transportation Noise and Risk of Incident Stroke: A Pooled Study of Nine Scandinavian Cohorts

BACKGROUND

Transportation noise is increasingly acknowledged as a cardiovascular risk factor, but the evidence base for an association with stroke is sparse.

OBJECTIVE

We aimed to investigate the association between transportation noise and stroke incidence in a large Scandinavian population.

METHODS

We harmonized and pooled data from nine Scandinavian cohorts (seven Swedish, two Danish), totaling 135,951 participants. We identified residential address history and estimated road, railway, and aircraft noise for all addresses. Information on stroke incidence was acquired through linkage to national patient and mortality registries. We analyzed data using Cox proportional hazards models, including socioeconomic and lifestyle confounders, and air pollution.

RESULTS

During follow-up (median=19.5y), 11,056 stroke cases were identified. Road traffic noise (Lden) was associated with risk of stroke, with a hazard ratio (HR) of 1.06 [95% confidence interval (CI): 1.03, 1.08] per 10-dB higher 5-y mean time-weighted exposure in analyses adjusted for individual- and area-level socioeconomic covariates. The association was approximately linear and persisted after adjustment for air pollution [particulate matter (PM) with an aerodynamic diameter of ≤2.5μm (PM2.5) and NO2]. Stroke was associated with moderate levels of 5-y aircraft noise exposure (40-50 vs. ≤40 dB) (HR=1.12; 95% CI: 0.99, 1.27), but not with higher exposure (≥50 dB, HR=0.94; 95% CI: 0.79, 1.11). Railway noise was not associated with stroke.

DISCUSSION

In this pooled study, road traffic noise was associated with a higher risk of stroke. This finding supports road traffic noise as an important cardiovascular risk factor that should be included when estimating the burden of disease due to traffic noise. https://doi.org/10.1289/EHP8949.

Long-Term Exposure to Road Traffic Noise and Air Pollution, and Incident Atrial Fibrillation in the Danish Nurse Cohort

BACKGROUND

Associations between long-term exposure to air pollution and road traffic noise have been established for ischemic heart disease, but findings have been mixed for atrial fibrillation (AF).

OBJECTIVES

The goal of the study was to examine associations of long-term exposure to road traffic noise and air pollution with AF.

METHODS

Time-varying Cox regression models were used to estimate associations of 1-, 3-, and 23-y mean road traffic noise and air pollution exposures with AF incidence in 23,528 women enrolled in the Danish Nurse Cohort (age >44y at baseline in 1993 or 1999). AF diagnoses were ascertained via the Danish National Patient Register. Annual mean weighted 24-h average road traffic noise levels (Lden) at the nurses' residences, since 1970, were estimated using the Nord2000 model, and annual mean levels of particulate matter with a diameter <2.5μm (PM2.5) and nitrogen dioxide (NO2) were estimated using the DEHM/UBM/AirGIS model.

RESULTS

Of 23,528 nurses with no prior AF diagnosis at the cohort baseline, 1,522 developed AF during follow-up. In a fully adjusted model (including PM2.5), the estimated risk of AF was 18% higher [hazard ratio (HR); 95% confidence interval (CI): 1.18; 1.02, 1.36] in nurses with residential 3-y mean Lden levels >58 dB vs. <48 dB, with similar findings for 1-y mean exposures. A 3.9-μg/m3 increase in 3-y mean PM2.5 was associated with incident AF before and after adjustment for concurrent exposure to road traffic noise (HR 1.09; 95% CI: 1.00, 1.20 and 1.08; 95% CI: 0.97, 1.19, respectively). Associations with 1-y mean PM2.5 exposures were positive but closer to the null and not significant. Associations with NO2 were null for all time periods before and after adjustment for road traffic noise and inverse when adjusted for concurrent PM2.5.

CONCLUSION

Our analysis of prospective data from a cohort of Danish female nurses followed for up to 14 y provided suggestive evidence of independent associations between incident AF and 1- and 3-y exposures to road traffic noise and PM2.5. https://doi.org/10.1289/EHP8090.

Long-term exposure to air pollution and liver cancer incidence in six European cohorts

Particulate matter air pollution and diesel engine exhaust have been classified as carcinogenic for lung cancer, yet few studies have explored associations with liver cancer. We used six European adult cohorts which were recruited between 1985 and 2005, pooled within the "Effects of low-level air pollution: A study in Europe" (ELAPSE) project, and followed for the incidence of liver cancer until 2011 to 2015. The annual average exposure to nitrogen dioxide (NO₂ ), particulate matter with diameter <2.5 μm (PM_2.5 ), black carbon (BC), warm-season ozone (O₃ ), and eight elemental components of PM_2.5 (copper, iron, zinc, sulfur, nickel, vanadium, silicon, and potassium) were estimated by European-wide hybrid land-use regression models at participants' residential addresses. We analyzed the association between air pollution and liver cancer incidence by Cox proportional hazards models adjusting for potential confounders. Of 330 064 cancer-free adults at baseline, 512 developed liver cancer during a mean follow-up of 18.1 years. We observed positive linear associations between NO₂ (hazard ratio, 95% confidence interval: 1.17, 1.02-1.35 per 10 μg/m³ ), PM_2.5 (1.12, 0.92-1.36 per 5 μg/m³ ), and BC (1.15, 1.00-1.33 per 0.5 10^-5 /m) and liver cancer incidence. Associations with NO₂ and BC persisted in two-pollutant models with PM_2.5 . Most components of PM_2.5 were associated with the risk of liver cancer, with the strongest associations for sulfur and vanadium, which were robust to adjustment for PM_2.5 or NO₂ . Our study suggests that ambient air pollution may increase the risk of liver cancer, even at concentrations below current EU standards.

Long-term exposure to ambient air pollution and road traffic noise and asthma incidence in adults: The Danish Nurse cohort

BACKGROUND

Ambient air pollution is likely a risk factor for asthma, and recent evidence suggests the possible relevance of road traffic noise.

OBJECTIVES

We examined the associations of long-term exposure to air pollution and road traffic noise with adult-asthma incidence.

METHODS

We followed 28,731 female nurses (age > 44 years) from the Danish Nurse Cohort, recruited in 1993 and 1999, for first hospital contact for asthma from 1977 until 2015. We estimated residential annual mean concentrations of particulate matter with diameter < 2.5 µm (PM_2.5) since 1990 and nitrogen dioxide (NO₂) since 1970 with the Danish DEHM/UBM/AirGIS modeling system, and road traffic noise (L_den) since 1970 with the Nord2000 model. Time-varying Cox regression models were used to associate air pollution and road traffic noise exposure with asthma incidence.

RESULTS

During 18.6 years' mean follow-up, 528 out of 23,093 participants had hospital contact for asthma. The hazard ratios (HR) and 95% confidence intervals for asthma incidence associated with 3-year moving average exposures were 1.29 (1.03, 1.61) per 6.3 µg/m³ for PM_2.5, 1.16 (1.07, 1.27) per 8.2 µg/m³ for NO₂, and 1.12 (1.00, 1.25) per 10 dB for L_den. The HR for NO₂ remained unchanged after adjustment for either PM_2.5 or L_den, while the HRs for PM_2.5 and L_den attenuated to unity after adjustment for NO₂.

CONCLUSIONS

Long-term exposure to air pollution was associated with adult-asthma incidence independently of road traffic noise, with NO₂ most relevant. Road traffic noise was not independently associated with adult-asthma incidence.

Long-term air pollution and road traffic noise exposure and COPD: the Danish Nurse Cohort

BACKGROUND

While air pollution has been linked to the development of chronic obstructive pulmonary disease (COPD), evidence on the role of environmental noise is just emerging. We examined the associations of long-term exposure to air pollution and road traffic noise with COPD incidence.

METHODS

We defined COPD incidence for 24 538 female nurses from the Danish Nurse Cohort (age>44 years) as the first hospital contact between baseline (1993 or 1999) and 2015. We estimated residential annual mean concentrations of particulate matter with diameter<2.5 µm (PM_2.5) since 1990 and nitrogen dioxide (NO₂) since 1970 by the Danish DEHM/UBM/AirGIS modeling system, and road traffic noise (L_den) since 1970 by the Nord2000 model. Time-varying Cox regression models were applied to assess the associations of air pollution and road traffic noise with COPD incidence.

RESULTS

977 nurses developed COPD during 18.6 years' mean follow-up. We observed associations with COPD for all three exposures with hazard ratios (HRs) and 95% confidence intervals (CIs) of 1.19 (1.01, 1.41) per 6.26 µg·m^-3 for PM_2.5, 1.13 (1.05, 1.20) per 8.19 µg·m^-3 for NO₂, and 1.15 (1.06, 1.25) per 10 dB for L_den. Associations with NO₂ and L_den attenuated slightly after mutual adjustment, but were robust to adjustment for PM_2.5. Associations with PM_2.5 were attenuated to null after adjustment for either NO₂ or L_den. No potential interaction effect was observed between air pollutants and noise.

CONCLUSIONS

Long-term exposure to air pollution, especially traffic-related NO₂, and road traffic noise were independently associated with COPD.

Breast cancer rate after oophorectomy: A Prospective Danish Cohort Study

The association between oophorectomy and risk of breast cancer in the general population is uncertain. The aim of our study was to determine the breast cancer rate in women from the general population after oophorectomy (performed before/after menopause), and whether this varies by use of hormone replacement therapy (HRT), hysterectomy, body mass index (BMI) and shift work. The study included 24 409 female nurses (aged ≥45 years) participating in the Danish Nurse Cohort. Nurses were followed from cohort entry until date of breast cancer, death, emigration or end of follow-up at 31 December 2018, whichever came first. Poisson regression with log-transformed person-years as the offset examined the association between oophorectomy and breast cancer (all ages and stratified by menopausal status at time of oophorectomy). The potential modifying effect of HRT use, hysterectomy, BMI and shift work on the associations was estimated. During 502 463 person-years of follow-up, 1975 (8.1%) nurses were diagnosed with breast cancer. Bilateral oophorectomy was associated with a reduced breast cancer rate compared to nurses with preserved ovaries, adjusted rate ratio (95% confidence interval): 0.79 (0.64; 0.99). Similar associations (magnitude and direction) were detected for unilateral oophorectomy and when stratifying according to menopausal status at time of oophorectomy, but without statistical significance. Unilateral and bilateral oophorectomy is associated with a reduced breast cancer rate in women from the general population. This association is not modified by use of HRT, hysterectomy, BMI or shift work.

Long-term exposure to air pollution and stroke incidence: A Danish Nurse cohort study

Ambient air pollution has been linked to stroke, but few studies have examined in detail stroke subtypes and confounding by road traffic noise, which was recently associated with stroke. Here we examined the association between long-term exposure to air pollution and incidence of stroke (overall, ischemic, hemorrhagic), adjusting for road traffic noise. In a nationwide Danish Nurse Cohort consisting of 23,423 nurses, recruited in 1993 or 1999, we identified 1,078 incident cases of stroke (944 ischemic and 134 hemorrhagic) up to December 31, 2014, defined as first-ever hospital contact. The full residential address histories since 1970 were obtained for each participant and the annual means of air pollutants (particulate matter with diameter < 2.5 µm and < 10 µm (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), nitrogen oxides (NOx)) and road traffic noise were determined using validated models. Time-varying Cox regression models were used to estimate hazard ratios (HR) (95% confidence intervals (CI)) for the associations of one-, three, and 23-year running mean of air pollutants with stroke adjusting for potential confounders and noise. In fully adjusted models, the HRs (95% CI) per interquartile range increase in one-year running mean of PM_2.5 and overall, ischemic, and hemorrhagic stroke were 1.12 (1.01-1.25), 1.13 (1.01-1.26), and 1.07 (0.80-1.44), respectively, and remained unchanged after adjustment for noise. Long-term exposure to ambient PM_2.5 was associated with the risk of stroke independent of road traffic noise.

Long-Term Exposure to Air Pollution and Incidence of Myocardial Infarction: A Danish Nurse Cohort Study

BACKGROUND

Air pollution exposure has been linked to coronary heart disease, although evidence on PM2.5 and myocardial infarction (MI) incidence is mixed.

OBJECTIVES

This prospective cohort study aimed to investigate associations between long-term exposure to air pollution and MI incidence, adjusting for road traffic noise.

METHODS

We used data from the nationwide Danish Nurse Cohort on 22,882 female nurses (>44 years of age) who, at recruitment in 1993 or 1999, reported information on cardiovascular disease risk factors. Data on MI incidence was collected from the Danish National Patient Register until the end of 2014. Annual mean concentrations of particulate matter (PM) with a diameter <2.5 μg/m3 (PM2.5), PM10, nitrogen dioxide (NO2), and nitrogen oxides (NOx) at the nurses' residences since 1990 (PM10 and PM2.5) or 1970 (NO2 and NOx) were estimated using the Danish Eulerian Hemispheric Model/Urban Background Model/AirGIS (DEHM/UBM/AirGIS) dispersion model. We used time-varying Cox regression models to examine the association between 1- and 3-y running means of these pollutants, as well as 23-y running means of NO2 and NOx, with both overall and fatal incident MI. Associations were explored in three progressively adjusted models: Model 1, adjusted for age and baseline year; Model 2, with further adjustment for potential confounding by lifestyle and cardiovascular disease risk factors; and Model 3, with further adjustment for road traffic noise, modeled as the annual mean of a weighted 24-h average (Lden).

RESULTS

Of the 22,882 women, 641 developed MI during a mean follow-up of 18.6 y, 121 (18.9%) of which were fatal. Reported hazard ratios (HRs) were based on interquartile range increases of 5.3, 5.5, 8.1, and 11.5 μg/m3 for PM2.5, PM10, NO2, and NOx, respectively. In Model 1, we observed a positive association between a 3-y running mean of PM2.5 and an overall incident MI with an HR= 1.20 (95% CI: 1.07, 1.35), which attenuated to HR= 1.06 (95% CI: 0.92, 1.23) in Model 2. In Model 1 for incident fatal MI, we observed a strong association with a 3-y running mean of PM2.5, with an HR= 1.69 (95% CI: 1.33, 2.13), which attenuated to HR= 1.35 (95% CI: 1.01, 1.81) in Model 2. Similar associations were seen for PM10, with 3-y, Model 2 estimates for overall and fatal incident MI of HR= 1.06 (95% CI: 0.91, 1.23) and HR= 1.35 (95% CI: 1.01, 1.81), respectively. No evidence of an association was observed for NO2 or NOx. For all pollutants, associations in Model 2 were robust to further adjustment for road traffic noise in Model 3 and were similar for a 1-y running mean exposure.

CONCLUSIONS

We found no association between long-term exposure to PM2.5, PM10, NO2, or NOx and overall MI incidence, but we observed positive associations for PM2.5 and PM10 with fatal MI. We present novel findings that the association between PM and MI incidence is robust to adjustment for road traffic noise. https://doi.org/10.1289/EHP5818.

Long-term wind turbine noise exposure and the risk of incident atrial fibrillation in the Danish Nurse cohort

BACKGROUND

The potential health effects related to wind turbine noise (WTN) have received increased focus during the past decades, but evidence is sparse. We examined the association between long-term exposure to wind turbine noise and incidence of atrial fibrillation (AF).

METHODS

First ever hospital admission of AF amongst 28,731 female nurses in the Danish Nurse Cohort were identified in the Danish National Patient register until ultimo 2013. WTN levels at residential addresses between 1982 and 2013 were estimated using the Nord2000 noise propagation model, as the annual means of L_den, L_day, L_evening and L_night at the most exposed façade. Time-varying Cox proportional hazard regression models were used to examine the association between the 11-, 5- and 1-year rolling means of WTN levels and AF incidence.

RESULTS

1430 nurses developed AF by end of follow-up in 2013. Mean (standard deviation) baseline residential noise levels amongst exposed nurses were 26.3 (6.7) dB and slightly higher in those who developed AF (27.3 (7.31) dB), than those who didn't (26.2 (6.6)). We observed a 30% statistically significant increased risk (95% CI: 1.05-1.61) of AF amongst nurses exposed to long-term (11-year running mean) WTN levels ≥20 dB(A) at night compared to nurses exposed to levels <20 dB(A). Similar effects were observed with day (HR 1.25; 95% CI: 1.01-1.54), and evening (HR 1.25; 95% CI: 1.01-1.54) noise levels.

CONCLUSIONS

We found suggestive evidence of an association between long-term exposure to WTN and AF amongst female nurses. However, interpretation should be cautious as exposure levels were low.

Association Between Long-Term Exposure to Wind Turbine Noise and the Risk of Stroke: Data From the Danish Nurse Cohort

Background

Epidemiological studies suggest that road traffic noise increases the risk of stroke. Similar effects may be expected from wind turbine noise (WTN) exposure, but epidemiological evidence is lacking. The present study investigated the association between long‐term exposure to WTN and the risk for stroke.

Methods and Results

First‐ever stroke in 28 731 female nurses in the Danish Nurse Cohort was identified in the Danish National Patient register until the end of 2013. WTN, traffic noise, and air pollution exposures were estimated for all historic and present residential addresses between 1982 and 2013. Time‐varying Cox proportional hazard regression was used to examine the associations between the 11‐, 5‐, and 1‐year rolling means of WTN levels and stroke incidence. Of 23 912 nurses free of stroke at the cohort baseline, 1097 nurses developed stroke by the end of follow‐up. At the cohort baseline, 10.3% of nurses were exposed to WTN (≥1 turbine within a 6000‐meter radius of the residence) and 13.3% in 2013. Mean baseline residential noise levels among exposed nurses were 26.3 dB(A). No association between long‐term WTN exposure and stroke incidence was found. The adjusted hazard ratios and 95% CIs for the 11‐, 5‐, and 1‐year running mean residential WTN exposures preceding stroke diagnosis, comparing nurses with residential WTN levels above and below 20 dB(A) were 1.09 (0.90–1.31), 1.08 (0.89–1.31) and 1.08 (0.89–1.32), respectively.

Conclusions

This comprehensive cohort study lends no support to an association between long‐term WTN exposure and stroke risk.

Long-term wind turbine noise exposure and incidence of myocardial infarction in the Danish nurse cohort

BACKGROUND

Growing evidence supports the concept that traffic noise exposure leads to long-term health complications other than annoyance, including cardiovascular disease. Similar effects may be expected from wind turbine noise exposure, but evidence is sparse. Here, we examined the association between long-term exposure to wind turbine noise and incidence of myocardial infarction (MI).

METHODS

We used the Danish Nurse Cohort with 28,731 female nurses and obtained data on incidence of MI in the Danish National Patient and Causes of Death Registries until ultimo 2013. Wind turbine noise levels at residential addresses between 1982 and 2013 were estimated using the Nord2000 noise propagation model, as the annual means of a weighted 24-hour average (L_den) at the most exposed façade. Time-varying Cox proportional hazard regression was used to examine the association between the 11-, 5- and 1-year rolling means prior to MI diagnosis of wind turbine noise levels and MI incidence.

RESULTS

Of 23,994 nurses free of MI at cohort baseline, 686 developed MI by end of follow-up in 2013. At the cohort baseline (1993 or 1999), 10.4% nurses were exposed to wind turbine noise (≥1 turbine within a 6000-m radius of the residence) and 13.3% in 2013. Mean baseline residential noise levels among exposed nurses were 26.3 dB, higher in those who developed MI (26.6 dB) than among those who didn't develop MI (26.3 dB). We found no association between wind turbine noise and MI incidence: adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) comparing nurses with 11-years mean residential noise levels of <21.5 dB, 21.5-25.4 dB, 25.4-29.9 dB, and >29.9 dB, to non-exposed nurses were 0.89 (0.64-1.25), 1.20 (0.82-1.77), 1.38 (0.95-2.01), and 0.88 (0.53-1.28), respectively. Corresponding HR (95% CI) for the linear association between 11-year mean levels of wind turbine noise (per 10 dB increase) with MI incidence was 0.99 (0.77-1.28). Similar associations were observed when considering the 5- and 1-year running means, and with no evidence of dose-response.

CONCLUSIONS

The results of this comprehensive cohort study lend little support to a causal association between outdoor long-term wind-turbine noise exposure and MI. However, there were only few cases in the highest exposure groups and our findings need reproduction.

Intentional weight loss and mortality among initially healthy men and women

Most prospective observational studies suggest that weight loss increases the risk of premature death among obese individuals. This is surprising because clinical studies show that weight loss generally leads to overall improvements in cardiovascular risk factors. It is sometimes argued that the increased mortality observed with weight loss must depend on confounding or poor study designs. This review was conducted to summarize results from studies on intentional weight loss and mortality among healthy individuals, while carefully considering the designs and problems in these studies. Evaluation criteria with a rating scale were developed. Of the studies evaluated, two found decreased mortality with intentional weight loss, three found increased mortality, and four found no significant associations between intentional weight loss and total mortality. Thus, it is still not possible for health authorities to make secure recommendations on intentional weight loss. More studies designed to specifically address this issue are warranted.

A prospective study of the association between weight changes and self-rated health

Background

Obesity and self-rated health (SRH) are strong predictors of morbidity and mortality but their interrelation is sparsely studied. The aim of this study was to analyse the association between weight changes and changes in SRH among women. We also examined if poor SRH at baseline was associated with later weight gain.

Methods

The Danish Nurse Cohort Study is a prospective population study (1993–1999) and comprises 13,684 female nurses aged 44 to 69 years. Logistic regression analyses were used to examine the association between weight changes and changes in SRH.

Results

Women who gained weight during the study period had higher odds of reporting poorer self-rated health (Odds Ratio (OR): 1.18, 95% CI: 1.04–1.35). Weight loss among overweight women, did not result in an increase in self-rated health ratings, in fully adjusted analyses (0.96 (95% CI: 0.76–1.23). Poor self-rated health combined with normal weight at first examination was associated with higher odds of later weight gain (OR: 1.29, 95% CI: 1.10–1.51).

Conclusion

Weight changes may result in lower SRH. Further, poor self-rated health at baseline seems to predict an increase in weight, among women without any longstanding chronic diseases. Future obesity prevention may focus on normal weight individuals with poor SRH.

Collection of blood, saliva, and buccal cell samples in a pilot study on the Danish nurse cohort: comparison of the response rate and quality of genomic DNA

In this study, we compared the response rates of blood, saliva, and buccal cell samples in a pilot study on the Danish nurse cohort and examined the quantity and quality of the purified genomic DNA. Our data show that only 31% of the requested participants delivered a blood sample, whereas 72%, 80%, and 76% delivered a saliva sample, buccal cell sample via mouth swabs, or buccal cell sample on FTA card, respectively. Analysis of purified genomic DNA by NanoDrop and agarose gel electrophoresis revealed that blood and saliva samples resulted in DNA with the best quality, whereas the DNA quality from buccal cells was low. Genotype and PCR analysis showed that DNA from 100% of the blood samples and 72% to 84% of the saliva samples could be genotyped or amplified, whereas none of the DNA from FTA cards and only 23% of the DNA from mouth swabs could be amplified and none of the DNA from swabs and 94% of the DNA from FTA cards could be genotyped. Our study shows that the response rate of self-collection saliva samples and buccal cell samples were much higher than the response rate of blood samples in our group of Danish nurses. However, only the quality of genomic DNA from saliva samples was comparable with blood samples as accessed by purity, genotyping, and PCR amplification. We conclude that the use of saliva samples is a good alternative to blood samples to obtain genomic DNA of high quality and it will increase the response rate considerably in epidemiologic studies.