Effects Of Changes In Exposure Research Articles

Psychosocial factors at work and sleep problems: a longitudinal study of the general working population in Norway

A growing number of longitudinal studies report associations between adverse psychosocial factors at work and sleep problems. However, the evidence regarding the direction of these associations and the effects of changes in exposure across time is limited. This study examined the plausibility of normal, reverse, and reciprocal associations between ten psychosocial factors at work and sleep problems. In addition, we analyzed if reduced exposure across time had the anticipated result of reducing the risk of sleep problems. Randomly drawn from the general working-age population, the cohort comprised respondents with an active employee relationship in 2009 and 2013 (N=5760). Exposures and outcome were measured on two occasions separated by 4years. We computed several sex-stratified logistic regression models with adjustments for various plausible confounders. We found support for the commonly hypothesized unidirectional forward associations between psychosocial factors at work and sleep problems among women only. Among men, psychosocial stressors at work and sleep problems were reciprocally and reversely related. Nevertheless, reduced exposure levels across time pertaining to effort-reward imbalance (OR=0.36; 95% CI=0.19-0.69) and lack of social support (OR=0.55; 95% CI=0.32-0.93) among men, and work-family imbalance (OR=0.26; 95% CI=0.15-0.46) among women were associated with a robust significant lower risk of sleep problems compared to those in the stable high exposure groups. The study results suggest that preventive measures targeting effort-reward imbalance and lack of social support among men, and work-family imbalance among women, might contribute to reduce the risk of troubled sleep among employees.

Changes in Traffic Exposure and the Risk of Incident Myocardial Infarction and All-Cause Mortality

Traffic-related exposures, such as air pollution and noise, have been associated with increased cardiovascular morbidity and mortality. Few studies, however, have been able to examine the effects of changes in exposure on changes in risk. Our objective was to explore the associations of changes in traffic exposure with changes in risk between 1990 and 2008 in the Nurses' Health Study. Incident myocardial infarction (MI) and all-cause mortality were prospectively identified. As a proxy for traffic exposure, we calculated residential distance to roads at all residential addresses 1986-2006 and considered addresses to be "close" or "far" based on distance and road type. To examine the effect of changes in exposure, each consecutive pair of addresses was categorized as: (1) consistently close, (2) consistently far, (3) change from close to far, and (4) change from far to close. We also examined the change in NO2 levels between address pairs. In time-varying Cox proportional hazards models adjusted for a variety of risk factors, women living at residences consistently close to traffic were at a higher risk of an incident MI (hazard ratio [HR] = 1.11; 95% confidence interval [CI] = 1.01-1.22) and a higher risk of all-cause mortality (1.05; 1.00-1.10), compared with those consistently far. The highest risks were seen among women who moved from being far from traffic to close (incident MI: HR = 1.50 [95% CI = 1.11-2.03]; all-cause mortality: HR = 1.17 [95% CI = 1.00-1.37]). Each 1 ppb increase in NO2 compared with the previous address was associated with a HR = 1.22 for incident MI (95% CI = 0.99-1.50) and 1.03 for all-cause mortality (95% CI = 0.92-1.15). Our results suggest that changes in traffic exposure (measured as roadway proximity or change in NO2 levels) are associated with changes in risk of MI and all-cause mortality.

Annoyance responses to stable and changing aircraft noise exposure

This article reports the two extensive aircraft noise annoyance surveys subsequently carried out among residents in the vicinity of Zurich Airport in 2001 and 2003 in order to update and validate existing exposure-effect relationships for aircraft noise and annoyance in Switzerland. Logistic and polynomial approximations of the exposure-annoyance relationships for both the years 2001 and 2003 are presented for the L(dn), L(den), and L(A,eq24) noise metrics. The results confirm other recently published international research and provide further evidence that community annoyance due to aircraft noise has increased over the past decades. Between the two survey years, a considerable amount of early morning and late evening flight operations have been relocated to use an other runway than before; thus both the effects of a recent step decrease and recent step increase on the exposure-annoyance relationship could be investigated. Residents that experienced a step increase elicited a quite pronounced over-reaction of annoyance which correlated with the magnitude of the change. Two logistic regression models are provided to forecast the effects of changes in exposure during shoulder hours in the early morning and the late evening.

Time‐space trends in cancer incidence in The Netherlands in 1989–2003

Incidence of cancer may vary within a country and over time because of previous differences in exposure to risk factors or interventions for early detection (screening). This study describes time-space trends of incidence of common cancer sites across the Netherlands during the period 1989-2003 and speculates on the reasons for the observations. From the Netherlands Cancer Registry, World standardized incidence rates per municipality were smoothed calculating weighted averages for each 2 km by 2 km grid of the population mid-points of neighbouring municipalities and presented as map animations. Spatial relative changes in incidence were estimated by comparing the periods 1989-1994 and 1998-2003. Complete time-space trends can be found as map animations on http://maps.ikcnet.nl. The incidence of cervical and stomach cancer (for both sexes) decreased, being higher in the cities than in the rural areas during all periods and contrasting the trends in colorectal and breast cancer. The relative increase in incidence of lung cancer among females was highest in the rural north, but the incidence remained higher in the cities of the mid-west Netherlands. For males, there was a marked decrease in lung cancer incidence across the country since 1991. Incidence of melanoma increased, rates being twice as high in the coastal area than in the cities. Prostate cancer maps largely replicated the known history of PSA-testing in the Netherlands. Time-space cancer incidence patterns gave insight into effects of changes in exposure to risk determinants and early detection. The maps illustrate marked potential for cancer prevention at the national and regional level.

The Effect of Dose and Timing of Dose on the Association between Airborne Particles and Survival

BackgroundUnderstanding the shape of the concentration–response curve for particles is important for public health, and lack of such understanding was recently cited by U.S. Environmental Protection Agency (EPA) as a reason for not tightening the standards. Similarly, the delay between changes in exposure and changes in health is also important in public health decision making. We addressed these issues using an extended follow-up of the Harvard Six Cities Study.MethodsCox proportional hazards models were fit controlling for smoking, body mass index, and other covariates. Two approaches were used. First, we used penalized splines, which fit a flexible functional form to the concentration response to examine its shape, and chose the degrees of freedom for the curve based on Akaike’s information criterion. Because the uncertainties around the resultant curve do not reflect the uncertainty in model choice, we also used model averaging as an alternative approach, where multiple models are fit explicitly and averaged, weighted by their probability of being correct given the data. We examined the lag relationship by model averaging across a range of unconstrained distributed lag models.ResultsWe found that the concentration–response curve is linear, clearly continuing below the current U.S. standard of 15 μg/m3, and that the effects of changes in exposure on mortality are seen within two years.ConclusionsReduction in particle concentrations below U.S. EPA standards would increase life expectancy.

Acute Air Pollution Effects: Consequences of Exposure Distribution and Measurements

Acute effect air pollution studies estimate the effect of short-term change in exposure on a health outcome. The two designs most commonly used in air pollution epidemiology are panel studies and time-series studies. Typically, both designs rely on ambient concentration measurements and not the personal exposures of individuals. This article discusses how panel studies and time-series studies are related and reviews the use of ambient concentrations versus personal exposure measurements in the analyses. This work suggests that for estimating acute effects, ambient concentration measurements are quite adequate in time-series studies. In addition, time-series studies have ample power relative to panel studies, in spite of the ecologic nature of their design. Panel studies have the benefit of being able to use all the information from personal exposures in the analysis, but they are much more costly and difficult to conduct. Furthermore, nontraditional panel studies, where multiple repeat panels are followed over time, require additional considerations in the analysis.

Time trends and occupational risk factors for pleural mesothelioma in Sweden.

Epidemiologic data on pleural mesothelioma are scarce on regional and occupational time trends, which would monitor the effects of changes in exposure to asbestos. We aim to characterize time trends, regional, socioeconomic, and occupational risk factors for pleural mesothelioma in Sweden in the years from 1961 to 1998. The Swedish Family-Cancer Database was used to identify patients with pleural mesothelioma. Age-standardized incidence rates and standardized incidence ratio (SIR) were calculated for the population in the Database. A total of 1298 male and 233 female pleural mesotheliomas were retrieved. Age-standardized incidence of the disease was highest, and the trend increased in residents of large industrial and shipbuilding cities. In the last follow-up period, the male rate exceeded the female rate about 10-fold. Among male socioeconomic groups, manual workers showed the highest and ever-increasing SIR. No female socioeconomic group was at risk. For men, plumbers and seamen had the highest risk of 4.56 and 2.83, respectively, but the risks appeared to be decreasing for plumbers, whereas no clear trend was noted for seamen, probably because of indirect expose in ships. Farmers showed an SIR of 0.28, indicating that the population at large was at four times higher risk than farmers. The SIRs of many academic/college-educated groups were two to six times higher than those of farmers, suggesting indirect exposure to asbestos in these groups.

Design and analysis of studies of the health effects of ozone.

The design and analysis of studies that investigate the effect of exposure to ozone on health outcomes need to define carefully the methods for the assessment of the exposure and to determine precisely which is the outcome of biological relevance. The estimation of sample size for longitudinal studies requires the expected rates of change among the exposed and unexposed, the variance of the outcome, and the correlation of measurements taken within an individual. Methods of analysis whose primary interest is in the combination of cross-sectional studies for the determination of the marginal distribution of the outcome are particularly appropriate for biological processes where the effect of exposure is acute. Conditional models are particularly useful for investigating the effect of changes in exposure on changes in outcome at the individual level. In addition, conditional models incorporate a dampening effect of exposure that may provide a reasonable agreement with several biological mechanisms. The identification of susceptible individuals and the description of the behavior of their outcomes over time may be better accomplished by using the within-individual variance as the outcome of interest. Discrepancies of the within- and between-individual regressions may be suggestive of chronic effects, and methodological research in this area is needed. Studies of the health effects of ozone exposure need to address the incorporation of missing data, measurement error, and the combination of complementary studies.