[Show abstract][Hide abstract]ABSTRACT: Background
Women have elevated rates of thyroid disease compared to men. Environmental toxicants have been implicated as contributors to this dimorphism, including polybrominated diphenyl ethers (PBDEs), flame retardant chemicals that disrupt thyroid hormone action. PBDEs have also been implicated in the disruption of estrogenic activity, and estrogen levels regulate thyroid hormones. Post-menopausal women may therefore be particularly vulnerable to PBDE induced thyroid effects, given low estrogen reserves. The objective of this study was to test for an association between serum PBDE concentrations and thyroid disease in women from the United States (U.S.), stratified by menopause status.
Serum PBDE concentrations (BDEs 47, 99, 100 and 153) from the National Health and Examination Survey (NHANES) and reports on thyroid problems were available in the NHANES 2003–2004 cycle. Odds ratios (ORs) were calculated using multivariate logistic regression models accounting for population-weighted survey techniques and controlling for age, body mass index (BMI), education, smoking, alcohol consumption and thyroid medication. Menopause status was obtained by self-reported absence of menstruation in the previous 12 months and declared menopause.
Women in the highest quartile of serum concentrations for BDEs 47, 99, and 100 had increased odds of currently having thyroid disease (ORs: 1.5, 1.8, 1.5, respectively) compared to the reference group (1st and 2nd quartiles combined); stronger associations were observed when the analysis was restricted to postmenopausal women (ORs: 2.2, 3.6, 2.0, respectively).
Exposure to BDEs 47, 99, and 100 is associated with thyroid disease in a national sample of U.S. women, with greater effects observed post-menopause, suggesting that the disruption of thyroid signaling by PBDEs may be enhanced by the altered estrogen levels during menopause.
Electronic supplementary material
The online version of this article (doi:10.1186/s12940-016-0141-0) contains supplementary material, which is available to authorized users.
Preview · Article · Dec 2016 · Environmental Health
[Show abstract][Hide abstract]ABSTRACT: Few studies have examined the broad health effects of occupational exposures in flight attendants apart from disease-specific morbidity and mortality studies. We describe the health status of flight attendants and compare it to the U.S. population. In addition, we explore whether the prevalence of major health conditions in flight attendants is associated with length of exposure to the aircraft environment using job tenure as a proxy.
We surveyed flight attendants from two domestic U.S. airlines in 2007 and compared the prevalence of their health conditions to contemporaneous cohorts in the National Health and Nutrition Survey (NHANES), 2005-2006 and 2007-2008. We weighted the prevalence of flight attendant conditions to match the age distribution in the NHANES and compared the two populations stratified by gender using the Standardized Prevalence Ratio (SPR). For leading health conditions in flight attendants, we analyzed the association between job tenure and health outcomes in logistic regression models.
Compared to the NHANES population (n =5,713), flight attendants (n = 4,011) had about a 3-fold increase in the age-adjusted prevalence of chronic bronchitis despite considerably lower levels of smoking. In addition, the prevalence of cardiac disease in female flight attendants was 3.5 times greater than the general population while their prevalence of hypertension and being overweight was significantly lower. Flight attendants reported 2 to 5.7 times more sleep disorders, depression, and fatigue, than the general population. Female flight attendants reported 34% more reproductive cancers. Health conditions that increased with longer job tenure as a flight attendant were chronic bronchitis, heart disease in females, skin cancer, hearing loss, depression and anxiety, even after adjusting for age, gender, body mass index (BMI), education, and smoking.
This study found higher rates of specific diseases in flight attendants than the general population. Longer tenure appears to explain some of the higher disease prevalence. Conclusions are limited by the cross-sectional design and recall bias. Further study is needed to determine the source of risk and to elucidate specific exposure-disease relationships over time.
Full-text · Article · Mar 2014 · Environmental Health
[Show abstract][Hide abstract]ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) are found widely in the ambient air and result from combustion of various fuels and industrial processes. PAHs have been associated with adverse human health effects such as cognitive development, childhood IQ, and respiratory health. The Fresno Asthmatic Children's Environment Study enrolled 315 children aged 6-11 years with asthma in Fresno, CA and followed the cohort from 2000 to 2008. Subjects were evaluated for asthma symptoms in up to three 14-day panels per year. Detailed ambient pollutant concentrations were collected from a central site and outdoor pollutants were measured at 83 homes for at least one 5-day period. Measurements of particle-bound PAHs were used with land-use regression models to estimate individual exposures to PAHs with 4-, 5-, or 6-member rings (PAH456) and phenanthrene for the cohort (approximately 22,000 individual daily estimates). We used a cross-validation-based algorithm for model fitting and a generalized estimated equation approach to account for repeated measures. Multiple lags and moving averages of PAH exposure were associated with increased wheeze for each of the three types of PAH exposure estimates. The odds ratios for asthmatics exposed to PAHs (ng/m(3)) ranged from 1.01 (95% CI, 1.00-1.02) to 1.10 (95% CI, 1.04-1.17). This trend for increased wheeze persisted among all PAHs measured. Phenanthrene was found to have a higher relative impact on wheeze. These data provide further evidence that PAHs contribute to asthma morbidity.
No preview · Article · May 2012 · Journal of Exposure Science and Environmental Epidemiology
[Show abstract][Hide abstract]ABSTRACT: Exposure to neighborhood factors remains difficult to quantify when neighborhoods are often predefined and imprecisely measured. This study examines the association between neighborhood deprivation and participation in a community-based asthma case management (CM) program in Oakland, CA. We estimated neighborhoods by calculating walking distances of , and miles around each child's (n=2892) residence. The model assesses deprivation by the addition of weighted factors within a child's neighborhood-crime rates, alcohol outlets, and eight 2000 US Census characteristics. The results illustrate that neighborhood deprivation is weakly associated with greater levels of program participation, but neighborhood education level, measured by percentage of residents with less than a high school education, is strongly associated with greater program participation (OR: 4.43, 95% CI: [1.23, 15.99]). Neighborhood deprivation factors were significantly different between neighborhoods defined by walking distances and census blockgroups (Wilcoxon-signed rank test: p<0.05).
[Show abstract][Hide abstract]ABSTRACT: Despite large public investments in asthma interventions, there are few rigorous assessments of these programmes and little understanding of what comprises an effective intervention. There is a lack of appropriate data, little technical support is provided, and the programs themselves have little incentive to conduct these analyses. In this study, we apply optimal full matching using propensity scores to estimate the impact of an asthma intervention programme across a range of health outcomes. Our participation model is derived using the Deletion, Substitution and Addition (DSA) algorithm, a method used in epidemiology for model selection. We find that the asthma programme in question has no significant effect on participants that distinguishes them from matched nonparticipants, but it is not clear whether this is due to the effectiveness of the programme, heterogeneity of effects or barriers outside the programme's control. Our findings do show how current programmes could be modified to increase their effectiveness and better inform future research.
No preview · Article · Jan 2011 · Applied Economics
[Show abstract][Hide abstract]ABSTRACT: THIS PAPER HAS TWO AIMS: (1) to summarize various geographic information science methods; and (2) to provide a review of studies that have employed such methods. Though not meant to be a comprehensive review, this paper explains when certain methods are useful in epidemiological studies and also serves as an overview of the growing field of spatial epidemiology.
Full-text · Article · Apr 2010 · International Journal of Environmental Research and Public Health
[Show abstract][Hide abstract]ABSTRACT: To estimate the treatment effect of participation in an asthma intervention that was part of the National Asthma Control Program.
Cross-sectional; difference in outcomes between participants and comparable nonparticipants matched by using propensity scores.
Data on children who participated in asthma case management (n = 270) and eligible children who did not participate in case management (n = 2742) were extracted from a Medicaid claims database. We constructed measures of healthcare utilization, sociodemographics, and neighborhood characteristics. After creating a comparison group similar to the participants in terms of all characteristics before participation, we estimated the effect of the program on asthma outcomes.
Participants were more likely to have vaccinations for pulmonary illness (95% confidence interval [CI] = 1.82, 4.81), to fill a prescription for controller medications (95% CI = 1.07, 2.19), and to have a refill for rescue medication (95% CI = 1.07, 2.07) after the program than comparable nonparticipants. There was no statistically significant difference in the number of nebulizer treatments or emergency department visits between the 2 groups.
The program did increase the use of preventive healthcare by participants. Over the time period we studied, these behaviors did not decrease healthcare utilization for asthma exacerbations. We were unable to discern whether the lack of effect was because of the nature of the program, heterogeneity of the effects, or barriers outside the program's control.
No preview · Article · Apr 2010 · The American journal of managed care
[Show abstract][Hide abstract]ABSTRACT: IntroductionUrban Change and Land Use as a Driving ForceConceptual and Practical Aspects of Spatial Analysis in Environmental Health GeographyEnvironmental Justice, Spatial Risk Modeling, and PlanningEmerging Methods
[Show abstract][Hide abstract]ABSTRACT: Objective: To estimate the treatment effect from participating in an asthma intervention that was part of the National Asthma Control Program.Study Setting: Data on children who participated in asthma case management (N=270) and eligible children who did not participate in case management (N=2,742) were extracted from a claims database.Study Design: We created 81 measures of health care utilization and 40 measures of neighborhood characteristics that could be related to participation in the program. The participation model was selected using the cross-validation-based Deletion Substitution and Addition (DSA) algorithm. We used optimal full matching for the vector of Mahalanobis’ distances and propensity scores to estimate the difference between participants and non-participants in the probability of a range of asthma outcomes.Principal Findings: Compared to non-participants, participants were more likely to have vaccinations for pulmonary illness, use controller medications, and have a refill for rescue medication. There was no statistically significant difference in the number of nebulizer treatments or ED visits between the two groups. We find that the asthma program had no significant effect on overall asthma controlConclusion: We are not able to discern whether the lack of an effect in overall control is due to the effectiveness of the program, heterogeneity of effects or barriers outside the program’s control. We discuss how current programs could be modified to better inform future research and program design.