Cardiovascular Disease Incidence and Cardiovascular Health Among Diverse Women With Breast and Gynecologic Cancers

OBJECTIVES

To examine if racial differences in cardiovascular health (CVH) are associated with cardiovascular disease (CVD) disparities among women with breast and gynecologic cancers.

SAMPLE & SETTING

The sample consisted of 252 Black women and 93 White women without a self-reported history of cancer or CVD who developed a breast or gynecologic malignancy. Women who developed CVD before their cancer diagnosis were excluded.

METHODS & VARIABLES

CVH was classified using metrics of the American Heart Association's Life's Simple 7 framework. Metrics were summed to create a total CVH score (0-7). Associations among race, ideal CVH (score of 5-7), and CVD incidence following cancer diagnosis were estimated with Cox proportional hazards models.

RESULTS

Ideal CVH was similar between Black women (33%) and White women (37%). Race and CVH were not associated with CVD incidence.

IMPLICATIONS FOR NURSING

In a small sample of women diagnosed with breast and gynecologic cancers, racial disparities in CVH and CVD incidence were not observed. Additional investigation of potential confounders relating to social determinants of health tied to the construct of race is warranted.

Seminar: Scalable Preprocessing Tools for Exposomic Data Analysis

BACKGROUND

The exposome serves as a popular framework in which to study exposures from chemical and nonchemical stressors across the life course and the differing roles that these exposures can play in human health. As a result, data relevant to the exposome have been used as a resource in the quest to untangle complicated health trajectories and help connect the dots from exposures to adverse outcome pathways.

OBJECTIVES

The primary aim of this methods seminar is to clarify and review preprocessing techniques critical for accurate and effective external exposomic data analysis. Scalability is emphasized through an application of highly innovative combinatorial techniques coupled with more traditional statistical strategies. The Public Health Exposome is used as an archetypical model. The novelty and innovation of this seminar's focus stem from its methodical, comprehensive treatment of preprocessing and its demonstration of the positive effects preprocessing can have on downstream analytics.

DISCUSSION

State-of-the-art technologies are described for data harmonization and to mitigate noise, which can stymie downstream interpretation, and to select key exposomic features, without which analytics may lose focus. A main task is the reduction of multicollinearity, a particularly formidable problem that frequently arises from repeated measurements of similar events taken at various times and from multiple sources. Empirical results highlight the effectiveness of a carefully planned preprocessing workflow as demonstrated in the context of more highly concentrated variable lists, improved correlational distributions, and enhanced downstream analytics for latent relationship discovery. The nascent field of exposome science can be characterized by the need to analyze and interpret a complex confluence of highly inhomogeneous spatial and temporal data, which may present formidable challenges to even the most powerful analytical tools. A systematic approach to preprocessing can therefore provide an essential first step in the application of modern computer and data science methods. https://doi.org/10.1289/EHP12901.

A scoping review of the concept of resilience among African American women

Resilience, thriving in the face of adversity, is a critical component of well-being in African American women. However, traditional definitions and approaches to operationalize resilience may not capture race- and gender-related resilience experiences of African American women. A more complete conceptualization of resilience may help facilitate future investigation of the mechanisms through which resilience influences health in this group. Our team conducted a scoping review of the literature published during twenty years, between 2000 and 2019, on resilience and health in African American women. We included a multidisciplinary set of databases (PubMed, CINAHL, PsycINFO, Scopus, Social Work Abstracts, Sociological Abstracts, Academic Search Premier). Using Covidence software a multi-step review process was conducted; 904 abstracts were initially screened for eligibility, 219 full-text studies were screened in stage two, and 22 remaining studies were reviewed for extraction. The studies reviewed revealed limitations of unidimensional approaches to conceptualizing/operationalizing resilience in African American women. The review highlighted culturally-relevant components of resilience including spirituality/religion, strength, survival, active coping, and social support. Findings highlight the importance of operationalizing resilience as a multidimensional construct so it can be optimally included in research designed to investigate the quality of life, cardiovascular risk, and other health outcomes in African American women.

The Modifying Role of Resilience on Allostatic Load and Cardiovascular Disease Risk in the Jackson Heart Study

We examined whether resilience modified associations between allostatic load (AL), a physiological indicator of coping with repeated stressors, and cardiovascular disease (CVD) among 2758 African Americans in the Jackson Heart Study. Baseline AL was quantified using biological measures of metabolic, cardiovascular, and immune markers. We constructed a multidimensional resilience measure using validated questionnaires for social support, social networks, religious experiences, and optimism. Participants were followed until 2016 for stroke, coronary heart disease (CHD), and heart failure (HF). We used multivariable-adjusted, sex-stratified Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between dichotomous AL and CVD. High AL was associated with CHD among women (HR = 1.73, 95% CI = 1.00, 2.99) and HF among women (HR = 1.52, 95% CI = 0.98, 2.37) and men (HR = 2.17, 95% CI = 1.28, 3.68). Among women, resilience did not modify the AL-CVD relationship. Among men, we observed higher stroke risk among men with low resilience (HR = 2.21, 95% CI = 0.94, 5.22) and no association among those with high resilience. Counterintuitively, high AL was associated with greater HF (HR = 5.80, 95% CI = 2.32, 14.47) in the subgroup of men with high resilience. Future studies addressing different facets of resilience are needed to elucidate underlying mechanisms for CVD prevention among African Americans.

The association between cardiovascular disease and breast and gynecologic cancers among black female patients

INTRODUCTION

Little is known about whether a breast or gynecologic cancer diagnosis increases long-term cardiovascular disease (CVD) risk among Black females. The purpose of this study was to determine whether a breast or gynecologic cancer diagnosis is associated with CVD risk and identify determinants of subsequent CVD risk among Black females with an incident breast or gynecologic cancer diagnosis.

METHODS

Using the Southern Community Cohort Study data from 2002-2016, this study was designed to analyze CVD incidence among Black females without cancer or CVD at enrollment. Cox proportional hazards regression models with or without covariates were used to explore the relationship between a breast or gynecologic cancer diagnosis and CVD risk among women without cancer as well as without CVD at enrollment (N=11,486). In addition, Cox proportional hazards regression models, excluding those who developed CVD before breast and gynecologic cancer diagnosis and those with other types of cancers, were used to assess determinants of CVD risk among breast and gynecologic cancer survivors.

RESULTS

Of 11,486 Black females, 531 developed a breast or gynecological cancer (4.6%) over a median follow-up of 140 months (interquartile range: 123-159 months). Compared to women without cancer, women with a breast or gynecological cancers had greater than 20% higher risk of incident CVD during the follow-up period. Without adjusting for covariates, positive association between CVD risk and breast cancer was observed (hazard ratio (HR) = 1.24; 95% confidence interval (CI) = 1.11 - 1.39; p < 0.001); as well as between CVD risk and a gynecological cancer (HR = 1.23; 95% CI = 1.03 - 1.46; p = 0.021). Yet, after adjusting for covariates, CVD risk was only significantly associated with breast cancer (p = 0.001) but not gynecologic cancer. In cancer case-only analyses, CVD risk was significantly increasing with age (p < 0.05).

CONCLUSIONS

Like study populations of predominantly White females, our results suggest that, adjusting for covariates, Black females possess a higher risk of CVD following a breast cancer diagnosis compared to women who did not develop breast cancer. Our results suggest a need for active CVD surveillance in the cancer survivorship phase.

A Framework for Interfacing and Partnering with Environmental Justice Communities as a Prelude to Human Health and Hazard Identification in the Vulnerable Census Tracts of Columbus, Ohio

Columbus, Ohio is one of the more prosperous, well-educated, and progressive cities in the United States. However, it ranks as the second worst life expectancy at birth, has a census tract wealth gap (27-year disparity), and one of the higher infant mortality rates in the country. These data suggest that there are likely several high-risk, vulnerable neighborhoods in Columbus with residents experiencing disparate and adverse outcomes. Illustrative of this fact are studies that have examined the social processes and mechanisms through which neighborhood contexts are at the forefront, including exposures to chemical stressors such as particulate matter (PM_2.5) as well as non-chemical stressors including violence, social determinants of health, zoning, and land use policies. It is documented that disparate and adverse outcomes are magnified in the vulnerable neighborhoods on the Near East Side as compared to Columbus city proper, Franklin County and/or the state of Ohio. As such, we developed a nuanced community engagement framework to identify potential environmental hazards associated with adverse pregnancy outcomes in those census tracts. The refined framework uses a blended version of traditional community-based participatory research (CBPR) models and is referred to as E⁶, Enhancing Environmental Endeavors via e-Equity, Education, and Empowerment.

Big Data to Knowledge Analytics Reveals the Zika Virus Epidemic as Only One of Multiple Factors Contributing to a Year-Over-Year 28-Fold Increase in Microcephaly Incidence

During the 2015-2016 Zika Virus (ZIKV) epidemic in Brazil, the geographical distributions of ZIKV infection and microcephaly outbreaks did not align. This raised doubts about the virus as the single cause of the microcephaly outbreak and led to research hypotheses of alternative explanatory factors, such as environmental variables and factors, agrochemical use, or immunizations. We investigated context and the intermediate and structural determinants of health inequalities, as well as social environment factors, to determine their interaction with ZIKV-positive- and ZIKV-negative-related microcephaly. The results revealed the identification of 382 associations among 382 nonredundant variables of Zika surveillance, including multiple determinants of environmental public health factors and variables obtained from 5565 municipalities in Brazil. This study compared those factors and variables directly associated with microcephaly incidence positive to ZIKV and those associated with microcephaly incidence negative to ZIKV, respectively, and mapped them in case and control subnetworks. The subnetworks of factors and variables associated with low birth weight and birthweight where birth incidence served as an additional control were also mapped. Non-significant differences in factors and variables were observed, as were weights of associations between microcephaly incidence, both positive and negative to ZIKV, which revealed diagnostic inaccuracies that translated to the underestimation of the scope of the ZIKV outbreak. A detailed analysis of the patterns of association does not support a finding that vaccinations contributed to microcephaly, but it does raise concerns about the use of agrochemicals as a potential factor in the observed neurotoxicity arising from the presence of heavy metals in the environment and microcephaly not associated with ZIKV. Summary: A comparative network inferential analysis of the patterns of variables and factors associated with Zika virus infections in Brazil during 2015-2016 coinciding with a microcephaly epidemic identified multiple contributing determinants. This study advances our understanding of the cumulative interactive effects of exposures to chemical and non-chemical stressors in the built, natural, physical, and social environments on adverse pregnancy and health outcomes in vulnerable populations.

Structural and Social Determinants of Health Factors Associated with County-Level Variation in Non-Adherence to Antihypertensive Medication Treatment

Background: Non-adherence to antihypertensive medication treatment (AHM) is a complex health behavior with determinants that extend beyond the individual patient. The structural and social determinants of health (SDH) that predispose populations to ill health and unhealthy behaviors could be potential barriers to long-term adherence to AHM. However, the role of SDH in AHM non-adherence has been understudied. Therefore, we aimed to define and identify the SDH factors associated with non-adherence to AHM and to quantify the variation in county-level non-adherence to AHM explained by these factors. Methods: Two cross-sectional datasets, the Centers for Disease Control and Prevention (CDC) Atlas of Heart Disease and Stroke (2014–2016 cycle) and the 2016 County Health Rankings (CHR), were linked to create an analytic dataset. Contextual SDH variables were extracted from the CDC-CHR linked dataset. County-level prevalence of AHM non-adherence, based on Medicare fee-for-service beneficiaries’ claims data, was extracted from the CDC Atlas dataset. The CDC measured AHM non-adherence as the proportion of days covered (PDC) with AHM during a 365 day period for Medicare Part D beneficiaries and aggregated these measures at the county level. We applied confirmatory factor analysis (CFA) to identify the constructs of social determinants of AHM non-adherence. AHM non-adherence variation and its social determinants were measured with structural equation models. Results: Among 3000 counties in the U.S., the weighted mean prevalence of AHM non-adherence (PDC < 80%) in 2015 was 25.0%, with a standard deviation (SD) of 18.8%. AHM non-adherence was directly associated with poverty/food insecurity (β = 0.31, P-value < 0.001) and weak social supports (β = 0.27, P-value < 0.001), but inversely with healthy built environment (β = −0.10, P-value = 0.02). These three constructs explained one-third (R² = 30.0%) of the variation in county-level AHM non-adherence. Conclusion: AHM non-adherence varies by geographical location, one-third of which is explained by contextual SDH factors including poverty/food insecurity, weak social supports and healthy built environments.

Use of an Exposome Approach to Understand the Effects of Exposures From the Natural, Built, and Social Environments on Cardio-Vascular Disease Onset, Progression, and Outcomes

Obesity, diabetes, and hypertension have increased by epidemic proportions in recent years among African Americans in comparison to Whites resulting in significant adverse cardiovascular disease (CVD) disparities. Today, African Americans are 30% more likely to die of heart disease than Whites and twice as likely to have a stroke. The causes of these disparities are not yet well-understood. Improved methods for identifying underlying risk factors is a critical first step toward reducing Black:White CVD disparities. This article will focus on environmental exposures in the external environment and how they can lead to changes at the cellular, molecular, and organ level to increase the personal risk for CVD and lead to population level CVD racial disparities. The external environment is defined in three broad domains: natural (air, water, land), built (places you live, work, and play) and social (social, demographic, economic, and political). We will describe how environmental exposures in the natural, built, and social environments "get under the skin" to affect gene expression though epigenetic, pan-omics, and related mechanisms that lead to increased risk for adverse CVD health outcomes and population level disparities. We also will examine the important role of metabolomics, proteomics, transcriptomics, genomics, and epigenomics in understanding how exposures in the natural, built, and social environments lead to CVD disparities with implications for clinical, public health, and policy interventions. In this review, we apply an exposome approach to Black:White CVD racial disparities. The exposome is a measure of all the exposures of an individual across the life course and the relationship of those exposures to health effects. The exposome represents the totality of exogenous (external) and endogenous (internal) exposures from conception onwards, simultaneously distinguishing, characterizing, and quantifying etiologic, mediating, moderating, and co-occurring risk and protective factors and their relationship to disease. Specifically, it assesses the biological mechanisms and underlying pathways through which chemical and non-chemical environmental exposures are associated with CVD onset, progression and outcomes. The exposome is a promising approach for understanding the complex relationships among environment, behavior, biology, genetics, and disease phenotypes that underlie population level, Black: White CVD disparities.

The Health Opportunity Index: Understanding the Input to Disparate Health Outcomes in Vulnerable and High-Risk Census Tracts

The Health Opportunity Index (HOI) is a multivariate tool that can be more efficiently used to identify and understand the interplay of complex social determinants of health (SDH) at the census tract level that influences the ability to achieve optimal health. The derivation of the HOI utilizes the data-reduction technique of principal component analysis to determine the impact of SDH on optimal health at lower census geographies. In the midst of persistent health disparities and the present COVID-19 pandemic, we demonstrate the potential utility of using 13-input variables to derive a composite metric of health (HOI) score as a means to assist in the identification of the most vulnerable communities during the current pandemic. Using GIS mapping technology, health opportunity indices were layered by counties in Ohio to highlight differences by census tract. Collectively we demonstrate that our HOI framework, principal component analysis and convergence analysis methodology coalesce to provide results supporting the utility of this framework in the three largest counties in Ohio: Franklin (Columbus), Cuyahoga (Cleveland), and Hamilton (Cincinnati). The results in this study identified census tracts that were also synonymous with communities that were at risk for disparate COVID-19 related health outcomes. In this regard, convergence analyses facilitated identification of census tracts where different disparate health outcomes co-exist at the worst levels. Our results suggest that effective use of the HOI composite score and subcomponent scores to identify specific SDH can guide mitigation/intervention practices, thus creating the potential for better targeting of mitigation and intervention strategies for vulnerable communities, such as during the current pandemic.

The Effects of Social, Personal, and Behavioral Risk Factors and PM2.5 on Cardio-Metabolic Disparities in a Cohort of Community Health Center Patients

(1) Background: Cardio-metabolic diseases (CMD), including cardiovascular disease, stroke, and diabetes, have numerous common individual and environmental risk factors. Yet, few studies to date have considered how these multiple risk factors together affect CMD disparities between Blacks and Whites. (2) Methods: We linked daily fine particulate matter (PM2.5) measures with survey responses of participants in the Southern Community Cohort Study (SCCS). Generalized linear mixed modeling (GLMM) was used to estimate the relationship between CMD risk and social-demographic characteristics, behavioral and personal risk factors, and exposure levels of PM2.5. (3) Results: The study resulted in four key findings: (1) PM2.5 concentration level was significantly associated with reported CMD, with risk rising by 2.6% for each µg/m3 increase in PM2.5; (2) race did not predict CMD risk when clinical, lifestyle, and environmental risk factors were accounted for; (3) a significant variation of CMD risk was found among participants across states; and (4) multiple personal, clinical, and social-demographic and environmental risk factors played a role in predicting CMD occurrence. (4) Conclusions: Disparities in CMD risk among low social status populations reflect the complex interactions of exposures and cumulative risks for CMD contributed by different personal and environmental factors from natural, built, and social environments.

Stress, Resilience, and Cardiovascular Disease Risk Among Black Women

BACKGROUND

Empirical data on the link between stress and cardiovascular disease (CVD) risk among black women is limited. We examined associations of stressful life events and social strain with incident CVD among black women and tested for effect modification by resilience.

METHODS AND RESULTS

Our analysis included 10 785 black women enrolled in the Women's Health Initiative Observational Study and Clinical Trials cohort. Participants were followed for CVD for up to 23 years (mean, 12.5). Multivariable Cox regression was used to estimate hazard ratios and 95% CIs for associations between stress-related exposures and incident CVD. We included interactions between follow-up time (age) and stressful life events because of evidence of nonproportional hazards. Effect modification by resilience was examined in the sub-cohort of 2765 women with resilience and stressful life events measures. Higher stressful life events were associated with incident CVD at ages 55 (hazard ratio for highest versus lowest quartile=1.80; 95% CI, 1.27-2.54) and 65 (hazard ratio for highest versus lowest quartile=1.40; 95% CI, 1.16-1.68), but not at older ages. Adjustment for CVD risk factors attenuated these associations. Similar associations were observed for social strain. In the sub-cohort of women with updated stressful life events and resilience measures, higher stressful life events were associated with incident CVD in multivariable-adjusted models (hazard ratio=1.61; 95% CI, 1.04-2.51). Resilience did not modify this association nor was resilience independently associated with incident CVD.

CONCLUSIONS

In this cohort of older black women, recent reports of stressful life events were related to incident CVD. Resilience was unrelated to incident CVD.

CLINICAL TRIALS REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT00000611.

Allostatic load in the association of depressive symptoms with incident coronary heart disease: The Jackson Heart Study

African Americans are at heightened risk for coronary heart disease (CHD), with biologic pathways poorly understood. We examined the role of allostatic load (AL) in the association of depressive symptoms with incident CHD among 2,670 African American men and women in the prospective Jackson Heart Study. Depressive symptoms were quantified using the Center for Epidemiologic Studies Depression Scale (CES-D). Incident CHD was ascertained by self-report, death certificate survey, and adjudicated medical record surveillance. Baseline AL was quantified using biologic parameters of metabolic, cardiovascular, immune, and neuroendocrine subsystems and as a combined meta-factor. Sequential models adjusted for demographic, socioeconomic, and behavioral covariates, stratified to examine differences by sex. Greater depressive symptomatology was associated with greater metabolic, cardiovascular, and immune AL (p-values≤0.036) and AL meta-factor z-scores (p = 0.007), with findings driven by observations among females. Each 1-point increase in baseline depressive symptomatology, and 1-SD increase in metabolic AL, neuroendocrine AL, and AL meta-factor z-scores was associated with 3.3%, 88%, 39%, and 130% increases in CHD risk, respectively (p-values <0.001). Neuroendocrine AL and AL meta-factor scores predicted incident CHD among males but not females in stratified analyses. Metabolic AL partially mediated the association of depressive symptoms with incident CHD (5.79% mediation, p = 0.044), a finding present among females (p = 0.016) but not males (p = 0.840). Among African American adults, we present novel findings of an association between depressive symptomatology and incident CHD, partially mediated by metabolic AL. These findings appear to be unique to females, an important consideration in the design of targeted interventions for CHD prevention.

Application of the Public Health Exposome Framework to Estimate Phenotypes of Resilience in a Model Ohio African-American Women's Cohort

We report integration of the United States Environmental Protection Agency's (USEPA) United States Environmental Justice Screen (EJSCREEN) database with our Public Health Exposome dataset to interrogate 9232 census blocks to model the complexity of relationships among environmental and socio-demographic variables toward estimating adverse pregnancy outcomes [low birth weight (LBW) and pre-term birth (PTB)] in all Ohio counties. Using a hill-climbing algorithm in R software, we derived a Bayesian network that mapped all controlled associations among all variables available by applying a mapping algorithm. The results revealed 17 environmental and socio-demographic variables that were represented by nodes containing 69 links accounting for a network with 32.85% density and average degree of 9.2 showing the most connected nodes in the center of the model. The model predicts that the socio-economic variables low income, minority, and under age five populations are correlated and associated with the environmental variables; particulate matter (PM_2.5) level in air, proximity to risk management facilities, and proximity to direct discharges in water are linked to PTB and LBW in 88 Ohio counties. The methodology used to derive significant associations of chemical and non-chemical stressors linked to PTB and LBW from indices of geo-coded environmental neighborhood deprivation serves as a proxy for design of an African-American women's cohort to be recruited in Ohio counties from federally qualified community health centers within the 9232 census blocks. The results have implications for the development of severity scores for endo-phenotypes of resilience based on associations and linkages for different chemical and non-chemical stressors that have been shown to moderate cardio-metabolic disease within a population health context.

Abstract P317: Area Traffic Density Contributes to the Risk of Gestational Diabetes in a Sample of Central Ohio Pregnancies

Background: The prevalence of gestational diabetes mellitus (GDM) in the US and the state of Ohio is approximately 9.0%. GDM is associated with increased risks for mother and child, including macrosomia, preterm birth, preeclampsia, and development of type 2 diabetes. In addition to known risk factors, the role of exposure to environmental pollutants in development of GDM warrants further investigation. Because exposure to traffic-related pollutants has been shown to influence the development of type 2 diabetes, we assessed the contribution of exposure to high traffic to the development of GDM during pregnancy among women without prior diabetes history.

Methods: A population of 275 pregnant women in Ohio reported perceived exposure to high traffic areas and health behaviors. Clinical information and addresses were obtained through their electronic health records. Using ArcMap TM 10.2.2 (ESRI), addresses were geocoded to assess individual exposures, and linked with area exposures and demographic indicators at the level of the census block group from EJScreen (EPA). A woman was classified as “near” a major roadway if one fell within a 500m buffer of her home. Distance to nearest major roadway was also calculated. Logistic regression was used to examine the association between quintiles of traffic exposure at the census block group level, self-reported proximity, individual-level proximity, health behaviors, and demographic factors with development of GDM. Because assessment of individual-level exposures may be difficult to use in clinical and large scale population settings, a model was also fit using only data publically available from EJScreen and self-report.

Results: The prevalence of GDM was 8.0% (22/275) and distribution of demographics factors were similar between those with and without GDM. After adjustment for potential confounders, quintile of traffic exposure was significantly associated with development of GDM (p=.036). Compared to those residing in block groups in the lowest quintile, the odds of GDM for those in the second quintile were 8.1 times greater [95% CI 1.2, 56.3] and for those in fourth quintile were 10.4 times greater [95% CI 1.6, 67.6]. Addition of individual-level proximity factors did not significantly improve the model (p=.08).

Conclusions: This study suggests that living in an area with high traffic density contributes to the risk of developing GDM. For both the clinical practitioner and public health researcher it is difficult or impractical to obtain individual level environmental exposure data. From our analysis, the individually calculated exposure proxies did not significantly improve the fit of the model. We suggest examining ways to combine self-report measures with existing environmental data, such as EJScreen, to identify populations at elevated risk.

Active Use of Electronic Health Records (EHRs) and Personal Health Records (PHRs) for Epidemiologic Research: Sample Representativeness and Nonresponse Bias in a Study of Women During Pregnancy

Introduction:

With the growing use of electronic medical records, electronic health records (EHRs), and personal health records (PHRs) for health care delivery, new opportunities have arisen for population health researchers. Our objective was to characterize PHR users and examine sample representativeness and nonresponse bias in a study of pregnant women recruited via the PHR.

Design:

Demographic characteristics were examined for PHR users and nonusers. Enrolled study participants (responders, n=187) were then compared with nonresponders and a representative sample of the target population.

Results:

PHR patient portal users (34 percent of eligible persons) were older and more likely to be White, have private health insurance, and develop gestational diabetes than nonusers. Of eligible persons (all PHR users), 11 percent (187/1,713) completed a self-administered PHR based questionnaire. Participants in the research study were more likely to be non-Hispanic White (90 percent versus 79 percent) and married (85 percent versus 77 percent), and were less likely to be Non-Hispanic Black (3 percent versus 12 percent) or Hispanic (3 percent versus 6 percent). Responders and nonresponders were similar regarding age distribution, employment status, and health insurance status. Demographic characteristics were similar between responders and nonresponders.

Discussion:

Demographic characteristics of the study population differed from the general population, consistent with patterns seen in traditional population-based studies. The PHR may be an efficient method for recruiting and conducting observational research with additional benefits of efficiency and cost-cost-effectiveness.

A novel approach to analyzing lung cancer mortality disparities: Using the exposome and a graph-theoretical toolchain

OBJECTIVES

The aim is to identify exposures associated with lung cancer mortality and mortality disparities by race and gender using an exposome database coupled to a graph theoretical toolchain.

METHODS

Graph theoretical algorithms were employed to extract paracliques from correlation graphs using associations between 2162 environmental exposures and lung cancer mortality rates in 2067 counties, with clique doubling applied to compute an absolute threshold of significance. Factor analysis and multiple linear regressions then were used to analyze differences in exposures associated with lung cancer mortality and mortality disparities by race and gender.

RESULTS

While cigarette consumption was highly correlated with rates of lung cancer mortality for both white men and women, previously unidentified novel exposures were more closely associated with lung cancer mortality and mortality disparities for blacks, particularly black women.

CONCLUSIONS

Exposures beyond smoking moderate lung cancer mortality and mortality disparities by race and gender.

POLICY IMPLICATIONS

An exposome approach and database coupled with scalable combinatorial analytics provides a powerful new approach for analyzing relationships between multiple environmental exposures, pathways and health outcomes. An assessment of multiple exposures is needed to appropriately translate research findings into environmental public health practice and policy.

Validation of research trajectory 1 of an Exposome framework: Exposure to benzo(a)pyrene confers enhanced susceptibility to bacterial infection

The exposome provides a framework for understanding elucidation of an uncharacterized molecular mechanism conferring enhanced susceptibility of macrophage membranes to bacterial infection after exposure to the environmental contaminant benzo(a)pyrene, [B(a)P]. The fundamental requirement in activation of macrophage effector functions is the binding of immunoglobulins to Fc receptors. FcγRIIa (CD32a), a member of the Fc family of immunoreceptors with low affinity for immunoglobulin G, has been reported to bind preferentially to IgG within lipid rafts. Previous research suggested that exposure to B(a)P suppressed macrophage effector functions but the molecular mechanisms remain elusive. The goal of this study was to elucidate the mechanism(s) of B(a)P-exposure induced suppression of macrophage function by examining the resultant effects of exposure-induced insult on CD32-lipid raft interactions in the regulation of IgG binding to CD32. The results demonstrate that exposure of macrophages to B(a)P alters lipid raft integrity by decreasing membrane cholesterol 25% while increasing CD32 into non-lipid raft fractions. This robust diminution in membrane cholesterol and 30% exclusion of CD32 from lipid rafts causes a significant reduction in CD32-mediated IgG binding to suppress essential macrophage effector functions. Such exposures across the lifespan would have the potential to induce immunosuppressive endophenotypes in vulnerable populations.

Application of Citizen Science Risk Communication Tools in a Vulnerable Urban Community

A public participatory geographical information systems (PPGIS) demographic, environmental, socioeconomic, health status portal was developed for the Stambaugh-Elwood (SE) community in Columbus, OH. We hypothesized that soil at SE residences would have metal concentrations above natural background levels. Three aims were developed that allowed testing of this hypothesis. Aim 1 focused on establishing partnerships between academia, state agencies and communities to assist in the development of a community voice. Aim 2 was to design and conduct soil sampling for residents of the SE community. Aim 3 was to utilize our interactive, customized portal as a risk communication tool by allowing residents to educate themselves as to the potential risks from industrial sources in close proximity to their community. Multiple comparisons of means were used to determine differences in soil element concentration by sampling location at p < 0.05. The results demonstrated that eight metals (As, Cd, Cu, Pb, Mo, Se, Tl, Zn) occurred at statistically-significantly greater levels than natural background levels, but most were below risk-based residential soil screening levels. Results were conveyed to residents via an educational, risk-communication informational card. This study demonstrates that community-led coalitions in collaboration with academic teams and state agencies can effectively address environmental concerns.

Revealing Behavioral Learning Deficit Phenotypes Subsequent to In Utero Exposure to Benzo(a)pyrene

To characterize behavioral deficits in pre-adolescent offspring exposed in utero to Benzo(a)pyrene [B(a)P], timed-pregnant Long Evans Hooded rats were treated with B(a)P (150, 300, 600, and 1200 µg/kg BW) or peanut oil (vehicle) on E14, 15, 16, and 17. Following birth, during the pre-weaning period, B(a)P metabolites were examined in plasma and whole brain or cerebral cortex from exposed and control offspring. Tissue concentrations of B(a)P metabolites were (1) dose-dependent and (2) followed a time-dependence for elimination with ∼60% reduction by PND5 in the 1200 µg/kg BW experimental group. Spatial discrimination-reversal learning was utilized to evaluate potential behavioral neurotoxicity in P40-P60 offspring. Late-adolescent offspring exposed in utero to 600 and 1200 µg/kg BW were indistinguishable from their control counterparts for ability to acquire an original discrimination (OD) and reach criterion. However, a dose-dependent effect of in utero B(a)P-exposure was evident upon a discrimination reversal as exposed offspring perseverated on the previously correct response. This newly characterized behavioral deficit phenotype for the first reversal was not apparent in either the (1) OD or (2) subsequent reversal sessions relative to the respective control offspring. Furthermore, the expression of activity related-cytoskeletal-associated protein (Arc), an experience-dependent cortical protein marker known to be up-regulated in response to acquisition of a novel behavior, was greater in B(a)P-exposed offspring included in the spatial discrimination cohort versus home cage controls. Collectively, these findings support the hypothesis that in utero exposure to B(a)P during critical windows of development representing peak periods of neurogenesis results in behavioral deficits in later life.

Altered expression of histone deacetylases, inflammatory cytokines and contractile-associated factors in uterine myometrium of Long Evans rats gestationally exposed to benzo[a]pyrene

Etiology of preterm birth (PTB) is multifactorial; therefore, decreasing the incidence of PTB is a major challenge in the field of obstetrics. Epidemiological studies have reported an association between toxicants and PTB. However, there are no studies on the role of benzo[a]pyrene (BaP), an environmental toxicant, in the incidence of PTB. We first assessed the effects of BaP (150 and 300 µg kg(-1) body weight) dosed via gavage from day 14 to 17 of pregnancy on gestation length in Long Evans rats. We further assessed the histopathology of the uterus, expression of inflammatory cytokines, contractile-associated factors, histone deacetylases (HDACs) and NFқB-p65 in myometrium collected on day 22 postpartum versus vehicle-treated controls. In our study, rats exposed to BaP delivered prematurely (P < 0.05) compared to control. Hematoxylin and eosin staining of uterus showed squamous metaplasia, glandular and stromal hyperplasia in BaP-exposed rats versus control. The concentrations of BaP metabolites measured by high-pressure liquid chromatography were higher in uterine myometrium of BaP-exposed rats while they were undetectable in controls. Quantitative real-time polymerase chain reaction showed significant increases in mRNA expression of interleukin-1β and -8, tumor necrosis factor-α, connexin 43, cyclo-oxygenase-2 and prostaglandin F2α receptor as compared to controls (P < 0.05). Western blot analysis revealed that BaP exposure caused decreases in class I HDACs 1 and 3 and increases in class II HDAC 5, cyclo-oxygenase-2 and nuclear translocation of NFκB-p65 relative to controls. Our results suggest that gestational exposure to BaP increases incidence of PTB through epigenetic changes that causes increases in the expression of contractile-associated factors through the NFκB pathway. Copyright © 2015 John Wiley & Sons, Ltd.

The public health exposome: a population-based, exposure science approach to health disparities research

The lack of progress in reducing health disparities suggests that new approaches are needed if we are to achieve meaningful, equitable, and lasting reductions. Current scientific paradigms do not adequately capture the complexity of the relationships between environment, personal health and population level disparities. The public health exposome is presented as a universal exposure tracking framework for integrating complex relationships between exogenous and endogenous exposures across the lifespan from conception to death. It uses a social-ecological framework that builds on the exposome paradigm for conceptualizing how exogenous exposures "get under the skin". The public health exposome approach has led our team to develop a taxonomy and bioinformatics infrastructure to integrate health outcomes data with thousands of sources of exogenous exposure, organized in four broad domains: natural, built, social, and policy environments. With the input of a transdisciplinary team, we have borrowed and applied the methods, tools and terms from various disciplines to measure the effects of environmental exposures on personal and population health outcomes and disparities, many of which may not manifest until many years later. As is customary with a paradigm shift, this approach has far reaching implications for research methods and design, analytics, community engagement strategies, and research training.

Scalable combinatorial tools for health disparities research

Despite staggering investments made in unraveling the human genome, current estimates suggest that as much as 90% of the variance in cancer and chronic diseases can be attributed to factors outside an individual’s genetic endowment, particularly to environmental exposures experienced across his or her life course. New analytical approaches are clearly required as investigators turn to complicated systems theory and ecological, place-based and life-history perspectives in order to understand more clearly the relationships between social determinants, environmental exposures and health disparities. While traditional data analysis techniques remain foundational to health disparities research, they are easily overwhelmed by the ever-increasing size and heterogeneity of available data needed to illuminate latent gene x environment interactions. This has prompted the adaptation and application of scalable combinatorial methods, many from genome science research, to the study of population health. Most of these powerful tools are algorithmically sophisticated, highly automated and mathematically abstract. Their utility motivates the main theme of this paper, which is to describe real applications of innovative transdisciplinary models and analyses in an effort to help move the research community closer toward identifying the causal mechanisms and associated environmental contexts underlying health disparities. The public health exposome is used as a contemporary focus for addressing the complex nature of this subject.

Influence of dietary fat type on benzo(a)pyrene [B(a)P] biotransformation in a B(a)P-induced mouse model of colon cancer

In the US alone, around 60,000 lives/year are lost due to colon cancer. Diet and environment have been implicated in the development of sporadic colon tumors. The objective of this study was to determine how dietary fat potentiates the development of colon tumors through altered B(a)P biotransformation, using the Adenomatous polyposis coli with Multiple intestinal neoplasia mouse model. Benzo(a)pyrene was administered to mice through tricaprylin, and unsaturated (USF; peanut oil) and saturated (SF; coconut oil) fats at doses of 50 and 100 μg/kg via oral gavage over a 60-day period. Blood, colon, and liver were collected at the end of exposure period. The expression of B(a)P biotransformation enzymes [cytochrome P450 (CYP)1A1, CYP1B1 and glutathione-S-transferase] in liver and colon were assayed at the level of protein, mRNA and activities. Plasma and tissue samples were analyzed by reverse phase high-performance liquid chromatography for B(a)P metabolites. Additionally, DNA isolated from colon and liver tissues was analyzed for B(a)P-induced DNA adducts by the (32)P-postlabeling method using a thin-layer chromatography system. Benzo(a)pyrene exposure through dietary fat altered its metabolic fate in a dose-dependent manner, with 100 μg/kg dose group registering an elevated expression of B(a)P biotransformation enzymes, and greater concentration of B(a)P metabolites, compared to the 50 μg/kg dose group (P<.05). This effect was more pronounced for SF group compared to USF group (P<.05). These findings establish that SF causes sustained induction of B(a)P biotransformation enzymes and extensive metabolism of this toxicant. As a consequence, B(a)P metabolites were generated to a greater extent in colon and liver, whose concentrations also registered a dose-dependent increase. These metabolites were found to bind with DNA and form B(a)P-DNA adducts, which may have contributed to colon tumors in a subchronic exposure regimen.

Analysis of an environmental exposure health questionnaire in a metropolitan minority population utilizing logistic regression and Support Vector Machines

The goal of this study was to analyze a 54-item instrument for assessment of perception of exposure to environmental contaminants within the context of the built environment, or exposome. This exposome was defined in five domains to include 1) home and hobby, 2) school, 3) community, 4) occupation, and 5) exposure history. Interviews were conducted with child-bearing-age minority women at Metro Nashville General Hospital at Meharry Medical College. Data were analyzed utilizing DTReg software for Support Vector Machine (SVM) modeling followed by an SPSS package for a logistic regression model. The target (outcome) variable of interest was respondent's residence by ZIP code. The results demonstrate that the rank order of important variables with respect to SVM modeling versus traditional logistic regression models is almost identical. This is the first study documenting that SVM analysis has discriminate power for determination of higher-ordered spatial relationships on an environmental exposure history questionnaire.

In utero exposure to benzo(a)pyrene predisposes offspring to cardiovascular dysfunction in later-life

In utero exposure of the fetus to benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon, is thought to dysregulate cardiovascular development. To investigate the effects of in utero B(a)P exposure on cardiovascular development, timed-pregnant Long Evans Hooded (LEH) rats were exposed to diluent or B(a)P (150, 300, 600 and 1200 μg/kg/BW) by oral gavage on embryonic (E) days E14 (the metamorphosing embryo stage) through E17 (the 1st fetal stage). There were no significant effects of in utero exposure to B(a)P on the number of pups born per litter or in pre-weaning growth curves. Pre-weaning profiles for B(a)P metabolite generation from cardiovascular tissue were shown to be dose-dependent and elimination of these metabolites was shown to be time-dependent in exposed offspring. Systolic blood pressure on postnatal day P53 in the middle and high exposure groups of offspring were significantly elevated as compared to controls. Microarray and quantitative real-time PCR results were directly relevant to a biological process pathway in animal models for "regulation of blood pressure". Microarray and quantitative real-time PCR analysis revealed upregulation of mRNA expression for angiotensin (AngII), angiotensinogen (AGT) and endothelial nitric oxide synthase (eNOS) in exposed offspring. Biological network analysis and gene set enrichment analysis subsequently identified potential signaling mechanisms and molecular pathways that might explain the elevated systolic blood pressures observed in B(a)P-exposed offspring. Our findings suggest that in utero exposure to B(a)P predispose offspring to functional deficits in cardiovascular development that may contribute to cardiovascular dysfunction in later life.

PAH particles perturb prenatal processes and phenotypes: protection from deficits in object discrimination afforded by dampening of brain oxidoreductase following in utero exposure to inhaled benzo(a)pyrene

The wild-type (WT) Cpr(lox/lox) (cytochrome P(450) oxidoreductase, Cpr) mouse is an ideal model to assess the contribution of P(450) enzymes to the metabolic activation and disposition of environmental xenobiotics. In the present study, we examined the effect of in utero exposure to benzo(a)pyrene [B(a)P] aerosol on Sp4 and N-methyl-D-aspartate (NMDA)-dependent systems as well as a resulting behavioral phenotype (object discrimination) in Cpr offspring. Results from in utero exposure of WT Cpr(lox/lox) mice were compared with in utero exposed brain-Cpr-null offspring mice. Null mice were used as they do not express brain cytochrome P(450)1B1-associated NADPH oxidoreductase (CYP1B1-associated NADPH oxidoreductase), thus reducing their capacity to produce neural B(a)P metabolites. Subsequent to in utero (E14-E17) exposure to B(a)P (100 μg/m(3)), Cpr(lox/lox) offspring exhibited: (1) elevated B(a)P metabolite and F(2)-isoprostane neocortical tissue burdens, (2) elevated concentrations of cortical glutamate, (3) premature developmental expression of Sp4, (4) decreased subunit ratios of NR2B:NR2A, and (5) deficits in a novelty discrimination phenotype monitored to in utero exposed brain-Cpr-null offspring. Collectively, these findings suggest that in situ generation of metabolites by CYP1B1-associated NADPH oxidoreductase promotes negative effects on NMDA-mediated signaling processes during the period when synapses are first forming as well as effects on a subsequent behavioral phenotype.

Prenatal polycyclic aromatic hydrocarbon exposure leads to behavioral deficits and downregulation of receptor tyrosine kinase, MET

Gene by environment interactions (G × E) are thought to underlie neurodevelopmental disorder, etiology, neurodegenerative disorders, including the multiple forms of autism spectrum disorder. However, there is limited biological information, indicating an interaction between specific genes and environmental components. The present study focuses on a major component of airborne pollutants, polycyclic aromatic hydrocarbons (PAHs), such as benzo(a)pyrene [B(a)P], which negatively impacts cognitive development in children who have been exposed in utero. In our study, prenatal exposure of Cpr(lox/lox) timed-pregnant dams to B(a)P (0, 150, 300, and 600 μg/kg body weight via oral gavage) on embryonic day (E14-E17) consistent with our susceptibility-exposure paradigm was combined with the analysis of a replicated autism risk gene, the receptor tyrosine kinase, Met. The results demonstrate a dose-dependent increase in B(a)P metabolite generation in B(a)P-exposed Cpr(lox/lox) offspring. Additionally, a sustained persistence of hydroxy metabolites during the onset of synapse formation was noted, corresponding to the peak of Met expression. Prenatal B(a)P exposure also downregulated Met RNA and protein levels and dysregulated normal temporal patterns of expression during synaptogenesis. Consistent with these data, transcriptional cell-based assays demonstrated that B(a)P exposure directly reduces human MET promoter activity. Furthermore, a functional readout of in utero B(a)P exposure showed a robust reduction in novel object discrimination in B(a)P-exposed Cpr(lox/lox) offspring. These results confirm the notion that common pollutants, such as the PAH B(a)P, can have a direct negative impact on the regulated developmental expression of an autism risk gene with associated negative behavioral learning and memory outcomes.

Blueprint for communicating risk and preventing environmental injustice

Toxic environmental emissions have the potential to harm already susceptible populations living in close proximity to industries with pollutant emissions such as coal-fired electrical power plants. The organized dissemination of information in communities that find themselves susceptible to occupation by industries with pollutant emissions is a crucial step in the long and arduous process of preventing such harm. Here, we present a blueprint that can be used by community organizations to prevent industries that pollute the environment from locating in communities that are already disproportionately exposed to pollution (referred to here as environmental justice communities). We base this blueprint on a specific case in Taylor County, Florida, where the steps outlined successfully prevented the Taylor Energy Center (TEC) consortium from obtaining the necessary permits for the operation of a proposed coal-fired electrical power plant, thereby minimizing the risks of additional toxicant exposure to the affected community.

Abstract 3448: Synergistic effect of benzo(a)pyrene (BaP) and dietary fat on biotransformation enzymes, DNA adducts and colon tumors in ApcMin mice

Studies in our laboratory thus far have shown formation of colon tumors in ApcMin mice subsequent to ingestion of fat containing BaP, an environmental carcinogen. These findings have human health relevance in that around 60,000 lives/year are lost to colon cancer in US alone. Diet and environment have been implicated in the development of sporadic colon tumors. Since biotransformation of toxicants is one of the factors that trigger carcinogenesis, the objective of this study was to determine how dietary fat potentiates the development of colon tumors through altered BaP biotransformation, using the ApcMin mouse model. Benzo(a)pyrene was administered to ApcMin mice in unsaturated- (peanut oil) and saturated- (coconut oil) fats at doses of 50 and 100 μg/kg via oral gavage over a 60-day period. Blood, colon and liver were collected at the end of exposure period. The expression of BaP biotransformation enzymes (CYP1A1, CYP1B1 and GST) in liver and colon were assayed at the level of mRNA and activities. Tissue samples were analyzed by reverse phase-HPLC for BaP metabolites, and 32P-postlabeling method for BaP- DNA adducts. BaP exposure through dietary fat altered its biotransformation in a dose-dependent manner, with 100 μg/kg dose group registering an elevated expression of BaP biotransformation enzymes, greater concentration of BaP metabolites, BaP-DNA adducts and more adenomas compared to the 50 μg/kg dose group (p &lt; 0.05). This effect was more pronounced for saturated fat group compared to unsaturated fat group (p &lt; 0.05). These findings establish that saturated fat contributes to sustained induction of BaP biotransformation enzymes and extensive metabolism of this carcinogen. As a consequence, the reactive metabolites such as epoxides and quinones generated in colon bind with DNA, and form adducts resulting in colon tumors in a long term exposure situation (funded by NIH grants S11ES014156, 1F31ES017391-01, 5T32 HL007735-14 and RO3CA130112-01).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3448.

Dietary fat-influenced development of colon neoplasia in Apc Min mice exposed to benzo(a)pyrene

Colorectal cancer, responsible for 50,000 deaths per year, is a contributing factor for considerable mortalities in the United States. Consumption of well-done red meat and saturated fats rich in polycyclic aromatic hydrocarbons may be one of the causative factors for sporadic colon cancer. The objective of this study was to investigate whether the formation of colon tumors in adult Apc(Min) mice was influenced by the ingestion of different types of fat containing benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon compound. Treatment consisted of 50 and 100 microg B(a)P/kg body weight dissolved in peanut or coconut oil (representatives of unsaturated and saturated fats, respectively) administered daily to six-week-old male Apc(Min) mice via oral gavage for sixty days. At the end of exposure, mice were sacrificed; jejunum and colons were retrieved and preserved in 10% formalin for observation for gross pathological changes. An increased prevalence of adenomas in colons of mice that ingested B(a)P through saturated dietary fat compared to unsaturated fat and controls (p < .05) was noticed. Interestingly, we also observed adenomas with high-grade dysplasia in the B(a)P + saturated fat group, and these incidences were frequent at the 100 microg/kg B(a)P dose. On the other hand, the B(a)P-alone and unsaturated-fat groups did not show significant differences in the numbers of adenomas and invasive tumors in the both jejunum and the colon. Our studies established that dietary fat, especially saturated fat, potentiates the development of colon tumors caused by B(a)P in the Apc(Min) mouse.

Vehicle-dependent disposition kinetics of fluoranthene in Fisher-344 rats

The objective of this study was to evaluate how the vehicles of choice affect the pharmacokinetics of orally administered Fluoranthene [FLA] in rats. Fluoranthene is a member of the family of polycyclic aromatic hydrocarbon chemicals. Fluoranthene exposure to humans may occur as a result of cigarette smoking, consumption of contaminated food and water, heating woods in stoves and boilers, industrial sources such as coal gasification, carbon and graphite electrode manufacturing. Adult male Fisher-344 rats were given single oral doses of 25 and 50 μg/kg FLA in tricaprylin, peanut oil, cod liver oil, tween 80/isotonic saline (1:5) and 2% Alkamuls-EL620 through gavage. After administration, the rats were housed individually in metabolic cages and sacrificed at 2, 4, 6, 8, 10 and 12 hours post FLA exposure. Blood, lung, liver, small intestine, adipose tissue samples, urine, and feces were collected at each time point. Samples were subjected to a liquid-liquid extraction using methanol, chloroform, and water. The extracts were analyzed by a reverse-phase HPLC, equipped with a fluorescence detector. The results revealed a dose-dependent increase in FLA concentrations in plasma and tissues for all the vehicles used. Plasma and tissue FLA concentrations were greater for peanut oil; cod liver oil, and tricaprylin vehicles compared to Alkamuls (p < 0.05), and tween 80/isotonic saline (1:5). Most of the FLA administered through peanut oil, cod liver oil and tricaprylin was cleared from the body by 8 hours (90%) and 12 hours (80%) post administration for the 25 μg/kg and 50 μg/kg dose groups, respectively. With both doses employed, the metabolism of FLA was highest when cod liver oil was used as a vehicle and lowest in vehicles containing detergent/water [cod liver oil > peanut oil > tricaprylin > alkamuls > tween 80/isotonic saline (1:5)]. These findings suggest that uptake and elimination of FLA is accelerated when administered through oil-based vehicles. The low uptake of FLA from alkamuls and tween 80/isotonic saline may have been a result of the poor solubility of the chemical. In summary, our findings reiterate that absorption characteristics of FLA were governed by the dose as well as the dosing vehicle. The vehicle-dependent bioavailability of FLA suggests a need for the judicious selection of vehicles in evaluating oral toxicity studies for risk assessment purposes.

Down-regulation of early ionotrophic glutamate receptor subunit developmental expression as a mechanism for observed plasticity deficits following gestational exposure to benzo(a)pyrene

The focus of this study was to characterize the impact of gestational exposure to benzo(a)pyrene [B(a)P] on modulation of glutamate receptor subunit expression that is critical for the maintenance of synaptic plasticity mechanisms during hippocampal or cortical development in offspring. Previous studies have demonstrated that hippocampal and/or cortical synaptic plasticity (as measured by long-term potentiation and S1-cortex spontaneous/evoked neuronal activity) and learning behavior (as measured by fixed-ratio performance operant testing) is significantly impaired in polycyclic aromatic or halogenated aromatic hydrocarbon-exposed offspring as compared to controls. These previous studies have also revealed that brain to body weight ratios are greater in exposed offspring relative to controls indicative of intrauterine growth retardation which has been shown to manifest as low birth weight in offspring. Recent epidemiological studies have identified an effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons on neurodevelopment in the first 3 years of life among inner-city children [Perera FP, Rauh V, Whyatt RM, Tsai WY, Tang D, Diaz D, et al. Effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons on neurodevelopment in the first 3 years of life among inner-city children. Environ Health Perspect 2006;114:1287-92]. The present study utilizes a well-characterized animal model to test the hypothesis that gestational exposure to B(a)P causes dysregulation of developmental ionotropic glutamate receptor subunit expression, namely the N-methyl-d-aspartate receptor (NMDAR) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptor (AMPAR) both critical to the expression of synaptic plasticity mechanisms. To mechanistically ascertain the basis of B(a)P-induced plasticity perturbations, timed pregnant Long-Evans rats were exposed in an oral subacute exposure regimen to 0, 25 and 150mug/kg BW B(a)P on gestation days 14-17. The first sub-hypothesis tested whether gestational exposure to B(a)P would result in significant disposition in offspring. The second sub-hypothesis tested whether gestational exposure to B(a)P would result in down-regulation of early developmental expression of NMDA and AMPA receptor subunits in the hippocampus of offspring as well as in primary neuronal cultures. The results of these studies revealed significant: (1) disposition to the hippocampus and cortex, (2) down-regulation of developmental glutamate receptor mRNA and protein subunit expression and (3) voltage-dependent decreases in the amplitude of inward currents at negative potentials in B(a)P-treated cortical neuronal membranes. These results suggest that plasticity and behavioral deficits produced as a result of gestational B(a)P exposure are at least, in part, a result of down-regulation of early developmental glutamate receptor subunit expression and function at a time when excitatory synapses are being formed for the first time in the developing central nervous system. The results also predict that in B(a)P-exposed offspring with reduced early glutamate receptor subunit expression, a parallel deficit in behaviors that depend on normal hippocampal or cortical functioning will be observed and that these deficits will be present throughout life.

Gestational 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure effects on sensory cortex function

Gestational exposure to environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) poses a significant threat to normal growth and differentiation of the developing brain. To characterize the impact of gestational TCDD exposure on subsequent cortical function, pregnant Long Evans rats were exposed to a single acute dose (100 or 700ng/kg b.w. via gavage) on gestational day 15. This dosing regimen had no significant effect on birth index. After the TCDD-exposed animals were born and reached maturity, neural activity was recorded under urethane anesthesia from neurons in primary somatic sensory cortex. Spontaneous activity was reduced by approximately 50% in barrel cortex compared to corn oil vehicle controls. The magnitude of neuronal response to sensory (whisker) stimuli also was significantly reduced, and responses did not achieve control levels at any stimulus intensity. The greatest deficit was in the short latency component of the cortical responses. These decrements in cortical responsiveness were present in young F1 generation TCDD-exposed animals and persisted for up to 180 days. Because glutamate receptors are crucial to the evoked responses and show developmental regulation, selected iontotropic glutamate receptor subunits (NMDA NR2A+NR2B and GluR1) were profiled for RNA levels in the cortex of F1 generation rats. The expression of NR2B (NMDA receptor) and GluR1 (AMPA receptor) subunits was significantly reduced in the TCDD-exposed F1 generation animals compared to vehicle controls. The results indicate that gestational TCDD exposure results in cortical deficits that are paralled by diminished expression of certain NMDA and AMPA receptor subunits at a time when synapses are being formed for the first time in cortex.

Bioavailability and risk assessment of orally ingested polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. These chemicals commonly enter the human body through inhalation of cigarette smoke or consumption of contaminated food. Of these two pathways, dietary intake of PAHs constitutes a major source of exposure in humans. Although many reviews and books on PAHs have been published, factors affecting the accumulation of PAHs in the diet, their absorption following ingestion, and strategies to assess risk from exposure to these hydrocarbons following ingestion have received much less attention. This review, therefore, focuses on concentrations of PAHs in widely consumed dietary ingredients along with gastrointestinal absorption rates in humans. Metabolism and bioavailability of PAHs in animal models and the processes, which influence the disposition of these chemicals, are discussed. The utilitarian value of structure and metabolism in predicting PAH toxicity and carcinogenesis is also emphasized. Finally, based on intake, disposition, and tumorigenesis data, the exposure risk to PAHs from diet, and contaminated soil is presented. This information is expected to provide a framework for refinements in risk assessment of PAHs from a multimedia exposure perspective.

Inhaled benzo(a)pyrene impairs long-term potentiation in the F1 generation rat dentate gyrus

The purpose of this study is to provide a point of reference regarding the neurotoxic effects resulting from exposure to environmental contaminants. Benzo(a)pyrene is a member of the polycyclic aromatic hydrocarbon (PAH) family and it is a by-product of combustion processes. Thus, persons living near factories or hazardous waste sites face the danger of exposure through contact with contaminated air, water and soil. In an effort to understand the impact of environmental contaminants, we have investigated the effects of gestational B(a)P aerosol exposure on long-term potentiation (LTP), a cellular correlate of learning and memory in the F1 generation. Briefly, timed-pregnant rats were exposed to B(a)P via nose-only inhalation on gestation days 11-21 for 4 hr per day. Dams were maintained to term and pups were weaned on postnatal day 30. Subsequent electrophysiological studies during postnatal days 60-70 revealed a diminution in LTP across the perforant path-granular cells synapses in the hippocampus of F1 generation animals that were transplacentally exposed to B(a)P aerosol relative to unexposed controls. Additionally, NMDA receptor subunit 1 (NR1) protein was found to be downregulated in the hippocampus of B(a)P exposed F1 generation animals. Taken together, our results suggest that gestational exposure to B(a)P aerosol attenuates the capacity for LTP in the F1 generation.

Disruption of testicular steroidogenesis and epididymal function by inhaled benzo(a)pyrene

The objective of this study was to evaluate the effect of sub-acute exposure to inhaled benzo(a)pyrene (BaP) on testicular steroidogenesis and epididymal function in Fisher 344 rats. Animals were assigned randomly to two control groups and one experimental group for each exposure regimen. Treatment consisted of sub-acute exposure of rats via inhalation to 25, 75, and 100 microg BaP/m(3), 4 h daily for 10 days. Control animals were either exposed to carbon black (CB; sham) to control for inert BaP carrier or they remained unexposed (UNC). Blood samples were collected immediately after the cessation of exposures (time 0) and at 24, 48, and 72 h post-cessation of exposure, to assess the effect of bioavailable BaP on systemic testosterone and luteinizing hormone (LH) concentrations by radioimmunoassay (RIA). Progressive sperm motility of stored sperm (cauda epididymal sperm) was determined microscopically, while density of stored sperm was determined by hemocytometric counting. Progressive motility of stored sperm was reduced in rats exposed to 75 and 100 microg BaP/m(3) compared with their counterparts that were exposed to 25 microg BaP/m(3) or controls. Plasma testosterone concentrations declined as a result of exposure of rats to 75 microg BaP/m(3) from 0 to 48 h post-termination of exposure compared with controls (P<0.05; treatment x time interaction). This decrease was followed subsequently by a compensatory increase in the plasma concentrations of this steroid at 72 h post-cessation of exposures compared with previous time periods and controls (P<0.05). Increases in the mean plasma LH concentrations were observed in rats exposed to 75 microg BaP/m(3) compared with controls, throughout the time periods studied (P<0.05; treatment x time interaction). These data suggest that sub-acute exposure to inhaled BaP contributes to reduced testosterone concentrations and consequently impaired epididymal function of exposed animals.

Environmental contaminant-mixture effects on CNS development, plasticity, and behavior

Environmental contaminants within the polycyclic aromatic hydrocarbon (PAH) and halogenated aromatic hydrocarbon class have been shown to cross the placenta exposing the fetus to the contaminant body burden of the mother. Consequently, a gestational exposure to environmental contaminants may result in increased adverse health outcomes, possibly affecting cognitive performance. Benzo(a)pyrene [B(a)P] and 2,3,7,8, tetrachlorodibenzo-p-dioxin (TCDD) are two prototypical environmental contaminants. A systematic review of the literature suggests that there may be a relationship between vulnerability in susceptible populations and health disparities. The purpose of this mini-review is to provide a point of reference for neurotoxicological studies of environmental contaminant mixture effects on indices of development in general, and on neurodevelopment in particular. Environmental contaminant-mixture-induced decrements in (1) birth index, (2) N-methyl-D-aspartate receptor (NMDA) mRNA expression, (3) long-term potentiation (LTP), (4) fixed-ratio performance learning behavior, and (5) experience-dependent activity related cytoskeletal-associated protein (Arc) mRNA and protein expression collectively support associations between neurobehavioral deficits and gestational exposure to environmental levels of these contaminants. Collectively, data are presented in this mini-review evaluating the effect of gestational exposure to environmental contaminant-mixtures on specific indices of learning and memory, including hippocampal-based synaptic plasticity mechanisms. These indices serve as templates for learning and memory, and as such, from a vulnerability perspective, may serve as targets for dysregulation during development in susceptible populations that have been disproportionately exposed to these contaminants. Included in this review is also a discussion of the relevance of developing biomarkers for use within the framework of cumulative risk-assessment.

Downregulation of hippocampal NMDA receptor expression by prenatal exposure to dioxin

Gestational exposure to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) has been implicated as causative to disparities between ethnic groups with respect to learning disabilities. Dioxin is an extremely toxic environmental pollutant that bioaccumulates in maternal adipose tissue, and is transferred to the developing organism during gestation and lactation. Long-term cognitive deficits have been reported following prenatal exposure to dioxin. N-methyl-D-aspartate (NMDA) receptors in the central nervous system (CNS) have been well known to play an important role in the activity-dependent synaptic plasticity underlying learning and memory and in CNS development including brain cell differentiation. Here, the effects of prenatal exposure to dioxin on the developmental expression profiles of rat hippocampal NMDA receptor subtype 1 mRNA and protein was examined. F-344 rats were exposed to 0 and 700 ng of dioxin/kg on gestational day 15. Real-time PCR and Western blot analysis clearly revealed that dioxin significantly downregulated NMDAR1 mRNA and protein expression during the first postnatal month. The study provides support to the hypothesis that NMDA receptors are important targets for dioxin-induced neurotoxicity in F1 preweaning pups. The results also support the concept that prenatal exposure to dioxin may contribute to the pathogenesis of diseases in the adult.

Assessment of metabolites and AhR and CYP1A1 mRNA expression subsequent to prenatal exposure to inhaled benzo(a)pyrene

Few studies have focused on environmental aerosol contaminant, mechanistically-based, dose-related neurotoxicity with respect to development of the central nervous system. To fill this important data gap and to highlight possible mechanistic pathways, a study was undertaken to determine metabolite concentrations associated with the transplacental disposition of inhaled benzo(a)pyrene (B(a)P) and the resulting effects on the status of aryl hydrocarbon receptor (AhR), and cytochrome P450 1A1 (CYP1A1) mRNA in preweaning F1 generation animals. In this study, laparotomy on GD 8 was performed on timed-pregnant rats followed by dosing via nose-only exposure for 4h a day for 10 days (GD 11-GD 20) to three concentrations of a B(a)P: carbon black aerosol (25, 75 and 100 microg/m(3)). A dose-dependent decrease in birth index was observed in the B(a)P exposed group as compared to the controls (P<0.05). Analysis of cerebrocortical extracts from F1 generation pups revealed a dose-dependent (P<0.05) increase in total B(a)P metabolites. Analysis of cerebrocortical and hippocampal mRNA developmental expression profiles for AhR and CYP1A1 using 18sRNA as the internal standard, revealed that inhaled B(a)P upregulates AhR during the first postnatal month. The present study suggest that prenatal exposure to inhaled B(a)P upregulates hepatic aryl hydrocarbon receptor dependent mechanisms in the F1 generation. Hepatic upregulation of the aryl hydrocarbon receptor may modulate the potential for benzo(a)pyrene toxicity via the activation of cytochrome P450 and the subsequent deposition of lipophillic metabolites to developing central nervous system structures such as cerebral cortex and hippocampus.

Alteration of pregnancy related hormones and fetal survival in F-344 rats exposed by inhalation to benzo(a)pyrene

The objective of this study was to evaluate the effect of subacute exposure to inhaled benzo(a)pyrene (BaP) on fetal survival and luteal maintenance using timed-pregnant Fisher 344 rats. Prior to assignment of pregnant rats to treatment and control groups, numbers of implantation sites were determined on gestation day (GD) 8 via midventral laparotomy. Subsequently, animals were assigned randomly to three treatment groups and two control groups. Treatment consisted of subacute exposure of rats via inhalation to BaP 25, 75, and 100 micro g/m(3), 4h daily for 10 days (GD-11-20). Control animals were either sham exposed to carbon black (CB) to control for inert BaP carrier or remained unexposed (UNC). Blood samples were collected on days 15 and 17 of gestation via sinus orbital veini-puncture for plasma. Number of pups per litter was determined postpartum and fetal survival rate was expressed as a percentage of the corresponding implantation sites. Radioimmunoassays were used to determine plasma progesterone, estrogen, and prolactin (indirect measurement of decidual luteotropin) concentrations. Fetal survival among BaP-treated rats declined in a dose-dependent manner (25 micro g/m(3), 78.3% per litter; 75 micro g/m(3), 38.0% per litter; 100 micro g/m(3), 33.8% per litter; P<0.05) compared with CB (96.7% per litter) and UNC (98.9% per litter). Plasma progesterone, estrogen, and prolactin concentrations also declined as a result of subacute exposure of rats to BaP compared to controls. These data suggest that inhaled BaP compromised fetal survival and consequently luteotropic activity in the exposed animals.

Transplacental effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the temporal modulation of Sp1 DNA binding in the developing cerebral cortex and cerebellum

Gestational exposure to environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, (dioxin) often leads to neurodevelopmental and neurobehavioral deficits, which clearly suggest the involvement of the central nervous system. The objective of this study was to determine the effects of an acute, gestational exposure to dioxin on the developmental expression profile of a transcription factor (Sp1) that is involved in growth and differentiation in the developing brain of F, generation pups. Timed-pregnant Harlan Sprague Dawley rats were exposed to single oral doses of 0.25, 0.5, and 1.0 microg dioxin/kg body weight or vehicle corn oil on gestation day 15. Electrophoretic mobility shift assays (EMSA) of the nuclear extracts from the cerebral cortex and cerebellum of the resulting pups, on postnatal days (PND) 3.5, 10, 15, 20 and 30, with an Sp1 consensus oligonucleotide sequence revealed modulations in the DNA binding activity of Sp1 as a result of the transplacental dioxin exposure. In the cerebral cortex, a dose-dependent premature peak of Sp1 DNA-binding on PND 3 was observed when compared with the control animals where Sp1 DNA-binding was maximal on PND 10. In the postnatally-developing cerebellum, a dose-dependent premature peak of Sp1 DNA binding on PND 5 was observed when compared with the control animals where Spl DNA-binding was maximal on PND 15. The mean birth index, body weight gain, and gross brain weight of the pups were not statistically different from the control animals over the 30 day postnatal period studied. The data obtained on the Sp1 developmental expression profiles in the brain indicate that (1) Sp I DNA-binding is developmentally regulated and expressed very highly in actively developing brain regions, and (2) a potential consequence of the transplacental effect of dioxin to the fetus is in utero neurotoxicity.

Metabolism, bioavailability, and toxicokinetics of benzo(alpha)pyrene in F-344 rats following oral administration

The objective of this study was to evaluate the bioavailability of Benzo(a)pyrene [B(a)p], subsequent to oral exposure. Eight-week-old F-344 rats were dosed orally with 100 mg/kg body weight B(a)p and sacrificed at 0, 0.5, 1.0, 2.0, 4.0. 8.0, 24, 48 and 72 hours post exposure. Blood, liver, reproductive tissues, urine and fecal samples were collected at necropsy and were analyzed for parent B(a)p and metabolites by HPLC with fluorescence detection. Peak levels of B(a)p in plasma occurred 8 hours after exposure (67%) followed by a gradual decrease. Liver retained 10% of the administered B(a)p up to 24 hours following, which the levels dropped during the remaining time periods studied. Twenty-four hours after administration, 45% of the dose was excreted in feces and urine. Metabolite levels in plasma peaked at 24 hours (10%) and decreased to 1% at 72 hours. In the liver, metabolite levels were higher at 8 hours (10%) but were only 3% at 72 hours. Benzo(a)pyrene levels increased after 24 hours in the reproductive organs and constituted 10% of the administered dose at 72 hours. Blood showed high levels of 7,8-diol than 9,10 and 4,5-diols which were high in liver and reproductive organs. Compared to diols, the hydroxy metabolites were detected at high levels in urine and fecal samples. Among the aqueous phase metabolites, glucuronides were at higher levels compared to glutathiones and sulfates. The slow release of unmetabolized B(a)p from reproductive organs and the presence of reactive metabolites in these organs is a matter of concern as they could interfere with gonadal steroid synthesis and release and its regulatory role in gamete production, maturation and function of male animals in a continuous exposure paradigm.