Srimathi Kannan

Exposures to Airborne Particulate Matter and Adverse Perinatal Outcomes: A Biologically Plausible Mechanistic Framework for Exploring Potential Effect Modification by Nutrition

Objectives The specific objectives are threefold: to describe the biologically plausible mechanistic pathways by which exposure to particulate matter (PM) may lead to the adverse perinatal outcomes of low birth weight (LBW), intrauterine growth retardation (IUGR), and preterm delivery (PTD); review the evidence showing that nutrition affects the biologic pathways; and explain the mechanisms by which nutrition may modify the impact of PM exposure on perinatal outcomes. Methods We propose an interdisciplinary conceptual framework that brings together maternal and infant nutrition, air pollution exposure assessment, and cardiopulmonary and perinatal epidemiology. Five possible albeit not exclusive biologic mechanisms have been put forth in the emerging environmental sciences literature and provide corollaries for the proposed framework. Conclusions Protecting the environmental health of mothers and infants remains a top global priority. The existing literature indicates that the effects of PM on LBW, PTD, and IUGR may manifest through the cardiovascular mechanisms of oxidative stress, inflammation, coagulation, endothelial function, and hemodynamic responses. PM exposure studies relating mechanistic pathways to perinatal outcomes should consider the likelihood that biologic responses and adverse birth outcomes may be derived from both PM and non-PM sources (e.g., nutrition). In the concluding section, we present strategies for empirically testing the proposed model and developing future research efforts.

Social and Physical Environments and Disparities in Risk for Cardiovascular Disease: The Healthy Environments Partnership Conceptual Model

The Healthy Environments Partnership (HEP) is a community-based participatory research effort investigating variations in cardiovascular disease risk, and the contributions of social and physical environments to those variations, among non-Hispanic black, non-Hispanic white, and Hispanic residents in three areas of Detroit, Michigan. Initiated in October 2000 as a part of the National Institute of Environmental Health Sciences’ Health Disparities Initiative, HEP is affiliated with the Detroit Community–Academic Urban Research Center. The study is guided by a conceptual model that considers race-based residential segregation and associated concentrations of poverty and wealth to be fundamental factors influencing multiple, more proximate predictors of cardiovascular risk. Within this model, physical and social environments are identified as intermediate factors that mediate relationships between fundamental factors and more proximate factors such as physical activity and dietary practices that ultimately influence anthropomorphic and physiologic indicators of cardiovascular risk. The study design and data collection methods were jointly developed and implemented by a research team based in community-based organizations, health service organizations, and academic institutions. These efforts include collecting and analyzing airborne particulate matter over a 3-year period; census and administrative data; neighborhood observation checklist data to assess aspects of the physical and social environment; household survey data including information on perceived stressors, access to social support, and health-related behaviors; and anthropometric, biomarker, and self-report data as indicators of cardiovascular health. Through these collaborative efforts, HEP seeks to contribute to an understanding of factors that contribute to racial and socioeconomic health inequities, and develop a foundation for efforts to eliminate these disparities in Detroit.

Meeting Report: Atmospheric Pollution and Human Reproduction

Background There is a growing body of epidemiologic literature reporting associations between atmospheric pollutants and reproductive outcomes, particularly birth weight and gestational duration. Objectives The objectives of our international workshop were to discuss the current evidence, to identify the strengths and weaknesses of published epidemiologic studies, and to suggest future directions for research. Discussion Participants identified promising exposure assessment tools, including exposure models with fine spatial and temporal resolution that take into account time–activity patterns. More knowledge on factors correlated with exposure to air pollution, such as other environmental pollutants with similar temporal variations, and assessment of nutritional factors possibly influencing birth outcomes would help evaluate importance of residual confounding. Participants proposed a list of points to report in future publications on this topic to facilitate research syntheses. Nested case–control studies analyzed using two-phase statistical techniques and development of cohorts with extensive information on pregnancy behaviors and biological samples are promising study designs. Issues related to the identification of critical exposure windows and potential biological mechanisms through which air pollutants may lead to intrauterine growth restriction and premature birth were reviewed. Conclusions To make progress, this research field needs input from toxicology, exposure assessment, and clinical research, especially to aid in the identification and exposure assessment of feto-toxic agents in ambient air, in the development of early markers of adverse reproductive outcomes, and of relevant biological pathways. In particular, additional research using animal models would help better delineate the biological mechanisms underpinning the associations reported in human studies.

Neighborhood Retail Food Environment and Fruit and Vegetable Intake in a Multiethnic Urban Population

Purpose. To examine relationships between the neighborhood food environment and fruit and vegetable intake in a multiethnic urban population. Design. Analysis of cross-sectional survey and observational data. Setting. One hundred forty-six neighborhoods within three large geographic communities of Detroit, Michigan. Subjects. Probability sample of 919 African-American, Latino, and white adults. Measures. The dependent variable was mean daily fruit and vegetable servings, as measured by using a modified Block 98 food frequency questionnaire. Independent variables included the neighborhood food environment: store availability (i.e., large grocery, specialty, convenience, liquor, small grocery), supermarket proximity (i.e., street-network distance to nearest chain grocer), and perceived and observed neighborhood fresh fruit and vegetable supply (i.e., availability, variety, quality, affordability). Analysis. Weighted, multilevel regression. Results. Presence of a large grocery store in the neighborhood was associated with, on average, 0.69 more daily fruit and vegetable servings in the full sample. Relationships between the food environment and fruit and vegetable intake did not differ between whites and African-Americans. However, Latinos, compared with African-Americans, who had a large grocery store in the neighborhood consumed 2.20 more daily servings of fruits and vegetables. Presence of a convenience store in the neighborhood was associated with 1.84 fewer daily fruit and vegetable servings among Latinos than among African-Americans. Conclusion. The neighborhood food environment influences fruit and vegetable intake, and the size of this relationship may vary for different racial/ethnic subpopulations.

Acute effects of ambient particulate matter on blood pressure: differential effects across urban communities.

Recent studies have suggested a link between exposure to ambient particulate matter <2.5 &mgr;m in diameter (PM2.5) and adverse cardiovascular outcomes. The objective of this study was to examine the effects of differing community-level exposure to PM2.5 on daily measures of blood pressure (BP) among an adult population. During the period May 2002 through April 2003, BP was examined at 2 time points for 347 adults residing in 3 distinct communities of Detroit, Michigan. Exposure to PM2.5 was assessed in each community during this period, along with multivariate associations between PM2.5 and BP. In models combining all 3 of the communities, PM2.5 was significantly associated with systolic blood pressure; a 10-&mgr;g/m3 increase in daily PM2.5 was associated with a 3.2-mm Hg increase in systolic blood pressure (P=0.05). However, in models that added a location interaction, larger effects were observed for systolic blood pressure within the community with highest PM2.5 levels; a 10-&mgr;g/m3 increase in daily PM2.5 was associated with a 8.6-mm Hg increase in systolic blood pressure (P=0.01). We also found young age (<55 years) and not taking BP medications to be significant predictors of increased BP effects. Among those taking BP medications, the PM2.5 effect on BP appeared to be mitigated, partially explaining the age effect, because those participants <55 years of age were less likely to take BP medications. Short-term increases in exposure to ambient PM2.5 are associated with acute increases in BP in adults, especially within communities with elevated levels of exposure.

Healthy Eating and Exercising to Reduce Diabetes: Exploring the Potential of Social Determinants of Health Frameworks Within the Context of Community-Based Participatory Diabetes Prevention

OBJECTIVES We examined a community-based participatory diabetes intervention to identify facilitators of and barriers to sustained community efforts to address social factors that contribute to health. METHODS We conducted a case study description and analysis of the Healthy Eating and Exercising to Reduce Diabetes project in the theoretical context of a conceptual model of social determinants of health. RESULTS We identified several barriers to and facilitators of analysis of social determinants of a community-identified disease priority (in this case, diabetes). Barriers included prevailing conceptual models, which emphasize health behavioral and biomedical paradigms that exclude social determinants of health. Facilitating factors included (1) opportunities to link individual health concerns to social contexts and (2) availability of support from diverse partners with a range of complementary resources. CONCLUSIONS Partnerships that offer community members tangible resources with which to manage existing health concerns and that integrate an analysis of social determinants of health can facilitate sustained engagement of community members and health professionals in multilevel efforts to address health disparities.

Relational pathways between socioeconomic position and cardiovascular risk in a multiethnic urban sample: complexities and their implications for improving health in economically disadvantaged populations

Background: The study was designed to provide evidence of a cascade effect linking socioeconomic position to anthropometric indicators of cardiovascular disease (CVD) risk through effects on psychosocial stress, psychological distress and health-related behaviours, and consider implications for disease prevention and health promotion. Methods: A cross-sectional stratified two-stage probability sample of occupied housing units in three areas of Detroit, Michigan, was used in the study. 919 adults aged ⩾25 years completed the survey (mean age 46.3; 53% annual household income <

Ability to Taste 6-n-Propylthiouracil and BMI in Low-income Preschool-aged Children

20 000; 57% non-Hispanic black, 22% Latino, 19% non-Hispanic white). Variables included self-report (eg, psychosocial stress, depressive symptoms, health behaviours) and anthropometric measurements (eg, waist circumference, height, weight). The main outcome variables were depressive symptoms, smoking status, physical activity, body mass index and waist circumference. Results: Income was inversely associated with depressive symptoms, likelihood of current smoking, physical inactivity and waist circumference. These relationships were partly or fully mediated by psychosocial stress. A suppressor effect of current smoking on the relationship between depressive symptoms and waist circumference was found. Independent effects of psychosocial stress and psychological distress on current smoking and waist circumference were found, above and beyond the mediated pathways. Conclusions: The results suggest that relatively modest improvements in the income of economically disadvantaged people can set in motion a cascade of effects, simultaneously reducing exposure to stressful life conditions, improving mental well-being, increasing health-promoting behaviours and reducing anthropometric risks associated with CVD. Such interventions offer important opportunities to improve population health and reduce health disparities.

Exposures to airborne particulate matter and adverse perinatal outcomes: a biologically plausible mechanistic framework for exploring potential

Background: Sensitivity to the bitter compound 6‐n‐propylthiouracil (PROP) is genetically mediated. Sensitivity to PROP has been associated with weight status in both adults and children.

Multilevel correlates of satisfaction with neighborhood availability of fresh fruits and vegetables.

This article has three objectives: to describe the biologically plausible mechanistic pathways by which exposure to particulate matter (PM) may lead to adverse perinatal outcomes of low birth weight (LBW), intrauterine growth retardation (IUGR), and preterm delivery (PTD); review evidence showing that nutrition affects biologic pathways; and explain mechanisms by which nutrition may modify the impact of PM exposure on perinatal outcomes. We propose an interdisciplinary framework that brings together maternal and infant nutrition, air pollution exposure assessment, and cardiopulmonary and perinatal epidemiology. Five possible biologic mechanisms have been put forth in the emerging environmental sciences literature and provide corollaries for the proposed framework. The literature indicates that the effects of PM on LBW, PTD, and IUGR may manifest through the cardiovascular mechanisms of oxidative stress, inflammation, coagulation, endothelial function, and hemodynamic responses. PM exposure studies relating mechanistic pathways to perinatal outcomes should consider the likelihood that biologic responses and adverse birth outcomes may be derived from both PM and non-PM sources. We present strategies for empirically testing the proposed model and developing future research efforts.