Mary Ross

Particulate Matter―Induced Health Effects: Who Is Susceptible?

Background Epidemiological, controlled human exposure, and toxicological studies have demonstrated a variety of health effects in response to particulate matter (PM) exposure with some of these studies indicating that populations with certain characteristics may be disproportionately affected. Objective To identify populations potentially at greatest risk for PM-related health effects, we evaluated epidemiological studies that examined various characteristics that may influence susceptibility, while using results from controlled human exposure and toxicological studies as supporting evidence. Additionally, we formulated a definition of susceptibility, building from the varied and inconsistent definitions of susceptibility and vulnerability used throughout the literature. Data synthesis We evaluated recent epidemiological studies to identify characteristics of populations potentially susceptible to PM-related health effects. Additionally, we evaluated controlled human exposure and toxicological studies to provide supporting evidence. We conducted a comprehensive review of epidemiological studies that presented stratified results (e.g., < 65 vs. ≥ 65 years of age), controlled human exposure studies that examined individuals with underlying disease, and toxicological studies that used animal models of disease. We evaluated results for consistency across studies, coherence across disciplines, and biological plausibility to assess the potential for increased susceptibility to PM-related health effects in a specific population or life stage. Conclusions We identified a diverse group of characteristics that can lead to increased risk of PM-related health effects, including life stage (i.e., children and older adults), preexisting cardiovascular or respiratory diseases, genetic polymorphisms, and low-socioeconomic status. In addition, we crafted a comprehensive definition of susceptibility that can be used to encompass all populations potentially at increased risk of adverse health effects as a consequence of exposure to an air pollutant.

Prevalence of asthma and other allergic diseases in an adolescent population: association with gender and race

OBJECTIVES To estimate the prevalence and severity of asthma in an adolescent population by sex and race. METHODS Cross-sectional, population-based survey of school children. SETTING Midwestern city experiencing damage from the 1993 Mississippi River flood. PARTICIPANTS 2,693 children attending grades 7 to 12. MEASUREMENTS Questions from the International Study of Asthma and Allergies in Childhood (ISAAC). RESULTS Two thousand six hundred ninety-three children were surveyed, for a response rate of 90%. In this population, 16.4% reported having ever been diagnosed with asthma; 25% reported wheezing in the last 12 months; 32% reported symptoms of rhinitis in the last 12 months; and 22% reported ever having hay fever. The prevalence rate for current asthma was 12.6%. Female students had significantly greater prevalence rates for current asthma (16.4% vs 9.0%, OR = 1.85); ever-diagnosed asthma (18.5% vs 14.3%, OR = 1.36); wheezing > or = 4 times in the last 12 months (12.0% vs 5.6%, OR = 1.95); current rhinitis (38.7% vs 25.4%, OR = 1.73); and hay fever (26.4% vs 18.4%, OR = 1.57). All associations with sex remained significant, except ever-diagnosed asthma, after controlling for other known risk factors in logistic regression. African-Americans had higher prevalence rates than other races with differences reaching statistical significance for ever-diagnosed asthma and current asthma; however, these relationships did not remain significant after controlling for other known risk factors in logistic regression. CONCLUSIONS Our prevalence rates were similar to those reported by other studies that used the ISAAC questionnaire. Female students reported significantly more asthma, wheezing, rhinitis, and hay fever than male students. Female students also reported more severe symptoms and a greater number of emergency room and hospital admissions.

Association of asthma symptoms and severity with indoor bioaerosols

Background: In this study, repeated measurements were made of levels of mold spores, bacteria, and dust‐mite allergens over a 7‐month period in the homes of asthmatics, and relationships with measures of asthma severity were evaluated.

Practical Advancement of Multipollutant Scientific and Risk Assessment Approaches for Ambient Air Pollution

Objectives: The U.S. Environmental Protection Agency is working toward gaining a better understanding of the human health impacts of exposure to complex air pollutant mixtures and the key features that drive the toxicity of these mixtures, which can then be used for future scientific and risk assessments. Data sources: A public workshop was held in Chapel Hill, North Carolina, 22–24 February 2011, to discuss scientific issues and data gaps related to adopting multipollutant science and risk assessment approaches, with a particular focus on the criteria air pollutants. Expert panelists in the fields of epidemiology, toxicology, and atmospheric and exposure sciences led open discussions to encourage workshop participants to think broadly about available and emerging scientific evidence related to multipollutant approaches to evaluating the health effects of air pollution. Synthesis: Although there is clearly a need for novel research and analytical approaches to better characterize the health effects of multipollutant exposures, much progress can be made by using existing scientific information and statistical methods to evaluate the effects of single pollutants in a multipollutant context. This work will have a direct impact on the development of a multipollutant science assessment and a conceptual framework for conducting multipollutant risk assessments. Conclusions: Transitioning to a multipollutant paradigm can be aided through the adoption of a framework for multipollutant science and risk assessment that encompasses well-studied and ubiquitous air pollutants. Successfully advancing methods for conducting these assessments will require collaborative and parallel efforts between the scientific and environmental regulatory and policy communities.

Effect of ozone and aeroallergens on the respiratory health of asthmatics.

Abstract The effect of ambient air pollutants, pollens, and mold spores on respiratory health was studied in an area with low concentrations of chemical pollutants and abundant aeroallergens. A panel of 40 asthmatic subjects living near East Moline, Illinois, recorded peak expiratory flow rates (PEFRs), respiratory symptoms, frequency of asthma attacks, and asthma medication use between April and October 1994. Daily outdoor concentrations of pollutants and aeroallergens were measured, and indoor levels of bioaerosols were measured on several occasions in each participants home. Ozone was associated with increased morning and evening symptom scores and decreased evening PEFR, and these associations remained significant with adjustment for weather and aeroallergens. The association between ozone and asthma medication use was increased in magnitude and significance with adjustment for weather and aeroallergens; however, the association between ozone and morning PEFR became nonsignificant with weather and aeroallergen adjustment. Significant associations were also found between pollen concentration and decreased evening PEFR, as well as between increased morning and evening symptom scores and asthma medication use. In addition, associations were noted between total spore concentration and increased morning PEFR and decreased morning and evening symptom scores. The inverse associations found with mold spore concentrations were not consistent with the results of other studies; however, the associations between ozone and pollen concentration were consistent with previous studies. When results were stratified by a number of independent risk factors, no differences were noted relative to allergic status or presence of dampness or flooding in the home; however, the associations with outdoor ozone and pollens were seen mainly among participants with low levels of exposure to indoor bioaerosols (< 1,800 spores/m3) or with no environmental tobacco smoke exposure.

Panel discussion review: session three — issues involved in interpretation of epidemiologic analyses — statistical modeling

The Clean Air Act mandates that the US Environmental Protection Agency (EPA) develop National Ambient Air Quality Standards for criteria air pollutants and conduct periodic reviews of the standards based on new scientific evidence. In recent reviews, evidence from epidemiologic studies has played a key role. Epidemiologic studies often provide evidence for effects of several air pollutants. Determining whether there are independent effects of the separate pollutants is a challenge. Among the many issues confronting the interpretation of epidemiologic studies of multi-pollutant exposures and health effects are those specifically related to statistical modeling. The EPA convened a workshop on 13 and 14 December 2006 in Chapel Hill, North Carolina, USA, to discuss these and other issues; Session Three of the workshop was devoted specifically to statistical modeling. Prominent statistical modeling issues in epidemiologic studies of air pollution include (1) measurement error across the co-pollutants; (2) correlation and multi-collinearity among the co-pollutants; (3) the timing of the concentration–response function; (4) confounding; and (5) spatial analyses.The views expressed in this paper are those of the authors and do not necessarily reflect the views of policies of the US Environmental Protection Agency.

GIS-Modeled Indicators of Traffic-Related Air Pollutants and Adverse Pulmonary Health Among Children in El Paso, Texas

Investigators examined 5,654 children enrolled in the El Paso, Texas, public school district by questionnaire in 2001. Exposure measurements were first collected in the late fall of 1999. School-level and residence-level exposures to traffic-related air pollutants were estimated using a land use regression model. For 1,529 children with spirometry, overall geographic information system (GIS)-modeled residential levels of traffic-related ambient air pollution (calibrated to a 10-ppb increment in nitrogen dioxide levels) were associated with a 2.4% decrement in forced vital capacity (95% confidence interval (CI): -4.0, -0.7) after adjustment for demographic, anthropomorphic, and socioeconomic factors and spirometer/technician effects. After adjustment for these potential covariates, overall GIS-modeled residential levels of traffic-related ambient air pollution (calibrated to a 10-ppb increment in nitrogen dioxide levels) were associated with pulmonary function levels below 85% of those predicted for both forced vital capacity (odds ratio (OR) = 3.10, 95% CI: 1.65, 5.78) and forced expiratory volume in 1 second (OR = 2.35, 95% CI: 1.38, 4.01). For children attending schools at elevations above 1,170 m, a 10-ppb increment in modeled nitrogen dioxide levels was associated with current asthma (OR = 1.56, 95% CI: 1.08, 2.50) after adjustment for demographic, socioeconomic, and parental factors and random school effects. These results are consistent with previous studies in Europe and California that found adverse health outcomes in children associated with modeled traffic-related air pollutants.

Variability in childhood allergy and asthma across ethnicity, language, and residency duration in El Paso, Texas: a cross-sectional study

BackgroundWe evaluated the impact of migration to the USA-Mexico border city of El Paso, Texas (USA), parental language preference, and Hispanic ethnicity on childhood asthma to differentiate between its social and environmental determinants.MethodsAllergy and asthma prevalence was surveyed among 9797 fourth and fifth grade children enrolled in the El Paso Independent School District. Parents completed a respiratory health questionnaire, in either English or Spanish, and a sub-sample of children received spirometry testing at their school. Here we report asthma and allergy outcomes across ethnicity and El Paso residency duration.ResultsAsthma and allergy prevalence increased with longer duration of El Paso residency independent of ethnicity and preferred language. Compared with immigrants who arrived in El Paso after entering first grade (18%), lifelong El Paso residents (68%) had more prevalent allergy (OR, 1.72; 95% CI, 1.32 - 2.24), prevalent asthma (OR, 1.75; 95% CI, 1.24 - 2.46), and current asthma (OR, 2.01; 95% CI, 1.37 - 2.95). Spirometric measurements (FEV1/FVC and FEF25-75) also declined with increasing duration of El Paso residency (0.16% and 0.35% annual reduction, respectively).ConclusionThese findings suggest that a community-wide environmental exposure in El Paso, delayed pulmonary development, or increased health of immigrants may be associated with allergy and asthma development in children raised there.

Evaluating Potential Response-Modifying Factors for Associations between Ozone and Health Outcomes: A Weight-of-Evidence Approach

Background: Epidemiologic and experimental studies have reported a variety of health effects in response to ozone (O3) exposure, and some have indicated that certain populations may be at increased or decreased risk of O3-related health effects. Objectives: We sought to identify potential response-modifying factors to determine whether specific groups of the population or life stages are at increased or decreased risk of O3-related health effects using a weight-of-evidence approach. Methods: Epidemiologic, experimental, and exposure science studies of potential factors that may modify the relationship between O3 and health effects were identified in U.S. Environmental Protection Agency’s 2013 Integrated Science Assessment for Ozone and Related Photochemical Oxidants. Scientific evidence from studies that examined factors that may influence risk were integrated across disciplines to evaluate consistency, coherence, and biological plausibility of effects. The factors identified were then classified using a weight-of-evidence approach to conclude whether a specific factor modified the response of a population or life stage, resulting in an increased or decreased risk of O3-related health effects. Discussion: We found “adequate” evidence that populations with certain genotypes, preexisting asthma, or reduced intake of certain nutrients, as well as different life stages or outdoor workers, are at increased risk of O3-related health effects. In addition, we identified other factors (i.e., sex, socioeconomic status, and obesity) for which there was “suggestive” evidence that they may increase the risk of O3-related health effects. Conclusions: Using a weight-of-evidence approach, we identified a diverse group of factors that should be considered when characterizing the overall risk of health effects associated with exposures to ambient O3. Citation: Vinikoor-Imler LC, Owens EO, Nichols JL, Ross M, Brown JS, Sacks JD. 2014. Evaluating potential response-modifying factors for associations between ozone and health outcomes: a weight-of-evidence approach. Environ Health Perspect 122:1166–1176; http://dx.doi.org/10.1289/ehp.1307541

Bioaerosol Concentrations in the Quad Cities 1 Year after the 1993 Mississippi River Floods

Bioaerosol measurements were made in 45 Quad Cities, Illinois houses following the 1993 floods of the Mississip pi and Rock Rivers. Least squares log transformed means for fungal concentrations (in cfu m-3) were 1,449 in basements, 1,174 in living rooms, 1,234 in kitchens, 1,464 in first floor bedrooms, 1,197 in second floor bedrooms, and 2,590 outside. Mean least squares log transformed bacterial concentrations were 887 cfu m-3 in basements, 878 cfu m-3 in living rooms and 697 cfu m-3 outdoors. Levels of fungi and bacteria were not notably elevated in the basements or other rooms of the formerly flooded houses. Levels of fungi and bacteria indoors were significantly less in houses with dehumidifiers and in homes with natural gas odors. Air-conditioning during warm periods significantly reduced airborne concentra tions of fungi.