LuAnn E. White

Statistical methods for linking health, exposure, and hazards

The Environmental Public Health Tracking Network (EPHTN) proposes to link environmental hazards and exposures to health outcomes. Statistical methods used in case–control and cohort studies to link health outcomes to individual exposure estimates are well developed. However, reliable exposure estimates for many contaminants are not available at the individual level. In these cases, exposure/hazard data are often aggregated over a geographic area, and ecologic models are used to relate health outcome and exposure/hazard. Ecologic models are not without limitations in interpretation. EPHTN data are characteristic of much information currently being collected—they are multivariate, with many predictors and response variables, often aggregated over geographic regions (small and large) and correlated in space and/or time. The methods to model trends in space and time, handle correlation structures in the data, estimate effects, test hypotheses, and predict future outcomes are relatively new and without extensive application in environmental public health. In this article we outline a tiered approach to data analysis for EPHTN and review the use of standard methods for relating exposure/hazards, disease mapping and clustering techniques, Bayesian approaches, Markov chain Monte Carlo methods for estimation of posterior parameters, and geostatistical methods. The advantages and limitations of these methods are discussed.

Implementation of evidence-based asthma interventions in post-Katrina New Orleans: the Head-off Environmental Asthma in Louisiana (HEAL) study.

Background: Childhood asthma morbidity and mortality in New Orleans, Louisiana, is among the highest in the nation. In August 2005, Hurricane Katrina created an environmental disaster that led to high levels of mold and other allergens and disrupted health care for children with asthma. Objectives: We implemented a unique hybrid asthma counselor and environmental intervention based on successful National Institutes of Health asthma interventions from the National Cooperative Inner City Asthma (NCICAS) and Inner-City Asthma (ICAS) Studies with the goal of reducing asthma symptoms in New Orleans children after Hurricane Katrina. Methods: Children (4–12 years old) with moderate-to-severe asthma (n = 182) received asthma counseling and environmental intervention for approximately 1 year. HEAL was evaluated employing several analytical approaches including a pre–post evaluation of symptom changes over the entire year, an analysis of symptoms according to the timing of asthma counselor contact, and a comparison to previous evidence-based interventions. Results: Asthma symptoms during the previous 2 weeks decreased from 6.5 days at enrollment to 3.6 days at the 12-month symptom assessment (a 45% reduction, p < 0.001), consistent with changes observed after NCICAS and ICAS interventions (35% and 62% reductions in symptom days, respectively). Children whose families had contact with a HEAL asthma counselor by 6 months showed a 4.09-day decrease [95% confidence interval (CI): 3.25 to 4.94-day decrease] in symptom days, compared with a 1.79-day decrease (95% CI: 0.90, 2.67) among those who had not yet seen an asthma counselor (p < 0.001). Conclusions: The novel combination of evidence-based asthma interventions was associated with improved asthma symptoms among children in post-Katrina New Orleans. Post-intervention changes in symptoms were consistent with previous randomized trials of NCICAS and ICAS interventions.

Indoor environmental exposures for children with asthma enrolled in the HEAL study, post-Katrina New Orleans.

Background: Rain and flooding from Hurricane Katrina resulted in widespread growth of mold and bacteria and production of allergens in New Orleans, Louisiana, which may have led to increased exposures and morbidity in children with asthma. Objectives: The goal of the Head-off Environmental Asthma in Louisiana (HEAL) study was to characterize post-Katrina exposures to mold and allergens in children with asthma. Methods: The homes of 182 children with asthma in New Orleans and surrounding parishes were evaluated by visual inspection, temperature and moisture measurements, and air and dust sampling. Air was collected using vacuum-pump spore traps and analyzed for > 30 mold taxa using bright field microscopy. Dust was collected from the children’s beds and bedroom floors and analyzed for mouse (Mus m 1), dust mite (Der p 1), cockroach (Bla g 1), and mold (Alternaria mix) allergens using ELISA. Results: More than half (62%) of the children were living in homes that had been damaged by rain, flooding, or both. Geometric mean indoor and outdoor airborne mold levels were 501 and 3,958 spores/m3, respectively. Alternaria antigen was detected in dust from 98% of homes, with 58% having concentrations > 10 µg/g. Mus m 1, Der p 1, and Bla g 1 were detected in 60%, 35%, and 20% of homes, respectively, at low mean concentrations. Conclusions: Except for Alternaria antigen in dust, concentrations of airborne mold (ratio of indoor to outdoor mold) and dust allergens in the homes of HEAL children were lower than measurements found in other studies, possibly because of extensive post-Katrina mold remediation and renovations, or because children moved into cleaner homes upon returning to New Orleans.

The Head-off Environmental Asthma in Louisiana (HEAL) Study—Methods and Study Population

Background: In the city of New Orleans, Louisiana, and surrounding parishes (NOLA), children with asthma were perilously impacted by Hurricane Katrina as a result of disrupted health care, high home mold and allergen levels, and high stress. Objectives: The Head-off Environmental Asthma in Louisiana (HEAL) study was conducted to examine relationships between the post-Katrina environment and childhood asthma in NOLA and assess a novel asthma counselor intervention that provided case management and guidance for reducing home mold and allergen levels. Methods: Children (4–12 years old) with moderate-to-severe asthma were recruited from NOLA schools. Over 1 year, they received two clinical evaluations, three home environmental evaluations, and the asthma intervention. Quarterly end points included symptom days, medication use, and unscheduled emergency department or clinic visits. A community advisory group was assembled and informed HEAL at all phases. Results: Of the children (n = 182) enrolled in HEAL, 67% were African American, and 25% came from households with annual incomes <

Comparative analysis of nutrient data in the lower Mississippi River

15,000. HEAL children were symptomatic, averaging 6.6 symptom days in the 2 weeks before baseline, and had frequent unscheduled visits to clinics or emergency departments (76% had at least one unscheduled visit in the preceding 3 months). In this report, we describe study design and baseline characteristics of HEAL children. Conclusions: Despite numerous challenges faced by investigators, study staff, and participants, including destroyed infrastructure, disrupted lives, and lost jobs, HEAL was successful in terms of recruitment and retention, the high quality of data collected that will provide insight into asthma-allergen relationships, and the asthma intervention. This success was attributable to using an adaptive approach and refining processes as needed.

From research to policy: targeting the primary prevention of childhood lead poisoning

Abstract As the second phase of a large-scale Tulane University Mississippi River water-quality database project, nutrient data on the lower Mississippi River have been examined for potential differences among sampling agencies, geographic locations and chemically similar nitrogen parameters. These data represent the most comprehensive source of information on nutrients in the Mississippi River available as a single database. Monthly means, grouped by parameter, sampling location and agency, were calculated and compared as paired sets, excluding months where data were not available for both sets. Evaluations using ANOVA indicated few differences among agencies providing nitrogen-compound data, although differences were observed in phosphorus-compound data from different sources. Unfiltered and filtered fractions of nitrate–nitrite were found to be comparable throughout the study area. Spatial examination of the nutrient data indicated few differences in inorganic nitrogen concentrations throughout the study area, but significant variability in total Kjeldahl nitrogen (TKN). Orthophosphate and total phosphorus concentrations increased through the study area from Arkansas [river miles (RM) 500–810] downstream to St. Francisville (RM 231–315), but with little or no change from Baton Rouge (RM 111–230) to the Gulf of Mexico. Results provide a combined data set from which preliminary calculations of daily nutrient loads in the Mississippi River between 1960 and 1997 were conducted.

An improved method for analysis of 2,4,6-trinitrotoluene and its metabolites from compost and contaminated soils

Public policy can be an effective method of promoting public health and preventing disease in a population. The proposing and passing of a municipal ordinance regulating power-sanding of leaded paint in New Orleans is a policy-level intervention that implements a primary prevention measure to address a community-wide risk. The process of achieving policy change involves defining the problem and the proposed intervention, integrating the resources of the individuals and groups with a stake in the situation, and disseminating information to the general public and to legislators. The implementation of the ordinance regulating power-sanding in New Orleans is a community-level lead poisoning prevention strategy.

Health effects from indoor air pollution: Case studies

Abstract The United States Army Toxic and Hazardous Materials Agency (USATHAMA) Method SMO2, routinely used for the high pressure liquid chromatographic analysis of nitrobenzenes in contaminated soils, was modified to incorporate the use of para-nitroaniline (PNA) as an internal standard and also to permit the quantitation of two additional metabolites of 2,4,6-trinitrotoluene (TNT). In our laboratory, these two metabolites, 2-amino-4,6-dinitrotoluene (2-ADNT) and 4-amino-2,6-dinitrotoluene (4-ADNT), were found to co-elute with each other, as well as with dinitrotoluenes (DNT), 2,4-DNT and 2,6-DNT, using the original method. The modified method described below is a two-step procedure in which one aliquot of the extract mixture is analyzed directly to quantitate trinitrobenzene (TNB), meta-dinitrobenzene (m-DNB), and TNT, and a second aliquot is simultaneously treated with trifluoroacetic acid anhydride (TFAA) to convert 2-ADNT and 4-ADNT into derivatives that chromatographically separate cleanly from each other and from DNT. Standard curves for the derivatized compounds are linear over a range of 30–400 ng/25 μl injection. Quantitation of TNT and its metabolites in spiked municipal compost demonstrated intra-assay and inter-assay variabilities of ±15% or less. This two-step analysis for these compounds was found to be successful equally after extraction and dilution with either acetonitrile (ACN) [USATHAMA Method SMO2] or with methylene chloride as in an alternate method (EPA Method 3550). This new derivatization procedure allows for the quantitation of additional metabolites of TNT which is difficult or not possible with Method SMO2.

Success of the Undergraduate Public Health at Tulane University

In recent years there has been a growing awareness of the health effects associated with the presence of contaminants in indoor air. Numerous agents can accumulate in public buildings, homes and automobiles as a result of ongoing activities that normally occur in these closed spaces. Ventilation is a major factor in the control of indoor air pollutants since proper movement of air can prevent or minimize the build up of compounds in buildings. The recent emphasis on energy conservation has lead to measures which economize on energy for heating and air conditioning, but which also trap pollutants within a building. Three cases of indoor air pollution were investigated. A typical investigation of indoor air pollutant problems includes the following: 1) interviews with building occupants; 2) history of the building with regard to maintenance, pesticide treatment, etc.; 3) a survey of the building and ventilation; and when warranted, 4) sampling and analysis of air. Each case presented is unique in that atypical situations caused agents to accumulate in a building or section of a building. The indoor air problems in these cases were solved by identifying and removing the source of the offending agent and/or improving the ventilation in the building.

Increased Concentrations of Cyclic GMP in Fetal Liver Cells Stimulated by Erythropoietin

Tulane University School of Public Health and Tropical Medicine launched the Bachelors of Science in Public Health (BSPH) in 2005. The BSPH has steadily grown and comprises one-third of the total enrollment in the school. A review of the organizational structure demonstrates that direct responsibility for undergraduate education by a school of public health is advantageous to the success of the program. The competency and skills-based curriculum attracts students. Outcome measures show the enrollment is steadily increasing. The majority of the BSPH graduates continue onto competitive graduate and professional degree programs. Those who seek jobs find employment related to their public health education, but outside of the traditional governmental public health agencies. The combined BSPH/masters of public health (MPH) degree is a pipeline for students to pursue a MPH and increases the likelihood students will pursue careers in public health. The range and depth of study in the bachelors program is continually examined. Topics once within the purview of graduate education are now being incorporated into undergraduate courses. Undergraduate public health is one of a number of factors that is influencing changes in the MPH degree.