Quantifying Multipollutant Health Impacts Using the Environmental Benefits Mapping and Analysis Program-Community Edition (BenMAP-CE): A Case Study in Atlanta, Georgia

BACKGROUND

Air pollution risk assessments do not generally quantify health impacts using multipollutant risk estimates, but instead use results from single-pollutant or copollutant models. Multipollutant epidemiological models account for pollutant interactions and joint effects but can be computationally complex and data intensive. Risk estimates from multipollutant studies are therefore challenging to implement in the quantification of health impacts.

OBJECTIVES

Our objective was to conduct a case study using a developmental multipollutant version of the Environmental Benefits Mapping and Analysis Program-Community Edition (BenMAP-CE) to estimate the health impact associated with changes in multiple air pollutants using both a single and multipollutant approach.

METHODS

BenMAP-CE was used to estimate the change in the number of pediatric asthma emergency department (ED) visits attributable to simulated changes in air pollution between 2011 and 2025 in Atlanta, Georgia, applying risk estimates from an epidemiological study that examined short-term single-pollutant and multipollutant (with and without first-order interactions) exposures. Analyses examined individual pollutants (i.e., ozone, fine particulate matter, carbon monoxide, nitrogen dioxide (NO 2 ), sulfur dioxide, and particulate matter components) and combinations of these pollutants meant to represent shared properties or predefined sources (i.e., oxidant gases, secondary pollutants, traffic, power plant, and criteria pollutants). Comparisons were made between multipollutant health impact functions (HIF) and the sum of single-pollutant HIFs for the individual pollutants that constitute the respective pollutant groups.

RESULTS

Photochemical modeling predicted large decreases in most of the examined pollutant concentrations between 2011 and 2025 based on sector specific (i.e., source-based) estimates of growth and anticipated controls. Estimated number of avoided asthma ED visits attributable to any given multipollutant group were generally higher when using results from models that included interaction terms in comparison with those that did not. We estimated the greatest number of avoided pediatric asthma ED visits for pollutant groups that include NO 2 (i. e., criteria pollutants, oxidants, and traffic pollutants). In models that accounted for interaction, year-round estimates for pollutant groups that included NO 2 ranged from 27.1 [95% confidence interval (CI): 1.6, 52.7; traffic pollutants] to 55.4 (95% CI: 41.8, 69.0; oxidants) avoided pediatric asthma ED visits. Year-round results using multipollutant risk estimates with interaction were comparable to the sum of the single-pollutant results corresponding to most multipollutant groups [e.g., 52.9 (95% CI: 43.6, 62.2) for oxidants] but were notably lower than the sum of the single-pollutant results for some pollutant groups [e.g., 77.5 (95% CI: 66.0, 89.0) for traffic pollutants].

DISCUSSION

Performing a multipollutant health impact assessment is technically feasible but computationally complex. It requires time, resources, and detailed input parameters not commonly reported in air pollution epidemiological studies. Results estimated using the sum of single-pollutant models are comparable to those quantified using a multipollutant model. Although limited to a single study and location, assessing the trade-offs between a multipollutant and single-pollutant approach is warranted. https://doi.org/10.1289/EHP12969.

A systematic evidence map for the evaluation of noncancer health effects and exposures to polychlorinated biphenyl mixtures

Assessing health outcomes associated with exposure to polychlorinated biphenyls (PCBs) is important given their persistent and ubiquitous nature. PCBs are classified as a Group 1 carcinogen, but the full range of potential noncancer health effects from exposure to PCBs has not been systematically summarized and evaluated. We used systematic review methods to identify and screen the literature using combined manual review and machine learning approaches. A protocol was developed that describes the literature search strategy and Populations, Exposures, Comparators, and Outcomes (PECO) criteria used to facilitate subsequent screening and categorization of literature into a systematic evidence map of PCB exposure and noncancer health endpoints across 15 organs/systems. A comprehensive literature search yielded 62,599 records. After electronic prioritization steps, 17,037 studies were manually screened at the title and abstract level. An additional 900 studies identified by experts or supplemental searches were also included. After full-text screening of 3889 references, 1586 studies met the PECO criteria. Relevant study details such as the endpoints assessed, exposure duration, and species were extracted into literature summary tables. This review compiles and organizes the human and mammalian studies from these tables into an evidence map for noncancer health endpoints and PCB mixture exposure to identify areas of robust research as well as areas of uncertainty that would benefit from future investigation. Summary data are available online as interactive visuals with downloadable metadata. Sufficient research is available to inform PCB hazard assessments for most organs/systems, but the amount of data to inform associations with specific endpoints differs. Furthermore, despite many years of research, sparse data exist for inhalation and dermal exposures, which are highly relevant human exposure routes. This evidence map provides a foundation for future systematic reviews and noncancer hazard assessments of PCB mixtures and for strategic planning of research to inform areas of greater uncertainty.

The relationship between childhood blood lead levels below 5 µg/dL and childhood intelligence quotient (IQ): Protocol for a systematic review and meta-analysis

BACKGROUND

The causal association between childhood lead (Pb) exposure and decrements in intelligence quotient (IQ) is well-established, and no safe blood lead level (BLL) in children has been identified. An international pooled analysis of seven prospective studies published by Lanphear et al. in 2005 quantified the relationship between childhood BLL and IQ. Further studies of Pb and IQ have been published more recently with mean BLLs generally lower than in the studies analyzed by Lanphear et al. In this article, we present the protocol for a systematic review to estimate an updated Pb-IQ relationship focusing on BLLs below 5 µg per deciliter (µg/dL).

STUDY QUESTION

What is the quantitative relationship between childhood BLLs and IQ at ages 3-17 years at BLLs below 5 μg/dL?

DATA SOURCES

A comprehensive search of the scientific literature will utilize citation mapping and key word searching. In the citation mapping approach, we will identify seed references that are relevant to our study question, and will then identify more recent references that have cited at least one of the seed references. The key word search will be conducted in the PubMed, Biosis Previews, Scopus, and Web of Science databases. We will also search electronic grey literature databases for conference proceedings, dissertations, and preprints.

STUDY ELIGIBILITY CRITERIA, STUDY SCREENING AND DATA EXTRACTION

We will include studies that measured BLL in children at any age, assessed full-scale IQ of the same children (concurrent with or subsequent to BLL sample collection) at ages 3-17, and estimated a continuous quantitative relationship between BLL and IQ. We will consider only studies with a central tendency BLL < 10 µg/dL. The title and abstract of each record will be reviewed independently by two authors to determine whether the study in question satisfies the inclusion criteria. The full text of each article remaining after title-abstract screening will be reviewed independently by two authors to determine whether the study in question satisfies the inclusion criteria. Two authors will independently extract study characteristics and data from each included study.

RISK OF BIAS ASSESSMENT

Studies meeting inclusion criteria will be evaluated for risk of bias (RoB) using the Navigation Guide method applied in a previous systematic review of neurodevelopmental effects (Lam et al., 2017), with adaptation to our study question. Each study will be independently evaluated by two review authors.

DATA ANALYSIS AND SYNTHESIS

We intend to conduct a random-effects meta-analysis to summarize the effects of children's exposure to Pb on IQ scores. Additionally, we plan to perform sensitivity analyses using sub-group analyses and/or meta-regression techniques to assess the impact of study design and study population characteristics to examine potential heterogeneity of results across studies. We will assign a confidence level rating (high, moderate, low, or very low) to the effect estimate from the meta-analyses/meta-regressions.

The Role of Temperature in Modifying the Risk of Ozone-Attributable Mortality under Future Changes in Climate: A Proof-of-Concept Analysis

Air pollution risk assessments typically estimate ozone-attributable mortality counts using concentration-response (C-R) parameters from epidemiologic studies that treat temperature as a potential confounder. However, some recent epidemiologic studies have indicated that temperature can modify the relationship between short-term ozone exposure and mortality, which has potentially important implications when considering the impacts of climate change on public health. This proof-of-concept analysis quantifies counts of temperature-modified ozone-attributable mortality using temperature-stratified C-R parameters from a multicity study in which the pooled ozone-mortality effect coefficients change in concert with daily temperature. Meteorology downscaled from two global climate models is used with a photochemical transport model to simulate ozone concentrations over the 21st century using two emission inventories: one holding air pollutant emissions constant at 2011 levels and another accounting for reduced emissions through the year 2040. The late century climate models project increased summer season temperatures, which in turn yields larger total counts of ozone-attributable deaths in analyses using temperature-stratified C-R parameters compared to the traditional temperature confounder approach. This analysis reveals substantial heterogeneity in the magnitude and distribution of the temperature-stratified ozone-attributable mortality results, which is a function of regional variability in both the C-R relationship and the model-predicted temperature and ozone.

Quantitative Characterization of Uncertainty in the Concentration-Response Relationship between Long-Term PM2.5 Exposure and Mortality at Low Concentrations

Extensive epidemiologic evidence supports a linear, no-threshold concentration-response (C-R) relationship between long-term exposure to fine particles (PM_2.5) and mortality in the United States. While examinations of the C-R relationship are designed to assess the shape of the C-R curve, they do not provide the information needed to quantitatively characterize uncertainty at specific PM_2.5 concentrations, which is often needed in the context of risk assessments and benefits analyses. We developed a novel approach, using information that is typically available in published epidemiologic studies, to quantitatively characterize uncertainty at different concentrations along the PM_2.5 concentration distribution. Our approach utilizes the annual mean PM_2.5 concentration and corresponding standard deviation from a published epidemiologic study to estimate the standard deviation of hypothetical PM_2.5 concentration distributions defined at 0.1 μg/m³ increments. The hypothetical distributions are then used to derive adjusted uncertainty estimates in the reported effect estimate at low concentrations (i.e., concentrations lower than the annual mean observed in the study). We demonstrate the application of this method in six individual epidemiologic studies that examined the relationship between long-term PM_2.5 exposure and mortality and were conducted in different geographic locations worldwide and at different PM_2.5 concentrations. This new method allows for a more comprehensive quantitative evaluation of uncertainty in the shape of the C-R relationship between long-term PM_2.5 exposure and mortality at concentrations below the mean annual concentrations observed in current studies.

The estimated change in the level and distribution of PM2.5-attributable health impacts in the United States: 2005-2014

BACKGROUND

Photochemical modeling can predict the level and distribution of pollutant concentrations over time, but is resource-intensive. Partly for this reason, there are few studies exploring the multi-year trajectory of the historical change in fine particle (PM_2.5) levels and associated health impacts in the U.S.

OBJECTIVES

We used a unique dataset of Community Multi-Scale Air Quality (CMAQ) model simulations performed for a subset of years over a decade-long period fused with observations to estimate the change in ambient levels of PM_2.5 across the contiguous U.S. We also quantified the change in PM_2.5-attributable health risks and characterized the level of risk inequality over this period.

METHODS

We estimated annual mean PM_2.5 concentrations in 2005, 2011 and 2014. Using log-linear and logistic concentration-response coefficients we estimated changes in the numbers of deaths, hospital admissions and other morbidity outcomes. Calculating the Gini coefficient and Atkinson Index, we characterized the extent to which PM_2.5 attributable risks were shared equally across the population or instead concentrated among certain subgroups.

RESULTS

In 2005 the estimated fraction of deaths due to PM_2.5 was 6.1%. This estimated value falls to 4.6% by 2014. Every portion of the contiguous U.S. experiences a decline in the risk of PM-related premature death over the 10-year period. As measured by the Gini coefficient and Atkinson index, the level of PM mortality risk is shared more equally in 2014 than in 2005 among all subgroups.

CONCLUSIONS

Between 2005 and 2014, the level of PM_2.5 concentrations fall, and the risk of premature death, declined and became more equitably distributed across the U.S.

Associations between Maternal Water Consumption and Birth Defects in the National Birth Defects Prevention Study (2000-2005)

BACKGROUND

Water and water-based beverages constitute a major part of daily fluid intake for pregnant women, yet few epidemiologic studies have investigated the role of water consumption on birth outcomes.

METHODS

We used data from the National Birth Defects Prevention Study to conduct a case-control study investigating associations between maternal water consumption during pregnancy and birth defects (BD). We used interview data on water consumption during the first trimester of pregnancy in 14,454 cases (major BDs n ≥ 50) and 5,063 controls. Total water consumption was analyzed as a continuous variable and in quartiles. We evaluated the role of dietary quality and sugar sweetened beverage consumption. Logistic regression models were used to assess effects of water consumption on risk of BDs with adjustment for relevant covariates.

RESULTS

Mean daily maternal water consumption among controls was 4.4 eight-ounce glasses. We observed decreases in estimated risk associated with increases in water consumption for several BDs, including neural tube defects (spina bifida), oral clefts (cleft lip), musculoskeletal defects (gastroschisis, limb deficiencies), and congenital heart defects (hypoplastic left heart syndrome, right-sided obstructions, pulmonary valve stenosis). Our results were generally unchanged when an indicator for overall dietary quality was included; however, there was evidence of effect measure modification by heavy consumption of sugar-sweetened beverages for some defects, but not all.

CONCLUSION

These analyses suggest the importance of sufficient water consumption during early pregnancy, above and beyond it being a marker of higher diet quality. Additional analyses are warranted to understand the biological mechanism for this association. Birth Defects Research 109:193-202, 2017. © 2016 Wiley Periodicals, Inc.

A cross-disciplinary evaluation of evidence for multipollutant effects on cardiovascular disease

BACKGROUND

The current single-pollutant approach to regulating ambient air pollutants is effective at protecting public health, but efficiencies may be gained by addressing issues in a multipollutant context since multiple pollutants often have common sources and individuals are exposed to more than one pollutant at a time.

OBJECTIVE

We performed a cross-disciplinary review of the effects of multipollutant exposures on cardiovascular effects.

METHODS

A broad literature search for references including at least two criteria air pollutants (particulate matter [PM], ozone [O₃], oxides of nitrogen, sulfur oxides, carbon monoxide) was conducted. References were culled based on scientific discipline then searched for terms related to cardiovascular disease. Most multipollutant epidemiologic and experimental (i.e., controlled human exposure, animal toxicology) studies examined PM and O₃ together.

DISCUSSION

Epidemiologic and experimental studies provide some evidence for O₃ concentration modifying the effect of PM, although PM did not modify O₃ risk estimates. Experimental studies of combined exposure to PM and O₃ provided evidence for additivity, synergism, and/or antagonism depending on the specific health endpoint. Evidence for other pollutant pairs was more limited.

CONCLUSIONS

Overall, the evidence for multipollutant effects was often heterogeneous, and the limited number of studies inhibited making a conclusion about the nature of the relationship between pollutant combinations and cardiovascular disease.

Exposure to Perfluorinated Alkyl Substances and Health Outcomes in Children: A Systematic Review of the Epidemiologic Literature

Perfluoroalkyl substances (PFAS), chemicals used to make products stain and stick resistant, have been linked to health effects in adults and adverse birth outcomes. A growing body of literature also addresses health effects in children exposed to PFAS. This review summarizes the epidemiologic evidence for relationships between prenatal and/or childhood exposure to PFAS and health outcomes in children as well as to provide a risk of bias analysis of the literature. A systematic review was performed by searching PubMed for studies on PFAS and child health outcomes. We identified 64 studies for inclusion and performed risk of bias analysis on those studies. We determined that risk of bias across studies was low to moderate. Six categories of health outcomes emerged. These were: immunity/infection/asthma, cardio-metabolic, neurodevelopmental/attention, thyroid, renal, and puberty onset. While there are a limited number of studies for any one particular health outcome, there is evidence for positive associations between PFAS and dyslipidemia, immunity (including vaccine response and asthma), renal function, and age at menarche. One finding of note is that while PFASs are mixtures of multiple compounds few studies examine them as such, therefore the role of these compounds as complex mixtures remains largely unknown.

Evaluation of real time polymerase chain reaction assays for confirmation of Neisseria gonorrhoeae in clinical samples tested positive in the Roche Cobas Amplicor assay

OBJECTIVE

Development of a rapid, sensitive, and accurate assay for confirmation of Neisseria gonorrhoeae in clinical samples.

METHOD

Two real time polymerase chain reaction (PCR) assays, developed on the LightCycler for amplification of the N gonorrhoeae cppB gene, were utilised for confirmation of this bacterial pathogen in samples positive by the Roche Cobas Amplicor assay. Performance characteristics of the two assays were compared with other commercial nucleic acid amplification assays, including the Abbott LCx and Roche 16S rRNA tests.

RESULTS

All related Neisseria as well as other bacterial species tested negative by both cppB gene based assays, whereas 120 N gonorrhoeae clinical isolates from various geographical regions gave in positive results. Both assays had a sensitivity of one copy per reaction. 122 clinical samples positive and another 50 samples negative for N gonorrhoeae by Roche Cobas Amplicor were selected from a specimen pool of more than 3000 women tested previously. Overall, 73 of 122 (59.8%) samples were confirmed as positive. The two real time assays had sensitivities of 99% and 100% and specificities of 98% and 100%, respectively. The 16S and LCx assays produced similar results to the real time assays, indicating a similar sensitivity to and specificity of both real time assays.

CONCLUSION

The data from this study highlight the need to confirm N gonorrhoeae positive Cobas Amplicor PCR results as an important part of the testing algorithm of all diagnostic laboratories utilising this assay.