National Air Toxics Assessment Research Articles

Risk of bladder cancer and lymphoma in dogs is associated with pollution indices by county of residence.

Human urothelial cell carcinoma (UCC) and non-Hodgkin lymphoma are considered environmental cancers in people, but less is known about environment risk for UCC and lymphoma in dogs. The objective of this study was to determine whether dogs with these cancers, compared to unaffected control dogs, live in counties with higher tap water contaminants or higher levels of air pollution as measured by the Environmental Protection Agency (EPA) and by National Air Toxics Assessment chemical exposure risk estimates. Dogs with available home addresses from two previously published case-control populations were included: 66 dogs with UCC and 70 unaffected controls; and 56 boxer dogs with lymphoma and 84 unaffected boxer controls. Tap water total trihalomethanes, which are water disinfection by-products, were more than threefold higher in UCC case counties of residence compared to controls (p < .0001), and a higher proportion of dogs with UCC lived in counties exceeding EPA ozone limits (41.8%) compared to controls (13.6% p=.0008). More boxers with lymphoma lived in counties exceeding EPA ozone limits (52.1%) compared to controls (29.0%; p=.018), with higher exposure risk estimates for airborne 1,3-butadiene and formaldehyde (p=.004-.005). These data support the hypothesis that tap water contaminants and airborne environmental pollutants contribute to the risk of both urothelial carcinoma and lymphoma in dogs. If these findings reflect causal relationships, then it is possible that tap water filtration units and more effective air pollution controls could decrease the overall incidence of these cancers in dogs.

Environmental Cadmium Exposure and Odds of Residing in a Breast Cancer Hotspot in Kentucky

BACKGROUND AND AIM: Breast cancer is the most common invasive cancer diagnosed in US women. Cadmium is a carcinogenic heavy metal pollutant found in cigarettes and as an agricultural and industrial byproduct. Studies of cadmium exposure and breast cancer risk have produced mixed results depending upon methodology. We examined environmental cadmium exposure and risk of residing in a breast cancer hotspot in Kentucky. METHODS: Invasive breast cancer cases diagnosed between 1995-2018 were identified from the Kentucky Cancer Registry (n=66,413) and 68 of the 1,114 KY census-tracts were identified as breast cancer clusters using Getis-Ord Gi* for age-standardized rates. Census-tract cadmium concentrations from the 2014 National Air Toxics Assessment interpolated estimations were linked to cases’ residential addresses. Logistic regression was performed to assess the odds of residing in a hotspot across quartiles of cadmium exposure adjusted for individual-level (demographic, reproductive factors, Appalachian residence, insurance, tobacco use) and neighborhood factors (population density, poverty, and physical inactivity). Effect modification by smoking was assessed. RESULTS:4,134 women with breast cancer resided in hotspots (6.2%), which were located in major cities and southeast Kentucky. The mean age was 61 years. Hotspot cases were more likely than other cases to be black, single, uninsured or have public insurance, live in Appalachia, and reside in more densely populated neighborhoods with greater poverty. The odds of living in a hotspot were 4.2-times higher for those who resided in areas with the highest quartile of cadmium exposure compared to those in the lowest (95% CI: 3.6, 4.8; p-trend 0.0001). Results were similar (Q4 vs Q1: OR=4.4 95% CI 3.6, 5.4) among non-smokers. CONCLUSIONS:The observed associations of environmental cadmium exposure and residing in breast cancer hotspots in Kentucky warrant further research with more appropriate epidemiologic study designs. KEYWORDS: heavy metals, cancer and cancer precursors, environmental epidemiology, female, hotspot, air pollution

Associations between birthweight and metals: A real world example of bias amplification in a North Carolina birth cohort

BACKGROUND AND AIM: Air pollution comprises a mixture of gases and small particles, including metals, and has been associated with changes in mean birthweight (BW). Often, studies estimate exposure for a single metal in isolation or multiple metals simultaneously, but rarely evaluate both or examine the potential bias amplification. METHODS: We evaluated census tract level concentrations of 8 metals (arsenic, cadmium, chromium, cobalt, lead, manganese, mercury, and nickel) from the 2011 National Air Toxics Assessment linked with 431,929 infant-mother pairs with births between 2012-2015. Correlations were low to moderate (r0.62) between the metals. The change in BW (grams, g) and 95% confidence interval (CI) per one log-transformed unit of change in concentration was estimated with generalized estimation equation models, adjusted for race/ethnicity, age, marital status, education, and Medicaid status. Exposure to each metal was considered in isolation (IPM) and part of a multiple pollutant model (MPM) of 8 metals (mutually adjusted). RESULTS:We observed the largest decrease in BW for manganese [-8.0g(95% CI:-10.0,-6.1)] in the IPM and for arsenic [-11.5g(-19.0,-4.0)] in the MPM. The greatest increase in BW was observed with cadmium for both models [isolated: 16.5g(11.5,21.56); multiple: 13.7g(6.2,21.2)]. The direction of association changed with arsenic, chromium, and lead between the IPM and MPM. All metals, except manganese, were associated with more than a 10% change in BW per one log-transformed unit change in metal concentration when comparing the results from the IPM to the MPM, suggesting possible bias amplification. CONCLUSIONS:We observed changes in directionality and substantial changes in the magnitude of the associations between IPM and MPM. Evaluating MPM may over or under emphasize associations due to residual confounding or collinearity, leading to bias amplification. Considering the potential for bias amplification and its magnitude is useful in evaluating MPM. This abstract does not reflect EPA policy. KEYWORDS: Birth outcomes, Heavy metals, Multi-pollutant, Mixtures analysis, Air pollution

Observational Study of the Association between Air Cadmium Exposure and Prostate Cancer Aggressiveness at Diagnosis among a Nationwide Retrospective Cohort of 230,540 Patients in the United States

Although studies have investigated cadmium and prostate cancer (PC) incidence and mortality, the role of cadmium in PC progression might be more clinically relevant. In this observational study, we assessed the association between air cadmium exposure and PC aggressiveness, with PC stage defined as metastatic or localized and Gleason grade defined as high (Gleason score ≥ 8) or low (Gleason score ≤ 6) among PC patients from the 2010–2014 US Surveillance, Epidemiology, and End Results database. The 2005 and 2011 National Air Toxics Assessment provided county-level air cadmium concentrations. Results were presented as odds ratios (OR) with 95% confidence intervals (CI) and were calculated using random intercept mixed effects logistic regression, comparing the 80th to 20th percentile of exposure. We adjusted for age, sociodemographic status, smoking prevalence, and overall air quality at the county level, and stratified by race, age, and degree of urbanization. The cohort consisted of 230,540 cases from 493 counties. Strong associations were observed in nonmetropolitan, urban areas: (OR 1.26, CI 1.14–1.39) for metastatic vs. localized and (OR 1.41, CI 1.27–1.57) for high- vs. low-grade PC where 40 million Americans reside. This study may be hypothesis-generating to inform future studies and public health measures.

Using the US National Air Toxics Assessment to benchmark the USEtox inhalation-mediated carcinogenic impacts of air emissions

Using the US National Air Toxics Assessment to benchmark the USEtox inhalation-mediated carcinogenic impacts of air emissions

Bayesian G-Computation for Estimating Impacts of Interventions on Exposure Mixtures: Demonstration With Metals From Coal-Fired Power Plants and Birth Weight.

The importance of studying the health impacts of exposure mixtures is increasingly being recognized, but such research presents many methodological and interpretation difficulties. We used Bayesian g-computation to estimate effects of a simulated public health action on exposure mixtures and birth weights in Milwaukee, Wisconsin, in 2011-2013. We linked data from birth records with census-tract-level air toxics data from the Environmental Protection Agency's National Air Toxics Assessment model. We estimated the difference between observed and expected birth weights that theoretically would have followed a hypothetical intervention to reduce exposure to 6 airborne metals by decommissioning 3 coal-fired power plants in Milwaukee County prior to 2010. Using Bayesian g-computation, we estimated a 68-g (95% credible interval: 25, 135) increase in birth weight following this hypothetical intervention. This example demonstrates the utility of our approach for using observational data to evaluate and contrast possible public health actions. Additionally, Bayesian g-computation offers a flexible strategy for estimating the effects of highly correlated exposures, addressing statistical issues such as variance inflation, and addressing conceptual issues such as the lack of interpretability of independent effects.

An Examination of National Cancer Risk Based on Monitored Hazardous Air Pollutants.

Background:Hazardous air pollutants, or air toxics, are pollutants known to cause cancer or other serious health effects. Nationwide cancer risk from these pollutants is estimated by the U.S. EPA National Air Toxics Assessment. However, these model estimates are limited to the totality of the emissions inventory used as inputs, and further, they cannot be used to examine spatial and temporal trends in cancer risk from hazardous air pollutants.Objectives:To complement model estimates of nationwide cancer risk, we examined trends in cancer risk using monitoring data from 2013 to 2017 across the 27 U.S. National Air Toxics Trends Stations.Methods:For each monitoring site, we estimated cancer risk by multiplying the annual concentration for each monitored pollutant by its corresponding unit risk estimate. We examined the 5-y average (2013–2017) cancer risk across sites and the population levels and demographics within 1-mi of the monitors, as well as changes in estimated cancer risk over time. Finally, we examined changes in individual pollutant concentrations and their patterns of covariance.Results:We found that the total estimated cancer risk is higher for urban vs. rural sites, with the risk at seven urban sites (of 21) above 75 in 1 million. Furthermore, while most pollutant concentrations have not changed over the time period explored, we found 38 site-pollutant combinations that significantly declined and 12 that significantly increased between 2013 and 2017. We also identified a positive correlation between estimated cancer risk and percent of the population within 1-mi of a monitor that is low income.Discussion:Long-term trends show that annual mean concentrations of most measured air toxics have declined. Our evaluation of a more recent snapshot in time finds that most pollutant concentrations have not changed from 2013 to 2017. This analysis of cancer risk based on monitored values provides an important complement to modeled nationwide cancer risk estimates and can further inform future approaches to mitigate risk from exposure to hazardous air pollutants. https://doi.org/10.1289/EHP8044

Estimating future industrial emissions of hazardous air pollutants in the United States using the National Energy Modeling System (NEMS)

Retrospective studies such as the National Air Toxics Assessment have focused on modeling hazardous air pollutant (HAP) concentrations and exposures in the near past; however, future projections of HAPs emissions are relatively unexplored compared to those for greenhouse gases or criteria pollutants, and HAPs are typically not included in energy systems optimization or integrated assessment modeling. In this study, we demonstrate a method that harnesses sector-based emissions data from the US environmentally extended input-output (USEEIO) model and scenario results from the National Energy Modeling System (NEMS) to project HAPs emissions from industrial sectors in United States, disaggregated to 9 regions. The results show that most HAPs have higher projected emissions in 2050 compared to the baseline year when assuming constant emissions intensities per unit of economic output, but lower emissions when trend values for pollution control and technology improvements are incorporated. Regional and temporal patterns are diverse among the 237 HAPs considered. Using formaldehyde as a prominent example, the oil and gas sector is the largest national contributor (49%-77%) to future formaldehyde emissions across scenarios. Overall, this method enables projections of industrial HAPs emissions, aligned with official NEMS scenarios, that can be used in assessments of future air quality and potential health impacts from HAPs.

Satellite Formaldehyde to Support Model Evaluation.

Formaldehyde (HCHO), a known carcinogen classified as a hazardous pollutant by the United States Environmental Protection Agency (U.S. EPA), is measured through monitoring networks across the U.S. Since these data are limited in spatial and temporal extent, model simulations from the U.S. EPA Community Multiscale Air Quality (CMAQ) model are used to estimate ambient HCHO exposure for the EPA National Air Toxics Assessment (NATA). Here, we employ satellite HCHO retrievals from the Ozone Monitoring Instrument (OMI)-the NASA retrieval developed by the Smithsonian Astrophysical Observatory (SAO), and the European Union Quality Assurance for Essential Climate Variables (QA4ECV) retrieval-to evaluate three CMAQ configurations, spanning the summers of 2011 and 2016, with differing biogenic emissions inputs and chemical mechanisms. These CMAQ configurations capture the general spatial and temporal behavior of both satellite retrievals, but underestimate column HCHO, particularly in the western U.S. In the southeastern U.S., the comparison with OMI HCHO highlights differences in modeled meteorology and biogenic emissions even with differences in satellite retrievals. All CMAQ configurations show low daily correlations with OMI HCHO (r = 0.26 - 0.38), however, we find higher monthly correlations (r = 0.52 - 0.73), and the models correlate best with the OMI-QA4ECV product. Compared to surface observations, we find improved agreement over a 24-hour period compared to afternoon-only, suggesting daily HCHO amounts are captured with more accuracy than afternoon amounts. This work highlights the potential for synergistic improvements in modeling and satellite retrievals to support near-surface HCHO estimates for the NATA and other applications.

Children’s exposure to vehicular air pollution in the United States: environmental injustices at the intersection of race/ethnicity and language

ABSTRACT Children’s exposure to hazardous air pollutants (HAPs) from vehicular sources negatively affects their development and health. Using an intersectional approach, we examined differences in exposure based on race/ethnicity and language used at children’s homes. We linked 2014 HAP data from the Environmental Protection Agency’s (EPA) National Air Toxics Assessment with children’s sociodemographic data from the Early Childhood Longitudinal Study, Kindergarten Class of 2010–2011. We analyzed residential exposures for 13,150 US third-grade children (2013–2014) using generalized estimating equations. Results show that Hispanic and Black children faced disproportionately high exposures to vehicular HAPs as compared to White children, and children from non-English-speaking homes (regardless of race/ethnicity) experienced disproportionate exposure when compared to children from English-speaking homes. Among children who did not speak English at home, Black children were significantly more exposed than White children. White, Asian, and Hispanic children from non-English speaking homes faced disproportionate exposures when compared to their counterparts from English-speaking homes; we did not find the same for Black children. Our intersectional approach illuminates how children’s multiple identities shaped their differential exposure to vehicular air pollution, and illustrates the importance of considering within-group inequalities and English-language usage when examining distributional environmental injustices.

An Ecological Evaluation of Vinyl Chloride Exposure and Liver Cancer Incidence and Mortality in Texas.

The goal of this analysis was to evaluate the association between county-level ambient vinyl chloride (VC) and county-level liver cancer incidence and mortality rates in Texas. Modeled county-level ambient VC data were obtained from the National Air Toxics Assessment. Age-adjusted county-level liver cancer incidence rates were abstracted from the Texas Cancer Registry and age-standardized county-level liver cancer mortality rates were obtained from the peer-reviewed literature. Multivariable imputation was utilized to impute incidence rates in counties with suppressed liver cancer incidence rates. Negative binomial and Poisson regression models were utilized to evaluate the association between county-level ambient VC and county-level liver cancer incidence and mortality rates, respectively, adjusted for county-level heavy drinking prevalence, hepatitis mortality rates, median income, and race (percent Hispanic). County-level ambient VC was not associated with county-level liver cancer incidence or mortality rates. Specifically, when compared to the lowest tertile of ambient VC, the middle (relative risk [RR]: 1.06, 95% confidence interval [CI]: 0.95–1.19) and highest (RR: 1.03, 95% CI: 0.90–1.17) tertiles of ambient VC were not associated with liver cancer incidence. Similarly, county-level ambient VC in the middle (RR: 0.95, 95% CI: 0.85–1.05) and highest (RR: 0.93, 95% CI: 0.82–1.05) tertiles were not associated with liver cancer mortality. This analysis suggests that county-level ambient VC is not associated with liver cancer incidence or mortality in Texas. Our study provides novel results regarding liver cancer risk from low-level non-occupational exposure to ambient VC.

Convergence of COVID-19 and chronic air pollution risks: Racial/ethnic and socioeconomic inequities in the U.S

Recent research suggests greater COVID-19 prevalence in areas burdened with higher exposure to chronic air pollution, but previous studies have not examined if socially disadvantaged populations are more likely to reside in communities located at the convergence of both COVID-19 and air pollution health risks. This article presents a national scale U.S. study that investigates whether racial/ethnic minorities, socioeconomically deprived residents, and other vulnerable groups are significantly overrepresented in counties where significantly higher COVID-19 incidence spatially coincides with higher respiratory health risks from outdoor exposure to hazardous air pollutants (HAPs). COVID-19 data from the Johns Hopkins Center for Systems Science and Engineering database are linked to respiratory risk estimates from the U.S. Environmental Protection Agency's National Air Toxics Assessment and variables from the 2018 American Community Survey. Bivariate local measures of spatial association are implemented to identify county clusters representing relationships between COVID-19 incidence rate and respiratory risk from HAP exposure. Socio-demographic characteristics of these clusters are compared using bivariate statistical tests and multivariable generalized estimating equations. Counties where greater COVID-19 incidence coincides significantly with higher HAP respiratory risk contain disproportionately higher percentages of non-Hispanic Black, socioeconomically deprived, and uninsured residents than all other U.S. counties, after controlling for spatial clustering, population density, older age, and other contextual factors. These significant socio-demographic inequities represent an important starting point for more detailed investigations of places facing the double burden of elevated COVID-19 prevalence and air pollution exposure, and also emphasize the urgent need to develop mitigation strategies for addressing both COVID-19 and chronic air pollution in socially vulnerable communities.

Contribution of mobile sources to secondary formation of carbonyl compounds

ABSTRACT In the 2014 National Air Toxics Assessment (NATA), the carbonyl compounds formaldehyde and acetaldehyde were identified as key cancer risk drivers and acrolein was identified as one of the three air toxics that drive most of the noncancer risk. In this assessment, averaged across the Continental United States, about 75% of ambient formaldehyde and acetaldehyde, and about 18% of acrolein, is formed secondarily. This study was conducted to estimate the potential contribution to these secondarily formed carbonyl compounds from mobile sources. To develop such estimates, we conducted several CMAQ runs, where emissions are set to zero for different mobile source sectors, to determine their potential contribution. Although zeroing out emissions from an individual sector can offer only a rough approximation of how the sector might contribute to overall secondary concentrations, our results suggest that across the U. S., mobile sources contribute about 6–18% to secondary formaldehyde, 0–10% to secondary acetaldehyde, and 0–70% to secondary acrolein, depending on location. Implications: Photochemical modeling of carbonyl compounds was conducted with emissions set to zero for various mobile source sectors to determine their contribution to secondary concentrations. Results indicated mobile sources contributed to total and secondary concentrations of formaldehyde, acetaldehyde, and acrolein in many locations across the U.S. with acrolein the dominant contributor in some locations. However, biogenic sources dominated secondary formaldehyde and acetaldehyde, and fires dominated secondary acrolein.

Airborne Metal Exposure and Risk of Hypertension in the Sister Study

Background Hypertension-related disease burden is a major challenge globally, and an estimated 1.56 billion adults will be affected by hypertension by 2025. Environmental factors, such as metals, could be risk factors for hypertension. However, the relationship between airborne metals and hypertension is rarely studied. Methods 49,876 women in the Sister Study cohort were included in this study. Census-tract airborne metal concentrations (arsenic, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, selenium, and antimony) from the 2005 National Air Toxics Assessment database were linked to participants’ enrollment residential address. Hypertension was defined as high systolic (≥140) or diastolic (≥90) blood pressure (measured by trained examiners at enrollment) or taking anti-hypertensive medication. Logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between individual metals and hypertension, with and without co-adjustment for other metals. Quantile-based g-computation was used to estimate the joint effect of the overall metal mixture. Results Risk of hypertension was higher among women of higher exposure to arsenic (OR quartile 4 vs 1=1.11, 95%CI=1.05,1.18), lead (OR quartile 4 vs 1=1.11, 95%CI=1.04,1.17), chromium (OR quartile 4 vs 1=1.07, 95%CI=1.01,1.14), cobalt (OR quartile 4 vs 1=1.07, 95%CI=1.01,1.14), and manganese (OR quartile 4 vs 1=1.07, 95%CI=1.01,1.13). Selenium was associated with lower risk of hypertension (OR quartile 4 vs 1=0.92, 95%CI=0.87,0.98). Results were similar with mutual adjustment for other metals. Race modified the associations, with greater ORs in non-white participants compared with non-Hispanic white participants. The joint effect of increasing all ten metals by one quartile was 1.04 (95%CI=0.98,1.10). Conclusion We found that living in areas of higher exposure to arsenic, lead, chromium, cobalt, and manganese was related to higher risk of hypertension, whereas exposure to selenium was inversely related to the risk of hypertension.

Evaluating Associations between Mixtures of Hazardous Air Pollutants and Birth Weight

Background: Prenatal exposure to ambient air pollutants has been associated with both reduced and increased birth weight (BW) in epidemiological studies. Many studies focus on the association of a single pollutant with BW rather than a mixture of pollutants.Methods: We compared two approaches for identifying prenatal exposure to hazardous air pollutants (HAPs), (1) each HAP and (2) mixture of 15 HAPs together, as predictors to changes in BW. We evaluated 15 HAPs at the census tract level from the 2011 National Air Toxics Assessment and linked with 735,507 infant-mother pairs in North Carolina with birth years between 2006-2011. We used random intercept mixed effects regression models to estimate the change in BW in grams (g), presented as β estimates and 95% confidence intervals (CI), adjusted for maternal race/ethnicity, age, marital status, and medicaid status.Results: Cyanide (CN), mercury, and cadmium were identified as the strongest individual predicators, with a consistent reduction in BW across all HAPs (range β: -3995.31g for CN to -1.34g for methyl-tert-butyl-ether). In the HAPs mixture, CN and xylene were the strongest predictors of increased BW (β:1908.65g CN and 213.91g for xylene) whereas toulene and benzene (β: -174.13g and -150.87g, respectively) were the strongest predictors for reduced BW. In the individual adjusted models, CN showed the strongest change in BW with a reduction of -1242.37g (-1939.27, -545.47). When analyzing HAPs as a mixture, in the adjusted models, toulene had the greatest change in BW with a reduction of -87.62g (-120.65, -54.59).Conclusions: Comparing the two approaches, CN was the only consistent HAP identified as a predictor for change in BW. Evaluating exposure to individual pollutants in relation to BW may be neglecting the synergistic and/or antagonistic effects and underlying confounding when there are concurrent exposures to multiple pollutants. This abstract does not reflect EPA policy.

Association between air cadmium exposure and prostate cancer aggressiveness at diagnosis

Background: There is conflicting evidence of an association between cadmium exposure and prostate cancer (PC) mortality in the general population. Since most PCs are indolent, low grade and low stage tumors may mask associations. We assessed associations between ambient exposure to air cadmium and PC aggressiveness at diagnosis in the US.Methods: We collected outcome data from the 2010 – 2014 Surveillance, Epidemiology, and End Results (SEER). Aggressiveness at diagnosis was defined as stage categorized as either metastatic or localized and Gleason grade as high or low. The 2011 National Air Toxics Assessment database provided county-level air cadmium concentrations. Odds Ratios (OR) and 95% confidence intervals (CI) were estimated using multivariable logistic regression comparing the 80th to 20th percentile of cadmium exposure and adjusted for age at diagnosis, sociodemographic status, smoking prevalence and overall air quality at the county-level and were stratified by race and degree of urbanization defined by Rural-Urban Continuum Codes (RUCC).Results: The study cohort consisted of 230,540 cases from 493 counties. Overall, higher air cadmium exposure was associated with an increased likelihood of metastatic PC compared to localized PC (OR 1.02, CI 1.01–1.03) and higher Gleason grade at diagnosis (OR 1.01, CI 1.00–1.02). The strongest associations were observed in nonmetropolitan areas with urban populations of 20,000 to 250,000 (RUCC2 counties): (OR 1.26, CI 1.14–1.39) for metastatic vs. localized PC, and (OR 1.36, CI 1.25–1.49) for high vs. low grade cases.Discussion: The strongest associations between air cadmium exposure and tumor aggressiveness were found among nonmetropolitan counties, where 40 million Americans reside. Research is necessary to identify air cadmium pollution sources in these communities and to rule out additional confounding factors. Air cadmium exposure in the general population may be a more important factor in prostate cancer and its progression than previously recognized.

Airborne metals exposure and risk of hypertension in the Sister Study

BackgroundHypertension-related disease burden is a major challenge globally, with an estimated 1.56 billion adults expected to be affected by hypertension by 2025. Environmental factors, such as metals, could be risk factors for hypertension, but the relationship between airborne metals and hypertension is rarely studied. MethodsCensus-tract airborne metal concentrations (arsenic, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, selenium, and antimony) from the U.S. Environmental Protection Agency 2005 National Air Toxics Assessment database were linked to enrollment residential addresses of 47,595 women in the Sister Study cohort. Hypertension was defined as high systolic (≥140 mm Hg) or diastolic (≥90 mm Hg) blood pressure measured by trained examiners at enrollment or taking anti-hypertensive medications. Multivariable log binomial regression was used to estimate adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) for the association between individual metals and hypertension, with and without co-adjustment for other metals. Quantile-based g-computation was used to estimate the joint effect of the overall metal mixture. ResultsComparing the highest to lowest quartiles, risk of hypertension was higher among women with higher residential exposure to arsenic (PR = 1.05, 95%CI = 1.02,1.09), lead (PR = 1.04, 95%CI = 1.01,1.08), chromium (PR = 1.03, 95%CI = 1.00,1.06), cobalt (PR = 1.03, 95%CI = 1.00,1.07), and manganese (PR = 1.03, 95%CI = 1.00,1.06). Selenium was associated with lower risk of hypertension (PR = 0.96, 95%CI = 0.93,0.99). Results were similar with mutual adjustment for all other metals. The associations varied by race/ethnicity, with greater PRs in other races/ethnicities (Hispanic, black, and other participants) compared to non-Hispanic white participants. The joint effect of a quartile increase in exposure to all the metals was 1.02 (95%CI = 0.99,1.04). ConclusionWe found that living in areas of higher exposure to arsenic, lead, chromium, cobalt, and manganese was related to higher risk of hypertension, whereas living in areas with higher selenium was inversely related to the risk of hypertension.

Hazardous air pollutant exposure as a contributing factor to COVID-19 mortality in the United States

To date, COVID-19 has claimed more than 100 000 American lives. Early inquiry suggests preexisting conditions are key risk factors contributing to COVID-19 mortality and air pollution exposure could exacerbate this relationship. Building on prior research linking deaths from respiratory viruses to air pollution exposures, we investigate how 2014 National Air Toxics Assessment hazardous air pollutants (HAPs) respiratory hazard quotient and respiratory hazard index are related to COVID-19 mortality. Our focus on HAPs builds upon the knowledge base linking poor air quality to COVID-19 mortality, since most (if not all) earlier studies only include criteria pollutants. Herein, we examine the relationship between HAP exposure and US-based COVID-19 mortality, while controlling for socioeconomic status, population health indicators, and exposure to PM2.5 and ozone. We fit county-level negative binomial mixed models, predicting COVID-19 mortality as a function of HAP respiratory toxicity levels and relevant covariates. We include models for combined exposure to HAPs, as well as for specific pollutants. We find that an increase in the respiratory hazard index is associated with a 9% increase in COVID-19 mortality. Although differing in magnitude, this association holds for individual HAPs acetaldehyde, and diesel PM. These findings help us to understand variation in US-based COVID-19 mortality rates, reinforce existing research linking air pollution to mortality, and emphasize the importance of regulatory efforts to limit air pollution exposure risk.

Abstract PR07: Latent class analysis of multipollutant exposure

Abstract Recent work suggests that air pollutants, toxic chemicals, and other environmental exposures negatively impact health in a synergistic way. In order to measure and understand this impact, we propose a latent class mixture model of multipollutant exposure. Our model incorporates the joint behavior of individual pollutants that inform overall exposure levels and provides clear measures of multipollutant exposure. We identify low, medium, and high levels of joint exposure to volatile organic compounds (VOC), particulate matter (PM), and heavy metals (HM), and present estimated class-membership for each census tract in the US (&amp;gt;76,000). We use publicly available data from the EPA, including the National Air Toxics Assessment (NATA), measured at the census tract level. Model results indicate that mixtures of 5 levels of VOC, 2 levels of PM, and 4 levels of HM best fit data at the national level. Twelve percent of U.S. census tracts are in the highest levels of all 3 categories of pollutants. While frequently observed in metropolitan areas, rural areas are sometimes detected at the highest levels, as well. Our next focus is to incorporate spatial correlations as well as linkages to our earlier latent model work on socioeconomic status (SES). Taken together, these extensions can then be incorporated into a holistic, exposome modeling framework for estimating disparities in cancer survival. This abstract is also being presented as Poster A31. Citation Format: Alexandra Larsen, Viktoria Kolpacoff, Kara McCormack, Terry Hyslop. Latent class analysis of multipollutant exposure [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr PR07.

Abstract A04: Geographic and socioeconomic disparities in exposure to carcinogenic air toxics in St. Louis, Missouri

Abstract Background: Residential segregation has been associated with exposure to hazardous air pollutants in the United States. However, few studies have utilized spatial approaches for measuring segregation at the neighborhood level. We used spatial epidemiologic methods to examine associations between neighborhood characteristics and exposure to carcinogenic air toxics in St. Louis, Missouri. Methods: We obtained cancer risk data from the United States Environmental Protection Agency’s 2011 National Air Toxics Assessment and used a geographic information system to identify air toxic hotspots in the St. Louis region. Census tract-level data from 2010 to 2014 from the American Community Survey were used to develop isolation measures that capture spatial patterns of residential segregation within the St. Louis region. In the current analysis, we developed a black isolation measure and a poverty isolation measure as indicators of spatial separation from other racial/ethnic populations and from nonpoverty populations, respectively. Relative risks were used to evaluate relationships between neighborhood characteristics and air toxic hotspots. Results: The distribution of carcinogenic air toxics varied throughout the St. Louis region and clustered near interstate highways. Neighborhood-level measures of the racial and economic isolation were associated with air toxic hotspots. Census tracts in the highest quartile of black isolation were eight times more likely to be located in an air toxic hotspot than tracts in the lowest quartile (RR = 8.1, 95% Confidence Interval = 5.9-12.1). Census tracts in the highest quartile of economic isolation were five times more likely to be located in an air toxic hotspot than tracts in the lowest quartile (RR = 5.0 95% Confidence Interval = 3.3-9.4). Conclusions: There are geographic and socioeconomic disparities in exposure to carcinogenic air toxics in the St. Louis region. The identification of local air toxic hotspots can inform public health efforts to eliminate disparities in exposure to air toxics. Citation Format: Christine Ekenga, Cheuk Yui Yeung, Masayoshi Oka. Geographic and socioeconomic disparities in exposure to carcinogenic air toxics in St. Louis, Missouri [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A04.