The effects of the historical practice of residential redlining in the United States on recent temporal trends of air pollution near New York City schools

Association Between Air Pollution, Neighborhood Opportunity, and Pediatric Intensive Care Unit Admissions in Acute Respiratory Illness

This retrospective study examined 673 children admitted to a single pediatric intensive care unit (PICU) for associations between PM2.5 exposure, neighborhood deprivation, and PICU length of stay (LOS) for acute respiratory illness. Higher PM2.5 was correlated with longer LOS, especially during respiratory season. Child Opportunity Index was not independently associated with LOS, but inclusion of this marker strengthened the association between PM2.5 and LOS.

Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada

BACKGROUND

Socioeconomic inequities in outdoor ultrafine particles (UFP) and black carbon (BC) are understudied in Canada, where metropoles like Montreal and Toronto feature distinct sociodemographic diversity and urban characteristics compared to U.S. cities.

METHODS

We collected vulnerability indicators, including social, economic, household composition, and immigration status, at the dissemination area level for Montreal and Toronto using data from the 2006 and 2021 Canadian Census of Population. Areas were classified as disadvantaged, intermediate, or advantaged following K-means clustering analysis. We aggregated and calculated population-weighted average concentrations of BC and UFP, and UFP size at the dissemination area and cluster levels using high-resolution exposure surfaces, derived from year-long mobile monitoring campaigns conducted in each city during 2020-2021. Final exposure surfaces were generated by integrating predictions from land-use regression models and deep convolutional neural network models.

FINDINGS

We observed high within-city variations in aggregated air pollutant levels, with higher outdoor BC and UFP concentrations and smaller UFP sizes in areas near local sources such as major roads, railways, airports, and densely populated regions. Advantaged areas experienced the lowest median UFP concentrations in both Montreal (10,707 pt/cm3) and Toronto (10,988 pt/cm3), as well as the lowest BC concentrations (650 ng/m3) in Montreal. The highest median UFP concentrations were observed in intermediate areas in Montreal (15,709 pt/cm3) and disadvantaged areas in Toronto (12,228 pt/cm3). Conversely, the highest BC concentrations were observed in disadvantaged and intermediate areas in Montreal (805-811 ng/m3), and disadvantaged and advantaged areas in Toronto (1,228-1,252 ng/m3). Notably, high priority areas for the double burden of vulnerability and high BC and UFP concentrations were located near air pollutants local emission sources.

INTERPRETATION

Our findings highlight the importance of prioritizing exposure mitigation for populations residing near local sources and to understand contextual factors influencing inequities across cities and pollutants.

Redlining in New York City: impacts on particulate matter exposure during pregnancy and birth outcomes

BACKGROUND

Evidence suggests historical redlining shaped the built environment and health outcomes in urban areas. Only a handful of studies have examined redlining's association with air pollution and adverse birth outcomes in New York City (NYC). Additionally, no NYC-specific studies have examined the impact of redlining on birth weight.

METHODS

This longitudinal cohort study analysed data from the National Institute of Health Environmental Influences on Child Health Outcomes Programme to investigate the extent to which maternal residence in a historically redlined neighbourhood is associated with fine particulate matter (PM2.5) exposure during pregnancy using multivariable regression models. Additionally, we examined how maternal residence in a historically redlined neighbourhood during pregnancy influenced birth weight z-score, preterm birth and low birth weight.

RESULTS

Our air pollution model showed that living in a historically redlined census tract or an ungraded census tract was associated with increased PM2.5 exposure during pregnancy. We also found living in a historically redlined census tract or an ungraded census tract was associated with a lower birth weight z-score. This finding remained significant when controlling for individual and census tract-level race, ethnicity and income. When we controlled PM2.5 in our models assessing the relationship between redlining grade and birth outcome, our results did not change.

DISCUSSION

Our study supports the literature linking redlining to contemporary outcomes. However, our research in ungraded tracts suggests redlining alone is insufficient to fully explain inequality in birth outcomes and PM2.5 levels today.

Effects of Air Pollution on Respiratory Events and Pain Crises among Children with Sickle Cell Disease in New York City

Rationale: The disease burden of sickle cell disease (SCD) is highest among U.S. Black and Hispanic populations, which are often disproportionately represented in communities with poor air quality. There are limited data on the effects of air pollution exposure and social environmental factors on health outcomes in children with SCD. Objectives: The objectives of our study were to examine the associations between air pollution exposure and acute respiratory and vaso-occlusive pain crises (VOCs) and to further study the associations when stratifying by asthma status and neighborhood disadvantages. Methods: We conducted a retrospective study, collecting data on outpatient sick and emergency department visits, hospital admissions for respiratory events (i.e., respiratory tract infections, asthma exacerbation, acute chest syndrome), and hospitalizations for VOCs among children with SCD in a tertiary care center in New York City from 2015 to 2018. Modeled data from the New York City Community Air Survey data using home addresses' estimated street-level annual average exposure to air pollution (i.e., black carbon, particulate matter with an aerodynamic diameter ≤2.5 μm, and nitrogen dioxide). The area deprivation index (ADI) continuous national ranking percentile (1-100) was used, representing a composite index for neighborhood-level social disadvantage. We further dichotomized study participants at the upper tertile (high vs. low ADI). Multivariable Poisson regression in generalized estimating equation models were used to estimate relative risks (RRs) after adjusting for potential covariates. Results: A total of 114 children with SCD were included in this study and had between one and four annual repeated measures of annual average air pollutants over a total of 425 visits. Overall, there were no significant associations between air pollution levels and acute respiratory pain crises and VOCs among children with SCD and when stratified by asthma status. We found significant interactions between air pollution levels and the continuous ADI variable on respiratory outpatient and frequent respiratory outpatient/ED visits (P < 0.1). When stratified by high ADI, increased exposure to particulate matter with an aerodynamic diameter ≤2.5 μm was significantly associated with more frequent respiratory outpatient/emergency department visits among children residing in higher ADI neighborhoods (RR [95% confidence interval], 1.13 [1.01, 1.27]; P < 0.05), but not among those in lower ADI neighborhoods. Increased exposure to nitrogen dioxide was associated with more outpatient respiratory events for children in high ADI neighborhoods (RR [95% confidence interval], 2.74 [1.24, 6.08]; P < 0.05) compared with low ADI neighborhoods. Conclusions: Air pollution exposures increased respiratory complications among children with SCD living in deprived neighborhoods.

Research Priorities in Pediatric Asthma Morbidity: Addressing the Impacts of Systemic Racism on Children with Asthma in the United States. An Official American Thoracic Society Workshop Report

Background: In the United States, Black and Latino children with asthma are more likely than White children with asthma to require emergency department visits or hospitalizations because of an asthma exacerbation. Although many cite patient-level socioeconomic status and access to health care as primary drivers of disparities, there is an emerging focus on a major root cause of disparities-systemic racism. Current conceptual models of asthma disparities depict the historical and current effects of systemic racism as the foundation for unequal exposures to social determinants of health, environmental exposures, epigenetic factors, and differential healthcare access and quality. These ultimately lead to biologic changes over the life course resulting in asthma morbidity and mortality. Methods: At the 2022 American Thoracic Society International Conference, a diverse panel of experts was assembled to identify gaps and opportunities to address systemic racism in childhood asthma research. Panelists found that to examine and address the impacts of systemic racism on children with asthma, researchers and medical systems that support biomedical research will need to 1) address the current gaps in our understanding of how to conceptualize and characterize the impacts of systemic racism on child health, 2) design research studies that leverage diverse disciplines and engage the communities affected by systemic racism in identifying and designing studies to evaluate interventions that address the racialized system that contributes to disparities in asthma health outcomes, and 3) address funding mechanisms and institutional research practices that will be needed to promote antiracism practices in research and its dissemination. Results: A thorough literature review and expert opinion discussion demonstrated that there are few studies in childhood asthma that identify systemic racism as a root cause of many of the disparities seen in children with asthma. Community engagement and participation in research studies is essential to design interventions to address the racialized system in which patients and families live. Dissemination and implementation studies with an equity lens will provide the multilevel evaluations required to understand the impacts of interventions to address systemic racism and the downstream impacts. To address the impacts of systemic racism and childhood asthma, there needs to be increased training for research teams, funding for studies addressing research that evaluates the impacts of racism, funding for diverse and multidisciplinary research teams including community members, and institutional and financial support of advocating for policy changes based on study findings. Conclusions: Innovative study design, new tools to identify the impacts of systemic racism, community engagement, and improved infrastructure and funding are all needed to support research that will address impacts of systemic racism on childhood asthma outcomes.

Household air pollution disparities between socioeconomic groups in Chicago

Purpose: To assess household air pollution levels in urban Chicago households and examine how socioeconomic factors influence these levels. Methods: We deployed wireless air monitoring devices to 244 households in a diverse population in Chicago to continuously record household fine particulate matter (PM2.5) concentration. We calculated hourly average PM2.5 concentration in a 24-hour cycle. Four factors-race, household income, area deprivation, and exposure to smoking-were considered in this study. Results: A total of 93085 h of exposure data were recorded. The average household PM2.5 concentration was 43.8 μg m-3. We observed a significant difference in the average household PM2.5 concentrations between Black/African American and non-Black/African American households (46.3 versus 31.6 μg m-3), between high-income and low-income households (18.2 versus 52.5 μg m-3), and between smoking and non-smoking households (69.7 versus 29.0 μg m-3). However, no significant difference was observed between households in less and more deprived areas (43.7 versus 43.0 μg m-3). Implications: Household air pollution levels in Chicago households are much higher than the recommended level, challenging the hypothesis that household air quality is adequate for populations in high income nations. Our results indicate that it is the personal characteristics of participants, rather than the macro environments, that lead to observed differences in household air pollution.

NPCC4: New York City climate risk information 2022-observations and projections

New York City (NYC) faces many challenges in the coming decades due to climate change and its interactions with social vulnerabilities and uneven urban development patterns and processes. This New York City Panel on Climate Change (NPCC) report contributes to the Panel's mandate to advise the city on climate change and provide timely climate risk information that can inform flexible and equitable adaptation pathways that enhance resilience to climate change. This report presents up-to-date scientific information as well as updated sea level rise projections of record. We also present a new methodology related to climate extremes and describe new methods for developing the next generation of climate projections for the New York metropolitan region. Future work by the Panel should compare the temperature and precipitation projections presented in this report with a subset of models to determine the potential impact and relevance of the "hot model" problem. NPCC4 expects to establish new projections-of-record for precipitation and temperature in 2024 based on this comparison and additional analysis. Nevertheless, the temperature and precipitation projections presented in this report may be useful for NYC stakeholders in the interim as they rely on the newest generation of global climate models.

Outdoor Air Pollution and Pediatric Respiratory Disease

Outdoor air pollution is ubiquitous, and no safe level of exposure has been identified for the most common air pollutants such as ozone and particle pollution. Children are uniquely more susceptible to the harms of outdoor air pollution, which can cause and exacerbate respiratory disease. Although challenging to identify the effects of outdoor air pollution on individual patients, understanding the basics of outdoor air pollution is essential for pediatric respiratory health care providers. This review covers basic information regarding outdoor air pollution, unique considerations for children, mechanisms for increased susceptibility, and association with incident and exacerbation of respiratory disease in children.

Prenatal exposure to persistent and non-persistent chemical mixtures and associations with adverse birth outcomes in the Atlanta African American Maternal-Child Cohort

BACKGROUND

African Americans (AAs) experience higher rates of preterm birth and fetal growth restriction relative to other pregnant populations. Differential in utero exposure to environmental chemicals may partially explain these health disparities, as AAs are disproportionately exposed to environmental hazards.

OBJECTIVE

We examined the individual and mixture effects of non-persistent chemicals and persistent organic pollutants (POPs) on gestational age at birth and birthweight for gestational age z-scores within a prospective cohort of pregnant AAs.

METHODS

First-trimester serum and urine samples obtained from participants within the Atlanta African American Maternal-Child cohort were analyzed for 43 environmental chemicals, including per-and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides, pyrethroid insecticides, phthalates, bisphenol A, nicotine, and the primary metabolite of delta-9-tetrahydrocannabinol. Linear regression was used to estimate individual associations between chemicals and gestational age and birthweight z-scores (N ranging from 107 to 523). Mixture associations were estimated using quantile g-computation, principal component (PC) analyses, and hierarchical Bayesian kernel machine regression among complete cases (N = 86).

RESULTS

Using quantile g-computation, increasing all chemical exposures by one quantile was modestly associated with a reduction in gestational age (mean change per quartile increase = -0.47, 95% CI = -1.56, 0.61) and birthweight z-scores (mean change per quartile increase = -0.49, 95% CI = -1.14, 0.15). All PCs were associated with a reduction in birthweight z-scores; associations were greatest in magnitude for the two PCs reflecting exposure to combined tobacco, insecticides, PBDEs, and phthalates. In single pollutant models, we observed inconsistent and largely non-significant associations.

SIGNIFANCE

We conducted multiple targeted exposure assessment methods to quantify levels of environmental chemicals and leveraged mixture methods to quantify their joint effects on gestational age and birthweight z-scores. Our findings suggest that prenatal exposure to multiple classes of persistent and non-persistent chemicals is associated with reduced gestational age and birthweight z-scores in AAs.

IMPACT

African Americans (AAs) experience higher rates of preterm birth and fetal growth restriction relative to other pregnant populations. Differential in utero exposure to environmental chemicals may partially explain these health disparities, as AAs are disproportionately exposed to environmental hazards. In the present study, we analyzed serum and urine samples for levels of 43 environmental chemicals. We used quantile g-computation, principal component analysis, and BKMR to assess associations between chemical exposure mixtures and adverse birth outcomes. Our findings suggest that prenatal exposure to multiple classes of chemicals is associated with reduced birthweight z-scores, a proxy for fetal growth, in AAs.

Historic redlining and health outcomes: A systematic review

OBJECTIVE

The purpose of this systematic review was to synthesize the existing literature on the associations between historic redlining and modern-day health outcomes across the lifespan.

METHOD

This review searched PubMed and CINAHL for peer-reviewed, data-based articles examining the relationship between historic redlining and any health outcome. Articles were appraised using the JBI critical appraisal checklist. The results were synthesized using a narrative summary approach.

RESULTS

Thirty-six articles were included and focused on various health outcomes, including cardiovascular outcomes, breast cancer incidence and mortality, firearm injury or death, birth-related outcomes, and asthma outcomes. Most of the included articles (n = 31; 86%) found significant associations between historic redlining and adverse health outcomes such as increased cardiovascular disease, higher rates of preterm births, increased cancer incidence, reduced survival time after breast cancer diagnosis, and increased firearm injury incidence.

DISCUSSION

This review demonstrates the persistent effect of historic redlining on individuals' health. Public health nurses should recognize redlining as a form of structural racism when caring for affected communities and should advocate for policies and programs that advance health equity. Nurse researchers should develop and test multilevel interventions to address systemic racism and improve health outcomes in communities affected by redlining.

Long-term exposure to ambient fine particulate matter constituents and mortality from total and site-specific gastrointestinal cancer

BACKGROUND

Ambient fine particulate matter (PM2.5) exposure has been associated with an increased risk of gastrointestinal cancer mortality, but the attributable constituents remain unclear.

OBJECTIVES

To investigate the association of long-term exposure to PM2.5 constituents with total and site-specific gastrointestinal cancer mortality using a difference-in-differences approach in Jiangsu province, China during 2015-2020.

METHODS

We split Jiangsu into 53 spatial units and computed their yearly death number of total gastrointestinal, esophagus, stomach, colorectum, liver, and pancreas cancer. Utilizing a high-quality grid dataset on PM2.5 constituents, we estimated 10-year population-weighted exposure to black carbon (BC), organic carbon (OC), sulfate, nitrate, ammonium, and chloride in each spatial unit. The effect of constituents on gastrointestinal cancer mortality was assessed by controlling time trends, spatial differences, gross domestic product (GDP), and seasonal temperatures.

RESULTS

Overall, 524,019 gastrointestinal cancer deaths were ascertained in 84.77 million population. Each interquartile range increment of BC (0.46 μg/m3), OC (4.56 μg/m3), and nitrate (1.41 μg/m3) was significantly associated with a 27%, 26%, and 34% increased risk of total gastrointestinal cancer mortality, respectively, and these associations remained significant in PM2.5-adjusted models and constituent-residual models. We also identified robust associations of BC, OC, and nitrate exposures with site-specific gastrointestinal cancer mortality. The mortality risk generally displayed increased trends across the total exposure range and rose steeper at higher levels. We did not identify robust associations for sulfate, ammonium, or chlorine exposure. Higher mortality risk ascribed to constituent exposures was identified in total gastrointestinal and liver cancer among women, stomach cancer among men, and total gastrointestinal and stomach cancer among low-GDP regions.

CONCLUSIONS

This study offers consistent evidence that long-term exposure to PM2.5-bound BC, OC, and nitrate is associated with total and site-specific gastrointestinal cancer mortality, indicating that these constituents need to be controlled to mitigate the adverse effect of PM2.5 on gastrointestinal cancer mortality.

Municipal Compost Public Health, Waste Management, and Urban Agriculture: A Decadal Study of Fugitive Pb in City of Boston, Massachusetts, USA

Compostable materials constitute roughly half of waste generated globally, but only 5% of waste is actually processed through composting, suggesting that expanding compost programs may be an effective way to process waste. Compostable waste, if properly collected and processed, has value-added end use options including: residential and park landscaping, remediation of brownfield sites, and as growing media in urban agriculture (UA). Since 2001, our lab has partnered with The Food Project, a non-profit focused on youth leadership development through urban farming. From 2006 to 2022 we collected compost materials that were delivered to the farm from a variety of local sources and analyzed a suite of biogeochemical properties including lead (Pb) concentrations, organic carbon, and grain size distribution. Pb concentrations of Boston's municipal compost always exceeded the current City of San Francisco soil and compost purchase standard (80 μg/g). In 2012 Boston's composting program was halted when it exceeded the 400 μg/g Environmental Protection Agency's Pb in soil benchmark. Urban Pb is geomobile and must be managed to minimize resuspension and transport of fines whose Pb concentration is often elevated compared to bulk compost. Consequently, urban farmers have to source lower Pb compost from suburban suppliers at significantly greater cost. Over a 15 year period and through several city vendor contracts, Pb concentrations in municipal compost remain at levels that warrant continued surveillance and risk assessment.

Spatial Patterning of Spontaneous and Medically Indicated Preterm Birth in Philadelphia

Preterm birth (PTB) remains a key public health issue that disproportionately affects Black individuals. Since spontaneous PTB (sPTB) and medically indicated PTB (mPTB) may have different causes and interventions, we quantified racial disparities for sPTB and mPTB, and we characterized the geographic patterning of these phenotypes, overall and according to race/ethnicity. We examined a pregnancy cohort of 83,952 singleton births at 2 Philadelphia hospitals from 2008-2020, and classified each PTB as sPTB or mPTB. We used binomial regression to quantify the magnitude of racial disparities between non-Hispanic Black and non-Hispanic White individuals, then generated small area estimates by applying a Bayesian model that accounts for small numbers and smooths estimates of PTB risk by borrowing information from neighboring areas. Racial disparities in both sPTB and mPTB were significant (relative risk of sPTB = 1.83, 95% confidence interval: 1.70, 1.98; relative risk of mPTB = 2.20, 95% confidence interval: 2.00, 2.42). The disparity was 20% greater in mPTB than sPTB. There was substantial geographic variation in PTB, sPTB, and mPTB risks and racial disparity. Our findings underscore the importance of distinguishing PTB phenotypes within the context of public health and preventive medicine. Future work should consider social and environmental exposures that may explain geographic differences in PTB risk and disparities.

Neighborhood environmental vulnerability and pediatric asthma morbidity in US metropolitan areas

BACKGROUND

Research suggests demographic, economic, residential, and health-related factors influence vulnerability to environmental exposures. Greater environmental vulnerability may exacerbate environmentally related health outcomes. We developed a neighborhood environmental vulnerability index (NEVI) to operationalize environmental vulnerability on a neighborhood level.

OBJECTIVE

We explored the relationship between NEVI and pediatric asthma emergency department (ED) visits (2014-19) in 3 US metropolitan areas: Los Angeles County, Calif; Fulton County, Ga; and New York City, NY.

METHODS

We performed separate linear regression analyses examining the association between overall NEVI score and domain-specific NEVI scores (demographic, economic, residential, health status) with pediatric asthma ED visits (per 10,000) across each area.

RESULTS

Linear regression analyses suggest that higher overall and domain-specific NEVI scores were associated with higher annual pediatric asthma ED visits. Adjusted R2 values suggest that overall NEVI scores explained at least 40% of the variance in pediatric asthma ED visits. Overall NEVI scores explained more of the variance in pediatric asthma ED visits in Fulton County. NEVI scores for the demographic, economic, and health status domains explained more of the variance in pediatric asthma ED visits in each area compared to the NEVI score for the residential domain.

CONCLUSION

Greater neighborhood environmental vulnerability was associated with greater pediatric asthma ED visits in each area. The relationship differed in effect size and variance explained across the areas. Future studies can use NEVI to identify populations in need of greater resources to mitigate the severity of environmentally related outcomes, such as pediatric asthma.

Exposure Disparities by Income, Race and Ethnicity, and Historic Redlining Grade in the Greater Seattle Area for Ultrafine Particles and Other Air Pollutants

BACKGROUND

Growing evidence shows ultrafine particles (UFPs) are detrimental to cardiovascular, cerebrovascular, and respiratory health. Historically, racialized and low-income communities are exposed to higher concentrations of air pollution.

OBJECTIVES

Our aim was to conduct a descriptive analysis of present-day air pollution exposure disparities in the greater Seattle, Washington, area by income, race, ethnicity, and historical redlining grade. We focused on UFPs (particle number count) and compared with black carbon, nitrogen dioxide, and fine particulate matter (PM 2.5 ) levels.

METHODS

We obtained race and ethnicity data from the 2010 U.S. Census, median household income data from the 2006-2010 American Community Survey, and Home Owners' Loan Corporation (HOLC) redlining data from the University of Richmond's Mapping Inequality. We predicted pollutant concentrations at block centroids from 2019 mobile monitoring data. The study region encompassed much of urban Seattle, with redlining analyses restricted to a smaller region. To analyze disparities, we calculated population-weighted mean exposures and regression analyses using a generalized estimating equation model to account for spatial correlation.

RESULTS

Pollutant concentrations and disparities were largest for blocks with median household income of < $ 20,000 , Black residents, HOLC Grade D, and ungraded industrial areas. UFP concentrations were 4% lower than average for non-Hispanic White residents and higher than average for racialized groups (Asian, 3%; Black, 15%; Hispanic, 6%; Native American, 8%; Pacific Islander, 11%). For blocks with median household incomes of < $ 20,000 , UFP concentrations were 40% higher than average, whereas blocks with incomes of > $ 110,000 had UFP concentrations 16% lower than average. UFP concentrations were 28% higher for Grade D and 49% higher for ungraded industrial areas compared with Grade A. Disparities were highest for UFPs and lowest for PM 2.5 exposure levels.

DISCUSSION

Our study is one of the first to highlight large disparities with UFP exposures compared with multiple pollutants. Higher exposures to multiple air pollutants and their cumulative effects disproportionately impact historically marginalized groups. https://doi.org/10.1289/EHP11662.

Neighborhood Walkability, Historical Redlining, and Childhood Obesity in Denver, Colorado

Childhood obesity is a precursor to future health complications. In adults, neighborhood walkability is inversely associated with obesity prevalence. Recently, it has been shown that current urban walkability has been influenced by historical discriminatory neighborhood disinvestment. However, the relationship between this systemic racism and obesity has not been extensively studied. The objective of this study was to evaluate the association of neighborhood walkability and redlining, a historical practice of denying home loans to communities of color, with childhood obesity. We evaluated neighborhood walkability and walkable destinations for 250 participants of the Healthy Start cohort, based in the Denver metropolitan region. Eligible participants attended an examination between ages 4 and 8. Walkable destinations and redlining geolocations were determined based on residential addresses, and a weighting system for destination types was developed. Sidewalks and trails in Denver were included in the network analyst tool in ArcMap to calculate the precise walkable environment for each child. We implemented linear regression models to estimate associations between neighborhood characteristics and child body mass index (BMI) z-scores and fat mass percent. There was a significant association between child BMI and redlining (β: 1.36, 95% CI: 0.106, 2.620). We did not find an association between walkability measures and childhood obesity outcomes. We propose that cities such as Denver pursue built environment policies, such as inclusionary zoning and direct investments in neighborhoods that have been historically neglected, to reduce the childhood health impacts of segregated poverty, and suggest further studies on the influences that redlining and urban built environment factors have on childhood obesity.

Environmental exposure and the role of AhR in the tumor microenvironment of breast cancer

Activation of the aryl hydrocarbon receptor (AhR) through environmental exposure to chemicals including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins (PCDDs) can lead to severe adverse health effects and increase the risk of breast cancer. This review considers several mechanisms which link the tumor promoting effects of environmental pollutants with the AhR signaling pathway, contributing to the development and progression of breast cancer. We explore AhR's function in shaping the tumor microenvironment, modifying immune tolerance, and regulating cancer stemness, driving breast cancer chemoresistance and metastasis. The complexity of AhR, with evidence for both oncogenic and tumor suppressor roles is discussed. We propose that AhR functions as a "molecular bridge", linking disproportionate toxin exposure and policies which underlie environmental injustice with tumor cell behaviors which drive poor patient outcomes.