Prenatal exposure to wildfire-related air pollution and birth defects in Brazil

Living Near Wildfires and the Risk of Fetal Congenital Heart Defects: Evaluating Critical Windows of Vulnerability

Background  Wildfires produce air pollutants that have been associated with complications during pregnancy. This study examined the association between wildfire exposure before and during pregnancy and the odds of congenital heart defect (CHD) in the offspring. Methods  This retrospective cohort study used the California Linked Birth File and the Forestry and Fire Protection data between 2007 and 2010. Patients living within 15 miles of wildfire during pregnancy were considered exposed. Multivariate logistic regression models were used to estimate the association between wildfire exposure by these various exposure metrics and atrial septal defect (ASD) or ventricular septal defect (VSD) types of CHD compared to pregnancies without wildfire exposure. Results  Compared to births without wildfire exposure, those with first-, second-, and third-trimester exposure were associated with a higher risk of ASD with a first-trimester adjusted odds ratio (aOR) of 1.11 (95% confidence interval (CI): 1.04-1.18), second-trimester aOR of 1.12 (95% CI: 1.07-1.18), and third-trimester aOR of 1.08 (95% CI: 1.02-1.14). Wildfire exposure during the critical window of fetal heart development (weeks 3-8) was associated with aOR of 1.12 (95% CI: 1.02-1.23). Conclusion  Wildfire exposure during pregnancy appears to increase the risk of developing ASD. Key points Wildfire exposure during critical periods in pregnancy are associated with congenital cardiac malformation.Pre-pregnancy exposure to wildfire is not associated with increased risk of congenital cardiac malformation.Pregnant individuals should avoid wildfire exposure.

Approaches in landscape fire smoke pregnancy research and the impact on offspring: A review of knowledge gaps and recommendations

The increase in wildfires and bushfires due to climate change means that more people, including pregnant women and their fetuses will be exposed to landscape fire smoke. Although there is evidence to suggest that pregnancy landscape fire exposure is associated with lower birth weight, preterm birth and pregnancy loss, there is a lack of information on many other perinatal outcomes, as well as information on subsequent respiratory outcomes in children. Furthermore, due to the generally short term (hours/days) and intermittent nature of landscape fire smoke exposure, the knowledge to date has largely relied on natural experiments and ecological studies which can be subject to misclassification of exposure and a lack of precision. On the other hand, general urban outdoor air pollution exposure during pregnancy and subsequent perinatal and respiratory effects has been well studied. In particular, as air exposure modelling has improved so have the adaptations of methods to analyze the effects of air pollution exposure during pregnancy enabling critical windows of exposure to be identified. In this narrative review we summarize the current state of knowledge about the perinatal and respiratory effects of pregnancy landscape fire and particulate matter <2.5 μm in diameter (PM2.5) air pollution exposure, including a comment on analysis methods to date, and an assessment of how methodologies used in general air pollution research in relation to pregnancy exposure can be further harnessed for landscape fire smoke exposure pregnancy research.

Wildfire Smoke: Health Effects, Mechanisms, and Mitigation

Wildfires are becoming more frequent and intense on a global scale, raising concerns about their acute and long-term effects on human health. We conducted a systematic review of the current epidemiological evidence on wildfire health risks and a meta-analysis to investigate the association between wildfire smoke exposure and various health outcomes. We discovered that wildfire smoke increases the risk of premature deaths and respiratory morbidity in the general population. Meta-analysis of cause-specific mortality and morbidity revealed that wildfire smoke had the strongest associations with cardiovascular mortality (RR: 1.018, 95% CI: 1.014-1.021), asthma hospitalization (RR: 1.054, 95% CI: 1.026-1.082), and asthma emergency department visits (RR: 1.117, 95% CI: 1.035-1.204) in the general population. Subgroup analyses of age found that adults and elderly adults were more susceptible to the cardiopulmonary effects of wildfire smoke. Next, we systematically addressed the toxicological mechanisms of wildfire smoke, including direct toxicity, oxidative stress, inflammatory reactions, immune dysregulation, genotoxicity and mutations, skin allergies, inflammation, and others. We discuss wildfire smoke risk mitigation strategies including public health interventions, regulatory measures, and personal actions. We conclude by highlighting current research limitations and future directions for wildfire research, such as elucidating the complex interactions of wildfire smoke components on human health, developing personalized risk assessment tools, and improving resilience and adaptation strategies to mitigate the health effects of wildfires in changing climate.

Landscape Fire Air Pollution as a Mediator in Drought and Childhood Stunting Pathway in Low- and Middle-Income Countries

Drought induces dry hazards, including wildfire, and increased air pollution from wildfire may be a mechanism by which drought increases health risks. We examined whether the drought-wildfire pathway increases the risk of childhood stunting. We analyzed all geocoded children under five across 44 low- and middle-income countries (LMICs). We first conducted mixed-effect regressions to examine the three pairwise associations between standardized precipitation evapotranspiration index (SPEI), fire-sourced PM2.5, and childhood stunting. We then employed a causal mediation analysis to determine whether compounding drought-wildfire (cascading or co-occurring) events significantly impact the drought-stunting pathway. We found that each 1-unit decrease in SPEI exposure was associated with a 2.16% [95% confidence interval (CI): 0.79, 3.49%] increase in stunting risk and 0.57 (95% CI 0.55, 0.59%) μg/m3 increase in fire-sourced PM2.5. Additionally, each 1 μg/m3 increase in 24 month average fire-sourced PM2.5 was associated with an increased risk of 2.46% (95% CI: 2.16, 2.76%) in stunting. Drought-mediated fires accounted for 26.7% (95% CI: 14.5, 36.6%) of the linkage between SPEI and stunting. Our study revealed fire-sourced PM2.5 is a mediator in the drought-stunting pathway in LMICs. To protect child health under increasing drought conditions, personal interventions against wildfire should be considered to enhance climate resilience.

Ambient Environment and the Epidemiology of Preterm Birth

Preterm birth (PTB) is associated with substantial mortality and morbidity. We describe environmental factors that may influence PTB risks. We focus on exposures associated with an individual's ambient environment, such as air pollutants, water contaminants, extreme heat, and proximities to point sources (oil/gas development or waste sites) and greenspace. These exposures may further vary by other PTB risk factors such as social constructs and stress. Future examinations of risks associated with ambient environment exposures would benefit from consideration toward multiple exposures - the exposome - and factors that modify risk including variations associated with the structural genome, epigenome, social stressors, and diet.

Obstetric care for environmental migrants

BACKGROUND

Migration due to environmental factors is an international crisis affecting many nations globally. Pregnant people are a vulnerable subgroup of migrants.

AIM

This article explores the potential effects of environmental migration on pregnancy and aims to draw attention to this rising concern.

METHODS

Based on the study aim, a semi-structured literature review was performed. The following databases were searched: MEDLine (PubMed) and Google Scholar. The search was originally conducted on 31st January 2021 and repeated on 22nd September 2022.

RESULTS

Pregnant migrants are at increased risk of mental health disorders, congenital anomalies, preterm birth, and maternal mortality. Pregnancies exposed to natural disasters are at risk of low birth weight, preterm birth, hypertensive disorders, gestational diabetes, and mental health morbidity. Along with the health risks, there are additional complex social factors affecting healthcare engagement in this population.

CONCLUSION

Maternity healthcare providers are likely to provide care for environmental migrants over the coming years. Environmental disasters and migration as individual factors have complex effects on perinatal health, and environmental migrants may be at risk of specific perinatal complications. Obstetricians and maternity healthcare workers should be aware of these challenges and appreciate the individualised and specialised care that these patients require.

"Air That Once Was Breath" Part 2: Wildfire Smoke and Airway Disease - "Climate Change, Allergy and Immunology" Special IAAI Article Collection: Collegium Internationale Allergologicum Update 2023

BACKGROUND

Population growth and climate change have led to more frequent and larger wildfires, increasing the exposure of individuals to wildfire smoke. Notably, asthma exacerbations and allergic airway sensitization are prominent outcomes of such exposure.

SUMMARY

Key research questions relate to determining the precise impact on individuals with asthma, including the severity, duration, and long-term consequences of exacerbations. Identifying specific risk factors contributing to vulnerability, such as age, genetics, comorbidities, or environmental factors, is crucial. Additionally, reliable biomarkers for predicting severe exacerbations need exploration. Understanding the long-term health effects of repeated wildfire smoke exposures in individuals with asthma and addressing healthcare disparities are important research areas.

KEY MESSAGES

This review discusses the need for comprehensive research efforts to better grasp wildfire smoke-induced respiratory health, particularly in vulnerable populations such as farmworkers, firefighters, pregnant women, children, the elderly, and marginalized communities. Effective mitigation would require addressing the current limitations we face by supporting research aimed at a better understanding of wildfire smoke-induced airway disease.

Health Impacts of Wildfire Smoke on Children and Adolescents: A Systematic Review and Meta-analysis

PURPOSE OF REVIEW

Wildfire smoke is associated with human health, becoming an increasing public health concern. However, a comprehensive synthesis of the current evidence on the health impacts of ambient wildfire smoke on children and adolescents, an exceptionally vulnerable population, is lacking. We conduct a systematic review of peer-reviewed epidemiological studies on the association between wildfire smoke and health of children and adolescents.

RECENT FINDINGS

We searched for studies available in MEDLINE, EMBASE, and Scopus from database inception up to October 11, 2022. Of 4926 studies initially identified, 59 studies from 14 countries were ultimately eligible. Over 33.3% of the studies were conducted in the USA, and two focused on multi-countries. The exposure assessment of wildfire smoke was heterogenous, with wildfire-specific particulate matters with diameters ≤ 2.5 µm (PM2.5, 22.0%) and all-source (22.0%) PM2.5 during wildfire period most frequently used. Over half of studies (50.6%) focused on respiratory-related morbidities/mortalities. Wildfire smoke exposure was consistently associated with enhanced risks of adverse health outcomes in children/adolescents. Meta-analysis results presented a pooled relative risk (RR) of 1.04 (95% confidence interval [CI], 0.96-1.12) for all-cause respiratory morbidity, 1.11 (95% Ci: 0.93-1.32) for asthma, 0.93 (95% CI, 0.85-1.03) for bronchitis, and 1.13 (95% CI, 1.05-1.23) for upper respiratory infection, whilst - 21.71 g for birth weight (95% CI, - 32.92 to - 10.50) per 10 µg/m3 increment in wildfire-specific PM2.5/all-source PM2.5 during wildfire event. The majority of studies found that wildfire smoke was associated with multiple adverse health outcomes among children and adolescents, with respiratory morbidities of significant concern. In-utero exposure to wildfire smoke may increase the risk of adverse birth outcomes and have long-term impacts on height. Higher maternal baseline exposure to wildfire smoke and poor family-level baseline birthweight respectively elevated risks in preterm birth and low birth weight associated with wildfire smoke. More studies in low- and middle-income countries and focusing on extremely young children are needed. Despite technological progress, wildfire smoke exposure measurements remain uncertain, demanding improved methodologies to have more precise assessment of wildfire smoke levels and thus quantify the corresponding health impacts and guide public mitigation actions.

Wildfire smoke exposure during pregnancy and perinatal, obstetric, and early childhood health outcomes: A systematic review and meta-analysis

BACKGROUND

Maternal exposure to air pollution during pregnancy is associated with adverse birth outcomes, although less is known for wildfire smoke. This systematic review evaluated the association between maternal exposure to wildfire smoke during pregnancy and the risk of perinatal, obstetric, and early childhood health outcomes.

METHODS

We searched CINAHL Complete, Ovid/EMBASE, Ovid/MEDLINE, ProQuest, PubMed, Scopus, Web of Science, and Google Scholar to identify relevant epidemiological observational studies indexed through September 2023. The screening of titles, abstracts, and full-texts, data extraction, and risk of bias assessment was performed by pairs of independent reviewers.

RESULTS

Our systematic search yielded 28,549 records. After duplicate removal, we screened 14,009 studies, identifying 31 for inclusion in the present review. Data extraction highlighted high methodological heterogeneity between studies, including a lack of geographic variation. Approximately 56.5% and 16% originated in the United States and Brazil, respectively, and fewer in other countries. Among the studies, wildfire smoke exposure during pregnancy was assessed using distance of residence from wildfire-affected areas (n = 15), measurement of air pollutant concentration during wildfires (n = 11), number of wildfire records (n = 3), aerosol index (n = 1), and geographic hot spots (n = 1). Pooled meta-analysis for birthweight and low birthweight were inconclusive, likely due to low number of methodologically homogenous studies. However, the reviewed studies provided suggestive evidence for an increased risk of birthweight reduction, low birthweight, preterm birth, and other adverse health outcomes.

CONCLUSIONS

This review identified 31 studies evaluating the impacts of maternal wildfire smoke exposure on maternal, infant, and child health. Although we found suggestive evidence of harm from exposure to wildfire smoke during pregnancy, more methodologically homogenous studies are required to enable future meta-analysis with greater statistical power to more accurately evaluate the association between maternal wildfire smoke and adverse birth outcomes and other health outcomes.

Science communication on the public health risks of air pollution: a computational scoping review from 1958 to 2022

BACKGROUND

Air pollutants are a health risk for the entire population. Particulate matter (PM) including the smallest fraction, ultra-fine particles (UFP), therefore continue to be the focus of scientific research in this area. To protect the population from the harmful effects of exposure to PM, communication and information of research results are of special relevance as individuals with heightened awareness of the harms of poor air quality are more likely to take action to improve their exposure.

METHODS

We conducted a scoping review of the scientific literature on science communication of public health information about risks associated with air pollutants to generate an initial over-view of existing research in this field. We searched the PubMed and Scopus databases and analyzed the data using a structured topic modeling (STM) approach.

RESULTS

The existing scientific literature dates back to 1958 but increases significantly from the 1990s onwards. Publications are mainly found in the discipline of environmental research and are primarily concerned with health effects. It is often stated that adequate communication of the results to the public would be important, but specific approaches are rare. Overall, the topic of risk communication seems to be underrepresented for both air pollutants and UFP.

CONCLUSIONS

To protect public health, it is important to conduct more intensive science and risk communication related to scientific findings on the risks of air pollutants. For adequate communication and information, further research is needed to provide specific approaches that also involve the affected population and take different target groups into account. In addition, the effectiveness of communication efforts should also be analyzed.

Wildfire Variable Toxicity: Identifying Biomass Smoke Exposure Groupings through Transcriptomic Similarity Scoring

The prevalence of wildfires continues to grow globally with exposures resulting in increased disease risk. Characterizing these health risks remains difficult due to the wide landscape of exposures that can result from different burn conditions and fuel types. This study tested the hypothesis that biomass smoke exposures from variable fuels and combustion conditions group together based on similar transcriptional response profiles, informing which wildfire-relevant exposures may be considered as a group for health risk evaluations. Mice (female CD-1) were exposed via oropharyngeal aspiration to equal mass biomass smoke condensates produced from flaming or smoldering burns of eucalyptus, peat, pine, pine needles, or red oak species. Lung transcriptomic signatures were used to calculate transcriptomic similarity scores across exposures, which informed exposure groupings. Exposures from flaming peat, flaming eucalyptus, and smoldering eucalyptus induced the greatest responses, with flaming peat grouping with the pro-inflammatory agent lipopolysaccharide. Smoldering red oak and smoldering peat induced the least transcriptomic response. Groupings paralleled pulmonary toxicity markers, though they were better substantiated by higher data dimensionality and resolution provided through -omic-based evaluation. Interestingly, groupings based on smoke chemistry signatures differed from transcriptomic/toxicity-based groupings. Wildfire-relevant exposure groupings yield insights into risk assessment strategies to ultimately protect public health.

Drought-heatwave nexus in Brazil and related impacts on health and fires: A comprehensive review

Climate change is drastically altering the frequency, duration, and severity of compound drought-heatwave (CDHW) episodes, which present a new challenge in environmental and socioeconomic sectors. These threats are of particular importance in low-income regions with growing populations, fragile infrastructure, and threatened ecosystems. This review synthesizes emerging progress in the understanding of CDHW patterns in Brazil while providing insights about the impacts on fire occurrence and public health. Evidence is mounting that heatwaves are becoming increasingly linked with droughts in northeastern and southeastern Brazil, the Amazonia, and the Pantanal. In those regions, recent studies have begun to build a better understanding of the physical mechanisms behind CDHW events, such as the soil moisture-atmosphere coupling, promoted by exceptional atmospheric blocking conditions. Results hint at a synergy between CDHW events and high fire activity in the country over the last decades, with the most recent example being the catastrophic 2020 fires in the Pantanal. Moreover, we show that HWs were responsible for increasing mortality and preterm births during record-breaking droughts in southeastern Brazil. This work paves the way for a more in-depth understanding on CDHW events and their impacts, which is crucial to enhance the adaptive capacity of different Brazilian sectors.

Birth Outcomes, Health, and Health Care Needs of Childbearing Women following Wildfire Disasters: An Integrative, State-of-the-Science Review

BACKGROUND

The frequency and severity of extreme weather events such as wildfires are expected to increase due to climate change. Childbearing women, that is, women who are pregnant, soon to be pregnant, or have recently given birth, may be particularly vulnerable to the effect of wildfire exposure.

OBJECTIVES

This review sought to systematically assess what is known about birth outcomes, health, and health care needs of childbearing women during and after exposure to wildfires.

METHODS

An integrative review methodology was utilized to enable article selection, data extraction, and synthesis across qualitative and quantitative studies. Comprehensive searches of SCOPUS (including MEDLINE and Embase), CINAHL, PubMed, and Google Scholar identified studies for inclusion with no date restriction. Included studies were independently appraised by two reviewers using the Crowe Critical Appraisal Tool. The findings are summarized and illustrated in tables.

RESULTS

Database searches identified 480 records. Following title, abstract, and full text screening, sixteen studies published between 2012 and 2022 were identified for this review. Eleven studies considered an association between in utero exposure to wildfire and impacts on birth weight and length of gestation. One study reported increased rates of maternal gestational diabetes mellitus and gestational hypertension following exposure; whereas one study reported differences in the secondary sex ratio. Two studies reported higher incidence of birth defects following in utero exposure to wildfire smoke. Three studies reported increased mental health morbidity, and one study associated a reduction in breastfeeding among women who evacuated from a wildfire disaster.

DISCUSSION

Evidence indicates that wildfire exposure may be associated with changes to birth outcomes and increased morbidity for childbearing women and their babies. These effects may be profound and have long-term and wide-ranging public health implications. This research can inform the development of effective clinical and public health strategies to address the needs of childbearing women exposed to wildfire disaster. https://doi.org/10.1289/EHP10544.