Environmental radon and childhood asthma

Biomarkers of inflammation associated with radon exposure in the School Inner-City Asthma Study (SICAS)

BACKGROUND

Radon is an omnipresent radioactive gas recently reported to be associated with increased asthma morbidity.

OBJECTIVES

We aimed to identify biomarkers associated with radon exposure and hypothesized elevated radon exposure to be associated with increased inflammatory biomarker levels in an exploratory analysis.

METHODS

In 137 schoolchildren with asthma in the School Inner-City Asthma Study, we assessed estimated radon exposure (1-month averaged radon) by a spatiotemporal model and 46 inflammatory biomarker outcomes, adjusting for copollutants (particulate matter with diameter ≤2.5 μm, NO2, O3) and performed mixed-effect regression analysis. Causal mediation analysis was used to determine the association between radon exposure and absolute eosinophil count.

RESULTS

In a total of 137 observations, we found a positive association with radon exposure and IL-5, a TH2-cell cytokine known to recruit eosinophils to asthmatic airways. Higher radon was significantly associated with a greater increase in IL-5 compared to low radon exposure (observations = 137; 1-month moving radon average [% change = 13.4%; 95% CI: 0.4%-28.0%; P = .044]). Mediation analysis revealed an indirect effect of IL-5 (β = 0.006; 95% CI:0.001-0.012; P = .024) on the association between radon exposure and absolute eosinophil count. This suggests the effect of radon on eosinophil count is mediated through IL-5.

CONCLUSIONS

Radon is a potential novel, modifiable risk factor for asthma recently reported to be associated with asthma morbidity. This work identifies important biological disease pathways via biomarkers that may be central to the exposure-outcome relationship.

EAACI Guidelines on Environmental Science for Allergy and Asthma-Recommendations on the Impact of Indoor Air Pollutants on the Risk of New-Onset Asthma and on Asthma-Related Outcomes

The EAACI Guidelines used the GRADE approach to evaluate the impact of major indoor air pollutants (dampness and mould, cleaning agents, volatile organic compounds and pesticides) on the risk of new-onset asthma and on asthma-related outcomes. The guideline also acknowledges the synergies among indoor air pollutants and other components of the indoor exposome (allergens, viruses, endotoxins). Very low to low certainty of evidence was found for the association between exposure to indoor pollutants and increased risk of new-onset asthma and asthma worsening. Only for mould exposure there was moderate certainty of evidence for new-onset asthma. Due to the quality of evidence, conditional recommendations were formulated on the risk of exposure to all indoor pollutants. Recommendations are provided for prevention, patient care and mitigation in a framework supporting rational decisions for healthcare professionals and patients to individualize and improve asthma management. For policymakers and regulators this evidence-informed guideline supports setting legally binding standards and goals for indoor air quality at international, national and local levels. Asthma management counselled by the current EAACI guidelines can improve asthma-related outcomes but community and governmental measures for improved indoor air quality are needed to achieve significant impact.

The Impact of the Indoor Environment on Childhood Asthma

PURPOSE OF REVIEW

This manuscript reviews the impact of important indoor environmental exposures on pediatric asthma, with a focus on recent literature in the field.

RECENT FINDINGS

Studies continue to support an association between numerous indoor aeroallergens and air pollutants found in homes and schools and increased asthma morbidity overall. Several recent home and school intervention studies have shown promise, though results have been overall mixed. Indoor environmental exposures contribute to the development of asthma and impact asthma morbidity. Further research is needed to improve our understanding of how to optimize mitigation of these indoor exposures to significantly affect asthma outcomes.

Recommendations for Clinicians to Combat Environmental Disparities in Pediatric Asthma: A Review

TOPIC IMPORTANCE

Asthma is a common and complex lung disease in children, with disproportionally higher prevalence and related adverse outcomes among children in racial and ethnic minority groups and of lower socioeconomic position. Environmental factors, including unhealthy housing and school-based exposures, can contribute to increased asthma morbidity and widening disparities. This underscores a significant environmental justice issue and suggests the need for clinical interventions to reduce sources of environmental exposures and ultimately diminish the observed disparities in childhood asthma.

REVIEW FINDINGS

Unhealthy housing conditions, including secondhand tobacco smoke, allergen exposure, and indoor air pollution, can exacerbate asthma symptoms in children. Although unhealthy housing can occur anywhere, such situations most frequently occur in urban, low-income environments where renting is common. To reduce environmental triggers, clinicians can recommend smoking cessation, cleaning techniques to mitigate exposure, and even directly contacting landlords to address poor housing conditions. Children spend much of their time in schools, where this built environment is also a source of asthma triggers (eg, poor ventilation) and allergens (eg, mold and pests, chemicals). As such, a multidisciplinary approach is needed to adequately address the burden of childhood asthma to equitably reduce disparities to both harmful exposures and negative health outcomes.

SUMMARY

Racial, ethnic, and socioeconomic disparities exist in asthma morbidity in children, and such disparities are driven in part by environmental factors at the housing and school level. Clinicians can make evidence-based recommendations to drive effective exposure reduction strategies to mitigate asthma morbidity and reduce observed disparities.

Radon exposure and potential health effects other than lung cancer: a systematic review and meta-analysis

Context and objective

To date, lung cancer is the only well-established health effect associated with radon exposure in humans. To summarize available evidence on other potential health effects of radon exposure, we performed a comprehensive qualitative and quantitative synthesis of the available literature on radon exposure and health effects other than lung cancer, in both occupational and general populations.

Method

Eligible studies published from January 1990 to March 2023, in English and French languages, were identified in PubMed, ScienceDirect, Scopus, ScieLo and HAL. In the meta-analysis, we estimated average weighted standardized incidence ratios (metaSIR), standardized mortality ratios (metaSMR), and risk ratio (metaRR) per 100 unit (Bq/m3 or Working level Month) increase in radon exposure concentration by combining estimates from the eligible studies using the random-effect inverse variance method. DerSimonian & Laird estimator was used to estimate the between-study variance. For each health outcome, analyses were performed separately for mine workers, children, and adults in the general population.

Results

A total of 129 studies were included in the systematic review and 40 distinct studies in the meta-analysis. For most of these health outcomes, the results of the meta-analyses showed no statistically significant association, and heterogeneity was only present among occupational studies, especially between those included in the metaSIR or metaSMR analyses. However, the estimated exposure-risk associations were positive and close to the statistical significance threshold for: lymphohematological cancer incidence in children (metaRR = 1.01; 95%CI: 1.00-1.03; p = 0.08); malignant melanoma mortality among adults in the general population (metaRR = 1.10; 95%CI: 0.99-1.21; p = 0.07); liver cancer mortality among mine workers (metaRR = 1.04; 95%CI: 1.00-1.10; p = 0.06); intestine and rectal cancer mortality combined among mine workers (metaRR = 1.02; 95%CI: 1.00-1.04; p = 0.06).

Conclusion

Although none of the exposure-risk associations estimated in the meta-analyses reached statistical significance, the hypothesis that radon may have other health effects apart from lung cancer could not be ruled-out and call for additional research. Larger and well-designed studies are needed to further investigate this question.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023474542, ID: CRD42023474542.

Recent Insights into the Environmental Determinants of Childhood Asthma

PURPOSE OF REVIEW

Ubiquitous environmental exposures, including ambient air pollutants, are linked to the development and severity of childhood asthma. Advances in our understanding of these links have increasingly led to clinical interventions to reduce asthma morbidity.

RECENT FINDINGS

We review recent work untangling the complex relationship between air pollutants, including particulate matter, nitrogen dioxide, and ozone and asthma, such as vulnerable windows of pediatric exposure and their interaction with other factors influencing asthma development and severity. These have led to interventions to reduce air pollutant levels in children's homes and schools. We also highlight emerging environmental exposures increasingly associated with childhood asthma. Growing evidence supports the present threat of climate change to children with asthma. Environmental factors play a large role in the pathogenesis and persistence of pediatric asthma; in turn, this poses an opportunity to intervene to change the course of disease early in life.

Effects of Allergen Exposure and Environmental Risk Factors in Schools on Childhood Asthma

PURPOSE OF REVIEW

This review aims to assess the prevalence of common allergen exposures and environmental risk factors for asthma in schools, examine the underlying mechanisms of these environmental risk factors, and explore possible prevention strategies.

RECENT FINDINGS

Cockroach, mouse, dust mites, fungi, viral infections, ozone pollution, and cleaning products are common allergen exposures and environmental risk factors in schools which may affect asthma morbidity. Novel modifiable environmental risk factors in schools are also being investigated to identify potential associations with increased asthma morbidity. While several studies have investigated the benefit of environmental remediation strategies in schools and their impact on asthma morbidity, future studies are warranted to further define the effects of modifiable risk factors in schools and determine whether school mitigation strategies may help improve asthma symptoms in students with asthma.

Effect of radon exposure on asthma morbidity in the School Inner-City Asthma study

BACKGROUND

Radon may have a role in obstructive lung disease outside its known carcinogenicity. Little is known about radon's effects on asthma morbidity.

OBJECTIVE

To determine the effect of radon on fractional exhaled nitric oxide (FE NO), asthma symptom-days, and lung function in inner-city asthmatic school children.

METHODS

Two hundred ninety-nine school-aged asthmatic children enrolled in the School Inner-City Asthma Study (SICAS-1) were followed. One and two-month averaged radon was assessed using a spatiotemporal model predicting zip code-specific monthly exposures. FE NO and spirometry were measured twice during the academic year. Asthma symptoms were assessed four times during the academic year. The interaction between indoor radon exposure (Bq/m3 ) and seasonality predicting log-transformed FE NO, forced expiratory volume in 1 s (FEV1 ) % predicted, forced vital capacity (FVC) % predicted, FEV1 /FVC, and asthma symptom-days was evaluated.

RESULTS

Participants with high radon exposure had greater change in FE NO from warm to cold periods compared to low radon exposure (interaction p = 0.0013). Participants with >50th percentile radon exposure experience significant FE NO increase from warm to cold weather (β $\beta $  = 0.29 [95% confidence interval [CI]: 0.04-0.54], p = 0.0240). We report a positive association between radon 1-month moving average (incidence rate ratio [IRR] = 1.01, p = 0.0273) and 2-month moving average (IRR = 1.01, p = 0.0286) with maximum asthma symptom-days (n = 299, obs = 1167).

CONCLUSIONS

In asthmatic children, radon may be associated with increased asthma morbidity, suggesting radon may be a modifiable environmental risk factor for airway inflammation.

Socioeconomic determinants of asthma health

PURPOSE OF REVIEW

The current review provides an assessment of the recent pediatric literature evaluating socioeconomic drivers of asthma incidence and morbidity. The review addresses the specific social determinants of health related to housing, indoor and outdoor environmental exposures, healthcare access and quality, and the impact of systematic racism.

RECENT FINDINGS

Many social risk factors are associated with adverse asthma outcomes. Children living in low-income, urban neighborhoods have greater exposure to both indoor and outdoor hazards, including molds, mice, second-hand smoke, chemicals, and air pollutants, all of which are associated with adverse asthma outcomes. Providing asthma education in the community - via telehealth, school-based health centers, or peer mentors - are all effective methods for improving medication adherence and asthma outcomes. The racially segregated neighborhoods created by the racist 'redlining' policies implemented decades ago, persist today as hotspots of poverty, poor housing conditions, and adverse asthma outcomes.

SUMMARY

Routine screening for social determinants of health in clinical settings is important to identify the social risk factors of pediatric patients with asthma. Interventions targeting social risk factors can improve pediatric asthma outcomes, but more studies are needed related to social risk interventions.

Comparing Communication Methods to Increase Radon Knowledge and Home Testing: A Randomized Controlled Trial in a High-Radon City

INTRODUCTION

Exposure to residential radon is a preventable cause of cancer. Prevention requires testing, but the percentage of homes that have been tested is small. One reason for the low testing rates may be that printed brochures fail to motivate people to obtain and return a radon test.

METHODS

We developed a radon app for smartphones that contained the same information as printed brochures. We conducted a randomized, controlled trial that compared the app to brochures in a population comprised largely of homeowners. Cognitive endpoints included radon knowledge, attitudes toward testing, perceived severity and susceptibility to radon, and response and self-efficacy. Behavioral endpoints were participants' requests for a free radon test and the return of the test to the lab. Participants (N = 116) were residents of Grand Forks, North Dakota, a city with one of the nation's highest radon levels. Data were analyzed by general linear models and logistic regression.

RESULTS

Participants in both conditions showed significant increases in radon knowledge (p < 0.001), perceived susceptibility (p < 0.001), and self-efficacy (p = 0.004). There was a significant interaction, with app users showing greater increases. After controlling for income, app users were three times more likely to request a free radon test. However, contrary to expectation, app users were 70% less likely to return it to the lab (p < 0.01).

CONCLUSIONS

Our findings confirm the superiority of smartphones in stimulating radon test requests. We speculate that the advantage of brochures in promoting test returns may be due to their ability to serve as physical reminders.

Environment and the development of severe asthma in inner city population

PURPOSE OF REVIEW

Higher asthma prevalence and morbidity are seen in inner-city areas, disproportionately affecting low-income families living in substandard housing. Children within these families experience more frequent asthma exacerbations, acute care and emergency department visits, and hospitalizations, thus characterizing severe asthma. In this review, we assess recent published literature focused on indoor and outdoor exposures that contribute to the development and morbidity of asthma.

RECENT FINDINGS

Many urban environmental exposures contribute to asthma burden, including tobacco/e-cigarette smoke, pest allergens, molds, and possibly synthetic chemicals such as phthalates and bisphenol A, radon, and volatile organic compounds. Individuals living in inner-city areas also experience higher levels of air pollutants and ambient heat, further perpetuating asthma incidence and severity.

SUMMARY

This article summarizes the latest advances and provides direction for future research on risk factors, interventions, and public policy to help alleviate the burden of asthma due to urban environment exposures.

Air pollution and childhood asthma

PURPOSE OF REVIEW

Asthma is the most common chronic disease of childhood. Environmental exposures, such as allergens and pollutants, are ubiquitous factors associated with asthma development and asthma morbidity. In this review, we highlight the most recent studies relevant to childhood asthma risk, onset, and exacerbation related to air pollution exposure.

RECENT FINDINGS

In this article, we review current research that has been published between 2021 and 2022, demonstrating the effects of early-life exposure to key air pollutants (e.g., particulate matter (PM), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ) and ground-level ozone (O 3 ), environmental tobacco smoke, radon, and volatile organic compounds (VOC) on respiratory health.

SUMMARY

Air pollution continues to be a global burden with serious consequences related to respiratory health. Interventions aimed at reducing air pollution in the environment must be achieved in an effort to improve asthma outcomes and pediatric health.

Chronic Home Radon Exposure Is Associated with Higher Inflammatory Biomarker Concentrations in Children and Adolescents

Children are particularly vulnerable to the deleterious impacts of toxic environmental exposures, though the effects of some rather ubiquitous toxins have yet to be characterized in youths. One such toxin, radon gas, is known to accumulate to hazardous levels in homes, and has been linked with the incidence of lung cancer in aging adults. However, the degree to which chronic home radon exposure may impact risk for health problems earlier in life is unknown. Herein, we explored the degree to which chronic home radon exposure relates to biomarkers of low-grade inflammation in 68 youths ages 6- to 14 years old residing in an area of the United States prone to high home radon concentrations. Parents completed a home radon test kit, and youths provided a saliva sample to assess concentrations of five biomarkers. Using a multiple regression approach, we found that greater radon exposure was specifically associated with higher levels of C-reactive protein (β = 0.31, p = 0.007) and interleukin-1β (β = 0.33, p = 0.016). The data suggested specificity in associations between chronic home radon exposure and different biomarkers of inflammatory activity and highlight a pathway which may confer risk for future mental and physical health maladies.