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Telomeres are vulnerable to various environmental exposures and lifestyle factors, encompassed in the exposome. Recent research shows that telomere length is substantially determined early in life and that exposures in childhood may have important consequences in setting later life telomere length. We explore in a child population the associations of 17 exposures with telomere length and longitudinal telomere change. Children (2.8–10.3y at baseline, 51.3% boys) were followed-up for five to seven years. Relative telomere length was measured at baseline and follow-up using quantitative real-time PCR. Exposures and lifestyle factors included: body composition (body mass index and waist circumference), dietary habits (sugar- and fat-rich food intake, vegetables and fruit intake), psychosocial stress (events, emotions, behaviour), sleep duration, physical activity, and residential environmental quality (longterm black carbon, particulate matter exposure, and residential green space). Cross-sectional (n=182) and longitudinal (n=150) analyses were assessed using linear regression models, adjusting for age, sex, socioeconomic status and multiple testing. Our longitudinal analyses showed that higher residential green space at baseline was associated with (β=0.261, p=0.002) lower telomere attrition and that children with a higher waist circumference at baseline showed a higher telomere attrition (β=−0.287, p=0.001). These two predictors were confirmed via LASSO variable selection and correction for multiple testing. In addition, children with more unhealthy exposures at baseline had a significantly higher telomere attrition over the follow-up period compared to children with more healthy exposures (β=−0.200, p=0.017). Waist circumference and residential green space were identified as predictors associated with telomere attrition in childhood. These results further support the advantages of a healthy lifestyle from early age onwards and the importance of a green environment to promote molecular longevity from childhood onwards. • Telomere attrition over 5-7y and 17 exposures were measured in 4-7y old children. • More unhealthy exposures at baseline resulted in higher telomere attrition. • Residential green space at baseline was associated with lower telomere attrition. • Waist circumference partially mediated this association. • Lifestyle and green space during childhood seems important for molecular longevity. [ABSTRACT FROM AUTHOR]

Air pollution exposure is a major global health concern and has been associated with molecular aging. Unfortunately, the situation has not received much attention in the African region. The aim of this study was to investigate whether current personal ambient NO 2 and benzene, toluene, ethyl-benzene and xylenes (ortho (o)-, meta (m)- and para (p)-xylene (BTEX) exposure is associated with leukocyte telomere length (LTL), a marker of molecular ageing, in apparently healthy women (mean ± SD age: 42.5 ± 13.4 years) residing in the Cape Town region of South Africa. The repeated measures study collected data from 61 women. Seven-day median (interquartile range (IQR)) personal NO 2 and BTEX exposure levels were determined via compact passive diffusion samplers carried on the person prior to baseline (NO 2 : 14.2 (9.4–17.2) μg/m³; Benzene: 3.1 (2.1–5.3) μg/m³) and 6-month follow-up (NO 2 : 10.6 (6.6–13.6) μg/m³; Benzene: 2.2 (1.3–4.9) μg/m³) visits. LTL was measured at baseline and follow-up using a real-time PCR method. Multiple linear mixed model analyses (adjusting for age, body mass index, smoking, employment status, level of education and assessment visit) showed that each IQR increment increase in NO 2 (7.0 μg/m³) and benzene (3.3 μg/m³) was associated with −7.30% (95% CI: −10.98 to −3.46%; p < 0.001) and −6.78% (95% CI: −11.88 to −1.39%; p = 0.015) difference in LTL, respectively. The magnitude of these effects of NO 2 and benzene corresponds to the effect of an increase of 10.3- and 6.0-year in chronological age on LTL. Our study shows that personal exposures to NO 2 and benzene are associated with molecular ageing as indicated by LTL in healthy women residing in the Cape Town region. Image 1 • First ever report on the effects of personal NO 2 and benzene exposure on LTL in a South African population. • Personal NO 2 and benzene exposure was inversely associated with leukocyte telomere length. • The magnitude of the effects corresponds to >6-year increase in chronological age. [ABSTRACT FROM AUTHOR]

Mitochondria are known to respond to environmental stressors but whether green space is associated with mitochondrial abundance is unexplored. Furthermore, as exposures may affect health from early life onwards, we here evaluate if residential green space is associated with mitochondria DNA content (mtDNAc) in children. In primary schoolchildren (COGNAC study), between 2012 and 2014, buccal mtDNAc was repeatedly (three times) assessed using qPCR. Surrounding low (<3m), high (≥3m) and total (sum of low and high) green space within different radii (100m–1000m) from the residence and distance to the nearest large green space (>0.5ha) were estimated using a remote sensing derived map. Given the repeated measures design, we applied a mixed-effects model with school and subject as random effect while adjusting for a priori chosen fixed covariates. Results: mtDNAc was assessed in 246 children with a total of 436 measurements (mean age 10.3 years). Within a 1000m radius around the residential address, an IQR increment in low (11.0%), high (9.5%), and total (13.9%) green space was associated with a respectively 15.2% (95% CI: 7.2%–23.7%), 10.8% (95% CI: 4.5%–17.5%), and 13.4% (95% CI: 7.4%–19.7%) higher mtDNAc. Conversely, an IQR increment (11.6%) in agricultural area in the same radius was associated with a −3.4% (95% CI: 6.7% to −0.1%) lower mtDNAc. Finally, a doubling in distance to large green space was associated with a −5.2% (95% CI: 7.9 to −2.4%) lower mtDNAc. To our knowledge, this is the first study evaluating associations between residential surrounding green space and mtDNAc in children. Our results showed that green space was associated with a higher mtDNAc in children, which indicates the importance of the early life environment. To what extent these findings contribute to later life health effects should be further examined. [Display omitted] • Residential surrounding green space is associated with higher child mtDNA content. •Exposure to agriculture is associated with lower child mtDNA content. •Living closer to large green space is associated with higher mtDNA content. [ABSTRACT FROM AUTHOR]

Green spaces are associated with increased well-being and reduced risk of developing psychiatric disorders. In this study, we aimed to investigate how residential proximity to green spaces was associated with stress response buffering during the COVID-19 pandemic in a prospective cohort of young mothers. We collected information on stress in 766 mothers (mean age: 36.6 years) from the ENVIR ON AGE birth cohort at baseline of the study (from 2010 onwards), and during the COVID-19 pandemic (from December 2020 until May 2021). Self-reported stress responses due to the COVID-19 pandemic were the outcome measure. Green space was quantified in several radiuses around the residence based on high-resolution (1 m2) data. Using ordinal logistic regression, we estimated the odds of better resistance to reported stress, while controlling for age, socio-economic status, stress related to care for children, urbanicity, and household change in income during the pandemic. In sensitivity analyses we corrected for pre-pandemic stress levels, BMI, physical activity, and changes in health-related habits during the pandemic. We found that for an inter-quartile range contrast in residential green space 300 m and 500 m around the residence, participants were respectively 24% (OR = 1.24, 95%CI: 1.03 to 1.51) and 29% (OR = 1.29, 95%CI: 1.04 to 1.60) more likely to be in a more resistant category, independent of the aforementioned factors. These results remained robust after additionally controlling for pre-pandemic stress levels, BMI, physical activity, smoking status, urbanicity, psychological disorders, and changes in health-related habits during the pandemic. This prospective study in young mothers highlights the importance of proximity to green spaces, especially during challenging times. • Stress responses to the COVID19 pandemic were collected in a prospective cohort of mothers of young children. • Residential proximity to green spaces was quantified using high resolution (1 m2) land cover map data. • Higher residential proximity to green space is associated with a stress buffering effect to increased feelings of stress during the COVID19-pandemic. • The association remained significant after adjusting for baseline pre-pandemic stress levels and other important potential confounders. [ABSTRACT FROM AUTHOR]