Shorter telomere length in cord blood associated with prenatal air pollution exposure: Benefits of intervention

In-Utero exposure to potential sources of indoor air pollution and umbilical cord blood leukocyte telomere length

Indoor air pollution (IAP) has been associated with various adverse health effects. However, the evidence regarding such an association with leukocyte telomere length (LTL) in cord blood samples is still scarce. Therefore, the present study aimed to assess the relationship between exposure to indicators of IAP and LTL in umbilical cord blood samples. This cross-sectional study was based on 188 mother-newborn pairs who participated in our study between 2020 and 2022 in Isfahan, Iran. Umbilical LTL was measured by quantitative real-time polymerase chain reaction (qRT-PCR) technique. Linear mixed-effect models were used to assess the relationship between IAP indicators and umbilical LTL, adjusted for relevant covariates. The median (interquartile range (IQR)) of umbilical LTL was 0.92 (0.47). In fully adjusted models, frequency of using degreasing spray during pregnancy (times per month) (β = -0.047, 95% CI:0.09, -0.05, P-value = 0.02), using air freshener spray during pregnancy (β = -0.26, 95% CI: -0.5, -0.02, P-value = 0.03) and frequency of using insecticides during pregnancy (times per month) (β = -0.025, 95% CI: -0.047, -0.003, P-value = 0.02) were significantly associated with shorter umbilical LTL. There was a positive significant relationship between the frequency of using cleaning spray during pregnancy (times per month) with umbilical LTL (β = 0.019, 95% CI: 0.005, 0.033, P-value = 0.01). Furthermore, the direct connection of the parking with home and the frequency of using barbecue (times per week) were marginally associated with shorter umbilical LTL. For other indicators of IAP, we did not observe any statistically significant associations. Overall, this study suggested a negative association between prenatal exposure to IAP during pregnancy and umbilical LTL.

Exposure to pollution during the first thousand days and telomere length regulation: A literature review

Telomere length (TL) is a biomarker for cellular senescence and TL erosion is predictive of the risk for age-related diseases. Despite being genetically determined at birth, TL may be susceptible to modifications through epigenetic mechanisms. Pollutant agents are considered one of the major threats to both human and planetary health. Their ability to cross the placental barrier and induce oxidative stress in fetal cells is particularly concerning and it may be associated with early TL erosion. In consideration of the timely relevance of this topic, we conducted a literature review on the impact of prenatal exposure to pollutant agents on newborn TL. The search yielded a total of 1099 records, of which only 32 met the inclusion criteria for the review. These criteria included the participation of human subjects, a longitudinal design or collection of longitudinal data, reporting of original TL data, and a focus on exposure to pollutant agents. The majority of the studies reported a significant inverse association between prenatal exposure to pollutant agents and TL. Furthermore, the second trimester of pregnancy emerged as a special sensitive period for the occurrence of pollutant agent-driven TL modifications. Sex differences were inconsistently reported across studies. This review contributes to highlighting biochemical pathways for the threats of environmental pollution to human health. Future research is warranted to further highlight potential buffering mechanisms.

Outdoor fine particulate matter exposure and telomere length in humans: A systematic review and meta-analysis

Although the association between changes in human telomere length (TL) and ambient fine particulate matter (PM2.5) has been documented, there remains disagreement among the related literature. Our study conducted a systematic review and meta-analysis of epidemiological studies to investigate the health effects of outdoor PM2.5 exposure on human TL after a thorough database search. To quantify the overall effect estimates of TL changes associated with every 10 μg/m3 increase in PM2.5 exposure, we focused on two main topics, which were outdoor long-term exposure and prenatal exposure of PM2.5. Additionally, we included a summary of short-term PM2.5 exposure and its impact on TL due to limited data availability. Our qualitative analysis included 20 studies with 483,600 participants. The meta-analysis showed a statistically significant association between outdoor PM2.5 exposure and shorter human TL, with pooled impact estimates (β) of -0.12 (95% CI: -0.20, -0.03, I2= 95.4%) for general long-term exposure and -0.07 (95% CI: -0.15, 0.00, I2= 74.3%) for prenatal exposure. In conclusion, our findings suggest that outdoor PM2.5 exposure may contribute to TL shortening, and noteworthy associations were observed in specific subgroups, suggesting the impact of various research variables. Larger, high-quality studies using standardized methodologies are necessary to strengthen these conclusions further.

Associations between maternal serum neonicotinoid pesticide exposure during pregnancy and newborn telomere length: Effect modification by sampling season

BACKGROUND

An increasing amount of evidence suggests that telomere length (TL) at birth can predict lifespan and is associated with chronic diseases later in life, but newborn TL may be affected by environmental pollutants. Neonicotinoids (NEOs) are widely used worldwide, and despite an increasing number of studies showing that they may have adverse effects on birth in mammals and even humans, few studies have examined the effect of NEO exposure on newborn TLs.

OBJECTIVE

To investigate the effects of prenatal exposure to NEOs and the interactions between NEOs and sampling season on newborn TL.

METHODS

We conducted a prospective cohort study of 500 mother-newborn pairs from the Guangxi Zhuang Birth Cohort. Ultraperformance liquid chromatographymass spectrometry was used to detect ten NEOs in maternal serum, and fluorescence quantitative PCR was used to estimate the newborn TL. A generalized linear model (GLM) was used to evaluate the relationships between individual NEO exposures and TLs , and quantile g-computation (Qgcomp) model and Bayesian kernel machine regression (BKMR) model were used to evaluate the combined effect of mixtures of components.

RESULTS

The results of the GLM showed that compared with maternal TMX levels < LOD, maternal TMX levels < median were negatively correlated with newborn TL (-6.93%, 95% CI%: -11.92%, -1.66%), and the decrease in newborn TL was more pronounced in girls (-9.60%, 95% CI: -16.84%, -1.72%). Moreover, different kinds of maternal NEO exposure had different effects on newborn TL in different sampling seasons, and the effect was statistically significant in all seasons except in autumn. Mixed exposure analysis revealed a potential positive trend between NEOs and newborn TL, but the association was not statistically significant.

CONCLUSION

Prenatal exposure to TMX may shorten newborn TL, and this effect is more pronounced among female newborns. Furthermore, the relationship between NEO exposure and TL may be modified by the sampling season.

Prenatal air pollution exposure in relation to the telomere-mitochondrial axis of aging at birth: A systematic review

BACKGROUND

Telomere length (TL) and mitochondrial DNA (mtDNA) are central markers of vital biological mechanisms, including cellular aging. Prenatal air pollution exposure may impact molecular markers of aging leading to adverse health effects.

OBJECTIVE

To perform a systematic review on human population-based studies investigating the association between prenatal air pollution exposure and TL or mtDNA content at birth.

METHODOLOGY

Searches were undertaken on PubMed and Web of Science until July 2023. The framework of the review was based on the PRISMA-P guidelines.

RESULTS

Nineteen studies studied prenatal air pollution and TL or mtDNA content at birth. Studies investigating TL or mtDNA content measured at any other time or did not evaluate prenatal air pollution were excluded. Twelve studies (including 4381 participants with study sample range: 97 to 743 participants) investigated newborn TL and eight studies (including 3081 participants with study sample range: 120 to 743 participants) investigated mtDNA content at birth. Seven studies focused on particulate matter (PM2.5) exposure and newborn TL of which all, except two, showed an inverse association in at least one of the gestational trimesters. Of the eight studies on mtDNA content, four focused on PM2.5 air pollution with two of them reporting an inverse association. For PM2.5 exposure, observations on trimester-specific effects were inconsistent. Current literature showing associations with other prenatal air pollutants (including nitrogen oxides, sulfur dioxide, carbon monoxide and ozone) is inconsistent.

CONCLUSION

This review provides initial evidence that prenatal PM2.5 exposure impacts the telomere-mitochondrial axis of aging at birth. The current evidence did not reveal harmonious observations for trimester-specific associations nor showed consistent effects of other air pollutants. Future studies should elucidate the specific contribution of prenatal exposure to pollutants other than PM in relation to TL and mtDNA content at birth, and the potential later life health consequences.

Epigenome-wide association study on short-, intermediate- and long-term ozone exposure in Han Chinese, the NSPT study

Epidemiological and epigenetic studies have acknowledged ambient ozone exposure associated with inflammatory and cardiovascular disease. However, the molecular mechanisms still remained unclear, and epigenome-wide analysis in cohort were lacking, especially in Chinese. We included blood-derived DNA methylation for 3365 Chinese participants from the NSPT cohort and estimated individual ozone exposure level of short-, intermediate- and long-term, based on a validated prediction model. We performed epigenome-wide association studies which identified 59 CpGs and 30 DMRs at a strict genome-wide significance (P < 5 ×10-8). We also conducted comparison on the DNA methylation alteration corresponding to different time windows, and observed an enhanced differentiated methylation trend for intermediate- and long-term exposure, while the short-term exposure associated methylation changes did not retain. The targeted genes of methylation alteration were involved in mechanism related to aging, inflammation disease, metabolic syndrome, neurodevelopmental disorders, and oncogenesis. Underlying pathways were enriched in biological activities including telomere maintenance process, DNA damage response and megakaryocyte differentiation. In conclusion, our study is the first EWAS on ozone exposure conducted in large-scale Han Chinese cohort and identified associated DNA methylation change on CpGs and regions, as well as related gene functions and pathways.

Early Environment and Telomeres: a Long-Term Toxic Relationship

PURPOSE OF REVIEW

Telomere length (TL) shortening is a hallmark of biological aging. While studies have extensively focused on the impact of environmental exposures on TL in older populations, consistent evidence indicates that prenatal environmental exposures to air pollutants, polycyclic aromatic hydrocarbons, metals, and endocrine-disrupting chemicals influence TL shortening. Here, we summarize evidence linking prenatal environmental exposures with children's TL and discuss potential long-term effects.

RECENT FINDINGS

Current evidence shows that prenatal environmental exposures alter TL and identify pregnancy as a critical window of susceptibility for telomere damage in children. However, results vary across studies, possibly depending on the source, exposure time window, and stage evaluated. Additional research is needed to investigate whether early TL alterations mediate long-term health effects of offspring. Prenatal environmental exposures induce early childhood changes in TL. Based on known links between TL and biological aging, these alterations may have long-term impact on individuals' health throughout life.

Ambient air pollution exposure and telomere length: a systematic review and meta-analysis

OBJECTIVE

This study aimed to provide evidence of the associations between pre- and post-birth and adulthood air pollution exposure with telomere length.

STUDY DESIGN

The databases of PubMed, Embase, and Web of Science were searched up to June 1st, 2022 in order to include relevant observational studies and perform a systematic review and meta-analysis.

METHODS

The random-effects meta-analysis was grouped by air pollutant and exposure window (pre- and post-birth and adulthood) to evaluate the summary effect estimate. Cochran's Q and I² statistics were used to evaluate the heterogeneity among the included studies. The quality of individual studies was evaluated using the national toxicology program/office of health assessment and translation risk of bias rating tool.

RESULTS

We identified 18 studies, covering 8506 children and 2263 adults from multiple countries. We found moderate evidence that particulate matter less than 2.5 μm (PM_2.5) exposure during the entire pregnancy (-0.043, 95% CI: -0.067, -0.018), nitrogen dioxide (NO₂) exposure during the first trimester (-0.016, 95% confidence interval [CI]: -0.027, -0.005), long-term adulthood PM_2.5 exposure were associated with shortening telomere length. Mild to high between-study heterogeneity was observed for the most tested air pollutant-telomere length combinations in different exposure windows.

CONCLUSIONS

This systematic review and meta-analysis provides the evidence which strongly supports that prenatal PM_2.5 and NO₂ exposures were related to reduced telomere length, while prenatal sulfur dioxide (SO₂) and carbon monoxide (CO) exposures, childhood PM_2.5, particulate matter less than 10 μm (PM₁₀), NO₂ exposures and short-term adulthood PM_2.5 and PM₁₀ exposures were not associated with telomere length. Further high-quality studies are needed to elaborate our suggestive associations.

Effects of air pollution on telomere length: Evidence from in vitro to clinical studies

Air pollution remains the major environmental problem globally. There is extensive evidence showing that the variety of air pollutants from environmental and occupational exposures cause adverse effects to our health. The clinical symptoms of those effects may present at a late stage, so surveillance is difficult to manage. Several biomarkers have been used for the early detection of health issues following exposure to air pollution, including the use of telomere length which indicates cellular senescence in response to oxidative stress. Oxidative stress is one of the most plausible mechanisms associated with exposure to air pollutants. Some specific contexts including age groups, gender, ethnicity, occupations, and health conditions, showed significant alterations in telomere length after exposure to air pollutants. Several reports demonstrated both negative and positive associations between telomere length and air pollution, the studies using different concentrations and exposure times to air pollution on the study of telomere lengths. Surprisingly, some studies reported that low levels of exposure to air pollutants (lower than regulated levels) caused the alterations in telomere length. Those findings suggest that telomere length could be one of most practical biomarkers in air pollution surveillance. Therefore, this review aimed to summarize and discuss the relationship between telomere length and exposure to air pollution. The knowledge from this review will be beneficial for the planning of public health to reduce health problems in the general population, particularly in vulnerable people, who still live in areas with high air pollution.

Gestational exposure to NO2 aggravates placental senescence

Placental senescence is a normal physiological process of placenta, while premature placental senescence has been confirmed to be associated with some adverse pregnancy complications. Epidemiological studies indicate that NO₂ exposure can aggravate placental senescence which is represented by fibrosis and abnormal telomere homeostasis, etc. In this study, pregnant C57BL/6 mice were exposed to NO₂ (2.5 ppm, 5 h/day) daily in a dynamic exposure chamber throughout the gestation period, and were sacrificed at embryonic day 13.5 (E13.5), E15.5 and E18.5. Placenta were harvested and conducted for histopathological examination and telomere evaluation. Our results showed that gestational NO₂ exposure significantly aggravated placental fibrosis and calcification, and up-regulated the related bio-markers (connective tissue growth factor (Ctgf) and transforming growth factor-β1 (Tgf-β1)) at E18.5. In addition, gestational exposure to NO₂ also activated senescence related pathway (p53/p21) at E18.5. Furthermore, gestational NO₂ exposure significantly shortened telomere length at E18.5, and the expression of telomere homeostasis regulation genes telomeric repeat binding factor 1 (Trf1), protection of telomeres 1a (Pot1a) and Pot1b were significantly increased while telomerase reverse transcriptase (Tert) was suppressed after NO₂ exposure at E13.5 or E18.5, respectively. Importantly, DNA methylation status of the 22^nd at E13.5 and 32^nd at E18.5 site in sub-telomeric region of chromosome 1 was significantly altered. Based on the above results, our present study indicated that gestational NO₂ exposure could lead to premature placental senescence during the late trimester of pregnancy via aggravation of fibrosis and telomere length shortening regulated by telomere regulatory enzyme and DNA methylation.

Ambient ozone exposure during pregnancy and telomere length in newborns: a prospective investigation in Wuhan, China

Recent studies suggest that environmental exposures, including air pollution, may influence initial (newborn) telomere length (TL), which has important implications for lifetime health. However, the effect of prenatal ozone exposure on newborn TL is unclear. This study aimed to examine the association of ozone exposure during pregnancy with newborn TL. We used data from a birth cohort study of 762 mother-newborn pairs performed in Wuhan, China, during 2013-2015. Land-use regression models were used to assess prenatal ozone exposure. Newborn TL was quantified in cord blood by qPCR assay. We applied multiple informant model to explore the relationship of prenatal ozone exposure with newborn TL. After adjustment for potential confounders, an interquartile range (IQR) increase in ozone exposure during the 2nd trimester, 3rd trimester, and whole pregnancy were associated with 6.00% (95% confidence interval [CI]: 1.59%, 10.62%), 12.64% (95% CI: 7.52%, 18.00%), and 7.10% (95% CI: 4.09%, 10.20%) longer cord blood TL, respectively. In contrast, an IQR increase in ozone exposure during the 1st trimester was associated with a 8.39% (95% CI: - 12.90%, - 3.65%) shorter cord blood TL. In multipollutant models, consistent associations were observed between ozone exposures during the 2nd trimester and whole pregnancy and cord blood TL, but not significant for the 1st and 3rd trimesters. In conclusion, our findings suggest positive associations of ozone exposure during the 2nd trimester, 3rd trimester, and whole pregnancy with newborn TL and a negative association during the 1st trimester. This study provides new evidence in humans for a potential "programming" mechanism linking maternal ozone exposure to the initial (newborn) setting of offspring's telomere biology.

Association between telomere length in human umbilical cord tissues and polychlorinated biphenyls in maternal and cord serum

Environmental exposure to persistent organic pollutants during pregnancy has potential adverse health effects on the fetus. One of the environmental pollutants is polychlorinated biphenyl (PCB). Earlier, we reported the presence of PCBs in fetal tissues such as the umbilical cord. Telomere length (TL) is a biomarker of aging because it shortens with each cell division. According to the Developmental Origins of Health and Disease hypothesis, fetal exposure to environmental pollutants during pregnancy affects the occurrence of non-communicable diseases in later life. In the current study, we investigated the association between cord tissue TL and serum levels of PCBs. The subjects were 114 mother-child pairs participating in a birth cohort study, the Chiba Study of Mother and Child Health (C-MACH). Maternal serum was collected during pregnancy, and cord serum and tissue were obtained at birth. TL was assessed by qPCR using genomic DNA extracted from the cord tissue. Maternal and cord serum PCB congener levels were assessed using gas chromatography and negative ion chemical ionization qMS. In male fetuses, serum levels of PCB74 in the cord blood were significantly associated with TL following covariate adjustment, but no significant association was found in female fetuses. These data suggest that the TL of the umbilical cord is affected by fetal exposure to PCBs.

Association of both prenatal and early childhood multiple metals exposure with neurodevelopment in infant: A prospective cohort study

BACKGROUND

Impaired neurodevelopment of children has become a growing public concern; however, the associations between metals exposure and neurocognitive function have remained largely unknown.

OBJECTIVES

We systematically evaluated the associations of multiple metals exposure during pregnancy and childhood on the neurodevelopment of children aged 2-3 years.

METHODS

We measured 22 metals in the serum and urine among703 mother-child pairs from the Guangxi Birth Cohort Study. The neurocognitive development of children was assessed by the Gesell Development Diagnosis Scale (GDDS; Chinese version). Multiple linear regression models were used to evaluate the relationship between the metals (selected by elastic net regression) and the outcomes. The Bayesian kernel machine regression (BKMR) was used to evaluate the possible joint effect between the multiple metal mixture and the outcomes.

RESULTS

Prenatal aluminum (Al) exposure was negatively associated with the fine motor developmental quotient (DQ) (β = -1.545, 95%CI: 2.231, -0.859), adaption DQ (β = -1.182, 95%CI: 1.632, -0.732), language DQ (β = -1.284, 95% CI: 1.758, -0.809), and social DQ (β = -1.729, 95% CI: 2.406, -1.052) in the multi-metal model. Prenatal cadmium (Cd) exposure was negatively associated with gross motor DQ (β = -2.524, 95% CI: 4.060, -0.988), while postpartum Cd exposure was negatively associated with language DQ (β = -1.678, 95% CI: 3.227, -0.129). In stratified analyses, infants of different sexes had different sensitivities to metal exposure, and neurobehavioral development was more significantly affected by metal exposure in the first and second trimester. BKMR analysis revealed a negative joint effect of the Al, Cd, and selenium (Se) on the language DQ score; postpartum Cd exposure played a major role in this relationship.

CONCLUSION

Prenatal exposure to Al, Ba, Cd, molybdenum (Mo), lead (Pb), antimony (Sb), and strontium (Sr), and postpartum exposure to cobalt (Co), Cd, stannum (Sn), iron (Fe), nickel (Ni), and Se are associated with neurological development of infants. The first and second trimester might be the most sensitive period when metal exposure affects neurodevelopment.

Association between maternal per- and polyfluoroalkyl substance exposure and newborn telomere length: Effect modification by birth seasons

BACKGROUND

Telomere length (TL) is an important biomarker of biological aging and disease that may be affected by prenatal exposure to environmental pollutants. Birth seasons have been linked to reproductive and immune-related diseases. Prenatal exposure to per- and polyfluoroalkyl substance (PFAS) has been associated with adverse birth outcomes, but the effects of PFAS and birth seasons on newborn TL are poorly understood.

OBJECTIVES

To explore the individual and combined effects of maternal PFAS exposure on newborn TL, with exploration of the interaction between PFAS and birth seasons on newborn TL.

METHODS

Between June 2015 and May 2018, a total of 499 mother-newborn pairs were recruited for a birth cohort study in Guangxi, China. Maternal blood samples were collected during pregnancy. Nine PFASs were measured by ultraperformance liquid chromatography-mass spectrometry. Newborn TL was assessed using quantitative real-time polymerase chain reaction. Modeling newborn TL as the outcome, multivariable linear regressions were performed for individual PFAS exposures, and Bayesian Kernel Machine Regressions were performed for PFAS mixtures. Furthermore, interaction analyses were conducted to evaluate the effect modification by birth seasons in these relationships.

RESULTS

For both single and multipollutant models, PFASs exposure were inversely associated with newborn TL, although none of the relationships were significant. The mixture of PFASs showed a potential positive trend of combined effect on newborn TL but non-statistically significant. Each ln-transformed unit concentration increase in PFOA was related to a 20.41% (95% CI: -30.44%, -8.93%) shorter TL in spring-born infants but not in those born in other birth seasons. Mothers in the middle and highest tertiles of PFOA exposure had 11.69% and 10.71% shorter TLs in spring-born infants, respectively.

CONCLUSION

Maternal PFAS exposure showed little association with newborn TL. The results suggested potential effect modification by birth season on the association between PFOA exposure and newborn TL.

Urinary monohydroxylated polycyclic aromatic hydrocarbons in the general population from 26 provincial capital cities in China: Levels, influencing factors, and health risks

Polycyclic aromatic hydrocarbons (PAHs) derived from the incomplete combustion of organic materials are associated with adverse health effects. However, little is known about PAH exposure levels and their influencing factors on a large scale in developing countries. In this study, urinary monohydroxylated metabolites of PAHs (OH-PAHs), including the metabolites of naphthalene, fluorene, phenanthrene, pyrene, chrysene, and benzo[a]pyrene, were measured in 1154 samples in the general population nationwide from 26 provincial capitals in China. Concentrations of OH-PAHs ranged from 1.39 to 228 μg/L. OH-Nap, metabolite of naphthalene, was the predominant compound, accounting for 65.1% of totals. People in eastern, southwest and northeast China, such as Shanghai, Kunming, Nanning, and Changchun, suffered more PAH exposure than other regions which might associate with sampling time, living habits of the subjects, and the imbalance of economic development and energy consumption across regions. Urinary OH-PAH concentrations were associated with body mass index, gender, and age, and smoking was the main correlating factor. Inhalation and diet might be the main exposure route of human exposure to PAHs, especially for smokers by inhalation. Hazard indices showed that no subject was exposed to PAHs with potential non-carcinogenic risk. Furthermore, the carcinogenic risk was the most significant health effects, with almost all subjects having carcinogenic risk values higher than the acceptable level of 10^-6. Naphthalene and phenanthrene were the main contributors. The results also suggested a possible relationship between PAH exposure and lung cancer in the Chinese population. This first nationwide study on human internal exposure to PAHs provides a large body of scientific information for governmental decision-making about associated human health and the prevention of human exposure to PAHs.

Effects of prenatal exposures to air sulfur dioxide/nitrogen dioxide on toddler neurodevelopment and effect modification by ambient temperature

Emerging evidence suggests that prenatal exposure to ambient SO2 or NO2 induces fetal brain-damage. However, effects of prenatal exposure to SO2 or NO2 on toddler neurodevelopment and the effect-modification by ambient temperature remain unclear. Therefore, a prospective birth-cohort study was conducted from 2010 to 2012 in Shanghai, and 225 mother-child pairs were followed-up from mid-to-late pregnancy until 24-36 months postpartum. During the whole pregnancy, daily SO2/NO2 and temperature levels were obtained for each woman. Gesell-Development-Schedule was used to assess toddler neurodevelopment in the domains of gross-motor, fine-motor, adaptive-behavior, language and social-behavior. Distributed-lag-nonlinear-models simultaneously accounting for exposure-response and lag-response associations were applied to assess the impacts of prenatal SO2/NO2 exposure on neurodevelopment. Each 10-μg/m3 increase in weekly average SO2 concentrations had adverse associations with gross-motor in gestational-weeks 1-6, with adaptive-behavior in weeks 26-30, and with language in weeks 30-36 (developmental-quotient changes: - 1.17% to - 0.12%, P-values < 0.05). Each 10-μg/m3 increase in weekly average NO2 concentrations had adverse associations with gross-motor in gestational-weeks 33-36, with fine-motor in weeks 26-36 and with social-behavior in weeks 31-36 (developmental-quotient changes: - 0.91% to - 0.20%, P-values < 0.05). The cumulative effects for the whole pregnancy showed that each 10-μg/m3 increase in SO2 induced significant deficits in gross-motor and adaptive-behavior (developmental-quotient changes: - 4.71% and - 4.06%, respectively, P < 0.05). We found prenatal cumulative SO2 exposure induced more deficits in low temperature in language and adaptive-behavior than in high/moderate temperature. Thus, prenatal ambient SO2/NO2 exposure in specific time-windows (1st and 3rd trimesters for SO2; 3rd trimester for NO2) could impair toddler neurodevelopment and low temperature may aggravate the SO2-induced neurotoxicity.

Prenatal PM2.5 Exposure in Relation to Maternal and Newborn Telomere Length at Delivery

Particulate matter with an aerodynamic diameter of 2.5 μm or less (PM_2.5) is a ubiquitous air pollutant that is increasingly threatening the health of adults and children worldwide. One health impact of elevated PM_2.5 exposure is alterations in telomere length (TL)-protective caps on chromosome ends that shorten with each cell division. Few analyses involve prenatal PM_2.5 exposure, and paired maternal and cord TL measurements. Here, we analyzed the association between average and trimester-specific prenatal PM_2.5 exposure, and maternal and newborn relative leukocyte TL measured at birth among 193 mothers and their newborns enrolled in a New-York-City-based birth cohort. Results indicated an overall negative relationship between prenatal PM_2.5 and maternal TL at delivery, with a significant association observed in the second trimester (β = -0.039, 95% CI: -0.074, -0.003). PM_2.5 exposure in trimester two was also inversely related to cord TL; however, this result did not reach statistical significance (β = -0.037, 95% CI: -0.114, 0.039), and no clear pattern emerged between PM_2.5 and cord TL across the different exposure periods. Our analysis contributes to a limited body of research on ambient air pollution and human telomeres, and emphasizes the need for continued investigation into how PM_2.5 exposure during pregnancy influences maternal and newborn health.

Prenatal Household Air Pollution Exposure, Cord Blood Mononuclear Cell Telomere Length and Age Four Blood Pressure: Evidence from a Ghanaian Pregnancy Cohort

Associations between prenatal household air pollution exposure (HAP), newborn telomere length and early childhood blood pressure are unknown. Methods: Pregnant women were randomized to liquefied petroleum gas (LPG) stove, improved biomass stove or control (traditional, open fire cook stove). HAP was measured by personal carbon monoxide (CO) (n = 97) and fine particulate matter (PM_2.5) (n = 60). At birth, cord blood mononuclear cells (CBMCs) were collected for telomere length (TL) analyses. At child age four years, we measured resting blood pressure (BP) (n = 97). We employed multivariable linear regression to determine associations between prenatal HAP and cookstove arm and assessed CBMC relative to TL separately. We then examined associations between CBMC TL and resting BP. Results: Higher prenatal PM_2.5 exposure was associated with reduced TL (β = -4.9% (95% CI -8.6, -0.4), p = 0.03, per 10 ug/m³ increase in PM_2.5). Infants born to mothers randomized to the LPG cookstove had longer TL (β = 55.3% (95% CI 16.2, 109.6), p < 0.01)) compared with control. In all children, shorter TL was associated with higher systolic BP (SBP) (β = 0.35 mmHg (95% CI 0.001, 0.71), p = 0.05, per 10% decrease in TL). Increased prenatal HAP exposure is associated with shorter TL at birth. Shorter TL at birth is associated with higher age four BP, suggesting that TL at birth may be a biomarker of HAP-associated disease risk.

Karyotype Aberrations in Action: The Evolution of Cancer Genomes and the Tumor Microenvironment

Cancer is a disease of cellular evolution. For this cellular evolution to take place, a population of cells must contain functional heterogeneity and an assessment of this heterogeneity in the form of natural selection. Cancer cells from advanced malignancies are genomically and functionally very different compared to the healthy cells from which they evolved. Genomic alterations include aneuploidy (numerical and structural changes in chromosome content) and polyploidy (e.g., whole genome doubling), which can have considerable effects on cell physiology and phenotype. Likewise, conditions in the tumor microenvironment are spatially heterogeneous and vastly different than in healthy tissues, resulting in a number of environmental niches that play important roles in driving the evolution of tumor cells. While a number of studies have documented abnormal conditions of the tumor microenvironment and the cellular consequences of aneuploidy and polyploidy, a thorough overview of the interplay between karyotypically abnormal cells and the tissue and tumor microenvironments is not available. Here, we examine the evidence for how this interaction may unfold during tumor evolution. We describe a bidirectional interplay in which aneuploid and polyploid cells alter and shape the microenvironment in which they and their progeny reside; in turn, this microenvironment modulates the rate of genesis for new karyotype aberrations and selects for cells that are most fit under a given condition. We conclude by discussing the importance of this interaction for tumor evolution and the possibility of leveraging our understanding of this interplay for cancer therapy.

Polycyclic aromatic hydrocarbons exposures and telomere length: A cross-sectional study on preschool children

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with shorter telomere length (TL), a marker of ageing at cellular level. However, the available evidence on this association among children is still scarce. We therefore aimed to assess, the relationship between urinary 1-hydroxipayrene (1-OHP), a marker of exposure to PAHs, and relative leukocyte TL (LTL) in children at preschool age. Our study was based on 200 children enrolled from 27 randomly-selected kindergartens in the city of Sabzevar, Iran (2017). 1-OHP levels in the participants' urine samples were measured using solid phase extraction (SPE) method and high-performance liquid chromatography (HPLC). Moreover, real-time PCR was used to measure the LTL in the participants' blood samples. Linear mixed effects models, controlled for relevant covariates, were applied to investigate the association of 1-OHP concentration and LTL. The median (interquartile range (IQR)) of relative LTL and urinary 1-OHP were 0.83 (0.7) and 257 (375.5) ng/L, respectively. In the fully adjusted model, an IQR increase in urinary 1-OHP was related to -0.05 (95% confidence interval (CI): 0.09, -0.01, P-value = 0.02) decrease in relative LTL. This association was similar among boys and girls; however, we observed indications for a stronger association for those children whose parents had university education. Our study suggested an inverse relationship between urinary 1-OHP and LTL in children at preschool age. However, further longitudinal research with repeated measures of PAHs and LTL are needed to confirm these findings.

Exposure to ambient air pollution in the first 1000 days of life and alterations in the DNA methylome and telomere length in children: A systematic review

BACKGROUND

Exposure to air pollution during the first 1000 days of life (from conception to the 2nd year of life) might be of particular relevance for long-term child health. Changes in molecular markers such as DNA methylation and telomere length could underlie the association between air pollution exposure and pollution-related diseases as well as serve as biomarkers for past exposure. The objective of this systematic review was to assess the association between air pollution exposure during pregnancy and the first two years of life and changes in DNA methylation or telomere length in children.

METHODS

PubMed was searched in October 2020 by using terms relative to ambient air pollution exposure, DNA methylation, telomere length and the population of interest: mother/child dyads and children. Screening and selection of the articles was completed independently by two reviewers. Thirty-two articles matched our criteria. The majority of the articles focused on gestational air pollution exposure and measured DNA methylation/telomere length in newborn cord blood or placental tissue, to study global, candidate-gene or epigenome-wide methylation patterns and/or telomere length. The number of studies in children was limited.

RESULTS

Ambient air pollution exposure during pregnancy was associated with global loss of methylation in newborn cord blood and placenta, indicating the beginning of the pregnancy as a potential period of susceptibility. Candidate gene and epigenome-wide association studies provided evidence that gestational exposure to air pollutants can lead to locus-specific changes in methylation, in newborn cord blood and placenta, particularly in genes involved in cellular responses to oxidative stress, mitochondrial function, inflammation, growth and early life development. Telomere length shortening in newborns and children was seen in relation to gestational pollutant exposure.

CONCLUSIONS

Ambient air pollution during pregnancy is associated with changes in both global and locus-specific DNA methylation and with telomere length shortening. Future studies need to test the robustness of the association across different populations, to explore potential windows of vulnerability and assess the role of the methylation and telomere length as mediators in the association between early exposure to ambient air pollutants and specific childhood health outcomes.

Telomere length in newborns is associated with exposure to low levels of air pollution during pregnancy

Telomere length (TL) is a biomarker of biological aging that may be affected by prenatal exposure to air pollution. The aim of this study was to assess the association between prenatal exposure to air pollution and TL in maternal blood cells (leukocytes), placenta and umbilical cord blood cells, sampled immediately after birth in 296 Danish mother-child pairs from a birth cohort. Exposure data was obtained using the high-resolution and spatial-temporal air pollution modeling system DEHM-UBM-AirGIS for PM_2.5, PM₁₀, SO₂, NH₄⁺, black carbon (BC), organic carbon (OC), CO, O₃, NO₂, and NO_x at residential and occupational addresses of the participating women for the full duration of the pregnancy. The association between prenatal exposure to air pollutants and TL was investigated using distributed lag models. There were significant and positive associations between TL in umbilical cord blood cells and prenatal exposure to BC, OC, NO₂, NO_x, CO, and O₃ during the second trimester. TL in umbilical cord blood was significantly and inversely associated with prenatal exposure to PM_2.5, BC, OC, SO₂, NH₄⁺, CO and NO₂ during the third trimester. There were similar inverse associations between TL from umbilical cord blood cells and air pollution exposure at the residential and occupational addresses. There were weaker or no associations between air pollution exposure and TL in placenta tissue and maternal blood cells. In conclusion, both the second and third trimesters of pregnancy are shown to be sensitive windows of exposure to air pollution affecting fetal TL.

Impact of ageing and soil contaminants on telomere length in the land snail

Telomeres (TLs) are non-coding DNA sequences that are usually shortened with ageing and/or chemical exposure. Bioindicators such as the land snail can be used to assess the environmental risk of contaminated soils. As for most invertebrates, the evolution of TLs with ageing or exposure to contaminants is unknown in this mollusc. The aims of this study were to explore the relationships between ageing, contaminant exposure, sublethal effects and TL length in the terrestrial gastropod Cantareus aspersus. TL length was investigated in haemocytes from five age classes of C. aspersus. The impact of contaminants on sub-adult snails exposed to Cd, Hg or a mixture of polycyclic aromatic hydrocarbons (PAHs) in soils for one or two months was studied. Bioaccumulation, growth, sexual maturity and TLs were measured. TL attrition was significant for the juvenile and sub-adult stages, but not later. Exposure to Cd increased the mortality (around 30%). Exposure to polluted soils inhibited growth (19-40%) and sexual maturity (6-100%). Although the health of the snails exposed to Cd, Hg and PAHs was altered, TL length in haemocytes was not disturbed, suggesting a high capacity of this snail species to maintain its TLs in haemocytes under chemical stress. These results first address TL length in snails and reveal that the relationship commonly proposed for vertebrates between TL shortening and ageing or exposure to contaminants cannot be generalized.

Long-term ozone exposure is positively associated with telomere length in critically ill patients

RATIONALE

Chronic air pollutant exposure has been associated with development of Acute Respiratory Distress Syndrome (ARDS) in patients at risk, particularly from severe trauma. We recently reported that shorter peripheral blood leukocyte (PBL) telomere length (TL) was associated with worse outcomes and higher severity of ARDS in critically ill patients. Since most major air pollutants are potent oxidants that can induce cellular oxidative stress, and oxidative stress can accelerate telomere shortening, we hypothesized that higher levels of chronic air pollutant exposure would be associated with shorter telomere length in critically ill patients including patients with ARDS.

METHODS

PBL-TL was measured in genomic DNA collected on the morning of ICU day 2 in 772 critically ill patients enrolled in a prospective observational study. Exposures to air pollutants including ozone (warm-season only), particulate matter < 2.5 µm (PM_2.5), particulate matter < 10 µm (PM₁₀), CO, NO₂ and SO₂, were estimated by weighted average of daily levels from all monitors within 50 km of each patient's residential address for the 3 years prior to admission. Associations of each air pollutant exposure and PBL-TL were investigated by multivariable linear regression models adjusting for age, ethnicity, sex, smoking history, alcohol abuse, insurance status, median household income, history of malignancy and APACHE II.

RESULTS

Contrary to our hypothesis, TL increased across exposure quartiles in both ozone and PM_2.5 analyses (p < 0.05). In a regression model controlling for potential confounders, long term ozone exposure was significantly associated with an increase in TL in the entire cohort (0.31 kb per 10 ppb), as well as in subgroups with sepsis, trauma and ARDS (all p < 0.05). In multivariable models, entire-year exposure to PM_2.5, PM₁₀, CO, NO₂ and SO₂ was not associated with TL after adjustment for potential confounders. In an analysis restricted to warm-season levels to assess the effect of seasonality, higher warm-season PM_2.5 and CO exposures were independently associated with longer TL.

CONCLUSIONS

Long-term exposure to ozone is associated with longer peripheral blood TL in critically ill patients. Further studies are needed to investigate the potential underlying mechanisms for this unexpected positive association between telomere length and air pollution exposure in critical illness.

Prenatal particulate air pollution and newborn telomere length: Effect modification by maternal antioxidant intakes and infant sex

BACKGROUND

Evidence links gestational exposure to particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) with changes in leukocyte telomere length in cord blood with some studies showing sex-specific effects. PM_2.5 exposure in utero increases oxidative stress, which can impact telomere biology. Thus, maternal antioxidant intakes may also modify the particulate air pollution effects.

METHODS

We examined associations among prenatal PM_2.5 exposure and newborn relative leukocyte telomere length (rLTL), and the modifying effects of maternal antioxidant intake and infant sex. We estimated daily PM_2.5 exposures over gestation using a validated spatiotemporally resolved satellite-based model. Maternal dietary and supplemental antioxidant intakes over the prior three months were ascertained during the second trimester using the modified Block98 food frequency questionnaire; high and low antioxidant intakes were categorized based on a median split. We employed Bayesian distributed lag interaction models (BDLIMs) to identify both sensitive windows of exposure and cumulative effect estimates for prenatal PM_2.5 exposure on newborn rLTL, and to examine effect modification by maternal antioxidant intakes. A 3-way interaction between PM_2.5, maternal antioxidant intake and infant sex was also explored.

RESULTS

For the main effect of PM_2.5, BDLIMs identified a sensitive window at 12-20 weeks gestation for the association between increased prenatal PM_2.5 exposure and shorter newborn rLTL and a cumulative effect of PM_2.5 over gestation on newborn telomere length [cumulative effect estimate (CEE) = -0.29 (95% CI -0.49 to -0.10) per 1μg/m³ increase in PM_2.5]. In models examining maternal antioxidant intake effects, BDLIMs found that children born to mothers reporting low antioxidant intakes were most vulnerable [CEE of low maternal antioxidant intake = -0.31 (95% CI -0.55 to -0.06) vs high maternal antioxidant intake = -0.07 (95% CI -0.34 to 0.17) per 1μg/m³ increase in PM_2.5]. In exploratory models examining effect modification by both maternal antioxidant intakes and infant sex, the cumulative effect remained significant only in boys whose mothers reported low antioxidant intakes [CEE = -0.38 (95% CI -0.80 to -0.004)]; no sensitive windows were identified in any group.

CONCLUSIONS

Prenatal PM_2.5 exposure in mid-gestation was associated with reduced infant telomere length. Higher maternal antioxidant intakes mitigated these effects.

Telomere erosion as a placental clock: From placental pathologies to adverse pregnancy outcomes

The placenta provides nutritional and gas exchange between fetus and mother. Early in pregnancy, placental trophoblasts proliferate rapidly and invade aggressively. As pregnancy progresses, placental cells begin to age. Indeed, pregnancy itself has a tightly regulated duration, determined in large part by placental lifespan. Late in pregnancy, placental cells reach a senescent apoptotic state, activated by a number of intrinsic and extrinsic factors, including oxidative stress (OS), and DNA damage. Pregnancy complications, stillbirths and neonatal deaths have been related to OS and abnormal placental aging. Telomeres, the protective nucleoprotein structures at the ends of linear chromosomes, shorten both from cell replication and from exposure to OS. When telomeres become critically short they trigger cell cycle arrest and eventually cell death. Telomere attrition thus provide an intrinsic mechanism to explain tissue senescence and aging. Mounting evidence suggests that senescence of placental and fetal membrane cells results from telomere attrition. We review the studies that have addressed the role of telomere length (TL) in placentas from normal and complicated pregnancies, including pre-eclampsia, intrauterine growth restriction, gestational diabetes, and stillbirth. To date studies have uncovered associations between TL and a number of obstetrical complications. Future research is needed to determine whether these associations are causative, i.e. whether these clinical conditions result from telomere dysfunction, and whether particular features of telomeres, e.g. mean or shortest length, etc. could serve as clinically useful biomarkers of placental health.

Association of exposure to air pollution and telomere length in preschool children

Exposure to air pollution is associated with adverse health effects; however, the available evidence of its association with telomere length (TL), an early marker of ageing, in children is still scarce with no study available for preschool children. This study aimed to investigate the association of exposure to air pollution and traffic indicators at home and kindergarten with relative leukocyte TL (LTL) in preschool children. This cross-sectional study included 200 preschool children (5-7 years old) recruited from 27 kindergartens in Sabzevar, Iran (2017). Outdoor annual average levels PM₁, PM_2.5, and PM₁₀ at residential address and kindergartens were estimated applying land use regression (LUR) models. Moreover, indoor levels of PMs at kindergartens were measured for four days in each season resulting in a total of 16 days of measurements for each kindergarten. Total streets length in different buffers and distance to major road were calculated as traffic indicators at residential address and kindergartens. We applied quantitative real-time polymerase chain reaction (qRT-PCR) to measure relative LTL in blood samples obtained from children. Mixed linear regression models were developed with qPCR plate and kindergarten as random effects, to estimate association of each pollutant and traffic indicator with LTL, controlled for relevant covariates. Higher concentrations of outdoor PM₁, PM_2.5, and PM₁₀, at home and kindergartens were associated with shorter relative LTL. Similarly, increase in indoor PM_2.5 concentrations at kindergartens was associated with shorter relative LTL (β = -0.18, 95% CI: -0.36, -0.01, P-value < 0.01). Moreover, higher total street length in 100 m buffer around residence and lower residential distance to major roads were associated with shorter relative LTL (β = -0.25, 95% CI: -0.37, -0.13, P-value < 0.01, and 0.32, 95% CI: 0.20, 0.44, P-value < 0.01, respectively). Overall, our study suggested that higher exposure to air pollution and traffic at kindergarten and residential home were associated with shorter relative LTL in preschool children.

Bacopa monnieri inhibits apoptosis and senescence through mitophagy in human astrocytes

Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon, is a potent neurotoxic agent that is responsible for impaired neuronal development and is associated with aging. Here, it was demonstrated that extracts of Bacopa monnieri (BM), a traditional Ayurvedic medicine, diminished the B[a]P-induced apoptosis and senescence in human astrocytes. BM was demonstrated to protect the immortalized primary fetal astrocytes (IMPHFA) from B[a]P-induced apoptosis and senescence by reducing the damaged mitochondria that produced reactive oxygen species (ROS). Furthermore, it was shown that B[a]P-triggered G2 arrest could be altered by BM, thus indicating that BM could reverse the cell cycle arrest and mediate a normal cell cycle in IMPHFA cells. In addition, the lifespan of Caenorhabditis elegans was assessed, which confirmed these effects in the presence of BM, compared to the B[a]P-treated group. Furthermore, the anti-senescence and anti-apoptotic activities of BM were observed to be mediated through the protective effect of mitophagy, and inhibition of mitophagy could not protect the astrocytes from mitochondrial ROS-induced apoptosis and senescence in BM-treated cells. Moreover, it was revealed that BM induced Parkin-dependent mitophagy to exert its cytoprotective activity in IMPHFA cells. In conclusion, the anti-senescence and anti-apoptotic effects of BM in astrocytes could combat pollution and aging-related neurological disorders.

Telomere Length and Autism Spectrum Disorder Within the Family: Relationships With Cognition and Sensory Symptoms

Telomeres are repetitive noncoding deoxynucleotide sequences that cap chromosomes to protect DNA. Telomere length (TL) is affected by both genetic and environmental factors, and shortening of telomeres is associated with multiple neuropsychiatric disorders, early life stress, and age-related cognitive dysfunction. Two previous studies associated shorter TL with autism spectrum disorder (ASD). We aimed to replicate this finding, describe TL in unaffected siblings, and explore novel relationships with symptoms and cognitive function in families with ASD. Participants were 212 male children and adolescents ages 1-17 years (86 with ASD, 57 unaffected siblings, and 69 typically developing [TD]) and 64 parents. TL was measured from blood leukocytes with quantitative real-time polymerase chain reaction and results are expressed by relative ratios with a single copy gene. We replicated that children and adolescents with ASD have shorter TL, compared to TD, and show that unaffected siblings have TL in between those of TD and ASD. We present novel associations between TL and sensory symptoms in ASD. Finally, we demonstrate cognitive functions, but not autistic traits, are related to TL in parents of children with ASD. Cognitive function and TL were not related in children and adolescents. As the third replication, our results elicit confidence in the finding that ASD is associated with shorter TL. Our novel sensory investigation suggests that shortened TL may be a biological mechanism of sensory symptoms in ASD. Furthermore, results highlight the need to better understand relationships between cognition, aging, and TL in families with ASD. Autism Res 2020, 13: 1094-1101. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Telomeres cap chromosomes to protect DNA. They progressively shorten as people age and are related to health outcomes. We replicated previous findings that children and adolescents with autism spectrum disorder (ASD) have shorter telomeres, compared to typically developing (TD), and show that unaffected siblings have telomere length (TL) in between those of TD and ASD. We find shortened TL is related to more severe sensory symptoms. This may mean families with ASD, especially those with elevated sensory symptoms, are at risk for worse age-related health outcomes.

Early Biological Aging and Fetal Exposure to High and Low Ambient Temperature: A Birth Cohort Study

BACKGROUND

Although studies have provided estimates of premature mortality to either heat or cold in adult populations, and fetal exposure to ambient temperature may be associated with life expectancy, the effects of temperature on aging in early life have not yet been studied. Telomere length (TL) is a marker of biological aging, and a short TL at birth may predict lifespan and disease susceptibility later in life.

OBJECTIVES

We studied to what extent prenatal ambient temperature exposure is associated with newborn TL.

METHODS

In the ENVIRONAGE (ENVIRonmental influence ON early AGEing) birth cohort in Flanders, Belgium, we measured cord blood and placental TL in 1,103 mother-newborn pairs (singletons with ≥36wk of gestation) using a quantitative real-time polymerase chain reaction (qPCR) method. We associated newborn TL with average weekly exposure to ambient temperature using distributed lag nonlinear models (DLNMs) while controlling for potential confounders. Double-threshold DLNMs were used to estimate cold and heat thresholds and the linear associations between temperature and TL below the cold threshold and above the heat threshold.

RESULTS

Prenatal temperature exposure above the heat threshold (19.5°C) was associated with shorter cord blood TL. The association with a 1°C increase in temperature was strongest at week 36 of gestation and resulted in a 3.29% [95% confidence interval (CI): -4.67, -1.88] shorter cord blood TL. Consistently, prenatal temperature exposure below the cold threshold (5.0°C) was associated with longer cord blood TL. The association with a 1°C decrease in temperature was strongest at week 10 of gestation with 0.72% (95% CI: 0.46, 0.97) longer cord blood TL.

DISCUSSION

Our study supports potential effects of prenatal temperature exposure on longevity and disease susceptibility later in life. Future climate scenarios might jeopardize the potential molecular longevity of future generations from birth onward. https://doi.org/10.1289/EHP5153.

Benchmark dose assessment for coke oven emissions-induced telomere length effects in occupationally exposed workers in China

Telomeres are DNA-protein structures that protect chromosome ends from degradation and fusion, which are shortened by oxidative stress, for example air pollution including benzene, toluene, Coke Oven Emissions (COEs), and so on. As a biomarker of health and disease, telomere length is associated with cardiovascular, diabetes and cancers. The aim of this study was to estimate the effects of COEs exposure on telomere length and the benchmark dose (BMD) of COEs. A total of 542 coke oven workers and 235 healthy controls without exposure to toxicants were recruited. Quantitative PCR was used to determine the telomere length in human peripheral blood leukocytes DNA. Propensity scoring was used to match coke oven workers to healthy controls. Linear regression models and trend tests were used to the relationship between COEs exposure and telomere length. Telomere length in COEs exposed group 0.764 (0.536, 1.092) was significantly shorter than that in the control group 1.064(0.762, 1.438), (P < 0.001). There were significantly dose-response relationships between COEs exposure and telomere damage with telomere length as a biomarker. A BMDL value lower than the present occupational exposure limits (OELs) of COEs exposure was evaluated using the BMD approach in coke oven workers. Our results suggested that shorter telomere length is related to occupational exposure to COEs and the level of COEs exposure lower than the current national OELs in China and many other countries could induce telomere damage.

The risk of preschool asthma at 2-4 years is not associated with leukocyte telomere length at birth or at 1 year of age

Background

Exposure to prenatal stress is associated with offspring allergic-disease development, and oxidative stress may mediate this relationship.

Objective

We aimed to evaluate whether leukocyte telomere length (LTL) shortening, a marker for exposure to oxidative stress, in early life is associated with increased risk of asthma development during the preschool period.

Methods

We assessed the follow-up clinical data of a subgroup from a birth cohort whose LTLs had been measured from cord-blood and 1-year peripheral-blood samples. We examined whether the LTLs would be associated with asthma development at the age of 2–4 years.

Results

The data of 84 subjects were analyzed. LTLs were measured from the cord-blood and 1-year peripheral blood of 75 and 79 subjects, respectively. Among them, 14 subjects (16.7%) developed bronchial asthma between 2–4 years old. Prenatally stressed subjects had marginally increased odds of developing asthma (p = 0.097). There was no significant difference in the odds of preschool-asthma development between the groups with shorter and longer cord-blood LTLs (odds ratio [OR], 0.651; 95% confidence interval [CI], 0.184–2.306) or in the odds between the groups with shorter and longer 1-year peripheral-blood LTLs (OR, 0.448; 95% CI, 0.135–1.483). Finally, subjects with both higher prenatal stress and shorter LTLs did not have significantly higher odds of preschool-asthma development (for cord-blood: OR, 1.242; 95% CI, 0.353–4.368; for 1-year peripheral-blood: OR, 1.451; 95% CI, 0.428–4.919).

Conclusion

There was no significant association between early life LTLs and higher risk of bronchial-asthma development during the preschool years.

Telomere dynamic in humans and animals: Review and perspectives in environmental toxicology

Telomeres (TLs) play major roles in stabilizing the genome and are usually shortened with ageing. The maintenance of TLs is ensured by two mechanisms involving telomerase (TA) enzyme and alternative lengthening telomeres (ALT). TL shortening and/or TA inhibition have been related to health effects on organisms (leading to reduced reproductive lifespan and survival), suggesting that they could be key processes in toxicity mechanisms (at molecular and cellular levels) and relevant as an early warning of exposure and effect of chemicals on human health and animal population dynamics. Consequently, a critical analysis of knowledge about relationships between TL dynamic and environmental pollution is essential to highlight the relevance of TL measurement in environmental toxicology. The first objective of this review is to provide a survey on the basic knowledge about TL structure, roles, maintenance mechanisms and causes of shortening in both vertebrates (including humans) and invertebrates. Overall, TL length decreases with ageing but some unexpected exceptions are reported (e.g., in species with different lifespans, such as the nematode Caenorhabditis elegans or the crustacean Homarus americanus). Inconsistent results reported in various biological groups or even between species of the same genus (e.g., the microcrustacean Daphnia sp.) indicate that the relation usually proposed between TL shortening and a decrease in TA activity cannot be generalized and depends on the species, stage of development or lifespan. Although the scientific literature provides evidence of the effect of ageing on TL shortening, much less information on the relationships between shortening, maintenance of TLs, influence of other endogenous and environmental drivers, including exposure to chemical pollutants, is available, especially in invertebrates. The second objective of this review is to connect knowledge on TL dynamic and exposure to contaminants. Most of the studies published on humans rely on correlative epidemiological approaches and few in vitro experiments. They have shown TL attrition when exposed to contaminants, such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), pesticides and metallic elements (ME). In other vertebrates, the studies we found deals mainly with birds and, overall, report a disturbance of TL dynamic consecutively to exposure to chemicals, including metals and organic compounds. In invertebrates, no data are available and the potential of TL dynamic in environmental risk assessment remains to be explored. On the basis of the main gaps identified some research perspectives (e.g., impact of endogenous and environmental drivers, dose response effects, link between TL length, TA activity, longevity and ageing) are proposed to better understand the potential of TL and TA measurements in humans and animals in environmental toxicology.

Biomonitoring of polycyclic aromatic hydrocarbons and synthetic musk compounds with Masson pine (Pinus massoniana L.) needles in Shanghai, China

Twenty-six polycyclic aromatic hydrocarbons (PAHs) and four synthetic musk compounds (SMCs) accumulated by Masson pine needles from different areas of Shanghai were investigated in the present study. Concentrations of Σ₂₆PAHs (sum of 26 PAHs) ranged from 234 × 10^-3 to 5370 × 10^-3 mg kg^-1. Levels of Σ₂₆PAHs in different sampling areas followed the order: urban areas (Puxi and Pudong) > suburbs > Chongming. Total concentrations of 16 USEPA priority PAHs ranged from 225 × 10^-3 to 5180 × 10^-3 mg kg^-1, ranking at a relatively high level compared to other regions around the world. Factor analysis and multi-linear regression model has identified six sources of PAHs with relative contributions of 15.1% for F1 (vehicle emissions), 47.8% for F2 (natural gas and biomass combustion), 7.8% for F3 (oil), 10.6% for F4 (coal combustion), 15.7% for F5 ("anthracene" source) and 3.0% for F6 (coke tar). Total concentrations of 4 SMCs varied between 0.071 × 10^-3 and 2.72 × 10^-3 mg kg^-1 in pine needles from Shanghai. SMCs with the highest detected frequency were Galaxolide and musk xylene, followed by musk ketone and Tonalide. The highest level of SMCs was found near industrial park and daily chemical plant. The results obtained from this study may have important reference value for local government in the control of atmospheric organic pollution.

Prenatal Exposure to Phthalates and Newborn Telomere Length: A Birth Cohort Study in Wuhan, China

BACKGROUND

Telomere length (TL) is a marker of biological aging and is inversely related to aging-related diseases. The setting of TL at birth may have important implications for lifelong telomere dynamics; however, its determinants remain poorly understood.

OBJECTIVES

The purpose of our study was to explore the relationships between prenatal exposure to phthalates and umbilical cord blood TL.

METHODS

A total of 762 mother–newborn pairs were recruited from a birth cohort study performed between November 2013 and March 2015 in Wuhan, China. Relative cord blood TL was measured using quantitative real-time polymerase chain reaction. Six phthalate metabolites were measured in urine samples acquired from pregnant women during the three trimesters. Multiple informant models were applied to estimate the associations between prenatal exposure to phthalates and cord blood TL and to evaluate potential windows of vulnerability.

RESULTS

Exposure to mono-ethyl phthalate (MEP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-butyl phthalate (MBP), and di(2-ethylhexyl) phthalate ([Formula: see text]) during the first trimester were inversely related to cord blood TL. In addition, we observed a female-specific association between maternal exposure to MEP during the first trimester and cord blood TL ([Formula: see text]). The associations between maternal exposure to MECPP, MEHHP, MEOHP, and [Formula: see text] during the first trimester and cord blood TL were consistent between males and females (all [Formula: see text]).

CONCLUSION

This prospective study demonstrated that prenatal exposure to some phthalate metabolites were associated with shorter cord blood TL. Our results, if confirmed in other populations, may provide more evidence of adverse health outcomes of phthalate exposure and support the hypothesis that the intrauterine environment may be one of the major determinants for newborn TL. https://doi.org/10.1289/EHP4492.

Exposure–Response Associations of Household Air Pollution and Buccal Cell Telomere Length in Women Using Biomass Stoves

BACKGROUND

Telomere shortening is associated with early mortality and chronic disease. Recent studies indicate that environmental exposures, including urban and traffic-related air pollution, may shorten telomeres. Associations between exposure to household air pollution from solid fuel stoves and telomere length have not been evaluated.

METHODS

Among 137 rural Chinese women using biomass stoves ([Formula: see text] of age), we measured 48-h personal exposures to fine particulate matter [PM [Formula: see text] in aerodynamic diameter ([Formula: see text])] and black carbon and collected oral DNA on up to three occasions over a period of 2.5 y. Relative telomere length (RTL) was quantified using a modified real-time polymerase chain reaction protocol. Mixed effects regression models were used to investigate the exposure–response associations between household air pollution and RTL, adjusting for key sociodemographic, behavioral, and environmental covariates.

RESULTS

Women's daily exposures to air pollution ranged from [Formula: see text] for [Formula: see text] ([Formula: see text]) and [Formula: see text] for black carbon ([Formula: see text]). Natural cubic spline models indicated a mostly linear association between increased exposure to air pollution and shorter RTL, except at very high concentrations where there were few observations. We thus modeled the linear associations with all observations, excluding the highest 3% and 5% of exposures. In covariate-adjusted models, an interquartile range (IQR) increase in exposure to black carbon ([Formula: see text]) was associated with shorter RTL [all observations: [Formula: see text] (95% CI: [Formula: see text], [Formula: see text]); excluding highest 5% exposures: [Formula: see text] (95% CI: [Formula: see text], [Formula: see text])]. Further adjustment for outdoor temperature brought the estimates closer to zero [all observations: [Formula: see text] (95% CI: [Formula: see text], 0.06); excluding highest 5% exposures: [Formula: see text] (95% CI: [Formula: see text], [Formula: see text])]. Models with [Formula: see text] as the exposure metric followed a similar pattern.

CONCLUSION

Telomere shortening, which is a biomarker of biological aging and chronic disease, may be associated with exposure to air pollution in settings where household biomass stoves are commonly used. https://doi.org/10.1289/EHP4041.

Prenatal polycyclic aromatic hydrocarbons metabolites, cord blood telomere length, and neonatal neurobehavioral development

BACKGROUND

Prenatal exposure to polycyclic aromatic hydrocarbon (PAH) is a potential risk factor for child neurobehavioral development. Telomere length (TL) has important implications for health over the life course.

OBJECTIVE

In this study, we aimed to investigate whether prenatal urinary PAH metabolites were associated with adverse neonatal neurobehavioral development and altered cord blood TL and to explore whether the change of TL was a predictor of neonatal neurobehavioral development.

METHOD

We enrolled 283 nonsmoking pregnant women in Taiyuan city. Eleven PAH metabolites were measured in maternal urine samples. TL in cord blood was measured by real time quantitative polymerase chain reaction. Neonatal behavioral neurological assessment (NBNA) tests were conducted when the infants were three days old. Multiple linear regression models were used to analyze the associations of maternal urinary PAH metabolites with NBNA scores and cord blood TL, and restricted cubic spline models were further used to examine the shapes of dose-response relationships. A mediation analysis was also conducted.

RESULT

We observed dose-response associations of maternal urinary 2-hydroxyfluorene (2-OHFlu) and 2-hydroxyphenanthrene (2-OH Phe) with decreased active tone scores, sum of NBNA scores, and cord blood TL (P for trend<0.05). Each 1 unit increase in urinary levels of Ln (2-OH Flu) or Ln (2-OH Phe) was associated with a 0.092 or 0.135 decrease in the active tone scores and a 0.174 or 0.199 decrease in the sum of NBNA scores. Mediation analysis showed TL could explained 21.74% of the effect of sum of NBNA scores change related to prenatal exposure to 2-OH Phe (P for mediator = 0.047).

CONCLUSION

Our data indicates maternal urinary specific PAH metabolites are inversely associated with neonatal neurobehavioral development and cord blood TL. TL mediates the associations of 2-OH Phe with neonatal neurobehavioral development and partly explains the effect of 2-OH Phe on neonatal neurobehavioral development.

Association between prenatal particulate air pollution exposure and telomere length in cord blood: Effect modification by fetal sex

INTRODUCTION

In utero particulate matter exposure produces oxidative stress that impacts cellular processes that include telomere biology. Newborn telomere length is likely critical to an individual's telomere biology; reduction in this initial telomere setting may signal increased susceptibility to adverse outcomes later in life. We examined associations between prenatal particulate matter with diameter ≤2.5 µm (PM_2.5) and relative leukocyte telomere length (LTL) measured in cord blood using a data-driven approach to characterize sensitive windows of prenatal PM_2.5 effects and explore sex differences.

METHODS

Women who were residents of Mexico City and affiliated with the Mexican Social Security System were recruited during pregnancy (n = 423 for analyses). Mothers' prenatal exposure to PM_2.5 was estimated based on residence during pregnancy using a validated satellite-based spatio-temporally resolved prediction model. Leukocyte DNA was extracted from cord blood obtained at delivery. Duplex quantitative polymerase chain reaction was used to compare the relative amplification of the telomere repeat copy number to single gene (albumin) copy number. A distributed lag model incorporating weekly averages for PM_2.5 over gestation was used in order to explore sensitive windows. Sex-specific associations were examined using Bayesian distributed lag interaction models.

RESULTS

In models that included child's sex, mother's age at delivery, prenatal environmental tobacco smoke exposure, pre-pregnancy BMI, gestational age, birth season and assay batch, we found significant associations between higher PM_2.5 exposure during early pregnancy (4-9 weeks) and shorter LTL in cord blood. We also identified two more windows at 14-19 and 34-36 weeks in which increased PM_2.5 exposure was associated with longer LTL. In stratified analyses, the mean and cumulative associations between PM_2.5 and shortened LTL were stronger in girls when compared to boys.

CONCLUSIONS

Increased PM_2.5 during specific prenatal windows was associated with shorter LTL and longer LTL. PM_2.5 was more strongly associated with shortened LTL in girls when compared to boys. Understanding sex and temporal differences in response to air pollution may provide unique insight into mechanisms.

Anthropogenic Effects on Natural Mammalian Populations: Correlation Between Telomere Length and Coal Exposure

The Candiota coal mine in Rio Grande do Sul (RS) is one of the largest in Brazil. Coal is a fossil fuel that causes environmental impacts from its extraction to combustion due to the release of different agents, such as polycyclic aromatic hydrocarbons (PAH) and heavy metals. Ctenomys torquatus are herbivorous and subterranean rodents that dig tunnels with their paws and teeth and can be exposed to coal through contaminated food. Exposure to pollutants can cause DNA damage and affect different tissues, inducing alterations in the population structure and genetic diversity. Our study aimed to evaluate the effect of exposure to coal and its derivatives on the C. torquatus population and to examine the relationship of coal exposure with variations in absolute telomere length (aTL), global DNA methylation and genotoxicity. Our study showed an inverse correlation between telomere length and coal exposure in addition to an increase in DNA damage. The results indicate that coal and its byproducts can contribute to the alteration of the C. torquatus population structure, as evidenced by a reduction in the number of adults.

Exploring telomere length in mother-newborn pairs in relation to exposure to multiple toxic metals and potential modifying effects by nutritional factors

BACKGROUND

The uterine environment may influence telomere length at birth, which is essential for cellular function, aging, and disease susceptibility over the lifespan. However, little is known about the impact of toxic chemicals on early-life telomeres. Therefore, we assessed the potential impact of multiple toxic metals on relative telomere length (rTL) in the maternal blood, cord blood, and placenta, as well as the potential modifying effects of pro-oxidants.

METHOD

In a mother-child cohort in northern Argentina (n = 169), we measured multiple toxic metals in the maternal blood or urine collected during late pregnancy, as well as the placenta and cord blood collected at delivery, using inductively coupled plasma mass spectrometry (ICP-MS). We assessed associations of log₂-transformed metal concentrations with rTL, measured in maternal and cord blood leukocytes and the placenta by real-time PCR, using multivariable-adjusted linear regression. Additionally, we tested for modifications by antioxidants (zinc, selenium, folate, and vitamin D₃).

RESULTS

Exposure to boron and antimony during pregnancy was associated with shorter maternal rTL, and lithium with longer maternal rTL; a doubling of exposure was associated with changes corresponding to 0.2-0.4 standard deviations (SD) of the rTL. Arsenic concentrations in the placenta (n = 98), blood, and urine were positively associated with placental rTL, about 0.2 SD by doubled arsenic. In the cord blood (n = 88), only lead was associated with rTL (inversely), particularly in boys (p for interaction 0.09). Stratifying by newborn sex showed ten times stronger association in boys (about 0.6 SD) than in girls. The studied antioxidants did not modify the associations, except that with antimony.

CONCLUSIONS

Elevated exposure to boron, lithium, arsenic, and antimony was associated with maternal or newborn rTL in a tissue-specific, for lead also sex-specific, manner. Nutritional antioxidants did not generally influence the associations.

Prenatal cadmium exposure is associated with shorter leukocyte telomere length in Chinese newborns

BACKGROUND

Newborn telomere length (TL) is considered a potential marker for future disease and lifelong health, but few epidemiological studies have examined the determinants of TL in early life. The study aim was to investigate whether there is an association between prenatal cadmium exposure and relative cord blood TL in Chinese newborns.

METHODS

Participants were 410 mother-newborn pairs drawn from a prospective birth cohort study conducted in Wuhan, China, between November 2013 and March 2015. Urine samples were collected from pregnant women during their period of institutional delivery. Urinary cadmium concentrations were measured by inductively coupled plasma mass spectrometry. The real-time quantitative polymerase chain reaction detection was used to measure relative TL using genomic DNA isolated from umbilical cord blood leukocytes. Multivariate linear regression models were used to estimate the effect of prenatal urinary cadmium concentration on relative cord blood TL.

RESULTS

The geometric mean of maternal urinary cadmium concentration was 0.68 μg/g creatinine. In the multivariate-adjusted linear regression model, per doubling of maternal urinary cadmium concentration was associated with 6.83% (95% CI - 11.44%, - 1.97%; P = 0.006) shorter relative cord blood TL. Stratified analyses indicated that the inverse association between prenatal urinary cadmium and newborn relative TL was more pronounced among female infants and mothers < 29 years, while there were no significant effect modification according to infant sex (P for interaction = 0.907) and maternal age (P for interaction = 0.797).

CONCLUSIONS

The findings indicated that increased maternal urinary cadmium was associated with shortened relative cord blood TL. The results provide more evidence of the negative effects of environmental cadmium exposure and suggest that accelerated aging or cadmium-related diseases may begin in early life.

Air pollution and telomere length: a systematic review of 12,058 subjects

Background

Over recent decades, adverse effects of ambient air pollution on the cardiovascular system have been clearly demonstrated. However, the underlying mechanisms are not fully elucidated. Air pollution may accelerates biological aging and thereby the susceptibility to cardiovascular diseases (CVDs). Telomeres are tandem repetitive DNA complexes that play a critical role in maintaining chromosome stability. There are, however, heterogeneities among the reported effects of air pollution on telomere. This study sought to evaluate the existing literature on the association between air pollution and telomere length (TL).

Methods

Two reviewers independently searched on electronic databases including PUBMED, EMBASE, SCOPUS, WEB OF SCIENCE and Ovid. The key terms were "air pollution" and "telomere" without language restriction. Articles relating to tobacco smoke were excluded.

Results

A total of 12,058 subjects from 25 articles remained for final review. All were observational studies: 14 cross-sectional, 6 cohort and 5 case-control studies. Nineteen (76%) assessed leukocyte telomere length (LTL) of which 15 found associations between air pollution and shorter TL, 2 with longer TL, 1 had mixed results, and a study of patients with type 2 diabetes found non-significant associations with TL. One found longer TL from saliva. The remaining studies were of placental cells, buccal cells or sperm and all reported shorter TL associated with air pollution. Particulate matter (PM) was investigated in 8 articles, and the remainder assessed black carbon (BC), benzene, lead, cadmium and polycyclic aromatic hydrocarbon (PAH). Geographically, 11 studies were conducted in Europe, with 10 in Asia and 4 in North America. While all followed Cawthon's protocol for TL assessment, discordance in the reporting formats did not allow us to perform a quantitative meta-analysis.

Conclusions

Most of the studies support the association of shorter TL with air pollution. Uniform reporting format would be warranted for future studies to estimate true effect size of air pollution on TL.

Ageing at the level of telomeres in association to residential landscape and air pollution at home and work: a review of the current evidence

Studies suggest that leukocyte telomere length is an index of systemic ageing. Here, we discuss telomere length as a marker of biological ageing in relation to residential landscape (greenness), residential air pollution and work-related exposures. Telomere lengths are memories of cumulative oxidative and inflammatory stress, and show to have inverse associations with the risk of non-communicable diseases. For this reason, telomeres are considered as markers of biological ageing. Studies at birth, in children, young adulthood, and elderly show that residential green space, lower traffic exposure and long-term lower exposure to particulate air pollution are associated with longer telomeres. Work-related exposures including exposure to toxic metals, polycyclic aromatic hydrocarbons and particulate matter are associated with shorter telomeres for a given age. In contrast to chronic exposures, evidence is present of the observation that recent exposure is associated with longer telomeres. Our overview shows that the magnitude of residential and work-related environmental factors on telomere length are often as important as many classical lifestyle factors.