Early life environmental factors associated with autism spectrum disorder symptoms in children at age 2 years: A birth cohort study

Mounting evidence finds that early life environmental factors increased the probability of autism spectrum disorder. We estimated prospective associations between early life environmental factors and autism spectrum disorder symptoms in children at the age of 2 years in a population-derived birth cohort, the Barwon Infant Study. Autism spectrum disorder symptoms at the age of 2 years strongly predicted autism spectrum disorder diagnosis by the age of 4 years (area under curve = 0.93; 95% CI (0.82, 1.00)). After adjusting for child’s sex and age at the time of behavioural assessment, markers of socioeconomic disadvantage, such as lower household income and lone parental status; maternal health factors, including younger maternal age, maternal pre-pregnancy body mass index, higher gestational weight gain and prenatal maternal stress; prenatal alcohol; environmental air pollutant exposures, including particulate matter < 2.5 µm at birth, child secondhand tobacco smoke exposure at 12 months, dampness/mould and home heating with oil, kerosene or diesel heaters at 2 years postnatal. Lower socioeconomic indexes for area, later birth order, higher maternal prenatal depression, and maternal smoking frequency had a dose-response relationship with autism spectrum disorder symptoms. Future studies on environmental factors and autism spectrum disorder should consider the reasons for the socioeconomic disparity and the combined impact of multiple environmental factors through common mechanistic pathways. Lay abstract Mounting evidence indicates the contribution of early life environmental factors in autism spectrum disorder. We aim to report the prospective associations between early life environmental factors and autism spectrum disorder symptoms in children at the age of 2 years in a population-derived birth cohort, the Barwon Infant Study. Autism spectrum disorder symptoms at the age of 2 years strongly predicted autism spectrum disorder diagnosis by the age of 4 years (area under curve = 0.93; 95% CI (0.82, 1.00)). After adjusting for child’s sex and age at the time of behavioural assessment, markers of socioeconomic disadvantage, such as lower household income and lone parental status; maternal health factors, including younger maternal age, maternal pre-pregnancy body mass index, higher gestational weight gain and prenatal maternal stress; maternal lifestyle factors, such as prenatal alcohol and environmental air pollutant exposures, including particulate matter < 2.5 μm at birth, child secondhand tobacco smoke at 12 months, dampness/mould and home heating with oil, kerosene or diesel heaters at 2 years postnatal. Lower socioeconomic indexes for area, later birth order, higher maternal prenatal depression and maternal smoking frequency had a dose-response relationship with autism spectrum disorder symptoms. Future studies on environmental factors and autism spectrum disorder should consider the reasons for the socioeconomic disparity and the combined impact of multiple environmental factors through common mechanistic pathways.

Elastin degradation markers are elevated in never-smokers with past history of prolonged exposure to secondhand tobacco smoke and are inversely associated with their lung function

Background- Prolonged past exposure to secondhand tobacco smoke (SHS) in never-smokers is associated with occult obstructive lung disease and abnormal lung function, in particular reduced diffusing capacity. Previous studies have shown ongoing SHS exposure to be associated with increased elastin degradation markers (EDM) desmosine and isodesmosine. Research Question- Are EDM levels elevated in persons with remote history of SHS exposure, and are those levels associated with reduced lung function? Study Design and Methods- We measured the plasma levels of EDM from 193 never-smoking flight attendants with history of remote but prolonged SHS exposure in aircraft cabin and 103 nonsmoking flight attendants or sea-level control participants without history of cabin SHS exposure, and examined those levels versus their lung function with adjustment for covariates. The cabin SHS exposure was estimated based on airline employment history and dates of smoking ban enactment. EDM plasma levels were quantified by high-performance liquid chromatography and tandem mass spectrometry. Results- The median [interquartile range; IQR] plasma EDM level for all participants was 0.30 [0.24 to 0.36] ng/mL with a total range of 0.16 to 0.65 ng/mL. Plasma EDM levels were elevated in those with history of exposure to cabin SHS compared to those not exposed (0.33±0.08 vs. 0.26±0.06 ng/mL; age- and sex-adjusted P<0.001). In those with history of cabin SHS-exposure, higher EDM levels were associated with lower diffusing capacity (parameter estimate (PE) [95%CI]=4.2 [0.4 to 8.0] %predicted decrease per 0.1 ng/mL increase in EDM; P=0.030). Furthermore, EDM levels were inversely associated with FEV1, FEV1/FVC, and FEF25-75 (PE [95%CI]=5.8 [2.1 to 9.4], 4.0 [2.2 to 5.7], and 12.5 [5.8 to 19.2]% predicted decrease per 0.1 ng/mL increase in EDM, respectively) (P<0.001).

Long-term Impact of Prior Secondhand Tobacco Smoke Exposure on Respiratory Health

Rationale: Ongoing secondhand tobacco smoke (SHS) exposure is associated with worsened respiratory health, but little is known about the long-term impact decades after exposure ended. Objective: Determine the long-term consequences of SHS exposure on respiratory health. Methods: Population-based, cohort study in subjects ≥50 years old who had >1 year versus ≤1 year of airline occupational SHS-exposure. Measurements and Main Results: Respiratory health was the primary outcome measured by the St. Georges Respiratory Questionnaire (SGRQ). Key secondary outcomes included respiratory symptoms measured by COPD Assessment Test (CAT) and pre-bronchodilator lung function. The study enrolled 183 SHS-exposed and 59 unexposed subjects. SHS-exposed subjects were exposed to airline SHS for 16.1±9.3 years, which ended 27.5±9.4 years prior to enrollment. Prior SHS-exposure was associated with worse respiratory health based on a 6.7-unit increase in SGRQ (95% CI=[2.7, 10.7]; p=0.001) and 3-unit increase in CAT (95% CI=1.4, 4.6]; p<0.001) versus unexposed subjects, but was not associated with airflow obstruction defined by FEV1:FVC<0.7. Clinically-significant respiratory symptoms (CAT≥10) in SHS-exposed never smokers with preserved lung function (FEV1:FVC ≥0.7 and FVC ≥lower limit of normal) were associated with decreased respiratory and non-respiratory quality-of-life, reduced lung function that remained within the normal range, increased comorbidities and inhaled bronchodilator use, higher plasma CRP and SAA-1 and fewer sinonasal basal stem/progenitor cells versus asymptomatic (CAT<10) SHS-exposed subjects. Conclusion: SHS is associated with a phenotype of impaired respiratory health almost 3 decades after exposure ended, consistent with a symptomatic form of COPD with preserved lung function recently described in smokers.

Home Tobacco Use Policies and Exposure to Secondhand Tobacco Smoke: Findings from Waves 1 through 4 of the Population Assessment of Tobacco and Health (PATH) Study

Background: The 2006 Surgeon General’s Report recommended the elimination of smoking in homes as an effective protective measure against the harmful effects of secondhand tobacco smoke exposure. This study aims to examine trends in the prevalence and levels of the adoption of home tobacco use policies specifically for cigarettes, e-cigarettes, smokeless tobacco, and the relationships between home tobacco use policies and self-reported exposure to secondhand tobacco smoke. Methods: This study utilizes data from Wave 1 (2013–2014) through Wave 4 (2016–2018) of the Population Assessment of Tobacco and Health (PATH) Study, a large prospective cohort study of youths and adults in the United States which collected information about both smoke-free and tobacco-free home policies. We present the weighted, population-based, self-reported prevalence of home tobacco use policies overall and by product, and the average number of self-reported hours of secondhand smoke (SHS) exposure by levels of home tobacco policy and by survey wave. In addition, we examine the characteristics of those who adopted (by yes or no) a home tobacco use ban between survey waves. Results: We found a high prevalence of completely tobacco-free home policies (69.5%). However, 10.6% of adults allow the use of any type of tobacco product inside their homes, and 19.8% have a policy allowing the use of some types of tobacco products and banning the use of others. Adults with a complete tobacco use ban inside their homes were more likely to be nonusers of tobacco (79.9%); living with children in the home (71.8%); at or above the poverty level (70.8%); non-white (76.0%); Hispanic (82.7%); and aged 45 or older (71.9%). The adoption of 100% tobacco-free home policies is associated with a 64% decrease in secondhand smoke exposure among youths and a 69% decrease in exposure among adults. Conclusions: Most US adults have implemented tobacco-free home policies; however, there is still exposure to SHS in the home, for both adults and children, particularly in the homes of tobacco users. Additional research should investigate tobacco-free home policies for different types of products and what effect they have on future tobacco use behaviors.

Children of Smoking and Non-Smoking Households’ Perceptions of Physical Activity, Cardiorespiratory Fitness, and Exercise

Previous research has shown secondhand tobacco smoke to be detrimental to children’s health. This qualitative study aimed to explore children from low socioeconomic status (SES) families and their reasons for being physically active, attitudes towards physical activity (PA), fitness and exercise, perceived barriers and facilitators to PA, self-perceptions of fitness and physical ability, and how these differ for children from smoking and non-smoking households. A total of 38 children (9–11 years; 50% female; 42% smoking households) from the deprived areas of North West England participated in focus groups (n = 8), which were analysed by utilizing thematic analysis. The findings support hypothesised mediators of PA in children including self-efficacy, enjoyment, perceived benefit, and social support. Fewer than a quarter of all children were aware of the PA guidelines with varying explanations, while the majority of children perceived their own fitness to be high. Variances also emerged between important barriers (e.g., sedentary behaviour and environmental factors) and facilitators (e.g., psychological factors and PA opportunity) for children from smoking and non-smoking households. This unique study provided a voice to children from low SES and smoking households and these child perspectives could be used to create relevant and effective strategies for interventions to improve PA, fitness, and health.

Secondhand tobacco smoke exposure among children under 5 years old: questionnaires versus cotinine biomarkers: a cohort study

ObjectivesCotinine is the gold standard to estimate prevalence of secondhand tobacco smoke (SHS) exposure, and assay limit of detection (LOD) cut-points are typically used regardless of age. Our aim was to compare the concordance between mother-reported SHS exposure and serum cotinine categorising children as exposed with the assay LOD or age-specific cut-points.DesignData from the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort.SettingHospital or participants’ homes.Participants389 pregnant women aged 18 years and older, between 13 and 19 weeks of gestation, living in a five-county region of the Cincinnati, Ohio metropolitan area, and with follow-up on their children at birth and ages 12, 24, 36 and 48 months.Primary and secondary outcome measuresChildren’s serum cotinine, mother-reported active smoking and SHS exposure were available at birth and during follow-up visits. We used Cohen’s kappa index to assess concordance between maternal self-report and child’s serum cotinine concentrations. We estimated optimal age-specific cut-points, their sensitivity–specificity and positive–negative predictive values with receiver operating characteristic curves.ResultsSelf-reported exposure and cotinine data were available for 280 women who gave birth to singleton child. When applying the assay LOD (0.015 ng/mL), concordance between maternal report and serum cotinine, without accounting for age, was below 0.23 at all times. When using age-specific cut-points (12 months: 0.11 ng/mL; 24 months: 0.08 ng/mL; 36 months: 0.05 ng/mL and 48 months: 0.04 ng/mL), concordance improved, being low at 12 months (0.39), moderate at 24 and 36 months (0.47 and 0.43) and high at 48 months (0.62).ConclusionsConcordance between mother-reported SHS exposure among children under 5 years and serum cotinine improved considerably after applying the cohort-specific and age-specific cut-points. Future studies are necessary to verify these results.

Remote exposure to secondhand tobacco smoke is associated with lower exercise capacity through effects on oxygen pulse- a proxy of cardiac stroke volume

Background: Prolonged past exposure to secondhand tobacco smoke (SHS) is associated with exercise limitation. Pulmonary factors including air trapping contribute to this limitation but the contribution of cardiovascular factors is unclear. Methods: To determine contribution of cardiovascular mechanisms to SHS-associated exercise limitation, we examined the cardiovascular responses to maximum effort exercise testing in 166 never-smokers with remote but prolonged occupational exposure to SHS and no known history of cardiovascular disease except nine with medically-controlled hypertension. We estimated the contribution of oxygen-pulse (proxy for cardiac stroke volume) and changes in systolic (SBP) and diastolic blood pressures (DBP) and heart rate (HR) over workload towards exercise capacity, and examined whether the association of SHS with exercise capacity was mediated through these variables. Results: Oxygen consumption (VO2Peak) and oxygen-pulse (O2-PulsePeak) at peak exercise were 1,516±431mL/min (100±23 %predicted) and 10.6±2.8mL/beat (117±25 %predicted), respectively, with 91 (55%) and 43 (26%) of subjects not being able to achieve their maximum predicted values. Sixty-two percent showed hypertensive response to exercise by at least one established criterion. In adjusted models, VO2Peak was associated directly with O2-Pulse and inversely with rise of SBP and DBP over workload (all P<0.05). Moreover, SHS exposure association with VO2Peak was mainly (84%) mediated through its effect on oxygen-pulse (P=0.034). Notably, although not statistically significant, a large proportion (60%) of air trapping effect on VO2Peak seemed to be mediated through oxygen-pulse (P=0.066). Discussion: In a never-smoker population with remote prolonged exposure to SHS, abnormal escalation of afterload and an SHS-associated reduction in cardiac output contributed to lower exercise capacity.