Is exposure to secondhand smoke associated with cognitive parameters of children and adolescents?--a systematic literature review

Voice Disorder Prevalence and Vocal Health Characteristics in Children

Importance

Voice disorders impede communication and limit quality of life for many children. However, research demonstrating the prevalence of pediatric voice problems and associated voice use patterns is scarce. This investigation examined the prevalence of voice problems and vocal health characteristics of school-aged children.

Objective

To examine the prevalence of voice problems in school-aged children throughout the US with reference to lifestyle, demographic characteristics, and voice use patterns.

Design, Setting, and Participants

This study used a cross-sectional design to survey a probability sample of caregivers of children aged 4 to 12 years living throughout the US in 2023.

Main Outcomes and Measures

Caregivers were surveyed regarding their children's voice use, voice symptoms, voice problems, extracurricular activities, and demographic information. Caregivers also competed the Pediatric Voice-Related Quality of Life questionnaire. The Fisher exact test, χ2 tests, and logistic regression were used to compare children with and without voice problems.

Results

Overall, 6293 panelists were invited to complete screening questions for the survey, and 1789 individuals were screened for eligibility between March and April 2023. Of these, 1175 parents (65.7%) completed the survey. Twenty-one (1.8%) were excluded for a combination of either high refusal rates (n = 16), speeding (n = 2), or straight lining (n = 12). The final number of participants included in analysis was 1154 caregivers of children aged 4 to 12 years (559 female children [48.4%]; 595 male children [51.6%]; mean [SD] age, 8.02 [2.49] years). The prevalence of voice problems in children was 6.7% (n = 78), and the lifetime prevalence was 12% (n = 138). Benign vocal fold lesions was the most common diagnosis underlying voice complaints, and other causes included respiratory illness, allergies, autism-related voice issues, and other neurological conditions. Risk factors for pediatric voice problems included being male (odds ratio [OR], 1.47; 95% CI, 1.0-2.1), having more than 4 individuals living in the household (OR, 2.30; 95% CI, 1.2-4.4), poor speech intelligibility (OR, 2.26; 95% CI, 1.2-4.3), maternal history of voice problems (OR, 4.54; 95% CI, 1.2-16.4), participating in online gaming (OR, 1.56; 95% CI, 1.0-2.3), and secondhand smoke exposure (OR, 1.7; 95% CI, 1.1-2.6). Voice use-related risk factors included frequent talking, coughing, throat clearing, tantrums/crying, and vocal strain. Voice problems were associated with substantially detracted quality of life as measured by the Pediatric Voice-Related Quality of Life questionnaire, limited social/extracurricular interactions, increased school absences, and negative attention from adults.

Conclusions

The results of this survey study suggest that pediatric voice problems are relatively common and detract from quality of life. Specific environmental and behaviorial factors are associated with increased risk for voice disorders.

Maternal smoking during pregnancy and cortical structure in children with attention-deficit/hyperactivity disorder

Maternal smoking during pregnancy (MSDP) is considered a risk factor for ADHD. While the mechanisms underlying this association are not well understood, MSDP may impact the developing brain in ways that lead to ADHD. Here, we investigated the effect of prenatal smoking exposure on cortical brain structures in children with ADHD using two methods of assessing prenatal exposure: maternal recall and epigenetic typing. Exposure groups were defined according to: (1) maternal recall (+MSDP: n = 24; -MSDP: n = 85) and (2) epigenetic markers (EM) (+EM: n = 14 -EM: n = 21). CIVET-1.1.12 and RMINC were used to acquire cortical brain measurements and perform statistical analyses, respectively. The vertex with highest significance was tested for association with Continuous Performance Test (CPT) dimensions. While no differences of brain structures were identified between +MSDP and -MSDP, +EM children (n = 10) had significantly smaller surface area in the right orbitofrontal cortex (ROFc), middle temporal cortex (RTc) and parahippocampal gyrus (RPHg) (15% FDR) compared to -EM children (n = 20). Cortical surface area in the RPHg significantly correlated with CPT commission errors T-scores. This study suggests that molecular markers may better define exposure to environmental risks, as compared to human recall.

Associations between parental adherence to healthy lifestyles and cognitive performance in offspring: A prospective cohort study in China

BACKGROUND

Previous studies have reported associations of specific maternal and paternal lifestyle factors with offspring's cognitive development during early childhood. This study aimed to investigate the prospective associations between overall parental lifestyle and offspring's cognitive performance during adolescence and young adulthood in China.

METHODS

We included 2531 adolescents aged 10-15 years at baseline in 2010 from the China Family Panel Studies. A healthy parental lifestyle score (ranged 0-5) was constructed based on the following five modifiable lifestyle factors: Smoking, drinking, exercise, sleep, and diet. Generalized estimating equation models were used to examine the association between baseline parental healthy lifestyle scores and offspring's fluid and crystallized intelligence in subsequent years (2012, 2014, 2016, and 2018).

RESULTS

Offspring in the top tertile of parental healthy lifestyle scores performed better in overall fluid intelligence (multivariable-adjusted β = 0.53, 95% confidence interval [CI]: 0.29-0.77) and overall crystallized intelligence (multivariable-adjusted β = 0.35, 95% CI: 0.16-0.54) than those in the bottom tertile of parental healthy lifestyle scores. The results were similar after further adjustment for the offspring's healthy lifestyle scores and persisted across the subgroups of parental socioeconomic status. Additionally, maternal and paternal healthy lifestyle scores were independently associated with better offspring's cognitive performance, with significant contribution observed for paternal never-smoking, weekly exercise, and diversified diet. When both parents and offspring adhered to a healthier lifestyle, we observed the highest level of the offspring's overall crystallized intelligence.

CONCLUSIONS

Our study indicates that parental adherence to a healthier lifestyle is associated with significantly better offspring's cognitive performance during adolescence and early adulthood, regardless of socioeconomic status. These findings highlight the potential cognitive benefits of promoting healthy lifestyles among parents of adolescents.

Sources of personal PM2.5 exposure during pregnancy in the MADRES cohort

BACKGROUND

Personal exposure to fine particulate matter (PM2.5) is impacted by different sources each with different chemical composition. Determining these sources is important for reducing personal exposure and its health risks especially during pregnancy.

OBJECTIVE

Identify main sources and their contributions to the personal PM2.5 exposure in 213 women in the 3rd trimester of pregnancy in Los Angeles, CA.

METHODS

We measured 48-hr integrated personal PM2.5 exposure and analyzed filters for PM2.5 mass, elemental composition, and optical carbon fractions. We used the EPA Positive Matrix Factorization (PMF) model to resolve and quantify the major sources of personal PM2.5 exposure. We then investigated bivariate relationships between sources, time-activity patterns, and environmental exposures in activity spaces and residential neighborhoods to further understand sources.

RESULTS

Mean personal PM2.5 mass concentration was 22.3 (SD = 16.6) μg/m3. Twenty-five species and PM2.5 mass were used in PMF with a final R2 of 0.48. We identified six sources (with major species in profiles and % contribution to PM2.5 mass) as follows: secondhand smoking (SHS) (brown carbon, environmental tobacco smoke; 65.3%), fuel oil (nickel, vanadium; 11.7%), crustal (aluminum, calcium, silicon; 11.5%), fresh sea salt (sodium, chlorine; 4.7%), aged sea salt (sodium, magnesium, sulfur; 4.3%), and traffic (black carbon, zinc; 2.6%). SHS was significantly greater in apartments compared to houses. Crustal source was correlated with more occupants in the household. Aged sea salt increased with temperature and outdoor ozone, while fresh sea salt was highest on days with westerly winds from the Pacific Ocean. Traffic was positively correlated with ambient NO2 and traffic-related NOx at residence. Overall, 76.8% of personal PM2.5 mass came from indoor or personal compared to outdoor sources.

IMPACT

We conducted source apportionment of personal PM2.5 samples in pregnancy in Los Angeles, CA. Among identified sources, secondhand smoking contributed the most to the personal exposure. In addition, traffic, crustal, fuel oil, fresh and aged sea salt sources were also identified as main sources. Traffic sources contained markers of combustion and non-exhaust wear emissions. Crustal source was correlated with more occupants in the household. Aged sea salt source increased with temperature and outdoor ozone and fresh sea salt source was highest on days with westerly winds from the Pacific Ocean.

Association between exposure to tobacco information through mass media, smoking households and secondhand smoke exposure in adolescents: Survey data from South Korea

INTRODUCTION

To explore the current situation of exposure of Korean adolescents to secondhand smoke (SHS) in households our study aimed to determine the relationship between family member smoking status, exposure to tobacco information through mass media, and household SHS exposure.

METHODS

The present study uses pooled data from the Korean adolescent health behavior online survey conducted in 2015, 2018 and 2021, with 157944 participants. The regression models were used to explore the association between the smoking status of households, and exposure to tobacco information through mass media, and household SHS exposure in adolescents, controlling for potential confounding factors.

RESULTS

SHS exposure duration of Korean adolescents in households was 0.88 days per week. The households with smokers including the father (β=1.087; 95% CI: 1.0-1.126), mother (β=1.461; 95% CI: 1.379- 1.543), siblings (β=0.545; 95% CI: 0.493-0.597), grandparents (β=0.224; 95% CI: 0.174-0.272), and other relatives (β=0.170; 95% CI: 0.126-0.214), showed a positive association with SHS exposure in adolescents within the household. At the same time, information about anti-smoking ads on television (β= -0.042; 95% CI: -0.069 - -0.015) and public transportation (β= -0.031; 95% CI: -0.054 - -0.010), showed a negative association with SHS exposure in adolescents. However, broadcasts, online, and newspaper non-smoking ads were not associated with SHS exposure (p>0.05). In addition, regression models revealed that exposure to cigarette advertising in magazines (β=0.131; 95% CI: 0.097-0.166), networks (β=0.151; 95% CI: 0.127-0.175), convenience stores (β=0.061; 95% CI: 0.035-0.087), and supermarkets (β=0.133; 95% CI: 0.108-0.158) is associated with SHS exposure in adolescents. Finally, our study showed stronger ties between SHS exposure, family smoking, and tobacco ads in girls. The link between maternal smoking, supermarket ads, and adolescent SHS exposure intensified in 2021 compared to 2015.

CONCLUSIONS

Family and media were identified as potential factors associated with SHS exposure in adolescents. Therefore, publicity and education regarding household SHS hazards, and smoking bans in media, can be helpful in protecting adolescents from SHS.

Indoor air pollution exposure and early childhood development in the Upstate KIDS Study

BACKGROUND

Limited human studies have investigated the impact of indoor air pollution on early childhood neurodevelopment among the US population. We aimed to examine the associations between prenatal and postnatal indoor air pollution exposure and early childhood development in a population-based birth cohort.

METHODS

This analysis included 4735 mother-child pairs enrolled between 2008 and 2010 in the Upstate KIDS Study. Indoor air pollution exposure from cooking fuels, heating fuels, and passive smoke during pregnancy, and at 12 and 36 months after birth were assessed by questionnaires. Five domains of child development were assessed by the Ages and Stages Questionnaire at 4, 8, 12, 18, 24, 30, and 36 months. Generalized estimating equations were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for potential confounders.

RESULTS

Exposure to unclean cooking fuels (natural gas, propane, or wood) throughout the study period was associated with increased odds of failing any development domain (OR = 1.28, 95% CI 1.07, 1.53), the gross motor domain (OR = 1.52, 95% CI: 1.09, 2.13), and the personal-social domain (OR = 1.36, 95% CI: 1.00, 1.85), respectively. Passive smoke exposure throughout the study period increased the odds of failing the problem-solving domain by 71% (OR = 1.71, 95% CI 1.01, 2.91) among children of non-smoking mothers. No association was found between heating fuel use and failing any or specific domains.

CONCLUSION

Unclean cooking fuel use and passive smoke exposure during pregnancy and early life were associated with developmental delays in this large prospective birth cohort.

Contextualizing the impact of prenatal alcohol and tobacco exposure on neurodevelopment in a South African birth cohort: an analysis from the socioecological perspective

Background

Alcohol and tobacco are known teratogens. Historically, more severe prenatal alcohol exposure (PAE) and prenatal tobacco exposure (PTE) have been examined as the principal predictor of neurodevelopmental alterations, with little incorporation of lower doses or ecological contextual factors that can also impact neurodevelopment, such as socioeconomic resources (SER) or adverse childhood experiences (ACEs). Here, a novel analytical approach informed by a socio-ecological perspective was used to examine the associations between SER, PAE and/or PTE, and ACEs, and their effects on neurodevelopment.

Methods

N = 313 mother-child dyads were recruited from a prospective birth cohort with maternal report of PAE and PTE, and cross-sectional structural brain neuroimaging of child acquired via 3T scanner at ages 8-11 years. In utero SER was measured by maternal education, household income, and home utility availability. The child's ACEs were measured by self-report assisted by the researcher. PAE was grouped into early exposure (<12 weeks), continued exposure (>=12 weeks), and no exposure controls. PTE was grouped into exposed and non-exposed controls.

Results

Greater access to SER during pregnancy was associated with fewer ACEs (maternal education: β = -0.293,p = 0.01; phone access: β = -0.968,p = 0.05). PTE partially mediated the association between SER and ACEs, where greater SER reduced the likelihood of PTE, which was positively associated with ACEs (β = 1.110,p = 0.01). SER was associated with alterations in superior frontal (β = -1336.036, q = 0.046), lateral orbitofrontal (β = -513.865, q = 0.046), caudal anterior cingulate volumes (β = -222.982, q = 0.046), with access to phone negatively associated with all three brain volumes. Access to water was positively associated with superior frontal volume (β=1569.527, q = 0.013). PTE was associated with smaller volumes of lateral orbitofrontal (β = -331.000, q = 0.033) and nucleus accumbens regions (β = -34.800, q = 0.033).

Conclusion

Research on neurodevelopment following community-levels of PAE and PTE should more regularly consider the ecological context to accelerate understanding of teratogenic outcomes. Further research is needed to replicate this novel conceptual approach with varying PAE and PTE patterns, to disentangle the interplay between dose, community-level and individual-level risk factors on neurodevelopment.

Children Learning About Secondhand Smoke (CLASS III): a protocol for a cluster randomised controlled trial of a school-based smoke-free intervention in Bangladesh and Pakistan

INTRODUCTION

Secondhand smoke (SHS) exposure is a major cause of premature death and disease, especially among children. Children in economically developing countries are particularly affected as smoke-free laws are typically only partially implemented and private homes and cars remain a key source of SHS exposure. Currently, firm conclusions cannot be drawn from the available evidence on the effectiveness of non-legislative interventions designed to protect children from SHS exposure. Following the success of two feasibility studies and a pilot trial, we plan to evaluate a school-based approach to protect children from SHS exposure in Bangladesh and Pakistan-countries with a strong commitment to smoke-free environments but with high levels of SHS exposure in children. We will conduct a two-arm cluster randomised controlled trial in Bangladesh and Pakistan to assess the effectiveness and cost effectiveness of a school-based smoke-free intervention (SFI) in reducing children's exposure to SHS and the frequency and severity of respiratory symptoms.

METHODS AND ANALYSIS

We plan to recruit 68 randomly selected schools from two cities-Dhaka in Bangladesh and Karachi in Pakistan. From each school, we will recruit approximately 40 students in a year (9-12 years old) with a total of 2720 children. Half of the schools will be randomly allocated to the intervention arm receiving SFI and the other half will receive usual education. Salivary cotinine concentration-a highly sensitive and specific biomarker of SHS exposure-is the primary outcome, which will be measured at month 3 post-randomisation. Secondary outcomes will include frequency and severity of respiratory symptoms, healthcare contacts, school absenteeism, smoking uptake and quality of life. Embedded economic and process evaluations will also be conducted.

ETHICS AND DISSEMINATION

The trial has received ethics approval from the Research Governance Committee at the University of York. Approvals have also been obtained from Bangladesh Medical Research Council and Pakistan Health Research Council. If SFI is found effective, we will use a variety of channels to share our findings with both academic and non-academic audiences. We will work with the education departments in Bangladesh and Pakistan and advocate for including SFI within the curriculum.

TRIAL REGISTRATION NUMBER

ISRCTN28878365.

The association between urinary cotinine level and metabolic syndrome profiles among adolescents: findings from the Ewha Birth and growth study

BACKGROUND

Secondhand smoke (SHS) exposure among adolescents who are still developing can negatively affect their physical and psychological health, including metabolic syndrome (MetS), which is a risk factor for cardiovascular disease. However, the relationship between exposure to SHS and MetS in adolescence has not been evaluated.

METHODS

A total of 240 subjects aged 13-15 years who were followed up in the Ewha Birth and Growth Study were included in this study. Using the urinary cotinine level, the participants' exposure to SHS was divided into tertiles, and the continuous MetS score (cMetS) and its components were compared among the three groups using a generalized linear model and trend analysis. Univariate and multivariate linear regression analyses were performed. We adjusted for several confounding variables including sex, father's education level, father's current alcohol consumption status, moderate physical activity, and overweight status.

RESULTS

The association between cMetS and the urinary cotinine level was not significant. However, the higher the urinary cotinine level, the lower the high-density lipoprotein cholesterol (HDL-C) level. In particular, the significance of the HDL-C level was maintained after adjusting for covariates.

CONCLUSIONS

This study supports an association between SHS exposure and the components of MetS in adolescents aged 13-15 years, and it suggests the need to address SHS exposure in adolescents to reduce the cardiovascular risk in later life.

Willingness to Use Commercial Nicotine Gums, Lozenges, and Gummies Among Nontobacco Using Adolescents in Southern California

PURPOSE

New oral nicotine products (ONPs), often advertised as "tobacco-free" (i.e., pouches, gum, lozenges, gummies), come in nontobacco flavors appealing to adolescents. It is unknown how adolescent willingness to use ONPs differs by product type and flavor, and whether sociodemographic disparities exist.

METHODS

Adolescent never tobacco product users (n = 1, 289) in ninth or 10th grade from 11 high schools in Southern California were surveyed in fall 2021 about ever and past 6-month use of ONPs and sociodemographic characteristics. Adolescents were randomized to view five different ONPs in either fruit or mint flavor, and asked to rate their willingness to use each product. Multivariable logistic random effect-repeated measures regression examined associations of product type, flavor, and sociodemographic characteristics with any willingness to use ONPs.

RESULTS

Compared to traditional smokeless tobacco (willingness = 17.8%), adolescents reported greater willingness to use ONPs (gum, 28.2%; pouches, 21.1%; lozenge, 22.4%; gummies, 24.1%); adjusted odd ratios [aORs] 1.25-1.84; p-values<.001). Mint flavor (23.3%) compared to fruit flavor (21.4%), significantly increased odds of willingness to use across all ONPs (aOR [95%CI] = 1.15 [1.05, 1.26], p = .004). Younger adolescents (ninth, 24.2% vs. 10th grade, 21.4%) and LGBTQ+ (34.2%) versus heterosexual (19.7%) and cisgender (18.8%) adolescents were more willing to use these products.

DISCUSSION

Adolescents reported greater willingness to use new ONPs compared to traditional smokeless tobacco. Adolescents who were younger (vs. older adolescents) or identified as LGBTQ+ (vs. heterosexual and cisgender) were more willing to use new ONPs. Efforts to monitor adolescents' willingness to use and actual use of these products are warranted.

Long-term impact of tobacco exposure during pregnancy on children's psychomotor development

BACKGROUND

Both active and second-hand smoking (SHS) can cause complications during pregnancy and after delivery. This study aimed to assess how tobacco exposure (active and passive) during the fetal period could impact the psychomotor development of children when they attain the age of 3-6 years.

METHODS

The study included 160 mothers and their 3-6 year-old children. Two research groups were set up of children born to active or SHS mothers during the period when they were pregnant and a control group of children of non-smoking mothers. The parameters of the psychomotor development of the children were measured using the Age & Stage Questionnaires 3® (ASQ-3).

RESULTS

Children, whose mothers were smokers themselves or who were exposed to SHS during the period of pregnancy had an average psychomotor development score of 221 points versus 243.5 points in the control group. Twenty-six percent had delays (near or under the cut-off scores) in one of the assessed psychomotor areas and 60% had two or more psychomotor delays; 36% of children whose mothers were not exposed to smoking during pregnancy had normal psychomotor development and only 34% presented multiple psychomotor delays.

CONCLUSIONS

Fetuses exposed to tobacco are more likely to achieve a psychomotor development in the 'monitor' and 'fail' areas compared to the non-exposed control group. The children exposed to smoking during their fetal development should be considered as a group at risk of developmental delays, therefore they should be closely monitored and supported by caregivers and developmental pediatricians.

Tobacco Smoke Exposure, School Engagement, School Success, and Afterschool Activity Participation Among US Children

BACKGROUND

Tobacco smoke exposure (TSE), defined as secondhand smoke (SHS) and thirdhand smoke (THS), is associated with negative health consequences. This study's objective was to assess the associations between home TSE status and school engagement, school success, and afterschool activity participation among school-aged children.

METHODS

We conducted a secondary analysis of 2018-2019 National Survey of Children's Health cross-sectional data. Children ages 6-11 years (N = 17,466) were categorized into home TSE groups: no home TSE; THS exposure only; and SHS and THS exposure. Weighted logistic and Poisson regression models were built.

RESULTS

Compared to children with no home TSE, children with home THS exposure only and SHS and THS exposure were at decreased odds of being engaged in school (AOR = 0.69, 95%CI = 0.57, 0.83; AOR = 0.63, 95%CI = 0.41, 0.97, respectively), and at increased odds of having ≥1 school-to-home contact about child problems in school (AOR = 1.83, 95%CI = 1.50, 2.23; AOR = 1.58, 95%CI = 1.05, 2.37, respectively). Children with THS exposure only were at increased odds of missing ≥1 school day (AOR = 1.43, 95%CI = 1.13, 1.81). Children with THS exposure only (ARR = 0.90, 95%CI = 0.83, 0.96) and SHS and THS exposure (ARR = 0.74, 95%CI = 0.61, 0.89) were at reduced likelihood of participating in a higher number of afterschool activities.

CONCLUSIONS

Children exposed to home tobacco smoke are at unique risk for poorer school engagement and success.

Exposure to Particulate Matter as a Potential Risk Factor for Attention-Deficit/Hyperactivity Disorder in Korean Children and Adolescents (KNHANES 2008-2018)

Many epidemiological studies have suggested that air pollution adversely affects neurodevelopment in children; however, evidence is still lacking. This study aimed to determine the association between particulate matter (PM) exposure and attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. Data were obtained from the Korean National Health and Nutrition Examination Survey 2008-2018. Outcomes were defined from parental reports of ever doctor-diagnosed ADHD, and ADHD cases were matched to non-cases with 1:10 age-sex matching. Individual exposure levels were assigned according to each study participant's administrative address during the year of diagnosis. Multivariate logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). After age-sex matching at a 1:10 ratio, the final study participants comprised 1,120 children aged 6-19 years old. A unit increase in the PM₁₀ concentration was significantly associated with ADHD (OR, 1.44; 95% CI, 1.02-2.02 per 10 µg/m³). The association with ADHD was stronger at higher quartiles than in the lower quartiles of PM₁₀ exposure; however, it was not statistically significant. Our results suggested that long-term PM₁₀ exposure was associated with increased ADHD in children and adolescents. Children diagnosed with ADHD suffer from a variety of social activity and have a significant economic burden. Therefore, it is considered an important role to find out the effects of environmental risk factors, including air pollution, on children and adolescents. This may also help to increase the body of knowledge in this field and to stimulate further research.

Association between Environmental Tobacco Smoke Exposure and Adaptive Behavior in Individuals with Autism Spectrum Disorder

The study focuses on current issues of adaptive behavior in individuals with autism spectrum disorder (ASD) and on the possible risk factor of environmental tobacco smoke (ETS). Children examined at the Academic Research Center for Autism (ARCA) in Bratislava were involved in the study. The study sample included 84 children (71 boys) with ASD (average age 5.35 years) and a non-ASD group of 24 children (20 boys; average age 8.10 years). The “ETS Questionnaire” focused on the detection of parental smoking habits and other ETS exposures. The concentrations of cotinine in urine were measured by ELISA kit. A significant delay in adaptive behavior of children with ASD in comparison with the non-ASD group was identified. The significant differences were in adaptive behavior, communication, and everyday skills. Children with ASD were more likely to be exposed to ETS, especially in the household. Good agreement was found between objective and subjective ETS exposure indicators (kappa = 0.613). Self-reported exposure to ETS corresponded significantly with the median levels of urinary cotinine. In addition to evaluation and assessment of the quality of adaptive behavior, an important goal of further research should be to identify, investigate, and eliminate environmental factors that interfere with adaptive behavior.

Maternal smoking during pregnancy and intelligence quotient of offspring aged 18 and 30 years: Evidence from two birth cohorts in southern Brazil

Maternal smoking during pregnancy causes several harmful effects, including deficits in the intelligence quotient (IQ), a measure associated with academic achievements and higher socioeconomic position. We aimed to measure the association between maternal smoking during pregnancy and offspring's IQ in two birth cohorts from Pelotas, Brazil. Data from the 1982 and 1993 birth cohorts were analyzed. Smoking during pregnancy was ascertained at the perinatal follow-up, and IQ was measured at 30 years (1982) and 18 years (1993). Simple and multiple linear regressions were used for crude and adjusted analysis. Mediation analysis was performed using birth weight and breastfeeding as possible mediators. Data analysis was conducted in 2020. There were 3611 and 4050 participants from the 1982 and 1993 cohorts, respectively. After adjustment for potential confounders, the inverse association between smoking during pregnancy and children's IQ remained significant in both cohorts. Offspring of mothers who smoked during pregnancy had an average of 1.32 less IQ points (95%CI: -2.23, -0.242) in the 1982 cohort, and an average of 1.66 less IQ points (95%CI: -2.42, -0.90) in the 1993 cohort. Neither cohort showed association with paternal smoking (negative controls) after adjustment. Breastfeeding's mediated effects accounted for 26.2% and 23.9% of the association in the 1982 and 1993 cohorts, respectively, while birth weight's accounted for 6.8% and 30.1%, respectively; indirect effects were not significant. The inverse association between maternal smoking and IQ and the lack of association with paternal smoking reinforces our findings of a negative association between exposure and outcome.

Clouding up cognition?: Secondhand cannabis and tobacco exposure related to cognitive functioning in youth

Background

Increasing legalization of cannabis, in addition to longstanding rates of tobacco use, raises concerns for possible cognitive decrements from secondhand smoke or environmental exposure, although little research exists. We investigate the relation between cognition and secondhand and environmental cannabis and tobacco exposure in youth.

Methods

The Adolescent Brain Cognitive Development (ABCD) Study year 2 follow-up (N = 5580; 48% female) cognitive performance and secondhand or environmental cannabis or tobacco exposure data were used. Principal components analysis identified a global cognition factor. Linear mixed-effects models assessed global cognition and individual cognitive task performance by cannabis and/or tobacco environmental exposure. Sociodemographics and other potential confounds were examined. p values were adjusted using the false discovery rate method.

Results

Global cognition was not related to any exposure group after testing corrections and considering confounds. Beyond covariates and family- and site-level factors, secondhand tobacco was related to poorer visual memory (p = .02), and environmental tobacco was associated with poorer visuospatial (p = .02) and language (p = .008) skills. Secondhand cannabis was related to cognition, but not after controlling for potential confounders (p > .05). Environmental cannabis was related to better oral reading (p = .01). Including covariates attenuated effect sizes.

Conclusions

Secondhand tobacco exposure was associated with poorer visual memory, while environmental tobacco exposure was related to poorer language and visuospatial skills. Secondhand cannabis was not related to cognition after controlling for sociodemographic factors, but environmental cannabis exposure was related to better reading. Because, to our knowledge, this is the first known study of its kind and thus preliminary, secondhand cannabis should continue to be investigated to confirm results.

The Effects of Traffic Air Pollution in and around Schools on Executive Function and Academic Performance in Children: A Rapid Review

This review summarises the extant literature investigating the relation between traffic-related air pollution levels in and around schools and executive functioning in primary-school-aged children. An electronic search was conducted using Web of Science, Scopus, and Education Literature Datasets databases (February 2020). Review articles were also searched, and forwards and backwards searches of identified studies were performed. Included papers were assessed for quality. We included 9 separate studies (published in 13 papers). Findings suggest that indoor and outdoor particulate matter with a diameter of 2.5 μm or less (PM_2.5) negatively influences executive function and academic achievement and that indoor and outdoor nitrogen dioxide (NO₂) adversely affects working memory. Evidence for the effects of particulate matter with a diameter of 10 μm or less (PM₁₀) is limited but suggests potential wide-ranging negative effects on attention, reasoning, and academic test scores. Air pollution in and around schools influences executive function and appears to impede the developmental trajectory of working memory. Further research is required to establish the extent of these effects, reproducibility, consequences for future attainment, and place within the wider context of cognitive development.

BDNF as a potential mediator between childhood BPA exposure and behavioral function in adolescent boys from the INMA-Granada cohort

BACKGROUND

Bisphenol A (BPA) exposure has been linked to altered behavior in children. Within the European Human Biomonitoring Initiative (HBM4EU), an adverse outcome pathway (AOP) network was constructed supporting the mechanistic link between BPA exposure and brain-derived neurotrophic factor (BDNF).

OBJECTIVE

To test this toxicologically-based hypothesis in the prospective INMA-Granada birth cohort (Spain).

METHODS

BPA concentrations were quantified by LC-MS/MS in spot urine samples from boys aged 9-11 years, normalized by creatinine and log-2 transformed. At adolescence (15-17 years), blood and urine specimens were collected, and serum and urinary BDNF protein levels were measured using immunoassays. DNA methylation levels at 6 CpGs in Exon IV of the BDNF gene were also assessed in peripheral blood using bisulfite-pyrosequencing. Adolescent's behavior was parent-rated using the Child Behavior Checklist (CBCL/6-18) in 148 boys. Adjusted linear regression and mediation models were fit.

RESULTS

Childhood urinary BPA concentrations were longitudinally and positively associated with thought problems (β = 0.76; 95% CI: 0.02, 1.49) and somatic complaints (β = 0.80; 95% CI: -0.16, 1.75) at adolescence. BPA concentrations were positively associated with BDNF DNA methylation at CpG6 (β = 0.21; 95% CI: 0.06, 0.36) and mean CpG methylation (β = 0.10; 95% CI: 0.01, 0.18), but not with total serum or urinary BDNF protein levels. When independent variables were categorized in tertiles, positive dose-response associations were observed between BPA-thought problems (p-trend = 0.08), BPA-CpG6 (p-trend ≤ 0.01), and CpG6-thought problems (p-trend ≤ 0.01). A significant mediated effect by CpG6 DNA methylation was observed (β = 0.23; 95% CI: 0.01, 0.57), accounting for up to 34% of the BPA-thought problems association.

CONCLUSIONS

In line with toxicological studies, BPA exposure was longitudinally associated with increased BDNF DNA methylation, supporting the biological plausibility of BPA-behavior relationships previously described in the epidemiological literature. Given its novelty and preliminary nature, this effect biomarker approach should be replicated in larger birth cohorts.

Does secondhand smoke exposure increase the risk of acute respiratory infections among children aged 0-59 months in households that use clean cooking fuel? A cross-sectional study based on 601 509 households in India

This study examines whether exposure to secondhand smoke (SHS) increases the risk of acute respiratory infections (ARI) among children aged 0-59 months. Study utilized nationally representative data from National Family Health Survey (2015-2016), which adopted two-stage stratified random sampling. Four mutually exclusive groups based on the type of cooking fuel usage and SHS exposure were created. Descriptive statistics and multivariate logistics regression analysis were applied. At the national level, 10.5% prevalence of ARI was reported during 2015-2016. About 47.9% (95%CI 47.7-48.2) of households was exposed to SHS and used solid biomass fuel for cooking. Nearly, 20.7% of households with clean fuel usage was exposed to SHS. Regression analysis suggests that the likelihood of ARI among children who were living in households with solid biomass fuel usage and exposed to SHS was 11% (95%CI 1.06-1.17) greater than children living in households with clean fuel usage with no SHS exposure. Moreover, our results further revealed that the odds of ARI among children living in households with clean fuel but exposed to SHS were 19% (95%CI 1.13-1.25) higher than the children living in the household with no SHS exposure and clean fuel use. Children living in households exposed to SHS are at higher risk of ARI.

Prenatal Environment and Neurodevelopmental Disorders

The internal and external environment of the mother during the developmental stages of the fetus affects the offspring's health. According to the developmental origins of health and disease (DOHaD) theory, environmental factors influence the offspring and also affect health in adulthood. Recently, studies based on this theory have gained attracted attention because of their clinical utility in identifying the risk groups for various diseases. Neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD) can be caused by exposure to certain prenatal environments during pregnancy. This review describes the latest findings on the effect of prenatal environment on the onset mechanism of NDDs based on the DOHaD theory. Unravelling the molecular mechanisms underlying the pathogenesis of NDDs is important, because there are no therapeutic drugs for these disorders. Furthermore, elucidating the relationship between the DOHaD theory and NDDs will contribute to the popularization of preventive medicine.

Rethinking the urban physical environment for century-long lives: from age-friendly to longevity-ready cities

In response to increasing life expectancies and urbanization, initiatives for age-friendly cities seek to facilitate active and healthy aging by strengthening supports and services for older people. While laudable, these efforts typically neglect early-life exposures that influence long-term well-being. With a focus on the urban physical environment, we argue that longevity-ready cities can accomplish more than initiatives focused solely on old age. We review features of cities that cumulatively influence healthy aging and longevity, discuss the need for proactive interventions in a changing climate, and highlight inequities in the ambient physical environment, especially those encountered at early ages, that powerfully contribute to disparities in later life stages. Compared with strategies aimed largely at accommodating older populations, longevity-ready cities would aim to reduce the sources of disadvantages across the life course and simultaneously improve the well-being of older people.

Association between environmental tobacco smoke exposure in early life and autistic-like behaviors in Chinese preschoolers

OBJECTIVE

Few studies have evaluated the association between children's exposure to environmental tobacco smoke (ETS) in early life (during pregnancy, from birth to one year and from one to three years) and autistic-like behaviors. This study aimed to explore this association.

METHODS

This cross-sectional study analyzed data collected in 2017 as part of the Longhua Child Cohort Study. Autistic-like behaviors were measured using the Autism Behavior Checklist (ABC). Data on ETS exposure and autistic-like behaviors of children were collected via self-administered questionnaires completed by the mothers. Multivariate logistic regression models were undertaken to assess the associations.

RESULTS

Of the 65,243 participants included in this study, 1958 children met criteria for having autistic-like behaviors. The results showed that children were more likely to exhibit autistic-like behaviors when they were exposed to ETS in early life (AOR = 1.38; 95% CI = 1.26-1.52), compared to preschoolers without ETS exposure at any period of their early life. Compared with their unexposed counterparts, children who were exposed to ETS during gestation (AOR = 1.42; 95% CI = 1.29-1.57), or from birth to one year old (AOR = 1.42; 95% CI = 1.19-1.69) had significantly increased risk of autistic-like behaviors. In addition, with the increase in duration of exposure and average number of cigarettes smoked in the child's immediate environment, the risk of autistic-like behaviors increased.

CONCLUSION

Our study indicated that children's ETS exposure in early life was significantly associated with autistic-like behaviors. When children's exposure to cigarettes in early life increased in duration and number, the likelihood of the presence of autistic-like behaviors was higher.

Exploring the relationship between metal exposure, BDNF, and behavior in adolescent males

BACKGROUND

Brain-derived neurotrophic factor (BDNF) plays an important role in brain development by regulating multiple pathways within the central nervous system. In the Human Biomonitoring for Europe Project (HBM4EU), this neurotrophin is being implemented as a novel effect biomarker to evaluate the potential threats of environmental chemicals on neurodevelopment.

OBJECTIVES

To explore the relationships among exposure to environmental metals, BDNF biomarkers at two levels of biological complexity, and behavioral function in adolescent males.

METHODS

Data were gathered from 125 adolescents on: spot urine sample total concentrations of the neurotoxic metal(oid)s arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb); serum BDNF protein concentrations; and concurrent behavioral functioning according to the Child Behavior Check List (CBCL/6-18). In 113 of the participants, information was also collected on blood BDNF DNA methylation at six CpGs. Associations were evaluated by multivariate linear regression analysis adjusted for confounders.

RESULTS

As, Cd, Hg, and Pb were detected in 100%, 98.5%, 97.0%, and 89.5% of urine samples, respectively. Median serum BDNF concentration was 32.6 ng/mL, and total percentage of BDNF gene methylation was 3.8%. In the adjusted models, urinary As was non-linearly associated with more internalizing problems and Cd with more externalizing behaviors. The percentage BDNF DNA methylation at CPGs #5 and the mean percentage CpG methylation increased across As tertiles (p-trend = 0.04 and 0.03, respectively), while 2nd tertile and 3rd tertile of Cd concentrations were associated with lower serum BDNF and higher CpG3 methylation percentage. Additionally, when BDNF was categorized in tertiles, serum BDNF at the 3rd tertile was associated with fewer behavioral problems, particularly withdrawn (p-trend = 0.04), social problems (p-trend = 0.12), and thought problems (p-trend = 0.04).

CONCLUSION

Exposure to As and Cd was associated with BDNF gene DNA methylation BDNF gene and serum BDNF, respectively. Associations with DNA methylation may be attributable to a higher variability over time in circulating BDNF concentrations than in the methylation status of this gene. Caution should be taken when interpreting the results relating postnatal Pb and Hg to behavioral functioning. Further studies are needed to verify these findings.

Early childhood exposure to maternal smoking and behavioral development

We examined the association between early childhood exposure to maternal smoking and behavioral issues at 8 years old using a large nationwide population-based longitudinal survey in Japan that began in 2001. We included 46,737 children with information about maternal smoking taken from the 6-month survey. We used logistic regression analysis to examine the hypothesis. Early childhood exposure to maternal smoking increased the risk of behavioral problems related to attention and aggressive or disruptive behavior. The adjusted odds ratios (95% confidence intervals) were 1.37 (1.22-1.54) for inability to wait their turn during play and 1.40 (1.27-1.55) for destroying toys and, compared with children of nonsmoking mothers. Children of mothers who were heavy smokers were more likely to develop behavioral problems than others. Stopping early childhood exposure to maternal exposure can protect children's neurodevelopment.

Brief Advice, Nicotine Replacement Therapy Sampling, and Active Referral for Expectant Fathers Who Smoke Cigarettes: A Randomized Clinical Trial

IMPORTANCE

Pregnancy presents an opportunity to engage expectant fathers in smoking cessation, but evidence from randomized clinical trials is scarce.

OBJECTIVE

To evaluate the effectiveness of a proactive, combined intervention for smoking cessation in expectant fathers.

DESIGN, SETTING, AND PARTICIPANTS

This pragmatic randomized clinical trial in prenatal clinics in 7 public hospitals in Hong Kong proactively recruited and enrolled 1053 participants from October 10, 2018, to February 8, 2020. Included male adults were 18 years or older, smoked cigarettes daily in the past 3 months, had partners who were pregnant and nonsmoking in the past 30 days, and had a landline or mobile telephone number for follow-up. These participants were randomized to either the intervention group or the control group. The primary analyses used an intention-to-treat approach.

INTERVENTIONS

The intervention group received brief cessation advice, a 1-week free sample of nicotine replacement therapy (NRT), and active referral to a community-based smoking cessation service. The control group received only brief cessation advice with a leaflet on the hazards of perinatal exposure to tobacco smoke and the toll-free quitline telephone number.

MAIN OUTCOMES AND MEASURES

The primary outcome was biochemically validated tobacco abstinence at 6 months after intervention initiation defined by an exhaled carbon monoxide level of 3 parts per million or lower. The secondary outcomes included self-reported 24-week continuous abstinence at 6 months after intervention initiation as well as 7-day point prevalence abstinence, use of any NRT, and use of a smoking cessation service at 3 and 6 months after intervention initiation.

RESULTS

All 1053 randomized participants were male adults with a mean (SD) age of 33.8 (6.9) years. The retention rate at 6-month follow-up was 80.7%. The primary outcome of biochemically validated tobacco abstinence at 6 months after intervention initiation was significantly higher in the intervention group than in the control group (6.8% [36 of 527 participants] vs 3.6% [19 of 526]; odds ratio [OR], 1.96; 95% CI, 1.11-3.46; P = .02). The main secondary outcomes of self-reported 24-week continuous abstinence at 6 months (OR, 1.87; 95% CI, 1.08-3.23; P = .03) and 7-day point prevalence abstinence at 3 months (OR, 1.48; 95% CI, 1.05-2.09; P = .03) and 6 months (OR, 1.74; 95% CI, 1.29-2.34; P < .001) were also significantly higher in the intervention group. The intervention group had a significantly higher increase in perceived family harmony (score range, 0-10, with a higher score indicating a higher level of harmony) from baseline to 6 months (B = 0.28; 95% CI, 0.063-0.50; P = .01).

CONCLUSIONS AND RELEVANCE

This trial found that combining brief advice with a 1-week sample of NRT and referral to smoking cessation programs nearly doubled the odds that expectant fathers who smoked would achieve validated abstinence compared with providing brief advice alone. The intervention was also effective in promoting family harmony.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03671707.

Effects of accumulated environmental, social and host exposures on early childhood educational outcomes

BACKGROUND

Persistent disparities in academic performance may result from a confluence of adverse exposures accruing disproportionately to specific subpopulations.

OBJECTIVE

Our overarching objective was to investigate how multiple exposures experienced over time affect early childhood educational outcomes. We were specifically interested in whether there were: racial/ethnic disparities in prevalence of adverse exposures; racial/ethnic disparities in associations observed between adverse exposures and early childhood educational outcomes; and interactions between exposures, suggesting that one exposure augments susceptibility to adverse effects of another exposure.

METHODS

We link geocoded North Carolina birth data for non-Hispanic white (NHW) and non-Hispanic black (NHB) children to blood lead surveillance data and 4th grade end-of-grade (EOG) standardized test scores (n = 65,151). We construct a local, spatial index of racial isolation (RI) of NHB at the block group level. We fit race-stratified multi-level models of reading and mathematics EOG scores regressed on birthweight percentile for gestational age, blood lead level, maternal smoking, economic disadvantage, and RI, adjusting for maternal- and child-level covariates and median household income.

RESULTS

There were marked racial/ethnic disparities in prevalence of adverse exposures. Specifically, NHB children were more likely than NHW children to be economically disadvantaged (80% vs. 40%), live in block groups with the highest quintile of RI (46% vs. 5%), have higher blood lead levels (4.6 vs. 3.7 μg/dL), and lower birthweight percentile for gestational age (mean: 39th percentile vs. 51st percentile). NHB children were less likely to have mothers who reported smoking during pregnancy (11% and 22%). We observed associations between key adverse exposures and reading and math EOG scores in 4th grade. Higher birthweight percentile for gestational age was associated with higher EOG scores, while economic disadvantage, maternal smoking, and elevated blood lead levels were associated with lower EOG scores. Associations observed for NHB and NHW children were generally not statistically different from one another, with the exception of neighborhood RI. NHB children residing in block groups in the highest RI quintile had reading and math scores 1.54 (0.74, 2.34) and 1.12 (0.38, 1.87) points lower, respectively, compared to those in the lowest RI quintile; statistically significant decrements in EOG scores associated with RI were not observed for NHW children. We did not find evidence of multiplicative interactions between exposures for NHB or NHW children.

DISCUSSION

Key adverse host, environmental, and social exposures accrue disproportionately to NHB children. Decrements in test scores associated with key adverse exposures were often but not always larger for NHB children, but were not significantly different from those estimated for NHW children. While we did not observe interactive effects, NHB children on average experience more deleterious combined exposures, resulting in larger decrements to test scores compared to NHW children.

Long-term cerebrovascular dysfunction in the offspring from maternal electronic cigarette use during pregnancy

Electronic cigarettes (E-cigs) have been promoted as harm-free or less risky than smoking, even for women during pregnancy. These claims are made largely on E-cig aerosol having fewer number of toxic chemicals compared with cigarette smoke. Given that even low levels of smoking are found to produce adverse birth outcomes, we sought to test the hypothesis that vaping during pregnancy (with or without nicotine) would not be harm-free and would result in vascular dysfunction that would be evident in offspring during adolescent and/or adult life. Pregnant female Sprague Dawley rats were exposed to E-cig aerosol (1 h/day, 5 days/wk, starting on gestational day 2 until pups were weaned) using e-liquid with 0 mg/mL (E-cig0) or 18 mg/mL nicotine (E-cig18) and compared with ambient air-exposed controls. Body mass at birth and at weaning were not different between groups. Assessment of middle cerebral artery (MCA) reactivity revealed a 51%-56% reduction in endothelial-dependent dilation response to acetylcholine (ACh) for both E-cig0 and E-cig18 in 1-mo, 3-mo (adolescent), and 7-mo-old (adult) offspring (P < 0.05 compared with air, all time points). MCA responses to sodium nitroprusside (SNP) and myogenic tone were not different across groups, suggesting that endothelial-independent responses were not altered. The MCA vasoconstrictor response (5-hydroxytryptamine, 5-HT) was also not different across treatment and age groups. These data demonstrate that maternal vaping during pregnancy is not harm-free and confers significant cerebrovascular health risk/dysfunction to offspring that persists into adult life. NEW & NOTEWORTHY These data established that vaping electronic cigarettes during pregnancy, with or without nicotine, is not safe and confers significant risk potential to the cerebrovascular health of offspring in early and adult life. A key finding is that vaping without nicotine does not protect offspring from cerebrovascular dysfunction and results in the same level of cerebrovascular dysfunction (compared with maternal vaping with nicotine), indicating that the physical and/or chemical properties from the base solution (other than nicotine) are responsible for the cerebrovascular dysfunction that we observed. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/maternal-vaping-impairs-vascular-function-in-theoffspring/.

Mitochondrial DNA Copy Number and Developmental Origins of Health and Disease (DOHaD)

Mitochondrial dysfunction is known to contribute to mitochondrial diseases, as well as to a variety of aging-based pathologies. Mitochondria have their own genomes (mitochondrial DNA (mtDNA)) and the abnormalities, such as point mutations, deletions, and copy number variations, are involved in mitochondrial dysfunction. In recent years, several epidemiological studies and animal experiments have supported the Developmental Origin of Health and Disease (DOHaD) theory, which states that the environment during fetal life influences the predisposition to disease and the risk of morbidity in adulthood. Mitochondria play a central role in energy production, as well as in various cellular functions, such as apoptosis, lipid metabolism, and calcium metabolism. In terms of the DOHaD theory, mtDNA copy number may be a mediator of health and disease. This paper summarizes the results of recent epidemiological studies on the relationship between environmental factors and mtDNA copy number during pregnancy from the perspective of DOHaD theory. The results of these studies suggest a hypothesis that mtDNA copy number may reflect environmental influences during fetal life and possibly serve as a surrogate marker of health risks in adulthood.

Prevalence and factors related to secondhand smoke exposure among secondary school-going adolescents in Malaysia: Findings from Malaysia Global Health School Survey 2012 and 2017

INTRODUCTION

Secondhand (SHS) smoke exposure has caused various health problems. Therefore, continuous monitoring of SHS exposure is important to determine the efficacy of various anti-tobacco measure implemented. The study aims to compare the prevalence and factor(s) associated with SHS exposure among secondary school-going adolescents in Malaysia during 2012 and 2017.

METHODS

We derived data from the Global School Health Survey (GSHS) 2012 and GSHS 2017, which was carried out in Malaysia using multistage sampling to select representative samples of secondary school-going adolescents. Both surveys used similar questionnaires to measure SHS exposure. Descriptive and multivariate logistic regression was used to determine the prevalence and factors associated with SHS exposure.

RESULTS

Approximately four in ten respondents were exposed to SHS in the past week in both surveys (41.5% in GSHS 2012 and 42.0% in GSHS 2017, respectively). Both surveys revealed a significantly higher SHS exposure among respondents who smoked than among non-smokers and higher among males compared to females. The likelihood of SHS exposure in both surveys was also similar, with a higher likelihood of SHS exposure among smoking adolescents and non-smoking adolescents who had at least one smoking parent/guardian, regardless of their own smoking status. Male adolescents had a higher risk of SHS exposure compared to their female counterparts. Meanwhile, SHS risk also increased with age, regardless of smoking status.

CONCLUSIONS

Our findings suggested that there were no changes in the prevalence of SHS exposure and recorded only a slight change in the factors associated with exposure to SHS among school-going adolescents in Malaysia between the years 2012 and 2017. A more pro-active, extensive and comprehensive programme should be implemented to address the problem of SHS exposure. Parents should be advised to stop smoking or abstain from smoking in the presence of their children, and smoking cessation interventions are necessary for smoking adolescents and their parents.

Identifying the Best Questions for Rapid Screening of Secondhand Smoke Exposure Among Children

INTRODUCTION

Many children suffer from secondhand smoke exposure (SHSe), which leads to a variety of negative health consequences. However, there is no consensus on how clinicians can best query parents for possible SHSe among children. We employed a data-driven approach to create an efficient screening tool for clinicians to quickly and correctly identify children at risk for SHSe.

METHODS

Survey data from mothers and biospecimens from children were ascertained from the Neurodevelopment and Improving Children's Health following Environmental Tobacco Smoke Exposure (NICHES) study. Included were mothers and their children whose saliva were assayed for cotinine (n = 351 pairs, mean child age = 5.6 years). Elastic net regression predicting SHSe, as indicated from cotinine concentration, was conducted on available smoking-related questions and cross-validated with 2015-2016 National Health and Nutrition Examination Survey (NHANES) data to select the most predictive items of SHSe among children (n = 1670, mean child age = 8.4 years).

RESULTS

Answering positively to at least one of the two final items ("During the past 30 days, did you smoke cigarettes at all?" and "Has anyone, including yourself, smoked tobacco in your home in the past 7 days?") showed area under the curve = .82, and good specificity (.88) and sensitivity (.74). These results were validated with similar items in the nationally representative NHANES sample, area under the curve = .82, specificity = .78, and sensitivity = .77.

CONCLUSIONS

Our data-driven approach identified and validated two items that may be useful as a screening tool for a speedy and accurate assessment of SHSe among children.

IMPLICATIONS

The current study used a rigorous data-driven approach to identify questions that could reliably predict SHSe among children. Using saliva cotinine concentration levels as a gold standard for determining SHSe, our analysis employing elastic net regression identified two questions that served as good classifier for distinguishing children who might be at risk for SHSe. The two items that we validated in the current study can be readily used by clinicians, such as pediatricians, as part of screening procedures to quickly identify whether children might be at risk for SHSe.

Maternal smoking during pregnancy and intelligence quotient in offspring: A systematic review and meta-analysis

BACKGROUND

Exposure to tobacco during pregnancy may disrupt fetal brain development and impact offspring cognitive development.

AIMS

To perform a systematic review and meta-analysis on maternal smoking during pregnancy and intelligence quotient (IQ) in childhood, adolescence, and adulthood.

METHODS

We searched PubMed, Lilacs, PsycINFO, and Web of Science. Original articles evaluating tobacco use/exposure during pregnancy and the offspring's IQ as the outcome. The review protocol is registered in PROSPERO (number CRD 42,019,116,257). For the meta-analysis, we included studies with information on the regression coefficient and its confidence interval (CI) or standard error. Random effects model was used for pooling the estimates.

RESULTS

25 studies were included in the review, and of these 14 met the inclusion criteria for the meta-analysis. The overall pooled estimate showed that subjects who were exposed to maternal smoking during pregnancy presented lower IQ scores, compared to those not exposed to maternal smoking (β -1.30; 95 % CI -1.74, -0.86; I² = 87.8 %); IQ scores were also lower in crude (β -5.46; 95 % CI -7.31, -3.60; I²: 79.0 %) and adjusted pooled estimates (β =-0.45; 95 % CI -0.76, -0.13; I² = 80.4 %), for the group exposed to maternal smoking. In the stratified analysis, an inverse association was also observed in studies with large sample size (n≥1000 participants) (β=-0.49; 95 % CI -0.96, -0.02), among those performed with adolescents (β=-1.16; 95 % CI -2.18, -0.14), and among those adjusted for maternal education (β=-0.57; 95 % CI -1.05, -0.08).

CONCLUSIONS

Our findings suggest that exposure to tobacco during pregnancy may have negative effects on IQ. However, the findings of this meta-analysis should be interpreted with caution.

Exposure to Tobacco Smoke and Temperament among U.S. Children 0-5 Years Old

OBJECTIVES

This study examined the association between tobacco smoke exposure (TSE) and temperament among children 0-5 years old overall and within age groups: 0-2 and 3-5 years.

METHODS

Data were obtained from the 2017-2018 NSCH (N = 14,345). TSE status was defined as whether children lived with a smoker who: does not smoke inside the home (no home TSE) or smokes inside the home (home TSE). We conducted logistic regression analyses while controlling for covariates.

RESULTS

Overall, 12.5% of children lived with a smoker with no home TSE and 1.1% had home TSE. Children with home TSE were at increased odds to not always: be affectionate and tender (aOR = 1.74, 95% CI = 1.18-2.58), show interest and curiosity (aOR = 1.81, 95% CI = 1.23-2.68), and smile and laugh (aOR = 1.77, 95% CI = 1.13-2.77) than those with no TSE. Among 0- to 2-year-olds, those with home TSE were more likely to not always be affectionate and tender (aOR = 1.97, 95% CI = 1.04-3.74). Among 3- to 5-year-olds, those who lived with a smoker with no home TSE were more likely to not always: bounce back quickly (aOR = 1.21, 95% CI = 1.05-1.40) and smile and laugh (aOR = 1.26, 95% CI = 1.03-1.54), and those with home TSE were more likely to not always: show interest and curiosity (aOR = 2.24, 95% CI = 1.40-3.59) and smile and laugh (aOR = 2.43, 95% CI = 1.43-4.11).

CONCLUSIONS

Tobacco smoke-exposed children were at increased odds of not always demonstrating positive early childhood temperament behaviors, with 3- to 5-year-olds having more pronounced odds.

Association between secondhand smoke exposure at home and cognitive performance among rural primary school children in Malaysia

INTRODUCTION

Secondhand smoke (SHS) exposure is linked to a series of serious health problems. Children may be particularly vulnerable to the effects of SHS exposure at home. This study aimed to determine the association between SHS exposure at home and cognitive performance in school children.

METHODS

A multistage sampling was performed across rural primary schools in Kuala Krai, Kelantan, Malaysia. Data were collected using self-administered questionnaires and the children aged 10-11 years (n=312) were subjected to cognitive tests including digit span, letter-number sequencing, coding, and symbol search. Cognitive performance was tested using subscales derived from the Wechsler Intelligence Scale for Children.

RESULTS

The prevalence of SHS exposure at home was 55.8%, where 11.9% of children lived with one smoker, while 43.9% of children lived with ≥2 smokers. There was a significant difference in the mean score of the combined cognitive tests between SHS-exposed and non-exposed children after adjustment for sex, parental educational level, family income and academic performance [Pillai's Trace=0.084, F statistic (df)=6.803 (4302), p<0.001].

CONCLUSIONS

More than half of the primary school children in rural Kuala Krai were exposed to SHS from at least one smoker at home. There was a significant association between SHS exposure at home and cognitive performance.

Exposure to Secondhand Smoke in Children is Associated with a Thinner Retinal Nerve Fiber Layer: The Hong Kong Children Eye Study

PURPOSE

We sought to assess the effects of exposure to secondhand smoke (SHS) on peripapillary retinal nerve fiber layer (p-RNFL) thickness in children.

DESIGN

Cross-sectional study.

METHODS

Children 6-8 years of age were consecutively recruited from the population-based Hong Kong Children Eye Study. All participants received comprehensive ophthalmic examinations and p-RNFL thickness was measured by spectral-domain optical coherence tomography. SHS data were derived from a validated questionnaire. Associations between p-RNFL thickness and SHS exposure status, number of smokers in the family, and quantity of smoking in the family were determined by multivariate linear regression after adjusting for potential confounders.

RESULTS

Among the Hong Kong Children Eye Study cohort (n = 3,103), approximately one-third of children were exposed to SHS (35.4%, n = 1,097). Compared to those without exposure to SHS, children exposed to SHS had similar age (P = .83), gender (P = .17), body mass index (P = .44), birth weight (P = .23), and axial length (P = .34), but had lower family income (P < .001) and lower parental education level (P < .001). After adjusting for all the above factors, exposure to SHS was associated with a thinner global p-RNFL by 4.4 μm (P < .001). Reduced p-RNFL was also associated with increased numbers of smokers in the family (β = -3.40, P < .001) and increased quantity of SHS (β = -0.22, P < .001).

CONCLUSIONS

Exposure to SHS in children was associated with a thinner p-RNFL. A thinner p-RNFL may increase the risk of irreversible visual impairment in the future. Our results provide evidence to recommend that children avoid exposure to SHS.

Maternal Tobacco and Alcohol Use in Relation to Child Malnutrition in Gauteng, South Africa: A Retrospective Analysis

Tobacco and alcohol use among mothers is associated with numerous adverse consequences for affected offspring, including poor growth and development. This study determined the association between maternal tobacco and alcohol use, and malnutrition, among infants aged ≤ 12 months (n = 300), in selected health facilities situated in Gauteng, South Africa. Data on alcohol and tobacco use were collected using a validated questionnaire, in addition to mothers’ socio-demographic characteristics and obstetric history. Stunting (low height/length-for-age), underweight (low weight-for-age) and thinness (low body mass index-for-age) were calculated using z-scores based on the World Health Organization child growth standards. The association of tobacco and alcohol use with stunting, underweight and thinness was analysed using logistic regression analysis. The results showed a mean age of 29 years (24.0; 35.0) for mothers and 7.6 ± 3 months for infants, and over half of the mothers were unemployed (63%). Approximately 18.7% of mothers had used tobacco and 3% had used alcohol during pregnancy. The prevalence of current tobacco and alcohol use among mothers were estimated at 14.3% and 49.7%, respectively, and almost three-quarters (67.3%) of them were still breastfeeding during the study period. Stunting (55%) was the most prevalent malnutrition indicator among infants, while underweight was 41.7%, and thinness was 22%. Current tobacco use was associated with increased odds of being thin [OR = 2.40, 95% CI: 1.09–5.45), and after adjusting for confounders, current alcohol use was associated with the likelihood of being underweight [AOR = 1.96, 95% CI: 1.06–3.63] among infants. Future prospective cohort studies that examine growth patterns among infants who are exposed to maternal tobacco and alcohol use from the intrauterine life to infancy are necessary to inform, partly, the public health programmes, to reduce malnutrition among children.

Prenatal Tobacco Exposure and Childhood Neurodevelopment among Infants Born Prematurely

OBJECTIVE

Nicotine is an established neuroteratogen, and prenatal tobacco exposure alters the structure of the developing nervous system. An association between prenatal tobacco exposure and impaired neurologic function is less well established. We examine the association between prenatal tobacco exposure and childhood neurodevelopment among infants born preterm.

STUDY DESIGN

Secondary analysis of a multicenter randomized controlled trial assessing the benefits of magnesium sulfate for the prevention of cerebral palsy in preterm infants. Women were included if they delivered a singleton and nonanomalous infant before 37 weeks. Exposure was any self-reported prenatal tobacco use. Primary outcome was the original trial composite outcome of moderate or severe cerebral palsy at 2 years of age, or stillbirth, or infant death by 1 year of age. Secondary outcomes included components of the composite and mild cerebral palsy at 2 years, Bayley Scales of Infant Development II motor and mental scores, death before two years, and use of auditory aids or corrective lenses. Multivariable logistic regression models were performed to estimate adjusted odds ratios (aOR) with 95% confidence intervals.

RESULTS

Of 1,826 women included, 503 (27.5%) used tobacco. Tobacco users were more likely to be older, unmarried, and white; have a prior preterm birth; have received no prenatal care; and to use illicit drugs or alcohol. Gestational age at delivery, betamethasone exposure, and magnesium exposure were not different between groups. There were no differences in the composite primary outcome or in rates of cerebral palsy by tobacco use. Moderate developmental delay was more common among tobacco exposed in bivariate but not adjusted analysis (20.5 vs. 15.9%, p = 0.035). In adjusted analysis, tobacco exposure was associated with increased use of corrective lenses (5.0 vs. 2.9%, aOR: 2.28, 95% confidence interval: 1.28-4.07).

CONCLUSION

Prenatal tobacco exposure is not associated with neurodevelopmental impairment in infants born preterm. However, tobacco exposure may be associated with impaired vision.

KEY POINTS

· Tobacco exposure is not associated with impaired neurodevelopment in this preterm population.. · Prenatal tobacco exposure is associated with increased need for corrective lenses.. · Tobacco use in pregnancy may be a risk factor for poorer visual acuity in children..

The Association between Secondhand Smoke and Stress, Depression, and Suicidal Ideation in Adolescents

Background: Secondhand smoke (SHS) is an important risk factor for adolescents’ health. Several studies have reported that SHS is as dangerous as active smoking. Therefore, this study aimed to investigate the association between exposure to SHS and mental health, including stress, depression, and suicidal ideation, in adolescents. Methods: Using raw data from the 2018 14th Korea Youth Risk Behavior Web-Based Survey, we analyzed the effects of sociodemographic characteristics on stress, depression, suicidal ideation in 51,500 students, including 85.8% of all sampled students (n = 60,040), after excluding students with a history of smoking, and then we performed logistic regression analysis to determine the level of exposure to SHS and its impact on stress, depression, and suicidal ideation. Results: The increased level of exposure to SHS was positively associated with stress, depression, and suicidal ideation. Furthermore, stress, depression, and suicidal ideation increased as the level of SHS increased, after adjusting for variables such as age, gender, education level of the father and mother, school achievement, economic status, inhabitation, and drinking. Conclusions: This study demonstrates that SHS is positively associated with risk of mental health problems, including stress, depression, and suicidal ideation, in adolescents. Further research and policy strategies and systems to prevent and manage exposure to SHS in adolescents are required.

Prevalence of Mental Health and Neurodevelopmental Conditions in U.S. Children with Tobacco Smoke Exposure

INTRODUCTION

This study investigated the prevalence and correlates of current mental health and neurodevelopmental conditions among U.S. school-age children with tobacco smoke exposure (TSE).

METHOD

Data from the 2016-17 National Survey of Children's Health were analyzed. Multivariable logistic regression analyses among 6-11-year-olds (n = 21,539) and among subsamples aged 6-8 years (n = 10,100) and 9-11 years (n = 11,439) were conducted.

RESULTS

Among 6-11-year-olds who lived with a smoker with no home TSE, the top mental health/neurodevelopmental conditions were other mental health conditions (22.1%), behavioral/conduct problems (21.7%), attention deficit disorder or attention deficit hyperactivity disorder (20.5%), depression (21.7%), and learning disability (19.3%). Children who lived with a smoker, with or without home TSE, were at increased odds of having anxiety problems, depression, attention deficit disorder or attention deficit hyperactivity disorder, behavioral/conduct problems, other mental health conditions, or learning disabilities. Many associations were more notable in younger children with home TSE.

DISCUSSION

TSE is associated with mental health and neurodevelopmental conditions. Interventions to decrease TSE are needed to protect children.

The association between maternal exposure to secondhand smoke during pregnancy and their children's cerebral palsy, Shandong, China

INTRODUCTION

Tobacco use poses a threat to the health of pregnant women and their children. Our study assessed the association between maternal exposure to secondhand smoke (SHS) during pregnancy and children's cerebral palsy (CP) in Shandong, China.

METHODS

In our observational study, 5067 mother-child pairs were included from Shandong Province, China. Mothers filled in questionnaires about exposure to SHS during pregnancy. Statistical analysis and logistic regression models were built in R program to estimate the association in adjusted odds ratio (AOR) between SHS exposure during pregnancy and risk of children's CP, after adjustment for potential confounders including delivery mode and baby's birthweight.

RESULTS

Exposure to SHS was noted among 3663 (72.3%) of the 5067 non-smoking mothers during their pregnancy. Of the 239 CP children within the study, 192 (80.3%) were exposed to SHS during pregnancy. Children born to mothers exposed to SHS during pregnancy had a higher risk of CP (AOR=1.44; 95% CI: 1.02-2.04) than those born to non-exposed mothers, the risk increased by exposure time in the logistic regression model. The association between SHS exposure during pregnancy and CP children remained significant when adjusting for delivery mode and infant's birthweight due to their significant association with CP, with an AOR of 1.46 (95% CI: 1.13-1.91) for 1-4 days/week and 1.63 (95% CI: 1.22-2.01) for 5-7 days/week exposure to SHS.

CONCLUSIONS

Our study suggests that maternal exposure to secondhand smoke during pregnancy is associated with children's CP. Future preventive interventions of CP should include strategies that target the antenatal women who are exposed to SHS.

Childhood Exposure to Parental Smoking and Midlife Cognitive Function

We studied whether exposure to parental smoking in childhood/adolescence is associated with midlife cognitive function, leveraging data from the Cardiovascular Risk in Young Finns Study. A population-based cohort of 3,596 children/adolescents aged 3-18 years was followed between 1980 and 2011. In 2011, cognitive testing was performed on 2,026 participants aged 34-49 years using computerized testing. Measures of secondhand smoke exposure in childhood/adolescence consisted of parental self-reports of smoking and participants' serum cotinine levels. Participants were classified into 3 exposure groups: 1) no exposure (nonsmoking parents, cotinine <1.0 ng/mL); 2) hygienic parental smoking (1-2 smoking parents, cotinine <1.0 ng/mL); and 3) nonhygienic parental smoking (1-2 smoking parents, cotinine ≥1.0 ng/mL). Analyses adjusted for sex, age, family socioeconomic status, polygenic risk score for cognitive function, adolescent/adult smoking, blood pressure, and serum total cholesterol level. Compared with the nonexposed, participants exposed to nonhygienic parental smoking were at higher risk of poor (lowest quartile) midlife episodic memory and associative learning (relative risk (RR) = 1.38, 95% confidence interval (CI): 1.08, 1.75), and a weak association was found for short-term and spatial working memory (RR = 1.25, 95% CI: 0.98, 1.58). Associations for those exposed to hygienic parental smoking were nonsignificant (episodic memory and associative learning: RR = 1.19, 95% CI: 0.92, 1.54; short-term and spatial working memory: RR = 1.10, 95% CI: 0.85, 1.34). We conclude that avoiding childhood/adolescence secondhand smoke exposure promotes adulthood cognitive function.

Impact of maternal hypertensive disorders on offspring's neurodevelopment: a longitudinal prospective cohort study in China

BACKGROUND

Maternal hypertensive disorders of pregnancy (HDP) are the major causes of maternal mortality. However, the association between HDP and offspring's neurodevelopment remains unclear.

METHOD

Participants were 4031 singleton live births from a prospective cohort study in Wuhan, China, during October 2013 to October 2014. Neurodevelopment of infant was evaluated by using Chinese version of Gesell Developmental Schedules at 0.5 year of age. Maternal HDP and potential confounders were ascertained by healthcare records at baseline.

RESULTS

Generalized linear model analysis indicated that maternal chronic hypertension were significantly associated with development quotient on fine motor (β = -3.32, 95% CI: -6.33 to -0.31), adaptability (β = -2.87, 95% CI: -5.31 to -0.43), language (β = -1.23, 95% CI: -2.12 to -0.34) and social behavior (β = -2.53, 95% CI: -4.69 to -0.37), and gestational hypertension was significantly associated with development quotient on social behavior (β = -1.42, 95% CI: -2.03 to -0.81), even after adjustment of major confounders. Multivariable logistic regression analysis showed that maternal chronic hypertension also increased the risk of diagnosis of "neurodevelopmental delay" on fine motor (OR = 1.85, 95% CI: 1.19-2.89), adaptability (OR = 2.32, 95% CI: 1.42-3.78), language (OR = 2.86, 95% CI: 1.74-4.70), and social behavior (OR = 2.13, 95% CI: 1.73-2.59).

CONCLUSION

This study suggests that exposure to HDP is associated with an increased risk of neurodevelopment impairment in the offspring at the age of 0.5 year.

Environmental Tobacco Smoke and Educational Self-Regulation and Achievement in First Grade High School Students

Environmental tobacco smoke, containing many toxic gases, suggests inevitable contact of humans with the damaging factors of cigarettes. On average, approximately 40% of children, 35% of women and 32% of men worldwide are exposed to environmental tobacco smoke. This study aims at investigating the relationship between environmental tobacco smoke in adolescents and their educational self-regulation and achievement. In this study, 770 students aged between 13 and 15 were selected and studied using the multistage sampling method. The tools used in this study consisted of four questionnaires, demographic characteristics, environmental tobacco smoke, educational self-regulation, and educational achievement. The validity and reliability of tools have been approved, and the data were analyzed using SPSS v22. The results indicated a significant inverse relationship between environmental tobacco smoke and students' educational self-regulation and achievement (p-value > 0.001). Given the relationship between exposure to environmental tobacco smoke and educational self-regulation and achievement, it is essential to keep children away from tobacco smoke. Family health and education policy-makers are recommended to design and operate fundamental schemes in order to deal with environmental tobacco smoke.

Secondhand Smoke Exposure and Subsequent Academic Performance Among U.S. Youth

INTRODUCTION

Previous research shows the associations between secondhand smoke exposure and health consequences among youth, but less is known about its effect on academic performance. This study examines a dose-response relationship between secondhand smoke exposure and subsequent academic performance among U.S. youth.

METHODS

Data were from a nationally representative sample of youth non-tobacco users (aged 12-16 years) in Wave 2 (2014-2015) who completed Wave 3 (2015-2016) of the Population Assessment of Tobacco and Health Study (n=9,020). Past-7-day number of hours exposed to secondhand smoke at Wave 2 and academic performance at Wave 3 (1=Mostly As to 9=Mostly Fs) were assessed. Weighted multivariable linear regression models were used to examine the association between hours of self-reported secondhand smoke exposure at Wave 2 and academic performance at Wave 3 (1=Mostly Fs, 9=Mostly As), adjusting for covariates including sociodemographics, prior academic performance, internalizing and externalizing problems, and substance use problems. Analyses were conducted in 2019.

RESULTS

More than 30% of U.S. youth non-tobacco users were exposed to secondhand smoke in the past 7 days. Compared with unexposed youth at Wave 2, those who were exposed for 1-9 hours had poorer academic performance at Wave 3 (adjusted regression coefficient= -0.11, 95% CI= -0.18, -0.04), and those who were exposed for ≥10 hours at Wave 2 had even poorer academic performance (adjusted regression coefficient = -0.31, 95% CI= -0.45, -0.18).

CONCLUSIONS

A dose-response relationship was observed between secondhand smoke exposure and academic performance among U.S. youth. Reducing youth secondhand smoke exposure may promote academic performance and subsequent educational attainment.

Socioeconomic characteristics, paternal smoking and secondhand tobacco smoke exposure among infants in Jakarta, Indonesia

INTRODUCTION

Prevalence of paternal smoking is high in Asia and babies are vulnerable to secondhand tobacco smoke (SHS) exposure at home. This study assesses socioeconomic characteristics and paternal smoking in households and infants' exposure to SHS.

METHODS

A cross-sectional analysis of data collected as part of a prospective cohort study was conducted in Jakarta, Indonesia during 2017-2019. Participants were 156 mother-baby pairs whose babies reached the age of 6 months. Socioeconomic characteristics and smoking behaviour in the household were assessed by questionnaires. Factors related to paternal smoking and infants' exposure to SHS were assessed using a multivariate logistic regression model.

RESULTS

Almost two-thirds of infants lived with fathers who were smokers. Lower levels of paternal education (OR=2.59; 95% CI: 1.19-5.63; p=0.045) and infants with one sibling (OR=2.41; 95% CI: 1.02-5.67; p=0.044) increased the risk of paternal smoking in the household. Moreover, infants with one sibling (OR=3.09; 95% CI: 1.15-8.32; p=0.026), lower level of father education (OR=18.73; 95% CI: 1.54-227.93; p=0.022), and a high number of other household members who smoke (OR=4.54; 95% CI : 1.42-14.48; p=0.011) were the risk factors of SHS exposure among infants at home.

CONCLUSIONS

These findings demonstrate the significant influence of educational level, number of children and/or number of other smokers in the household on paternal smoking and SHS exposure among infants at home. Comprehensive tobacco control programmes to increase adoption of smoke-free homes are likely to be an effective way to reduce SHS exposure and promote decreased cigarette smoking in families with children.

Exposure to household secondhand smoke among adolescents in Kuwait: Results from two school-based cross-sectional studies

INTRODUCTION

Detrimental effects of secondhand smoke (SHS) exposure are well established; however, data on SHS exposure among adolescents in Kuwait are lacking. Hence, this study sought to estimate the prevalence of household SHS exposure among two samples of adolescents in Kuwait and assess its variation by socioeconomic status and parental education level.

METHODS

Data from two large school-based cross-sectional studies were analyzed. Adolescents attending public middle (n=3864; aged 11–14 years) and high (n=1959; aged 14–19 years) schools throughout Kuwait were enrolled in 2016-2017, and parental self-reported household SHS exposure was ascertained. Associations were assessed using Poisson regression with robust variance estimation, and adjusted prevalence ratios (APRs) and 95% confidence intervals (CIs) were estimated.

RESULTS

Overall, 45.8% (1755/3836; 95% CI: 44.2–47.3%) of the enrolled middle school students and 51.6% (998/1936; 95% CI: 49.3–53.8%) of the enrolled high school students were exposed to household SHS. Among middle and high school students, the prevalence of household SHS exposure increased as maternal/paternal education level and family income decreased. Among middle school students, paternal educational attainment of middle school or less compared to bachelor’s degree or higher was associated with 1.60 times (95% CI: 1.44–1.79) higher household SHS exposure. Similarly, in the sample of middle school students, the prevalence of household SHS exposure significantly increased from 35.8% among children from families reporting the highest household income to 50.5% among children from families with the lowest reported household income (p-trend<0.001).

CONCLUSIONS

Household SHS exposure is substantially high among adolescents in Kuwait. Enrolled adolescents from families with low socioeconomic status or with low parental education level have the highest household SHS exposure. These findings highlight the need for national comprehensive tobacco control policies and increasing parental awareness of the impact of SHS exposure on children.

Children Learning About Secondhand Smoke (CLASS II): A Pilot Cluster Randomized Controlled Trial

Introduction

Children exposed to secondhand smoke (SHS) are at increased risk of respiratory illnesses. We piloted a Smoke Free Intervention (SFI) and trial methods before investigating its effectiveness and cost-effectiveness in primary school children.

Methods

In a pilot cluster randomized controlled trial in Bangladesh, primary schools were allocated to usual education (control) or SFI, using minimization. Year-5 children were recruited. Masking treatment allocation was not possible. Delivered by schoolteachers, SFI consisted of two 45-min and four 15-min educational sessions. Our primary outcome was SHS exposure at two months post randomization, verified by children’s salivary cotinine. The trial is registered at ISRCTN.com; ISRCTN68690577.

Results

Between April 1, 2015 and June 30, 2015, we recruited 12 schools. Of the 484 children present in Year-5, 481 consented. Six schools were allocated to both SFI (n = 245) and to usual education only (n = 236). Of them, 450 children (SFI = 229; control = 221) who had cotinine levels indicative of SHS exposure were followed-up. All schools were retained, 91% children (208/229) in SFI and 88% (194/221) in the control arm completed primary outcome assessment. Their mean cotinine at the cluster level was 0.53 ng/ml (SD 0.36) in SFI and 1.84 ng/ml (SD 1.49) in the control arm—a mean difference of −1.31 ng/ml (95% CI = −2.86 to 0.24).

Conclusion

It was feasible to recruit, randomize, and retain primary schools and children in our trial. Our study, though not powered to detect differences in mean cotinine between the two arms, provides estimates to inform the likely effect size for future trials.

Implications

In countries with high smoking prevalence, children remain at risk of many conditions due to secondhand smoke exposure. There is little empirical evidence on the effectiveness and cost-effectiveness of interventions that can reduce their exposure to secondhand smoke at homes. CLASS II trial found that a school-based intervention (SFI) has the potential to reduce children’s exposure to SHS—an approach that has been rarely used, but has considerable merit in school-based contexts. CLASS II trial provides key information to conduct a future definitive trial in this area of public health, which despite its importance has so far received little attention.