In-Home Secondhand Smoke Exposure Among Urban Children With Asthma: Contrasting Households With and Without Residential Smokers

Short-Term Effects of Side-Stream Smoke on Nerve Growth Factor and Its Receptors TrKA and p75NTR in a Group of Non-Smokers

Environmental tobacco smoke remains a major risk factor, for both smokers and non-smokers, able to trigger the initiation and/or the progression of several human diseases. Although in recent times governments have acted with the aim of banning or strongly reducing its impact within public places and common spaces, environmental tobacco smoke remains a major pollutant in private places, such as the home environment or cars. Several inflammatory and long-term biomarkers have been analysed and well-described, but the list of mediators modulated during the early phases of inhalation of environmental tobacco smoke needs to be expanded. The aim of this study was to measure the short-term effects after exposure to side-stream smoke on Nerve Growth Factor and its receptors Tropomyosin-related kinase A and neurotrophin p75, molecules already described in health conditions and respiratory diseases. Twenty-one non-smokers were exposed to a home-standardized level of SS as well as to control smoke-free air. Nerve Growth Factor and inflammatory cytokines levels, as well the expression of Tropomyosin-related kinase A and neurotrophin receptor p75, were analysed in white blood cells. The present study demonstrates that during early phases, side-stream smoke exposure induced increases in the percentage of neurotrophin receptor p75-positive white blood cells, in their mean fluorescent intensity, and in gene expression. In addition, we found a positive correlation between the urine cotinine level and the percentage of neurotrophin receptor-positive white blood cells. For the first time, the evidence that short-term exposure to side-stream smoke is able to increase neurotrophin receptor p75 expression confirms the very early involvement of this receptor, not only among active smokers but also among non-smokers exposed to SS. Furthermore, the correlation between cotinine levels in urine and the increase in neurotrophin receptor p75-positive white blood cells could represent a potential novel molecule to be investigated for the detection of SS exposure at early time points.

The influence of urban exposures and residence on childhood asthma

Children with asthma who live in urban neighborhoods experience a disproportionately high asthma burden, with increased incident asthma and increased asthma symptoms, exacerbations, and acute visits and hospitalizations for asthma. There are multiple urban exposures that contribute to pediatric asthma morbidity, including exposure to pest allergens, mold, endotoxin, and indoor and outdoor air pollution. Children living in urban neighborhoods also experience inequities in social determinants of health, such as increased poverty, substandard housing quality, increased rates of obesity, and increased chronic stress. These disparities then in turn can increase the risk of urban exposures and compound asthma morbidity as poor housing repair is a risk factor for pest infestation and mold exposure and poverty is a risk factor for exposure to air pollution. Environmental interventions to reduce in-home allergen concentrations have yielded inconsistent results. Population-level interventions including smoking bans in public places and legislation to decrease traffic-related air pollution have been successful at reducing asthma morbidity and improving lung function growth. Given the interface and synergy between urban exposures and social determinants of health, it is likely population and community-level changes will be needed to decrease the excess asthma burden in children living in urban neighborhoods.

United States prevalence of pediatric asthma by environmental tobacco smoke exposure, 2016-2017

OBJECTIVES

We sought to update the prevalence estimates of parent-reported asthma diagnosis by Environmental Tobacco Smoke (ETS) exposure in the United States (US) pediatric population.

METHODS

This cross-sectional study included 71,811 families with children who participated in the 2016-2017 National Survey of Children's Health (NSCH). Weighted asthma prevalence estimates were calculated for ETS-exposed and non-exposed children. Chi-square analysis compared asthma prevalence between the two exposure groups and logistic regression analysis generated adjusted odds ratios (aORs) of asthma diagnosis by ETS exposure by sex, race/ethnicity, and household education and income level.

RESULTS

Asthma prevalence estimates were significantly higher in ETS-exposed vs. non-exposed children (10.7% vs. 7.8%, p < 0.001). Children with a smoker in the house are 30% more likely to have an asthma diagnosis vs. children with no smokers in the house (aOR 1.29, 95% Confidence Interval [CI] 1.09-1.52). Significant predictors for ETS exposure included < high school education and lower family income. Conversely, non-Hispanic black and Hispanic children were less likely to have ETS exposure vs. non-Hispanic white children.

CONCLUSIONS

ETS exposure is a significant risk factor for asthma in the US pediatric population. Smoking cessation initiatives targeting non-Hispanic white parents from lower socioeconomic may improve children's chronic pulmonary health risk.