Evaluation of exposure to carbon monoxide associated with passive smoking

Secondhand smoking increased the possibility of hypertension with a significant time and frequency dose-response relationship

In this research, we investigated whether secondhand smoking (SHS) increases the possibility of hypertension. We used data from the Shaanxi baseline survey of the Regional Ethnic Cohort Study in Northwest China (RECS). Active smoking and SHS were determined by questionnaires. Hypertension was defined as self-reported or objectively measured. Multivariable logistic regression model was performed to estimate the risk of hypertension under active smoking and SHS. Compared to never-smokers, exposure to SHS had a 9% (P = 0.005) higher possibility of hypertension. The adjusted OR for exposure time of ≤ 3 h/week, 3-12 h/week, and > 12 h/week were 1.03 (P = 0.545), 1.10 ( P = 0.040), and 1.15 (P = 0.015), respectively. The adjusted OR for frequency of SHS of 1-2 times/week, 3-5 times/week, and nearly every day were 0.94 (P = 0.421), 1.01 (P = 0.846), and 1.14 (P < 0.001), respectively. Compared to smokers, additional exposure to SHS had a more than threefold increased possibility of having hypertension. The adjusted OR for hypertension was 1.07 (P = 0.254), and 1.23 (P = 0.007) in only smokers and smokers with SHS, respectively. Our study provided evidence that SHS could be a risk factor for hypertension, and additional exposure of active smokers to SHS significantly increases the possibility of hypertension. Reducing the frequency or time of SHS may be effective in preventing hypertension.

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.

Association of secondhand smoke exposure with mental health in men and women: Cross-sectional and prospective analyses using the UK Health and Lifestyle Survey

Objectives:

We examine cross-sectional and prospective associations between objectively measured SHS exposure and mental health using data from the Health and Lifestyle Survey (HALS), a large, UK-wide, general population-based, prospective cohort study with measurements of carbon monoxide or salivary cotinine levels.

Methods:

Mental health was assessed using the 30-item version of the General Health Questionnaire (GHQ). Multivariate logistic regression models adjusting for age, sex, height, body mass index, alcohol intake, social status, and longstanding illness were used to analyze the association between exposure to SHS (exhaled CO and salivary cotinine categories) and psychological distress (≥ 5 GHQ).

Results:

Fully adjusted cross-sectional analysis revealed a positive relationship between exhaled carbon monoxide and psychological distress among smokers (OR 1.36; 95% CI 1.04-1.78) but not among non-smoking adults. In a similar cross-sectional analysis between cotinine level and psychological distress, non-significant associations were found among smokers and non-smokers. Prospective analyses of the cotinine-psychological distress relationship among participants without psychological distress at baseline showed no significant increased risk of psychological distress among both smokers and non-smokers. In a prospective analysis of poor mental health outcome with respect to self-report smoking and SHS status, smokers had an increased risk of psychological distress while SHS and non-smokers did not.

Conclusions:

A non-significant association between objectively measured SHS exposure and poor mental health was found in this study. Our findings show discrepancies with recent studies suggesting the need for additional future research in this growing field of study.

Carbon monoxide pollution and neurodevelopment: A public health concern

Although an association between air pollution and adverse systemic health effects has been known for years, the effect of pollutants on neurodevelopment has been underappreciated. Recent evidence suggests a possible link between air pollution and neurocognitive impairment and behavioral disorders in children, however, the exact nature of this relationship remains poorly understood. Infants and children are uniquely vulnerable due to the potential for exposure in both the fetal and postnatal environments during critical periods in development. Carbon monoxide (CO), a common component of indoor and outdoor air pollution, can cross the placenta to gain access to the fetal circulation and the developing brain. Thus, CO is of particular interest as a known neurotoxin and a potential public health threat. Here we review overt CO toxicity and the policies regulating CO exposure, detail the evidence suggesting a potential link between CO-associated ambient air pollution, tobacco smoke, and learning and behavioral abnormalities in children, describe the effects of subclinical CO exposure on the brain during development, and provide mechanistic insight into a potential connection between CO exposure and neurodevelopmental outcome. CO can disrupt a number of critical processes in the developing brain, providing a better understanding of how this specific neurotoxin may impair neurodevelopment. However, further investigation is needed to better define the effects of perinatal CO exposure on the immature brain. Current policies regarding CO standards were established based on evidence of cardiovascular risk in adults with pre-existing comorbidities. Thus, recent and emerging data highlighted in this review regarding CO exposure in the fetus and developing child may be important to consider when the standards and guidelines are evaluated and revised in the future.

Environmental monitoring of secondhand smoke exposure

The complex composition of secondhand smoke (SHS) provides a range of constituents that can be measured in environmental samples (air, dust and on surfaces) and therefore used to assess non-smokers' exposure to tobacco smoke. Monitoring SHS exposure (SHSe) in indoor environments provides useful information on the extent and consequences of SHSe, implementing and evaluating tobacco control programmes and behavioural interventions, and estimating overall burden of disease caused by SHSe. The most widely used markers have been vapour-phase nicotine and respirable particulate matter (PM). Numerous other environmental analytes of SHS have been measured in the air including carbon monoxide, 3-ethenylpyridine, polycyclic aromatic hydrocarbons, tobacco-specific nitrosamines, nitrogen oxides, aldehydes and volatile organic compounds, as well as nicotine in dust and on surfaces. The measurement of nicotine in the air has the advantage of reflecting the presence of tobacco smoke. While PM measurements are not as specific, they can be taken continuously, allowing for assessment of exposure and its variation over time. In general, when nicotine and PM are measured in the same setting using a common sampling period, an increase in nicotine concentration of 1 μg/m³ corresponds to an average increase of 10 μg/m³ of PM. This topic assessment presents a comprehensive summary of SHSe monitoring approaches using environmental markers and discusses the strengths and weaknesses of these methods and approaches.

Respiratory and immune response to maximal physical exertion following exposure to secondhand smoke in healthy adults

We assessed the cardiorespiratory and immune response to physical exertion following secondhand smoke (SHS) exposure through a randomized crossover experiment. Data were obtained from 16 (8 women) non-smoking adults during and following a maximal oxygen uptake cycling protocol administered at baseline and at 0-, 1-, and 3- hours following 1-hour of SHS set at bar/restaurant carbon monoxide levels. We found that SHS was associated with a 12% decrease in maximum power output, an 8.2% reduction in maximal oxygen consumption, a 6% increase in perceived exertion, and a 6.7% decrease in time to exhaustion (P<0.05). Moreover, at 0-hours almost all respiratory and immune variables measured were adversely affected (P<0.05). For instance, FEV₁ values at 0-hours dropped by 17.4%, while TNF-α increased by 90.1% (P<0.05). At 3-hours mean values of cotinine, perceived exertion and recovery systolic blood pressure in both sexes, IL4, TNF-α and IFN-γ in men, as well as FEV₁/FVC, percent predicted FEV₁, respiratory rate, and tidal volume in women remained different compared to baseline (P<0.05). It is concluded that a 1-hour of SHS at bar/restaurant levels adversely affects the cardiorespiratory and immune response to maximal physical exertion in healthy nonsmokers for at least three hours following SHS.

Neurodevelopmental consequences of sub-clinical carbon monoxide exposure in newborn mice

Carbon monoxide (CO) exposure at high concentrations results in overt neurotoxicity. Exposure to low CO concentrations occurs commonly yet is usually sub-clinical. Infants are uniquely vulnerable to a variety of toxins, however, the effects of postnatal sub-clinical CO exposure on the developing brain are unknown. Apoptosis occurs normally within the brain during development and is critical for synaptogenesis. Here we demonstrate that brief, postnatal sub-clinical CO exposure inhibits developmental neuroapoptosis resulting in impaired learning, memory, and social behavior. Three hour exposure to 5 ppm or 100 ppm CO impaired cytochrome c release, caspase-3 activation, and apoptosis in neocortex and hippocampus of 10 day old CD-1 mice. CO increased NeuN protein, neuronal numbers, and resulted in megalencephaly. CO-exposed mice demonstrated impaired memory and learning and reduced socialization following exposure. Thus, CO-mediated inhibition of neuroapoptosis might represent an important etiology of acquired neurocognitive impairment and behavioral disorders in children.

Effects of environmental tobacco smoke on the pulmonary circulation in the ovine fetus

OBJECTIVE

Epidemiologic studies have highlighted an association between maternal smoking and persistent pulmonary hypertension of the newborn infant. However, the impact of exposure to tobacco smoke on the perinatal pulmonary circulation is currently unknown. The purpose of this study was to assess the pulmonary vascular effects of environmental tobacco smoke in the fetus.

STUDY DESIGN

We performed surgery on 16 fetal lambs and placed catheters in the main pulmonary artery, aorta, and left atrium to measure pressures. An ultrasonic blood flow transducer was placed around the left pulmonary artery to measure blood flow. The ewes were exposed to tobacco smoke for 2 hours. In another set of experiments, the pulmonary vascular response to increased fetal O(2) tension has been assessed after 2 hours of tobacco smoke inhalation or not (control group).

RESULTS

Exposure to tobacco smoke decreased pulmonary blood flow by 30% and elevated pulmonary vascular resistance by 40%. The vasodilator response to increased O(2) tension was blunted after smoke inhalation compared with control animals. Smoke inhalation was associated with a decrease in fetal PaO(2) and SaO(2).

CONCLUSION

Exposure to environmental tobacco smoke in pregnant ewes impairs both basal tone and vascular reactivity of the fetal lung.

Secondhand smoke inhibits both Cl- and K+ conductances in normal human bronchial epithelial cells

Secondhand smoke (SHS) exposure is an independent risk factor for asthma, rhinosinusitis, and more severe respiratory tract infections in children and adults. Impaired mucociliary clearance with subsequent mucus retention contributes to the pathophysiology of each of these diseases, suggesting that altered epithelial salt and water transport may play an etiological role. To test the hypothesis that SHS would alter epithelial ion transport, we designed a system for in vitro exposure of mature, well-differentiated human bronchial epithelial cells to SHS. We show that SHS exposure inhibits cAMP-stimulated, bumetanide-sensitive anion secretion by 25 to 40% in a time-dependent fashion in these cells. Increasing the amount of carbon monoxide to 100 ppm from 5 ppm did not increase the amount of inhibition, and filtering SHS reduced inhibition significantly. It was determined that SHS inhibited cAMP-dependent apical membrane chloride conductance by 25% and Ba²⁺-sensitive basolateral membrane potassium conductance by 50%. These data confirm previous findings that cigarette smoke inhibits chloride secretion in a novel model of smoke exposure designed to mimic SHS exposure. They also extend previous findings to demonstrate an effect on basolateral K⁺ conductance. Therefore, pharmacological agents that increase either apical membrane chloride conductance or basolateral membrane potassium conductance might be of therapeutic benefit in patients with diseases related to SHS exposure.

Sexual dimorphism in the acute effects of secondhand smoke on thyroid hormone secretion, inflammatory markers and vascular function

Experimental evidence for the physiological effects of secondhand smoke (SHS) is limited, although it affects millions of people globally and its prevalence is increasing, despite currently adopted antismoking measures. Also, scarce evidence suggests that the effects of SHS may be more pronounced in men. We conducted a randomized single-blind crossover study to investigate the sex-specific SHS effects in a controlled simulated bar/restaurant environment on gonadal and thyroid hormones, inflammatory cytokines, and vascular function. Twenty-eight (women = 14) nonsmoking adults underwent a 1-h exposure to moderate SHS and a 1-h control trial. Serum and urine cotinine, gonadal and thyroid hormones, inflammatory cytokines, heart rate, and arterial blood pressure were assessed before exposure and immediately after in both trials. Results showed that testosterone (P = 0.019) and progesterone (P < 0.001) in men and 17beta-estradiol (P = 0.001) and progesterone (P < 0.001) in women were significantly decreased after SHS. In men, SHS was accompanied by increased free thyroxine (P < 0.001), triiodothyronine (P = 0.020), and decreased the triiodothyronine-to-free thyroxine ratio (P = 0.033). In women, significant SHS-induced change was observed only in free thyroxine (P = 0.010), with considerable sex variation in free thyroxine and triiodothyronine and a decrease in luteinizing hormone (P = 0.026) and follicle-stimulating hormone (P < 0.001). After SHS, IL-1beta (P = 0.001) and systolic blood pressure (P = 0.040) were increased in men but not women. We concluded that a 1-h SHS exposure at bar/restaurant levels is accompanied by decrements in gonadal hormones in both sexes and marked increases in thyroid hormone secretion, IL-1beta production, and systolic blood pressure in men.

Carbon monoxide exposure assessment among toll operators in Klang Valley, Kuala Lumpur, Malaysia

A comparative cross-sectional study was conducted to determine tollbooth carbon monoxide (CO) levels and carboxyhaemoglobin (COHb) levels among the tollbooth operators and office workers in the Klang Valley, Kuala Lumpur. All tollbooths were equipped with well functioning air-conditioning. The total number of respondents was 180: 90 toll operators and 90 office workers aged between 19 and 52 years. The highest peak of CO level recorded was 61 ppm. The highest average peak CO level within a shift was 30 ppm. The CO level was higher during peak traffic at 6.00 - 8.00 a.m. There was no significant correlation between average peak CO level with vehicle load (r = -0.007, p = 0.474). The toll operators' median COHb level (1.0%, IQR = 0.8%) was significantly higher (p = 0.008) compared to office workers (0.7%, IQR = 0.8). There was a weak and significant correlation between COHb levels with average peak CO levels (r = 0.228, p = 0.031). In conclusion, tollbooth operators were chronically exposed to CO leading to higher COHb levels compared to office workers.

A brief exposure to moderate passive smoke increases metabolism and thyroid hormone secretion

CONTEXT

Active smoking influences normal metabolic status and thyroid function.

OBJECTIVE

The objective was to assess experimentally the effects of 1 h of moderate passive smoking in a controlled simulated bar/restaurant environment on the metabolism and thyroid hormone levels in healthy nonsmokers.

PARTICIPANTS

Eighteen (nine females, nine males) healthy individuals (mean +/- sd: age, 25.3 +/- 3.1 yr; height, 174.0 +/- 10.1 cm; weight, 65.2 +/- 13.7 kg) participated in the study.

DESIGN

In repeated-measures randomized blocks, participants visited the laboratory on 2 consecutive days. In the experimental condition, they were exposed to 1 h of moderate passive smoking at a carbon monoxide concentration of 23 +/- 1 ppm in an environmental chamber, whereas in the control condition participants remained in the same chamber for 1 h breathing normal atmospheric air.

MAIN OUTCOME MEASURES

In both conditions, cotinine serum and urine levels, resting energy expenditure (REE), as well as concentration of T3, free T4, and TSH were assessed before participants entered the chamber and immediately after their exit. Heart rate and blood pressure were tested in 10-min intervals during all REE assessments.

RESULTS

The mean +/- sd difference of serum and urine cotinine levels (-0.27 +/- 3.94 vs. 14.01 +/- 6.54 and 0.05 +/- 2.07 vs. 7.23 +/- 3.75, respectively), REE (6.73 +/- 98.06 vs. 80.58 +/- 120.91) as well as T3 and free T4 (0.05 +/- 0.11 vs. 0.13 +/- 0.12 and 0.02 +/- 0.15 vs. 0.22 +/- 0.20) were increased in the experimental compared with the control condition at baseline and follow-up (P < 0.05). No statistically significant variation was observed in the mean difference of the remaining parameters (P > 0.05). Serum and urine cotinine values were linearly associated with REE (P < 0.05).

CONCLUSION

One hour of passive smoking at bar/restaurant levels is accompanied by significant increases in metabolism and thyroid hormone levels.

Cardiovascular effects of secondhand smoke: nearly as large as smoking

BACKGROUND

Secondhand smoke increases the risk of coronary heart disease by approximately 30%. This effect is larger than one would expect on the basis of the risks associated with active smoking and the relative doses of tobacco smoke delivered to smokers and nonsmokers.

METHODS AND RESULTS

We conducted a literature review of the research describing the mechanistic effects of secondhand smoke on the cardiovascular system, emphasizing research published since 1995, and compared the effects of secondhand smoke with the effects of active smoking. Evidence is rapidly accumulating that the cardiovascular system--platelet and endothelial function, arterial stiffness, atherosclerosis, oxidative stress, inflammation, heart rate variability, energy metabolism, and increased infarct size--is exquisitely sensitive to the toxins in secondhand smoke. The effects of even brief (minutes to hours) passive smoking are often nearly as large (averaging 80% to 90%) as chronic active smoking.

CONCLUSIONS

The effects of secondhand smoke are substantial and rapid, explaining the relatively large risks that have been reported in epidemiological studies.