Cotinine/creatinine Ratio Research Articles

Relationship between oxidative stress biomarkers and micronuclei scoring as a biomarker for DNA damage in Egyptian nicotine-dependent smokers: A cross-sectional study

Background/aim About one-fifth of cancer deaths are caused by tobacco smoking. Nicotine-related DNA damage is thought to be the result of oxidative stress, whereas DNA damage can be represented in the form of binucleated micronuclei (BMNi). The aim of this study is to determine the relationship between oxidative stress biomarkers and micronuclei scoring in nicotine-dependent smokers. Subjects and methods The present study enrolled 112 Egyptian male participants, of which 45 nicotine-dependent smokers matched with 67 nonsmokers. All participants have been clinically evaluated and investigated for oxidative stress biomarkers, cytogenetic analysis of BMNi, and urinary cotinine creatinine ratio concentration. Results The smokers showed significantly higher mean values of the serum malondialdehayde concentration (P<0.05), and lower mean values of both reduced glutathione concentration and the serum total antioxidant capacity (P<0.05) in comparison to the nonsmokers. Moreover, the smokers showed significantly higher mean values of binucleated micronuclei score (P<0.05) than the nonsmokers. The linear regression model predicted that each increase in the serum malondialdehyde by 1 nmol/ml could increase the BMNi score by 2.7. On the other side, it is predicted that each decrease in the age of starting smoking by a year could be associated with a decrease in the plasma level of reduced glutathione by 0.5 mg/dl. Conclusion Serum level of MDA is a reliable tool to predict the binucleated micronuclei score in smokers. It is suggested that smoking at earlier ages worsens the natural antioxidant defense system. Smoking cessation and the use of supplementary antioxidants by smokers may regress the oxidative stress-induced DNA-damage.

Unintentional Tobacco Smoke Exposure in Children.

Secondhand smoke (SHS) exposure increases the prevalence and severity of sinopulmonary diseases in children. The primary source of SHS exposure in children is through adults who live in the same house; however, the level of exposure may vary based on the adult smoking habits at home. This prospective cross-sectional study in Alberta, Canada, investigated the relationship between self-reported caregiver smoking, location, outdoor temperature and children’s’ urine cotinine: creatinine ratio (CCR), a marker of nicotine metabolism. Participants aged 0–9 were recruited from the Child Health Clinics at the Misericordia Community Hospital in Edmonton, Alberta, from 8 January to 24 February 2016 and 30 June to 18 August 2016. Participant CCR levels were compared to caregiver-reported smoking location and environmental factors such as temperature and season. Of the 233 participants who reported smoking status, 21% reported smoking, in keeping with local smoking rates. More participants smoked indoors during the winter than the summer; however, some families limited indoor smoking to a garage. Of the 133 parent–child dyads who provided smoking information and a child urine sample, 18 had an elevated cotinine:creatinine ratio, suggestive of significant tobacco smoke exposure, 15 of whom were from homes that reported smoking. Age < 1 year and number of cigarettes smoked in the home weekly were risks for significant exposure while season, outdoor temperature and smoking location in the home did not reach significance. Smokers should be counseled to protect children, particularly infants, from exposure by limiting the number of cigarettes smoked and isolating smoking to outside the home. Segregated areas such as a garage may provide a useful harm mitigation strategy for indoor smokers, provided the garage does not share ventilation or is not in close proximity to high-traffic areas of the home.

The impact of secondhand smoke exposure on the pregnancy outcome: a prospective cohort study among Egyptian community

BackgroundSecondhand smoke (SHS) exposure gained lesser interest than active smoking. There is evidence from previous studies that SHS exposure had negative effects on fetal growth. This study aimed to examine the effect of smoke exposure on pregnancy outcome and to evaluate the level of nicotine urinary end-product cotinine in pregnant women in the late trimester. We included 36 women with a history of SHS exposure and 48 women without a history of exposure; all were in last trimester of pregnancy. We measured cotinine level in urine and followed the two groups until delivery and recorded fetal outcomes. Fetal biophysical parameters and blood flow waveforms were measured using B-mode and Doppler ultrasonography, respectively.ResultsThe total range of the urinary cotinine creatinine ratio (CCR) concentration in the SHS exposed pregnant women was 0.01–0.2, IQR = 0.18 ng/mg.cr, versus 0.01–0.1, and IQR = 0.03 ng/mg.cr in the non-exposed group. The mean value as well as the mean rank of CCR was significantly higher (0.1 ± 0.08 ng/mg.cr., 40.3 respectively) in the exposed pregnant women as compared to the non-exposed pregnant women ((0.04 ± 0.02), 29.3 respectively, p value < 0.05). Newborn of the exposed women had significantly low birth weight which negatively correlated with cotinine level and had a dose-response relationship.ConclusionsSHS exposure had negative effects on fetal outcomes. Efforts should be utilized to increase awareness of the consequences of secondhand smoke on the fetus and strict follow-up of exposed women for early detection.

The Micronuclei Scoring as a Biomarker for Early Detection of Genotoxic Effect of Cigarette Smoking.

The main aim of this study is to evaluate the micronuclei scoring as a biomarker for early detection and screening of genotoxic effect of cigarette smoking in the peripheral blood T- lymphocytes. A total number of eligible 148 individuals have participated in the study; 78 Current smokers and 70 never smokers. Cytokinesis-block micronucleus assay was performed for all the participants in the peripheral blood T-lymphocytes. Assessment of the smoking status of the participants was conducted through the detailed smoking history, Fagerström test for nicotine dependence (FTND) scoring, and determination of the urinary cotinine creatinine ratio (CCR). A significantly higher frequency of micronuclei in the binucleated T-lymphocytes(BMNi) was identified in the smokers group as compared to the nonsmokers; OR=4.9, 95% CI=1.9-12.5), P-value=0.006. Both of the pack years and the smoking duration of the smokers could significantly predict the BMNi scoring; P-value=0.001, 0.002 respectively. Our results indicate the association between BMNi and cigarette smoking, suggesting that BMNi Scoring can be a useful biomarker for early detection and screening of the genotoxic effect of cigarette smoking as a primary preventive measure for various smoking induced cancers.<br />.

Passive Smoking and Disease Severity in Childhood Pneumonia Under 5 Years of Age.

To objectively investigate the effect of passive smoking on pneumonia and disease severity in children aged less than 5 years by using cotinine as an indicator of passive smoking. Between December 2015 and April 2016, children aged less than 5 years with pneumonia and age-matched healthy controls were included in this study, which was conducted at three tertiary pediatric pulmonology centers. A questionnaire was given to the parents regarding demographic data and smoking status at home. Urinary cotinine/creatinine ratio (CCR) was measured. The data from the pneumonia and control groups, as well as children with mild and severe pneumonia within the pneumonia group, were compared. A total of 227 subjects were included in the study; there were 74 children in the pneumonia group and 153 in the control group. The mean age of all the children was 33.4 ± 1.28 months. Of all subjects, 140 were male and 102 were exposed to passive smoking by their parents at home. There were statistically significant differences in age, number of people in the home, and mother's and father's age between the control and pneumonia groups (p < 0.05). No difference was found in the CCR in the control and pneumonia group (p > 0.05). Age and urinary CCR were significantly different between children with mild and severe pneumonia (p < 0.05). We showed that passive smoking exposure was associated with the development of severe pneumonia in children. Further studies are needed to examine the underlying cause in detail.

A case control study to determine the association between Perthes' disease and the recalled use of tobacco during pregnancy, and biological markers of current tobacco smoke exposure.

It is well established that there is a strong association between Perthes' disease and worsening socioeconomic deprivation. It has been suggested that the primary determinant driving this association is exposure to tobacco smoke. This study aimed to examine this hypothesis. A hospital case-control study (n = 149/146) examined the association between tobacco smoke exposure and Perthes' disease, adjusting for area-level socioeconomic deprivation. Tobacco smoke exposure was assessed by parental questionnaire of smoking habits during pregnancy, and by quantitative assay of current exposure using the urinary cotinine-creatinine ratio, which is a widely used and validated measure of tobacco smoke exposure. The odds of Perthes' disease significantly increased with reported in utero exposure after adjustment for socioeconomic deprivation (maternal smoking odds ratio (OR) 2.06, 95% confidence interval (CI) 1.17 to 3.63; paternal smoking OR 2.09, 95% CI 1.26 to 3.46). The cotinine-creatinine ratio was significantly greater in cases, OR 1.63 (95% CI 1.09 to 2.43), suggesting a greater 'dose' of current tobacco exposure. An association exists between tobacco smoke exposure and Perthes' disease but we remain unable to disentangle the association with socioeconomic deprivation. Cite this article: Bone Joint J 2017;99-B:1102-8.

Effect of Active and Passive Smoking on Retinal Nerve Fibre Layer and Ganglion Cell Complex.

Aim. To evaluate the possible structural and functional changes in the retinal nerve fibre layer (RNFL) and the ganglion cell complex (GCC) of chronic smokers and compare them with those of passive healthy smokers using spectral domain optical coherence tomography (SD-OCT) and pattern electroretinogram (PERG). Materials and Methods. We include 80 active chronic smokers and 80 age- and sex-matched healthy passive smokers. After a full ophthalmological examination, SD-OCT and PERG were tested for all participants. Urinary levels of cotinine and creatinine with subsequent calculation of the cotinine creatinine ratio (CCR). Results. Inferior and superior quadrants of RNFL were thinner in group I, but nasal and temporal quadrants did not show significant difference between the groups. There were no significant differences of GCC values between the two groups. There was no significant difference of PERG-P50 amplitude and latency; however, PERG-N95 showed significant difference between the two groups. Multiple regression analyses demonstrated that the number of cigarettes/day, urinary cotinine, and PERG-N95 amplitude are the most important determinants for both superior and inferior RNFL thicknesses. Conclusion. RNFL thickness decreases in chronic, healthy, heavy cigarette smokers, and this thinning is related to the number of cigarettes/day, urinary cotinine, and PERG-N95 latency and amplitude.

Association of time–location patterns with urinary cotinine among asthmatic children under household environmental tobacco smoke exposure

IntroductionEnvironmental tobacco smoke (ETS) is a hazardous component of indoor air, and may increase the risk of respiratory diseases, atherosclerosis and otitis media in children. In this study, we explored the relationship between time inside the house, ETS exposure and urinary cotinine level, and also determined the association of time inside the house on asthma phenotypes when children exposed to ETS. MethodsA total of 222 asthmatic children and 205 non-asthmatic controls were recruited in the Genetic and Biomarker study for Childhood Asthma (GBCA). Structured questionnaires and time–location pattern questionnaires were administered by face-to-face interview. Urinary cotinine was measured by liquid chromatography tandem mass spectrometry (LC/MS/MS). The level of household ETS exposure was assessed using the cotinine/creatinine ratio (CCR). ResultsIn general, urinary cotinine and CCR were higher in subjects exposed to household ETS than those who never had ETS at home. A significant positive relationship was found between average time inside the house and urinary CCR in asthmatic children with current ETS at home (β=0.278, p=0.02). After adjustment for age and gender, average time inside the house was positively related to severe wheeze in asthmatic children with household ETS within 1 month (OR: 1.26, 95%: 1.02–1.64). ConclusionsOur study suggests that the major source of ETS exposure for children is due to longer period of exposures among children living with adult smokers at home. Home-smoking restrictions that effectively prevent children from being exposed to ETS would be worthwhile.

Optimum Cutoff Value of Urinary Cotinine Distinguishing South Korean Adult Smokers From Nonsmokers Using Data From the KNHANES (2008–2010)

Cutoff values for distinguishing smokers from nonsmokers have generally been derived from studies in White populations. Even though recent population-based studies have demonstrated that cutoff values can differ by race and ethnicity, few studies have explored cutoff values among Asian populations. We established the cutoff values for urinary cotinine and cotinine:creatinine ratio (CCR) using a nationally representative South Korean adult population sample. Data were obtained from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2010 with pooled sampling weights. Adult participants (n = 11,629) aged ≥19 were included. Optimal cutoff values were determined by performing receiver operating characteristic curve analysis. The optimum cutoff values for urinary cotinine and CCR for Korean adults were found to be 164ng/mL and 1122ng/mg, respectively. The application of these urinary cotinine and CCR cutoff values for the female subpopulations aged 19-34, 35-54, and ≥55 years provided sensitivities ranging from 87.1% to 93.8% and from 82.9% to 94.9%, respectively, while maintaining specificity of ≥92%. For the 3 male age-based subpopulations, we obtained sensitivities and specificities for cotinine ranging from 93.1% to 94.5% and from 92.8% to 97.0%, respectively, and for CCR ranging from 90.0% to 96.9% and from 92.2% to 96.8%, respectively. Our cutoff values should allow researchers conducting environmental epidemiological or clinical studies in South Korea to distinguish adult smokers from nonsmokers effectively. However, different values may be applicable for subpopulations with different smoking prevalence rates or higher exposure levels to secondhand smoke.

Passive smoking exposure might be associated with hypermetropia

The aim of the study was to explore the relationship between nicotine exposure in children via passive smoking and the refractive errors of these children. The study included 300 children between the age of 5 and 12 years. Children were subjected to detailed history taking with special emphasis on the degree of exposure to passive smoke. They underwent a complete ophthalmological evaluation including cycloplegic refraction. Urine samples were collected to measure urinary levels of cotinine and creatinine with subsequent calculation of the cotinine creatinine ratio (CCR). The refractive error assessment indicated 122 hypermetropic (40.7%), 86 myopic (28.7%) and 92 emmetropic (30.7%) children. Gender and age were not statistically different between the three groups. Urinary cotinine was significantly higher in the hypermetropic than myopic and emmetropic groups (p < 0.0001). Moreover, it was significantly higher in the emmetropic group than the myopic one (p = 0.02). Cotinine/creatinine ratio (CCR) and the parental number of cigarettes smoked per day showed the same pattern as urinary cotinine. Considering all 300 data, the spherical equivalent refractive error was significantly correlated with the number of cigarettes smoked by the parents, CCR and urinary cotinine levels cotinine (p < 0.0001 for all correlations). Passive smoking indices were related to the degree of refractive error and children with hypermetropia showed significantly higher passive smoking indices. We suggest that passive smoking might be associated with a refractive error shift towards hypermetropia.

Reliability of Self-Reported Tobacco Use in Bipolar Disorder: An Exploratory Study of Euthymic Patients Visiting a Tertiary Care Hospital in India

Unlike schizophrenia, only a little attention has been paid to tobacco dependence in patients with bipolar disorder despite a similarly high prevalence and predisposition to health risks. The euthymic phase is especially suitable for tobacco screening by the treating psychiatrist. However, the validity of self-report for tobacco use in this patient population remains undetermined. The current study aims to assess the validity of self-reported tobacco use in euthymic bipolar disorder. The psychiatric out-patients with DSM-IV TR diagnosis of bipolar type-I in remission who were males, > or =18 years, and euthymic as established by current scores of <7 on HAM-D and <4 on YMRS. Patients were specifically asked for the recent use of tobacco in any form. Ten ml urine sample was obtained after informed consent and subjected to a quantitative cotinine estimation by direct enzyme-linked immunosorbent assay. A total of 100 patients were screened, of which 79 were finally included. The self-report for recent tobacco use showed only a moderate concordance with urinary cotinine (k = 0.518) and cotinine-creatinine ratio (k = 0.492). Over 15% patients had denied the use of tobacco, but tested positive on urinary cotinine assessment. The sensitivity of self-report was 73.3% compared to urinary cotinine. The denial among users was 26.7% and denial among those with negative self-report was 30.8%. Mental health professionals should be vigilant for detection of tobacco dependence among remitted bipolar patients, who may not be so forthcoming about their tobacco use.

Passive smoking as a risk factor of dry eye in children.

Purpose. Adult active smoking is a risk factor for dry eye. We hypothesize that passive smoking in children can also produce the same effects. Methods. We included 112 school children presenting with eye discomfort. Assessment of eye dryness and its severity levels depending on symptoms of dry eye, visual symptoms, tear breakup time (TBUT), Schirmer-1 test, and corneal fluorescein staining were done for all of them. Exposure to cigarette smoking was assessed by history-taking and urinary cotinine levels. Results. Dry eye was found in 80/112 children. Passive smoking was documented in 76/112 children. Number of cigarettes to which the child was exposed per day and the duration of exposure to passive smoking were significantly higher in children with dry eye compared to those without. Urinary cotinine, and cotinine/creatinine ratio (CCR) was significantly higher in children with dry eye compared to those without dry eye. Multiregression analysis showed that the most important determinants of dry eye were CCR and number of cigarettes/day. Conclusion. Passive smoking represents a significant risk factor of dry eye in children comparable to that shown with active adult smoking. Male children are more prone to this effect.

TIME-LOCATION PATTERN, HOUSEHOLD ENVIRONMENTAL TOBACCO SMOKE EXPOSURE AND URINARY COTININE IN NON-SMOKING CHILDREN

Background and Aims:Environmental tobacco smoke (ETS) is an important exposure of indoor air, and may increase the risk of respiratory disease in children. The level of household ETS exposure may be associated with the time-location pattern for children. In this study, we will explore the association between the indoor time, household ETS exposure and urinary cotinine level in non-smoking children. Methods :Total of 429 children were recruited in Genetic and Biomarker for Childhood Asthma (GBCA). We will utilize parental report method to measure household ETS exposure in children using structure questionnaires. Indoor and outdoor time for non-smoking children was administrated by the time-location pattern questionnaires. The urinary cotinine level was measured using a sensitive high-performance liquid chromatographic (HPLC) technique and the level of household ETS exposure will be assessed using the cotinine/creatinine ratio (CCR). Results:Children exposed to ETS in household had higher cotinine level and CCR when compared with those children expose to ETS in outdoor environment. The CCR also showed a significant trend when children exposed to different amount of ETS in household. When the time-location pattern were considered in our analysis, we have found a significant trend of average CCR increased with indoor time for children in the groups of currently household ETS exposure, amount of household ETS exposure per day and number of smokers at home. Conclusions:We found a dose-response relationship between urinary cotinine level and indoor time for non-smoking children. Our study suggested that the major source of ETS exposure for Taiwanese children was from family members in the household.

Japanese spousal smoking study revisited: how a tobacco industry funded paper reached erroneous conclusions

Objectives: To provide a participant’s account of the development of a paper commissioned by the tobacco industry examining the reliability of self reported smoking status; to redress the distorted report...

Fluorophotometric Evaluation of Blood-Retinal Barrier Permeability in Patients with Essential Hypertension

Aim: The fluorophotometric evaluation of the blood-retinal barrier (BRB) integrity in patients with essential hypertension (EH) without signs of BRB damage. Material and Methods: 55 subjects participated in the study: 36 patients with EH and 19 normotensive healthy volunteers; 22 men and 33 women. The protocol included ophthalmic examination, fluorescein angiography, fluorophotometry, laboratory tests (total cholesterol, LDL and HDL cholesterol, triglycerides, fibrinogen, serum creatinine concentration, fasting glucose concentration, oral glucose test), urinary cotinine concentration measurement and cotinine-creatinine ratio (CCR) calculation. Results: BRB permeability (P_BRB) in patients with EH was significantly higher than in the control group (2.24 ± 0.68 vs. 1.64 ± 0.64 nm/s; p = 0.003). In hypertensive patients with CCR >50 ng/mg, the P_BRB was significantly higher than the P_BRB in healthy volunteers not exposed to smoke (2.32 vs. 1.68 nm/s; p < 0.05). Conclusions: The P_BRB in patients with EH is significantly higher than that in the normotensive control group, which shows the damaging effect of EH on the BRB.

A Controlled Trial of an Environmental Tobacco Smoke Reduction Intervention in Low-Income Children With Asthma

To determine the effectiveness of a cotinine-feedback, behaviorally based education intervention in reducing environmental tobacco smoke (ETS) exposure and health-care utilization of children with asthma. Randomized controlled trial of educational intervention vs usual care. The pediatric pulmonary service of a regional pediatric hospital. ETS-exposed, Medicaid/Medi-Cal-eligible, predominantly minority children who were 3 to 12 years old and who were seen for asthma in the hospital's emergency, inpatient, and outpatient services departments (n = 87). Three nurse-led sessions employing behavior-changing strategies and basic asthma education and that incorporated repeated feedback on the child's urinary cotinine level. The primary measurements were the urinary cotinine/creatinine ratio (CCR) and the number of acute asthma medical visits. The secondary measurements were number of hospitalizations, smoking restrictions in home, amount smoked, reported exposures of children, and asthma control. The intervention was associated with a significantly lower odds ratio (OR) for more than one acute asthma medical visit in the follow-up year, after adjusting for baseline visits (total visits, 87; OR, 0.32; p = 0.03), and a comparably sized but nonsignificant OR for one or more hospitalization (OR, 0.34; p = 0.14). The follow-up CCR measurement and the determination of whether smoking was prohibited inside the home strongly favored the intervention group (n = 51) (mean difference in CCR adjusted for baseline, -0.38; p = 0.26; n = 51) (60; OR [for proportion of subjects prohibiting smoking], 0.24; p = 0.11; n = 60). This intervention significantly reduced asthma health-care utilization in ETS-exposed, low-income, minority children. Effects sizes for urine cotinine and proportion prohibiting smoking were moderate to large but not statistically significant, possibly the result of reduced precision due to the loss of patients to active follow-up. Improving ETS reduction interventions and understanding their mechanism of action on asthma outcomes requires further controlled trials that measure ETS exposure and behavioral and disease outcomes concurrently.

Lung function in children and adolescents with occasional exposure to environmental tobacco smoke.

We investigated the effects of occasional exposure to environmental tobacco smoke (ETS) on lung function in children. A total of 317 healthy 12- to 15-yr-old nonsmoking children and adolescents, living in households in which none of the adults were active smokers, were selected for the present analysis. The urinary cotinine:creatinine ratio (CCR) was taken as the biologic indicator of exposure, and children were classified according to CCR quartiles. The ratio between FEV1 and FVC (FEV1/FVC) and both early (peak expiratory flow [PEF]) and midexpiratory flow rates (FEF25-75) were lower in children with higher CCR values. In percent terms, the decrease in adjusted lung function for children belonging to the second, third, and fourth quartiles in comparison with those in the first quartile was -1.37, -2.12, and -1.94 for FEV1/FVC (p for trend = 0.012); 0.98, -3.31, and -4.54 for PEF (p for trend = 0.024); and -0.05, -4.85, and -6.13 for FEF25-75 (p for trend = 0.022), respectively. The effects remained significant when possible confounding by father's education and urinary creatinine level had been taken into account, and when children whose parents' smoking status may have been misclassified were excluded. This study suggests an adverse effect on lung function from even low-level exposure to ETS among nonsmoking children living with reportedly nonsmoking parents.

Risk factors for childhood asthma and wheezing. Importance of maternal and household smoking.

To identify modifiable risk factors for wheezing illness in childhood, the associations between current asthma or wheezing and factors such as household smoking, damp and dietary salt preference were measured in a questionnaire-based prevalence study of schoolchildren 7 to 9 yr of age in Cape Town. In a random sample of 15 schools, questionnaires were completed by parents of 1,955 children, from which 368 cases and 294 controls were selected on the basis of reported asthma diagnosis or symptoms. Urinary cotinine concentrations were measured, and the parents were interviewed. An exposure-response relationship between the urinary cotinine creatinine ratio and asthma/wheeze was observed. In multivariate analysis, predictors of asthma/wheeze were hay fever (odds ratio [OR] - 5.30; 95% confidence interval [CI] = 3.16 to 8.89), eczema (OR = 2.19; 95% CI = 1.33-3.62), parental asthma (OR = 1.77; 95% CI = 1.11 to 2.84), absence of paternal contribution to income (OR = 1.72; 95% CI = 1.17 to 2.54), maternal smoking in pregnancy (OR = 1.87; 95% CI = 1.25 to 2.81), and each additional household smoker (OR = 1.15; 95% CI = 1.01 to 1.30). Findings were similar, with higher odds ratios for most variables, except number of household smokers, when the group was restricted to children with parent-reported asthma. The findings confirm that household smoking is an important modifiable risk factor in asthma/wheeze among young schoolchildren, and they suggest that maternal smoking in pregnancy and current household exposure are independent contributors to this effect.

In utero exposure to parental smoking, cotinine measurements, and cord blood IgE

The relationship between parental smoking and cord blood IgE has been studied in a survey conducted in 99 unselected newborn infants with a sensitive test for IgE and cotinine as a biologic marker to validate smoking data. For both cord blood cotinine and maternal urine cotinine creatinine ratio (CCR), significantly higher levels were observed for smokers compared to nonsmokers. Furthermore, among nonsmokers, passive smokers had significantly higher cotinine levels than true nonsmokers, which demonstrates that cord blood may be used to assess active as well as passive maternal smoking. No association was observed in this study between cord blood IgE and maternal smoking assessed by questionnaire (geometric means of cord blood IgE levels were 0.11 IU/ml for newborn infants of smoking mothers and 0.12 IU/ml for newborn infants of nonsmoking mothers). The same observations were drawn from the analysis of cord blood IgE and cotinine levels, with correlation coefficients of −0.005 for cord blood CCR and 0.003 for maternal CCR. Additional studies are needed to determine whether maternal smoking is causally related to cord blood IgE and by which mechanisms.