Measuring the exposure of infants to tobacco smoke. Nicotine and cotinine in urine and saliva

In utero, childhood, and adolescence tobacco smoke exposure, physical activity, and chronic kidney disease incidence in adulthood: evidence from a large prospective cohort study

BACKGROUND

The adverse effects of early-life tobacco smoke exposure on chronic kidney disease (CKD) risk remain unclear. This study aimed to investigate the associations of early-life tobacco smoke exposure with CKD incidence in adulthood, and further explore the modification effects of physical activity (PA).

METHODS

A total of 352,883 participants were included from the UK Biobank. The information on early-life tobacco smoke exposure was assessed by employing in utero tobacco smoke exposure and age of smoking initiation. Weekly moderate-to-vigorous physical activity (MVPA) was calculated for each individual. Cox proportional hazard regression was fitted to estimate the hazard ratio (HR) and 95% confidence interval (CI) of CKD risk, and to investigate the modification effects of MVPA.

RESULTS

CKD incidence significantly increased in participants with in utero tobacco smoke exposure (HR: 1.08, 95% CI: 1.04, 1.12). Compared with never-smokers, we found a monotonic increase in the risk of CKD with smoking initiation across adulthood (HR: 1.21, 95% CI: 1.16, 1.27), adolescence (HR: 1.29, 95% CI: 1.24, 1.35), and childhood (HR: 1.34, 95% CI: 1.25, 1.43) (P trend < 0.001). Additionally, we identified joint cumulative effects of MVPA and early-life tobacco smoke exposure on incident CKD. Compared with never-smokers with recommended MVPA, prenatal or childhood tobacco smokers without recommended MVPA had the highest CKD risk, and the HRs (95% CIs) were 1.17 (1.10, 1.24) and 1.51 (1.36, 1.68), respectively.

CONCLUSIONS

Early-life tobacco smoke exposure may contribute to CKD incidence in adulthood, and the observed associations could be modified by MVPA. These findings provide important information on CKD prevention in the participant's early life while urging a more rapid and powerful need for tobacco control among pregnant couples, children, and adolescents.

Secondhand Smoke Exposure Measured in Urinary Cotinine Levels and Severity of Pediatric Sleep Apnea

Importance

Exposure to secondhand smoke has been associated with numerous health problems in children, including obstructive sleep apnea. Secondhand smoke exposure may be a risk factor for increased pediatric sleep apnea severity.

Objectives

To assess the association of secondhand smoke exposure (SHSe), quantified by urinary cotinine levels, with severity of obstructive sleep apnea (OSA) in children.

Design, Setting, and Participants

This was a prospective cohort trial including pediatric patients from 3 to 16 years of age with sleep-disordered breathing who underwent a polysomnogram at a tertiary-level children's hospital in the US in either March 2014 to October 2016 or March 2020 to March 2021. Urine specimens were analyzed for cotinine, an important metabolite of nicotine. Each child's caregiver completed a validated SHSe questionnaire. Data were analyzed from February to June 2023.

Exposure

OSA and secondhand smoke.

Main Outcome and Measures

SHSe and severity of pediatric OSA, quantified by urinary cotinine levels and obstructive apnea hypopnea index (AHI) scores. Secondary outcomes were association of urinary cotinine levels with nadir oxygen saturation, sleep-related quality of life measured by the OSA-18 questionnaire, and caregiver-reported smoking habits (collected through a questionnaire).

Results

The study included 116 patients with a median (IQR) age of 6 (5-9) years, among whom 51 (45%) had obesity. The median (IQR) AHI was 3.0 (1.2-8.0), with 28 children (30.0%) having severe disease (AHI >10). Thirty-four children (29.0%) were found to have a positive result for urine cotinine screening, with a mean (SD) level of 11.7 (9.4) ng/mL. The percentage of children with SHSe was less than anticipated. There was no association identified between urinary cotinine levels and either AHI (ρ = -0.04; 95% CI, -0.22 to 0.15) or nadir oxygen saturation (ρ = -0.07; 95% CI, -0.26 to 0.11). Furthermore, SHSe was not associated with the presence of severe OSA (odds ratio, 0.70; 95% CI, 0.26 to 1.90). Children whose caregivers reported indoor SHSe were more likely to have a detectable urinary cotinine level (odds ratio, 20.3; 95% CI, 6.67 to 61.8).

Conclusions and Relevance

This cohort study did not identify any clinically meaningful association between SHSe, quantified by urinary cotinine level, and pediatric OSA severity. Future research with a larger number of children with SHSe is needed to confirm these findings and determine whether SHSe affects OSA treatment outcomes in children.

American pediatric society's 2017 John Howland award acceptance lecture: a tale of two toxicants: childhood exposure to lead and tobacco

This article summarizes the presentation of the 2017 Howland Award to Michael Weitzman, MD, at the Annual Pediatric Academic Society Meetings. It summarizes the remarkable advances in understanding the effects and pathways of exposure of the two most common and pernicious of our nation's child environmental exposures, namely lead and tobacco. It also summarizes the profound effect of the translation of these findings into prudent and effective clinical and public health policies such that exposure to both has dramatically decreased over the past 40 years due to the tenacious activities of pediatricians, other child-related professionals, government agencies at all levels, and the American Academy of Pediatrics. Research and clinical activities, although essential, were not sufficient to produce these successes, but required extensive mentoring to produce a generation of academic pediatricians capable of conducting the requisite research, and extensive advocacy by pediatricians and others to overcome the formidable inertia and outright opposition to efforts to protect our children from these exposures. Moreover, the article highlights that both of these environmental exposures have roots in social and environmental injustice and neither is solved, and that there is no safe level of exposure to either of these toxicants.

A tailored video intervention to reduce smoking and environmental tobacco exposure during and after pregnancy: Rationale, design and methods of Baby's Breath

Low-cost interventions to decrease environmental tobacco smoke (ETS) exposure of pregnant women and their newborns are needed to lower health risks of exposed fetuses and infants. Baby's Breath is a tailored video intervention developed and tested in a randomized controlled trial. The study aimed to test the efficacy of tailored video versus usual care approaches to reduce the ETS exposure of fetuses of low-income women during and after pregnancy; and to assess this intervention separately among non-smoking and smoking women. Participating women, recruited early in pregnancy, who spoke English, were at least 18years old, smoke exposed (current smokers, quit smoking on their own, or were exposed to smoke of others), pregnant with only one baby, and had access to a telephone and video player, were randomized to experimental or control conditions. Intervention participants received newsletters containing content aimed at smoking cessation and avoidance (5 during and 3 after pregnancy), in addition to videos (3 during and 2 after pregnancy) individually tailored on behavioral theory-based survey questions. Comparison participants received newsletters and videos on healthy pregnancy topics. Outcomes included salivary cotinine of both mother and baby (32weeks gestation and 6months postpartum) as well as self-reported ETS exposure and avoidance behaviors. This study may demonstrate the efficacy of a low-cost intervention to decrease ETS exposure, and will fill an important gap in describing the utility of this innovative intervention technology, as well as demonstration of potential benefits to this type of intervention.

A Comparison of Biochemical and Interview Measures of the Exposure of Infants to Environmental Tobacco Smoke

This study of 37 infants found substantial agreement among a biochemical indicator of infant passive smoking, an interview measure of the tobacco smoke environment of the infant, and active smoking in the household When any of the three measures were compared, both measures were positive for 75% to 82% of the subjects and negative for 88% to 92%. The correlations among the variables considered as continuous measures ranged from .64 to .74. These correlations are strong enough to suggest that both measures reflect exposure but too weak to assume that one measure can serve as a ready substitute for the other The agreement among continuous measures was due to their ability to distinguish between exposed and nonexposed infants, rather than to their continuous properties.

Joint Effect of Urinary Total Arsenic Level and VEGF-A Genetic Polymorphisms on the Recurrence of Renal Cell Carcinoma

The results of our previous study suggested that high urinary total arsenic levels were associated with an increased risk of renal cell carcinoma (RCC). Germline genetic polymorphisms might also affect cancer risk and clinical outcomes. Vascular endothelial growth factor (VEGF) plays an important role in vasculogenesis and angiogenesis, but the combined effect of these factors on RCC remains unclear. In this study, we explored the association between the VEGF-A -2578C>A, -1498T>C, -1154G>A, -634G>C, and +936C>T gene polymorphisms and RCC. We also evaluated the combined effects of the VEGF-A haplotypes and urinary total arsenic levels on the prognosis of RCC. This case-control study was conducted with 191 RCC patients who were diagnosed with renal tumors on the basis of image-guided biopsy or surgical resections. An additional 376 age- and gender-matched controls were recruited. Concentrations of urinary arsenic species were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Genotyping was investigated using fluorescent-based TaqMan allelic discrimination. We observed no significant associations between VEGF-A haplotypes and RCC risk. However, the VEGF-A ACGG haplotype from VEGF-A -2578, -1498, -1154, and -634 was significantly associated with an increased recurrence of RCC (OR = 3.34, 95% CI = 1.03–10.91). Urinary total arsenic level was significantly associated with the risk of RCC in a dose-response manner, but it was not related to the recurrence of RCC. The combination of high urinary total arsenic level and VEGF-A risk haplotypes affected the OR of RCC recurrence in a dose-response manner. This is the first study to show that joint effect of high urinary total arsenic and VEGF-A risk haplotypes may influence the risk of RCC recurrence in humans who live in an area without obvious arsenic exposure.

[Influence of tobacco smoking on the risk of developing asthma]

The aim of this general review is to investigate the influence of active and passive smoking on the development of asthma in children and adults. Passive smoking during and after pregnancy facilitates the onset of childhood asthma and wheezing. In particular, smoking during pregnancy is associated with the occurrence of wheezing prior to the age of 4 years. In contrast, the results of studies on the relationship between parental smoking in the post-natal period and the onset of asthma or wheezing are discordant. Exposure to passive smoking during childhood facilitates the occurrence of asthma in adulthood. In adults and adolescents, active smoking appears to be a factor favoring the development of asthma. On the other hand, non-smoking adult subjects without history of asthma exposed to passive smoking have a risk of asthma. The pathophysiological mechanisms by which tobacco smoke is the cause of asthma are still poorly known. Smoking cessation is an essential component in the management of asthmatic subjects who smoke, facilitating the control of the disease.

Second-hand tobacco smoke and children

Cigarette smoke contains harmful chemicals with hazardous adverse effects on almost every organ in the body of smokers as well as of nonsmokers exposed to environmental tobacco smoke (ETS). There has been increasing interest in the effects of passive smoking on the health of children. In order to detect the magnitude of passive smoking in children, parental questionnaires, measuring nicotine and cotinine body levels, and evaluating expired carbon monoxide (CO) concentrations, have been used. Passive smoking causes respiratory illness, asthma, poor growth, neurological disorders, and coronary heart diseases. Herein, we focused on the deleterious influences of passive smoking on immunity and liver. Besides, its effects on the concentrations of various biomarker levels related to the oxidant/antioxidant status were considered. Understanding these effects may help clinicians to counsel parents on smoking cessation and smoke exposure elimination. It may also help to develop interventions to improve the health of children. This review potentially demonstrated some nutraceuticals with a promising role in the prevention of smoking-related diseases.

Screening by pulse CO-oximetry for environmental tobacco smoke exposure in preanesthetic children

OBJECTIVE

The purpose of this study was to evaluate the ability of multiple wavelength pulse CO-oximetry (SpCO) to screen for environmental tobacco smoke (ETS) exposure in children.

BACKGROUND

Exposure to ETS is associated with an increased risk of perioperative respiratory complications in children. It is often difficult to obtain an accurate history for ETS exposure, so a preoperative screening tool is desirable. Carbon monoxide is a measurable product of tobacco combustion. Multiple wavelength pulse CO-oximetry is a recently developed point-of-care monitor.

METHODS

Following IRB approval and parental consent, 220 children aged 1-16 years having outpatient surgical procedures were enrolled. SpCO was measured preoperatively three times with the Radical-7 Rainbow SET CO-oximeter (Masimo, Irvine, CA, USA). Immediately following induction of anesthesia, a blood sample for laboratory measurement of carboxyhemoglobin (COHb) and serum cotinine was obtained. Regression analysis determined the correlation of SpCO with serum cotinine values. Receiver operator characteristic (ROC) curves analyzed the discriminating ability of SpCO or COHb to predict ETS exposure based on cotinine cutoff values known to be present in children exposed to ETS. Agreement of SpCO and COHb values was assessed using Bland-Altman plots.

RESULTS

SpCO did not correlate with cotinine (R(2) = 0.005). Both SpCO and COHb had poor discriminating ability for ETS exposure (area under the ROC curve = 0.606 and 0.562, respectively). SpCO values had poor agreement with COHb values.

CONCLUSIONS

The point-of-care multiple wavelength pulse CO-oximeter does not appear to be a useful preoperative screening tool for ETS exposure in children.

How and why chemicals from tobacco smoke can induce a rise in blood pressure

The primary objective of this article is to analyze the role of tobacco smoke compounds able to damage the cardiovascular system and, in particular, to interfere with blood pressure. They are products of tobacco plant leaves, like nicotine, thiocyanate and aromatic amines, and a chemical derived from cigarette combustion, carbon monoxide. Of the other thousands of chemicals, there is no clear evidence of cardiovascular damage. Nicotine and its major metabolite, cotinine, usually increase blood pressure by a direct action and an action stimulating neuro-humoral metabolites of the body as well as sympathetic stimulation. An indirect mechanism of damage exerted by elevated carboxyhemoglobin concentrations is mediated by carbon monoxide, which, mainly induces arterial wall damage and, consequently, late rising in blood pressure by a toxic direct action on endothelial and blood cells. Thiocyanate, in turn, reinforces the hypoxic effects determined by carbon monoxide. Aromatic amines, depending on their chemical structure, may exert toxic effects on the cardiovascular system although they have little effect on blood pressure. A rise in blood pressure determined by smoking compounds is a consequence of both their direct toxicity and the characteristics of their chemical chains that are strongly reactive with a large number of molecules for their spatial shape. In addition, a rise in blood pressure has been documented in individuals smoking a cigarette, acutely and chronically, with irreversible artery wall alterations several years after beginning smoking. Since cigarette smoking has a worldwide diffusion, the evidence of this topic meets the interest of both the scientific community and those individuals aiming to control smoking.

Effects of Active and Passive Smoking on Ear Infections

Otitis media (OM) is one of the most frequent diseases in young children, causing to visit a physician, and also the most common indication for antibiotic prescription. The peak incidence and prevalence of OM is 6 to 18 months of age. In children, second-hand smoke (SHS) exposure is associated with upper and lower respiratory tract infections, such as acute otitis media (AOM), pneumonia, and bronchitis. Despite the overwhelming evidence of the role of SHS exposure on infant health, a very high proportion of children still continue to be exposed. This important relationship between all kinds of smoking and poor health may not be appreciated universally. With this article, we aim to review tobacco smoke exposure and OM connection. How this exposure may cause OM especially in young children? What can be done to prevent and to reduce the harmfull effects of tobacco smoking?

Periodontal health in children exposed to passive smoking

AIM

To determine (1) the cotinine levels of saliva, urine and gingival crevicular fluid (GCF) of children in families with and without smoking members and (2) a possible association between the periodontal health of the children and exposure to passive smoking.

MATERIAL AND METHODS

The study population comprised of 109 children in the age range 6-12 years. Children were classified as exposed to passive tobacco smoking (PTS-exposed, n=51) and as unexposed controls (PTS-unexposed, n=58). Plaque index, gingival index, bleeding on probing, probing depth and clinical attachment level (CAL) were recorded. GCF, saliva and urine samples were also collected. The levels of cotinine in these fluids were determined by enzyme-linked immunosorbent assay.

RESULTS

The mean salivary cotinine concentration was significantly increased in PTS-exposed children compared with PTS-unexposed children (p<0.05). Further, in a dose-dependent way, the mean salivary concentration was significantly higher in children whose father or mother was a smoker (p<0.05) as compared, respectively, with children whose fathers and mothers were non-smokers. The mean CAL was significantly less in PTS-exposed children compared with non-PTS-exposed children (0.09 mm; p<0.05) and also in children whose father was a smoker (p<0.05), but not in children whose mother was a smoker as compared with non-smoker fathers and mothers, respectively. The GCF cotinine levels were below the detection limits with the assay method that was used.

CONCLUSIONS

We have observed that children who are exposed to passive smoking have elevated cotinine levels in their saliva concomitant with a lowered CAL.

Indicators of oxidative stress in weanling and pubertal rats following exposure to nicotine via milk

Nicotine, a major toxic component of tobacco, has been identified as an important risk factor for infant and children diseases. It is concentrated in breast milk and is absorbed by the infant. The purpose of the present study was to investigate the effects of maternal nicotine exposure during lactation on breast-fed rats and at the pubertal age by measuring biomarkers of oxidative stress. Particularly, a new parameter, the thiol concentration was evaluated. Two groups of lactating Wistar rats were used. For the first group, female rats were given an intraperitoenal injection of nicotine or saline (2 mg/kg per day) during lactation. For the second group, we reproduced the same process described above and then the female and male pups were separately kept after weaning without any treatment until the puberty (at 45 days of age). In the liver and lung of the offspring, we examined the malondialdehyde (MDA) level, the thiol concentration, and the activities of two antioxidant enzymes: superoxyde dismutase (SOD) and catalase (CAT). In the plasma, alanine amino transferase (ALT) and aspartate amino transferase (AST) activities were measured. For rats aged 21 days, the treatment significantly reduced the thiol concentration, SOD, and CAT activities but increased MDA level, AST, and ALT activities. For rats aged 45 days, the males and females did not react the same way. In fact, the males were more affected. These results indicate that maternal nicotine exposure during the lactation period induces oxidative stress in the liver and lung of lactating offspring, which is maintained until the puberty, especially for the male rats.

Exhaled carbon monoxide screening for environmental tobacco smoke exposure in preanesthetic children

OBJECTIVE

Exposure to environmental tobacco smoke (ETS) is associated with an increased risk of perioperative adverse events in children. The purpose of this study was to evaluate exhaled carbon monoxide (CO) as a preoperative ETS screening tool in children.

METHODS

Five hundred and one children aged 6-15 years were enrolled. The child's guardian completed a questionnaire that surveyed environmental exposures to CO and ETS. A preoperative urine sample was obtained from children who assented and were able to void, and urine cotinine values were measured. Exhaled CO was measured using the EC50-Micro Smokerlyzer (Bedfont Scientific Ltd, UK).

RESULTS

Four hundred and fifty-one subjects completed the study, and urine samples were obtained from 83. 25% of subjects were classified as exposed to ETS based on questionnaire results. Exhaled CO values did not correlate with either the qualitative (questionnaire) or quantitative (urine cotinine) measurements of ETS exposure. Exhaled CO predicted a urine cotinine/creatinine ratio >10 with a sensitivity of 10% and a specificity of 85%.

CONCLUSION

Exhaled CO measured by this device is not a useful preoperative screening tool for ETS exposure in children. Because exhaled CO has been used successfully to monitor ETS exposure in adolescents, we believe that its failure in our population is as a result of the limited ability of small children to perform vital capacity maneuvers in order to provide an adequate endtidal sample.

Deficiency of INFgamma producing cells in adenoids of children exposed to passive smoke

Exposure to passive smoke is a very common event associated with increased susceptibility to respiratory tract infections. Many related adverse effects result from the ability of cigarette smoke extracts to interfere with the immune system, but the mechanism is not yet completely understood. The aim of the present study is to evaluate the intracellular cytokine profile in adenoids and peripheral blood cells of children exposed to passive smoke. Children undergoing adenoidectomy exposed or not exposed to passive smoke were studied. The intracellular cytokine profile of lymphocyte subsets in adenoids and in peripheral blood were evaluated by flow cytometry analysis. Children exposed to tobacco smoke showed a significantly lower percentage of INF-gamma producing CD4+ and CD8+ cells in adenoids. Moreover a significant correlation was observed between the quantity of exposure and reduction in Th1 (CD4+INFgamma+ and CD8+INFgamma+) cells in adenoids. This reduction may be a contributing factor in the increasing susceptibility to respiratory tract infection in children exposed to tobacco smoke.

Smoking is associated with insulin resistance and cardiovascular autonomic dysfunction in type 2 diabetic patients

BACKGROUND

Smoking and cardiovascular autonomic dysfunction are associated with high mortality in type 2 diabetic patients. This study tested the hypothesis that smoking is associated with insulin resistance/hyperinsulinaemia and cardiovascular autonomic dysfunction in type 2 diabetic patients who are not treated with insulin.

MATERIALS AND METHODS

The study patients were 22 current smokers with type 2 diabetes mellitus (age: 57 +/- 5 years, mean +/- SD) and 30 age-matched never-smoked patients with type 2 diabetes mellitus (control group, 57 +/- 8 years). The quality of blood glucose was assessed by fasting plasma glucose (FPG), fasting immunoreactive insulin (F-IRI), homeostasis model assessment (HOMA) index and haemoglobin A1c (HbA1c). The severity of smoking status was expressed by the Brinkman index, which is calculated as number of cigarettes per day multiplied by years of smoking. Cardiovascular autonomic function was assessed by baroreflex sensitivity (BRS), heart-rate variability, plasma norepinephrine concentration and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphic findings.

RESULTS

Baroreflex sensitivity was lower in the current smokers group than in the never-smoked group (P < 0.05). Early and delayed (123)I-MIBG myocardial uptake values were lower (P < 0.05, and P < 0.01, respectively) and the percentage washout-rate of (123)I-MIBG was higher (P < 0.0001) in the current smokers group than in the never-smoked group. Fasting immunoreactive insulin (F-IRI) concentration (P < 0.0001) and the homeostasis model assessment (HOMA) index (P < 0.0001) were higher in the current smokers group than the never-smoked group. Multiple logistic regression analysis revealed that smoking was independently predicted by F-IRI and the percentage washout-rate of (123)I-MIBG.

CONCLUSIONS

The results of the study suggested that smoking was associated with cardiovascular autonomic dysfunction and hyperinsulinaemia and that F-IRI and the percentage washout-rate of (123)I-MIBG were independent predictors of smoking in these Japanese patients with type 2 diabetes mellitus.

Early developmental origins of impaired lung structure and function

Epidemiological studies show that exposure to factors that restrict fetal growth or lead to low birthweight can alter lung development and have later adverse effects on lung function and respiratory health. The major causal factors include reduced nutrient and oxygen availability, nicotine exposure via maternal tobacco smoking and preterm birth, each of which can affect critical stages of lung development. Experimental studies show that these environmental insults can permanently alter lung structure and hence lung function, increasing the risk of respiratory illness and accelerating the rate of lung aging. Further studies are required that address the molecular and cellular mechanisms by which these factors adversely affect lung development and whether such effects can be blocked or reversed. Ultimately however, a major goal should be to prevent prenatal compromises through clinical monitoring, and in the case of smoking through education, thereby ensuring that each fetus has the best possible environment in which to develop.

Effects of maternal nicotine exposure during lactation on breast-fed rat pups

BACKGROUND

Nicotine is known to be associated with adverse effects in infants and children. It is concentrated in breast milk and is absorbed by the infant. The aim of this study was to investigate the effects on breast-fed rat pups of maternal nicotine exposure during lactation.

METHODS

In the experimental group (n = 6), nicotine was given to lactating dams (2 mg/kg/day) after delivery and continued for 10 days during lactation. Control animals (n = 4) received saline for the same duration. The suckling rats were weighed and killed on postnatal day 10, and samples were taken from the lung, liver, kidney, spleen and small intestine for histopathological examination. Superoxide dismutase (SOD), catalase (CAT) activities and malondialdehyde (MDA) levels were measured in the liver of the dam and the offspring.

RESULTS

Histopathological changes in the liver of the nicotine-exposed group showed portal inflammatory infiltrate, ballooning degeneration of hepatocytes, and focal necrosis in the parenchyma. Thickening of alveolar walls because of interstitial inflammation was noted in the lungs. Histopathological examination of kidney, spleen and small intestine tissue did not reveal any abnormality. In the experimental group, SOD and CAT activities were significantly decreased (p <0.001) but MDA levels were significantly increased (p <0.001) compared with the control group.

CONCLUSION

These results indicate that maternal nicotine exposure induces oxidative stress and causes detrimental histopathological changes in the lung and liver of lactating offspring.

Measuring tobacco smoke exposure: quantifying nicotine/cotinine concentration in biological samples by colorimetry, chromatography and immunoassay methods

Procedures to assess tobacco smoke exposure are reviewed and biomarkers used for determining the smoking status of an individual are compared. Methods used to extract these biomarkers from saliva, urine, and blood and the advantages and disadvantages of the assays are discussed. Finally, the procedures used to measure the levels of cortisol, a stress hormone speculated to be linked to nicotine metabolism, are discussed.

Does passive smoke exposure trigger acute asthma attack in children?

The relationship between asthma and passive smoking has been well established. However, it is still not clear whether an acute asthma attack can be induced by acute smoke exposure. The specific aims of this study were: 1- To assess the degree of smoke exposure through urinary cotinine levels in asthmatic children during and 4 weeks after asthma attacks and, 2- To evaluate the reliability of parental questionnaires in asthmatic children by comparing the data obtained from cotinine measurements and parental reports. Thirty-two consecutive asthmatic children who were admitted to the emergency clinic were included in the study. Parents were asked to complete a questionnaire about their smoking habits and housing conditions. Urinary cotinine and creatinine levels were measured in children during and 4 weeks after the acute asthma attack. The mean age of the patients was 5.7 +/- 3.2 years. The mean attack rate was 3.5 +/- 3.8 per year. Thirty-eight percent of the patients were taking no preventive treatment. In 80 % of patients, urinary cotinine and creatinine ratios (CCR) were significantly above the non-exposed, non-smoker levels. However, CCR levels during acute asthma attacks were not higher than those measured 4 weeks after the acute attack (314.6 +/- 299.1 vs. 203.8 +/- 165.2 ng/mg respectively, p > 0.05). Although parental reports of passive smoke exposure was 71 %, CCR levels revealed that 81 % and 97 % of children were exposed to passive smoke during acute attacks and asymptomatic periods, respectively. In conclusion, although the proportion of children with acute asthma attacks who were exposed to passive smoking was high, the degree of passive smoke exposure was not higher during acute attacks. Parental questionnaires were found to be unreliable in reporting passive smoke exposure in asthmatic children during acute attacks.

Parental smoking and infant respiratory infection: how important is not smoking in the same room with the baby?

OBJECTIVES

We sought to quantify the effect of good smoking hygiene on infant risk of respiratory tract infection in the first 12 months of life.

METHODS

A cohort of 4486 infants in Tasmania, Australia, was followed from birth to 12 months of age for hospitalization with respiratory infection. Case ascertainment was 98.2%.

RESULTS

Relative to the infants of mothers who smoked postpartum but never in the same room with their infants, risk of hospitalization was 56% (95% confidence interval [CI] = 13%, 119%) higher if the mother smoked in the same room with the infant, 73% (95% CI = 18%, 157%) higher if the mother smoked when holding the infant, and 95% (95% CI = 28%, 298%) higher if the mother smoked while feeding the infant.

CONCLUSIONS

Parents who smoke should not smoke with their infants present in the same room.

Exposure to environmental tobacco smoke and urinary 1-hydroxypyrene levels in preschool children

Environmental tobacco smoke (ETS) contains relatively high concentrations of polycyclic aromatic hydrocarbons (PAHs). Urinary 1-hydroxypyrene (1-OHP), a metabolite of pyrene, is a good indicator of PAH exposure in occupational studies. In this study, we investigated the relationship between urinary 1-OHP concentration and ETS exposure in preschool children. Forty preschool children, aged 24-76 months, were studied during November and December, 1999. Two spot-urine specimens (one in the morning immediately after the subject woke up and the other at night before the subject went to bed) were collected 1 day after completion of a questionnaire, in order to determine 1-OHP concentrations by fluorescent spectrophotometry. Overall, urinary 1-OHP concentrations were relatively low but detectable (morning: median, 0.021 microg/g creatinine; range, 0.002-1.019 microg/g creatinine; night: median, 0.015 microg/g creatinine; range, 0.002-1.328 microg/g creatinine). Multiple linear regression analyses revealed that the total number of cigarettes smoked by the children's fathers during the 3 days prior to collection of the urine specimens was significantly associated with their urinary 1-OHP concentrations, after adjusting for other confounders. Each cigarette smoked by a child's father resulted in an average 9.6% increase in 1-OHP concentration in the morning urine specimen (95% confidence interval = 1.8-18.1%; p = 0.02). We did not find a significant increase in the 1-OHP concentration in night urine specimens (p = 0.19). Although the sample size was small, these findings indicate that urinary 1-OHP may be a suitable biomarker of ETS carcinogen exposure in children.

Influence of environmental tobacco smoke on vitamin C status in children

BACKGROUND

It is known that vitamin C status is compromised in smokers. The vitamin C status of nonsmokers who are exposed to environmental tobacco smoke (ETS) is now being elucidated.

OBJECTIVE

We assessed vitamin C status in children who were either exposed or not exposed to ETS, and we sought to associate changes in vitamin C status with the amount of ETS exposure.

DESIGN

The study group included 512 children aged 2-12 y; 50% of them were exposed to ETS in the home because their parents smoked. Dietary intake of vitamin C, obtained with a 24-h recall questionnaire, and blood ascorbate concentrations were compared in the exposed and unexposed groups. Smoke exposure was assessed by measuring a biomarker, urinary cotinine. Age, sex, and body mass index were examined as potential correlates of vitamin C status in each exposure category.

RESULTS

Plasma ascorbate concentrations were lower, by 3.2 micro mol/L on average, in ETS-exposed children than in unexposed children who consumed equivalent amounts of vitamin C; this was a highly significant difference (P = 0.002). This reduction in plasma ascorbate occurred even with very low exposure to ETS.

CONCLUSIONS

ETS can reduce concentrations of ascorbate, an important blood antioxidant, even when the amount of smoke exposure is minimal. Children exposed to ETS should be encouraged to consume increased amounts of foods rich in vitamin C or should be given the equivalent amount of this vitamin as a supplement.

Women's health after pregnancy and child outcomes at age 3 years: a prospective cohort study

OBJECTIVES

This study examined the persistence and comorbidity of women's physical and mental health conditions after pregnancy and the association of these conditions with child outcomes.

METHODS

A national cohort of women who recently gave birth were surveyed in 1988 and again in 1991. We examined longitudinal data on maternal poor physical health, depressive symptoms, and smoking, and maternal report of child outcomes (at age approximately 3 years).

RESULTS

Women's poor physical health and smoking had strong, graded associations with children's physical health and behavior problems, whereas women's depressive symptoms were associated with children's delayed language and behavior problems.

CONCLUSIONS

Substantial persistence and comorbidity of women's health conditions exist after pregnancy with adverse effects on early child outcomes. Child health professionals should support services and policies that promote women's health outside the context of pregnancy.

Is the hair nicotine level a more accurate biomarker of environmental tobacco smoke exposure than urine cotinine?

STUDY OBJECTIVE

The aim of this study was to compare the two biomarkers of exposure to environmental tobacco smoke (ETS); urine cotinine and hair nicotine, using questionnaires as the standard.

DESIGN

A cross sectional study of children consecutively admitted to hospital for lower respiratory illnesses during the period of the study.

SETTINGS

Three regional hospitals in the larger Wellington area, New Zealand.

PARTICIPANTS

Children aged 3-27 months and admitted to the above hospitals during August 1997 to October 1998. A total of 322 children provided 297 hair samples and 158 urine samples.

MAIN RESULTS

Hair nicotine levels were better able to discriminate the groups of children according to their household's smoking habits at home (no smokers, smoke only outside the home, smoke inside the house) than urine cotinine (Kruskall-Wallis; chi(2)=142.14, and chi(2)=49.5, respectively (p<0.0001)). Furthermore, hair nicotine levels were more strongly correlated with number of smokers in the house, and the number of cigarettes smoked by parents and other members of the child's households. Hair nicotine was better related to the questionnaire variables of smoking in a multivariate regression model (r(2)=0.55) than urine cotinine (r(2)=0.31).

CONCLUSIONS

In this group of young children, hair nicotine was a more precise biomarker of exposure to ETS than urine cotinine levels, using questionnaire reports as the reference. Both biomarkers indicate that smoking outside the house limits ETS exposure of children but does not eliminate it.

Cigarette smoking, salivary/gingival crevicular fluid cotinine and periodontal status. A 10-year longitudinal study

BACKGROUND, AIMS

The primary purpose of this study was to determine the association of salivary and gingival crevicular fluid (GCF) cotinine levels with periodontal disease status in smokers and non-smokers.

METHODS

147 male smokers and 30 male non-smokers were included in the current longitudinal study. The 177 individuals were part of a group of 200 subjects (89%) seen 10 years previously for a baseline survey. Oral hygiene indices, probing depth and attachment loss were recorded. Salivary and GCF cotinine levels of 58 smokers were determined by means of ELISA.

RESULTS

Results indicated that no significant difference was found in subjects who smoked, when compared to subjects who did not smoke with respect to plaque accumulation and calculus deposits. Smokers, however, had fewer gingival bleeding sites. Cigarette smoking was associated with a greater increase in probing depth and attachment loss, as well as greater tooth loss at an earlier age. There was greater tooth loss in smokers than non-smokers (p < 0.001). 11 smokers became edentulous, while only 1 non-smoker lost all his teeth within 10 years. The degree of periodontal tissue breakdown was different in each age group with greater periodontal deterioration as age increased. All smokers had detectable salivary and GCF cotinine. Mean GCF cotinine was about 4x higher than mean salivary cotinine levels. Individuals who smoked > or = 20 pack years when compared to <20 pack years, had significantly higher saliva and GCF cotinine levels (p < or = 0.05).

CONCLUSION

Neither salivary cotinine nor GCF cotinine was significantly correlated with probing depth, attachment loss and tooth loss (p > 0.05).

Infant stress and sleep deprivation as an aetiological basis for the sudden infant death syndrome

SIDS is almost invariably sleep-related. Viable syndrome aetiology must be compatible with its many epidemiologically diverse risk factors, each of which directly or indirectly associates with the creation of psychological and/or physiological infant stress, and the subsequent disruption of normal, contented sleep. During essential deep 'rebound' recovery sleep, arousal ability and upper airway muscle tone decrease further to that in normal sleep, with subsequent upper airway obstruction. When stress impact causes sufficient sleep disruption and physiological fatigue, a failure to arouse and so restore sufficient tone to overcome such obstruction results in sudden, unexpected death. SIDS has therefore many causes which share a final lethal mechanical pathway. Evidence is presented for obstructive apnoea during sleep as being the primary syndrome death mode, for sleep disruption, reduced arousal ability, and infant stress in SIDS, and for risk factor association with the creation of this stress. Specific infant vulnerability in the first 6 months of life to stress predominantly related to total dependency on a carer for gratification of need, and to obstructive sleep apnoea due to normal anatomical, physical, and respiratory immaturity, including rapid physiological fatigue, and peaks in sleep and thermal stress vulnerability, are discussed. Further reasons for the limited age period of SIDS, and for reduced neonatal risk, are given. Prone sleeping risk can relate to positional airway obstruction during normal sleep without prior infant stress. Much of SIDS aetiology appears to concern factors related to socio-economic deprivation and subsequent sub-optimal infant care.

Antioxidants and protein carbonyls in bronchoalveolar lavage fluid of children: normal data

Antioxidant-oxidant imbalances in bronchoalveolar lavage fluid (BAL) are thought to contribute to oxidative stress in respiratory disease. However, normal reference ranges for BAL antioxidants and oxidized proteins in children are not available. In this study, we recruited 124 children attending for elective surgery for a noninflammatory condition; 83 were nonasthmatic, nonatopic (N) and 41 were nonasthmatic, atopic (NA). A nonbronchoscopic lavage was performed and ascorbate, uric acid, alpha-tocopherol, and protein carbonyl (as a measure of oxidative damage) concentrations were determined in BAL fluid. The 95% reference range was 0.112-1.897 micromol/L for ascorbate, 0.149-2.163 micromol/L for urate, 0.0029-0.066 micromol/L for alpha-tocopherol, and 0.280-4.529 nmol/mg for protein carbonyls in BAL fluid. Age, gender, and exposure to environmental tobacco smoke did not affect the concentration of ascorbate, urate, alpha-tocopherol, or protein carbonyls. However, in multiple linear regression analyses, the type of home heating (glass-fronted fires or oil-fired central heating) was found to influence ascorbate and urate concentrations in the BAL fluid (ss-coefficient for ascorbate: 0.445, p = 0.031; for urate: 0.114, p = 0.001). There was no significant difference between the N and NA group in BAL fluid concentrations of ascorbate, urate, or protein carbonyls. The alpha-tocopherol concentration was significantly increased in the NA group (p = 0.037). Uric acid and alpha-tocopherol concentrations in BAL fluid and serum were not correlated. Intriguingly, serum and BAL ascorbate concentrations were significantly correlated (r = 0.297, p = 0.018, n = 63), which may offer an explanation for why supplementing the diet with vitamin C can improve asthma symptoms. Further studies will investigate the role of BAL antioxidant concentrations in children with inflammatory respiratory diseases.

Evaluation of the effect of passive smoking on otitis media in children by an objective method: urinary cotinine analysis

OBJECTIVES

We aimed to determine objectively the effect of the passive smoking on otitis media with effusion (OME) and recurrent otitis media (ROM) by using the method of cotinine urinalysis.

STUDY DESIGN

We designed a prospective case-control study with follow-up of the case group for 1 year after insertion of tympanostomy tubes to evaluate postoperative complications such as otorrhea and early extrusion (<6 months), in case a significant risk factor was found.

METHODS

One hundred fourteen children between 3 and 8 years of age requiring tympanostomy tubes because of OME and ROM were chosen and compared with 40 age-matched children. Exposure to environmental tobacco smoke was assessed by cotinine urinalysis, which was performed by means of the radioimmunoassay method.

RESULTS

In this study, 73.7% (84 of 114) of the children in the case group and 55.0% (22 of 40) of the children in the control group were found to be "exposed" (P = .0461). This difference was statistically significant. Comparing the cotinine urinalysis results with parental smoking histories, 23.1% (9 of 39) of the children without parental smoking histories were "exposed" to tobacco smoke versus 84.3% (97 of 115) of the children with parental smoking histories (at least one person smoking).

CONCLUSIONS

Our results indicate that sidestream smoking increases the risk of OME and ROM. Legal regulations and guidelines must be established to protect children from passive smoking. Because cotinine urinalysis is a noninvasive and reliable method for the determination of passive smoking, it can be used for that purpose.

Cord serum cotinine as a biomarker of fetal exposure to cigarette smoke at the end of pregnancy

This study investigated the association between biomarkers of fetal exposure to cigarette smoke at the end of pregnancy, cotinine in cord serum and in maternal and newborn urine samples, and quantitative measurement of smoking intake and exposure evaluated by maternal self-reported questionnaire. Study subjects were 429 mothers and their newborns from a hospital in Barcelona, Spain. A questionnaire including smoking habits was completed in the third trimester of pregnancy and on the day of delivery. Cotinine concentration in cord serum was associated with daily exposure to nicotine in nonsmokers and with daily nicotine intake in smokers. The geometric mean of cotinine concentration in cord serum statistically discriminated between newborns from nonexposed and exposed nonsmoking mothers, and between these two classes and smokers, and furthermore was able to differentiate levels of exposure to tobacco smoke and levels of intake stratified in tertiles. Urinary cotinine levels in newborns from nonsmoking mothers exposed to more than 4 mg nicotine daily were statistically different from levels in two other categories of exposure. Cotinine concentration in urine from newborns and from mothers did not differentiate between exposure and nonexposure to environmental tobacco smoke (ETS) in nonsmoking mothers. Cord serum cotinine appeared to be the most adequate biomarker of fetal exposure to smoking at the end of pregnancy, distinguishing not only active smoking from passive smoking, but also exposure to ETS from nonexposure.

Reported measures of environmental tobacco smoke exposure: trials and tribulations

OBJECTIVE

This report extends previous summaries of reported environmental tobacco smoke (ETS) exposure measures, reviews the empirical evidence of their validity for children's exposure, and discusses future research.

DATA SOURCES

Studies were identified by computer search and from the authors' research.

STUDY SELECTION

Studies were selected for inclusion of nicotine and/or cotinine and quantitative reported measures of ETS exposure.

DATA SYNTHESIS

Five studies found significant associations between reported quantitative exposure of children to ETS and either environmental nicotine or urine cotinine assays. Correlation coefficients between parent reports and nicotine ranged from 0.22 to 0.75. Coefficients for cotinine ranged from 0.28 to 0.71. Correlations increased over time and were stronger for parents' reports of their own smoking as a source of children's exposure than for reports of exposure from others.

CONCLUSIONS

Empirical studies show general concordance of reported and either environmental or biological measures of ETS exposure. Relationships were moderate, and suggest sufficient validity to be employed in research and service programs. Future studies need to identify the differences in types of reported or objective measures, population characteristics, etc, contributing to observed variability in order to understand better the conditions under which more valid reported ETS exposure and other measures can be obtained. Reported and either environmental or biological measures should be used in combination, and existing measures should be directed to interventions that may reduce ETS exposure among children.

Nicotine delays arousal during hypoxemia in lambs

A decreased ability to arouse from sleep in response to arterial hypoxemia may lead to severe asphyxia and has been proposed as a mechanism of sudden infant death syndrome. Based on previous observations that nicotine exposure, a major environmental risk factor for sudden infant death syndrome, may impair hypoxic defense in neonates, we hypothesized that a short-term infusion of nicotine could impair hypoxic arousal through interference with oxygen-sensing mechanisms. Seven chronically instrumented unanesthetized lambs were studied at the age of 4.6 +/- 1.3 d during normoxia and acute hypoxia (0.1 fraction of inspired oxygen) for 5 min. Ventilation, transcutaneous Hb oxygen saturation, blood pressure, heart rate, and time to arousal were compared during a control saline infusion and during a 0.5 microg x kg(-1) x min(-1) nicotine infusion. Activity states, i.e. wakefulness and quiet sleep as well as arousal, were defined by EEG, nuchal electromyogram, and electrooculogram. Each lamb acted as its own control. Arousal from quiet sleep occurred significantly later during nicotine infusion compared with control (177 +/- 93 versus 57 +/- 41 s, p < 0.01) and at a lower transcutaneous Hb oxygen saturation (60 +/- 12 versus 79 +/- 12%, p < 0.01) (paired t test). The ventilatory response to hypoxia in wakefulness was similar during both conditions but was significantly attenuated in quiet sleep during nicotine infusion (p < 0.001, 2-way ANOVA repeated-measures design). Blood pressure and heart rate responses were similar during both conditions. These results suggest that a brief nicotine exposure blunts oxygen sensitivity in young lambs, a finding of potential relevance for sudden infant death syndrome.

Salivary cotinine levels in children presenting with wheezing to an emergency department

We set out to evaluate salivary cotinine concentrations to judge tobacco smoke exposure among infants and children, and to examine the results in relation to age and wheezing. This was a case-control study of wheezing children (n = 165) and children without respiratory tract symptoms (n = 106) who were enrolled in the Pediatric Emergency Department at the University of Virginia. The age range of both wheezing and control patients was 2 months to 16 years. Questionnaires were combined with cotinine assays in saliva to evaluate exposure to environmental tobacco smoke (ETS) for each child. The prevalence of exposure to one or more smokers at home was high (68%); and 43% of the children enrolled were exposed to ETS from their mothers. According to the questionnaires, and after adjusting for age and race, a wheezing child in this study was more likely than a control to be exposed to at least one smoker at home (odds ratio = 1.9; 95% CI = 1.1-3.4). However, the odds of exposure to ETS from smoking mothers did not differ significantly between wheezing and control patients, and no significant association was found between the presence of wheezing and salivary cotinine levels. Among children exposed to ETS at home, cotinine levels were significantly higher in saliva from those under the age of two years, and from toddlers aged 2 and 3 years, compared to values from children over age 4 years. Moreover, the number of smokers in the home strongly influenced cotinine levels from children under age 4 years. In addition, higher cotinine levels were observed in saliva from children under age 2 years who were exposed to ETS from their mothers. Cotinine levels were similar and significantly correlated in paired samples of saliva and serum from children under 4 years of age (n = 54), (r = 0.92, P < 0.001). Based on information gathered from questionnaires, the results indicate that wheezing children were more likely than controls to be exposed to ETS at home. However, significant differences in ETS exposure between wheezing and control groups with respect to maternal smoke exposure or comparisons of salivary cotinine levels were not apparent. It was clear that determinations of salivary cotinine for monitoring the prevalence and intensity of household smoke exposure in this study were most valuable during the first 4 years of life.

Environmental tobacco smoke exposure in children: household and community determinants

To determine the most important sources of environmental tobacco smoke exposure to young children, the authors studied the associations among urinary cotinine, reported household smoking habits, and socioeconomic variables in 575 schoolchildren aged 6-11 y. The school children were among a population of prodigious smokers in Cape Town, South Africa. Eighty percent of the children were exposed to environmental tobacco smoke. Maternal smoking, which was adjusted for creatinine, accounted for 21.8% of the variation in urinary cotinine--more than all other sources combined. The male parent and other household smokers accounted for 12.7% of the variation, and socioeconomic indicators explained an additional 4.8%. By defining the ecological variable of smoking prevalence per school, the authors estimated a "community" contribution of 3.3%. The relative importance of different sources of smoke should be taken into account in the prevention of environmental tobacco smoke exposure in young children. Most importantly, of all the sources of environmental tobacco smoke, mothers' smoking habits had the greatest impact on exposure to children.

Effect of smoking one cigarette on antioxidant metabolites in the saliva of healthy smokers

Concentrations of glutathione, uric acid and total antioxidant activity, expressed as Trolox (a water-soluble vitamin E analogue) equivalent, were measured in the saliva of healthy non-smokers and smokers before and just after smoking a single cigarette. There was no statistically significant difference between smokers and non-smokers in uric acid concentrations and total radical-trapping antioxidant capacity, but glutathione concentrations were significantly (p < 0.05) higher in smokers. Smoking of a single cigarette induced a significant reduction in glutathione concentration (p < 0.05). Salivary antioxidant power may affect individual sensitivity toward tobacco stress.

Epidemiology of otitis media onset by six months of age

OBJECTIVE

Although early otitis media (OM) onset predicts later recurrent and chronic OM, little research has been directed at illuminating the role of prenatal exposures in early OM. This prospective study examined prenatal, innate, and early environmental exposures associated with acute otitis media (AOM) onset and recurrent OM (ROM) by age 6 months.

DESIGN AND METHODS

Prospective study of 596 infants from a health maintenance organization followed from birth to 6 months. Mothers completed monthly forms on prenatal exposures (diet, medications, and illnesses) and infant risk factors (eg, smoke exposure and child care) during pregnancy and until infants were 6 months old. Urine samples were collected when infants were 2 months of age and analyzed for cotinine and creatinine. Physicians and nurse practitioners examined infants at each clinic visit and completed standard ear examination forms.

RESULTS

Thirty-nine percent had an episode of AOM and 20% had ROM by age 6 months. Using Cox's regression models to control for confounding, respiratory tract infection (relative risk [RR] 7.5), day care (RR 1. 7), >1 sibling (RR 1.4), maternal, paternal, and sibling OM history (RR 1.6, 1.5, and 1.7, respectively) were significantly related to early OM onset. ROM was related to respiratory tract infection (RR 9. 5), day care (RR 1.9), conjunctivitis (RR 2.0), maternal OM history (RR 1.9), and birth in the fall (RR 2.6). Among prenatal exposures, only high prenatal dietary vitamin C intake was significantly inversely related to early AOM with univariate but not multivariate analysis.

CONCLUSION

Prenatal factors were not linked to early AOM onset with multivariate analysis, but environmental and innate factors play an important role in early AOM onset. Strategies to reduce exposure to environmental variables could reduce rates of early AOM, which could potentially result in declining rates of ROM and chronic OME.

Cotinine excretion as a predictor of peak flow variability

Environmental tobacco smoke (ETS) is suspected to be an important risk factor for bronchial hyperresponsiveness. In order to test the effect of ETS, we measured expiratory flow rates and urine cotinine excretion (UCE) within a narrow time window in two consecutive years. Maternal smoking habits and medical history were ascertained by standardized questionnaires. The percentage ratio of the amplitude over the mean (AVAM) of the diurnal peak flow rates of children (complete values from at least five consecutive days) was calculated as an indicator of bronchial responsiveness. The association of UCE and log10AVAM was analyzed by multiple linear regression. Complete data were available for a sample of 417 children. The median of UCE in children of parents who smoked (3.2 ng/mg and 2.9 ng/mg creatinine, Surveys 1 and 2, respectively) was higher than the median in children of nonsmoking parents (0 ng/mg in both surveys). With increasing UCE the log10AVAM rose in the first and second surveys, as well as in the longitudinal analysis (p = 0.003). This association, however, showed up only in boys (p = 0.0001) and not in girls (p = 0.31). Our data suggest that there is a need both for further analysis of the gender difference and for more support of strategies against passive smoking as far as children are concerned, since airway hyperresponsiveness is a risk factor for chronic airway impairment.

Exposure of young infants to environmental tobacco smoke: breast-feeding among smoking mothers

OBJECTIVES

This study examined the degree to which breast-feeding and cigarette smoking by mothers and smoking by other household members contribute to the exposure of infants to the products of tobacco smoke.

METHODS

The subjects were 330 mother-infant pairs derived from a cohort of 1000 pairs enrolled in a longitudinal study of the pulmonary effects of prenatal and postnatal smoking. The main outcome measure was corrected urinary cotinine levels.

RESULTS

Urinary cotinine levels were 10-fold higher in breast-fed infants of smoking mothers than among bottle-fed infants of smoking mothers. Among infants of nonsmoking mothers, urine cotinine levels were significantly increased in infants living in homes with other smokers; in this group there was no significant difference between bottle-fed and breast-fed infants. Infants whose mothers smoked in the same room as the infant had only nonsignificant increases in cotinine levels compared with infants whose mothers restricted their smoking to other rooms.

CONCLUSIONS

Breast-fed infants of smoking mothers have urine cotinine levels 10-fold higher than bottle-fed infants whose mothers smoke, suggesting that breast-feeding, rather than direct inhalation of environmental tobacco smoke, is the primary determinant of cotinine levels in infants whose mothers smoke.