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

Ecology of passive smoking by young infants

This study provides a detailed description of passive smoking by 433 infants (mean age 18 days) enrolled from a representative population of healthy neonates in central North Carolina during 1986 and 1987. Sixty-four percent (276) lived in households with smokers or had contact with nonhousehold smokers. During the week before data collection, two thirds (184) of these 276 infants reportedly had tobacco smoke produced in their presence. Seventy-five percent of smoking mothers smoked near their infants. The amount smoked by the mother near the infant correlated with the amount smoked near the infant by nonmaternal smokers. Cotinine, an indicator of smoke absorption, was found in the urine of 60% (258) of all study infants. The amount smoked in the infant's presence, as well as the amount smoked farther away from the infant, especially by the mother, were the most significant correlates of the urine cotinine concentration. The results of this study suggest that efforts to reduce passive smoking in young infants should emphasize the importance of the mother's smoking behavior, smoke produced anywhere in the home, and household social influences on smoking behavior near the infant.

Multidimensional gas chromatographic determination of cotinine as a marker compound for particulate-phase environmental tobacco smoke

Multidimensional gas chromatographic analysis of air particles for the tobacco alkaloid cotinine is described. The analytical procedure requires little sample preparation. Unambiguous identification of cotinine and nicotine in cigarette smoke and indoor air samples was achieved by precise, reproducible retention times observed with two parallel analytical columns of different polarities and a nitrogen-specific detector. Further investigation of smoking and environmental variables is needed to validate the use of cotinine as a marker compound for environmental tobacco smoke particulate matter.

Application of biochemical intake markers to passive smoking measurement and risk estimation

Measurement of the dose received from passive smoking complements epidemiological approaches and may provide an alternative method of estimating risk. Non-smokers absorb measurable amounts of nicotine from breathing other people's smoke, and dose-response relationships are apparent. On the basis of the limited data so far available, the dose of nicotine received by the average British non-smoker may represent about 0.5% of that of the heavy cigarette smoker, ranging up to 2% in more heavily exposed individuals. The dose of carbon monoxide appears relatively greater, as does that of tobacco-specific nitrosamines. The situation with respect to tar is unclear, but nicotine may provide a better guide than does CO.

Determination of cotinine in urine using glass capillary gas chromatography and selective detection, with special reference to the biological monitoring of passive smoking

A capillary gas chromatographic (GC) method using selected-ion monitoring (SIM) was developed for the analysis of cotinine (C.A.S. No. 486-56-6) in human urine. The method is based on basic extraction of cotinine from 2 ml of urine into dichloromethane. After evaporation of the dichloromethane solution to dryness, 100 microliters of toluene were added, prior to GC-mass spectrometric (MS) analysis. Trideuterated cotinine (C.A.S. No. 97664-65-8) was used as the internal standard. More than 1000 automatic chromatographic analyses were made without column degradation. Molecular ions (M) of cotinine and trideuterated cotinine, (m/e = 176 and 179), were monitored in the electron impact (EI) mode and m/e = 177 (M + 1) and m/e = 180 (M + 1) in the chemical ionization (CI) mode with isobutane. The correlation coefficient with SIM and EI was 0.998 (5-20 ng/ml) and with CI was (0.2-2 ng/ml). For thermionic specific detection the correlation coefficient was 0.998 (10-510 ng/ml). Only capillary columns with an apolar bonded stationary phase film thickness of 1 micron showed sufficient inertness for cotinine analysis at the sub ng/ml level. The relative standard deviations for 5 and 20 ng/ml were 5.2 and 3.5% respectively (n = 12) using EI. Spiked urine samples from six non-smokers (5 ng/ml) showed a relative standard deviation of 5%. The overall recovery (25 ng/ml) was 100 +/- 4%. The minimum detectable concentration, using SIM, was ca. 2 ng/ml in the EI mode and ca. 0.2 ng/ml in the CI mode. The half-time for cotinine was ca. 18 h for both active smokers and non-smokers.

Monoclonal antibody ELISA for cotinine in saliva and urine of active and passive smokers

The value of a monoclonal antibody-based ELISA for measuring cotinine in saliva and urine of active and passive smokers was assessed. Cotinine (mean +/- SEM) was detected in all 26 saliva (392 +/- 74 ng/ml) and 27 urine (4264 +/- 508 ng/mg creatinine; 2566 +/- 364 ng/ml) samples from smoking parents, but in only two of 36 salivas and one of 37 urines from nonsmokers (P less than 0.001). Similarly, mean cotinine levels in 30 salivas (4.67 +/- 1.10 ng/ml) and 33 urines (35.5 +/- 8.8 ng/mg creatinine; 25.3 +/- 8.1 ng/ml) from passively exposed children were significantly higher (P less than 0.001) than in fluids of 36 unexposed children. Children's levels showed a strong correlation (P less than 0.001) with the number of cigarettes smoked in the home, but only when data from nonsmoking households were included in the analysis. In adult smokers there was a positive correlation between salivary and urinary cotinine (P = 0.002) and a close relationship between urinary cotinine and cigarettes smoked per day (P = 0.066). The ELISA gives a reliable quantitative measure of cotinine as an indicator of active and passive exposure to tobacco smoke. However, correlations with cotinine can be overestimated if large numbers of nonsmokers are included in the comparison.

Passive exposure to cigarette smoke does not increase allergic sensitization in children

The purpose of this study was to learn whether children passively exposed to parental cigarette smoke would be more frequently sensitized to common allergens or would have higher concentrations of allergen-specific IgE. To evaluate this question, we studied two groups of children aged 2 to 17 years. The first group consisted of 100 children selected from a general pediatric group practice. These children were being observed for well-child care, and the only selection criteria were the need for a venous blood sample for a reason unrelated to the study. The second group of 91 patients were consecutively referred, from the same pediatric group, for allergy evaluation because of respiratory tract symptoms. Parental smoking histories were obtained, and total serum IgE, IgD, and IgE specific for cat, dog, mite, ragweed, grass, and cockroach were measured by ELISA. Children of smoking mothers had significantly greater IgD concentrations (p = 0.03) and were more likely to be referred for allergy evaluation (p = 0.0001), but these children did not have increased concentrations of total or allergen-specific IgE. Exposed children were not more likely to be serologically sensitive to any of the allergens tested. We conclude that children passively exposed to cigarette smoke do not produce more IgE to common allergens nor are they more likely to produce IgE to any particular allergen.

Cotinine in the serum, saliva, and urine of nonsmokers, passive smokers, and active smokers

Cotinine was measured in the serum, saliva, and urine of nonsmokers, passive smokers, and active smokers. Serum and saliva could not discriminate between nonsmokers and passive smokers. Mean urine cotinine was higher in passive smokers than nonsmokers but there was a great deal of intersubject overlap. Cotinine in all body fluids could separate active smokers from the other two groups. Among smokers, light smokers had lower levels than heavier smokers.

Health effects and sources of indoor air pollution. Part I

Since the early 1970s, the health effects of indoor air pollution have been investigated with increasing intensity. Consequently, a large body of literature is now available on diverse aspects of indoor air pollution: sources, concentrations, health effects, engineering, and policy. This review begins with a review of the principal pollutants found in indoor environments and their sources. Subsequently, exposure to indoor air pollutants and health effects are considered, with an emphasis on those indoor air quality problems of greatest concern at present: passive exposure to tobacco smoke, nitrogen dioxide from gas-fueled cooking stoves, formaldehyde exposure, radon daughter exposure, and the diverse health problems encountered by workers in newer sealed office buildings. The review concludes by briefly addressing assessment of indoor air quality, control technology, research needs, and clinical implications.

Passively inhaled tobacco smoke: a challenge to toxicology and preventive medicine

The difficulties in defining the exposure of a passive smoker might explain the controversial results regarding an association between passive smoking on one hand and lung cancer, tumors of all sites and ischemic heart diseases on the other. The plausibility of these epidemiological observations will be discussed in the light of analytical, toxicological, biochemical and oncological data. The minute amounts of nicotine and particulate matter, even the much higher concentrations of volatile substances, such as nitrosamines, NOx, acroleine and formaldehyde, present in diluted sidestream compared to mainstream smoke and breathed by involuntarily smoking people, cannot explain their relatively high cancer risk. It is plausible if one considers the high capacity of cigarette smoke to induce drug metabolizing enzymes. Diluted sidestream smoke, however, lacks compounds which induce several iso-enzymes of cyt. P-450 monooxygenase in the tissues. The best evidence is the up to 100-fold increase in placental enzymes if pregnant women smoke, whereas passively inhaled tobacco smoke is ineffective as inducer. The small amounts of paternal smoke inhaled by pregnant women, containing teratogenic and carcinogenic compounds, which are supposedly not detoxified in the placenta, seem to explain the higher risk for malformations of the fetus and the same or even increased risk for perinatal mortality, compared with the outcome of pregnancy if the mother smoked. The induction of placental enzymes very probably protects the fetus against the much higher amounts of toxic agents inhaled by the smoking mother. The increased activity of placental enzymes seems to be a model for the probably greater capacity of certain cyt. P-450 iso-enzymes in the lung and other tissues to convert carcinogens to inactive metabolites when the individual smokes actively. It is well known that concomitant administration of carcinogens with inducing agents inhibits tumor growth in animals because of a shift in the metabolism which favours the formation of ineffective substances. The negligible amounts of nicotine and CO in passively inhaled tobacco smoke cannot be responsible for the surprisingly high risk for ischemic heart diseases of passive smokers. A plausible explanation is offered by experiments with doves and chicken, which develop atherosclerotic lesions due to the action of carcinogens which are metabolized by certain inducible cyt. P-450 iso-enzymes in the aortic wall. Much circumstantial evidence will be presented, indicating that PAHs, contrary to the propagated opinion, play a minor role for the initiation of cancer in active smokers.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of biochemical validation measures in determination of smoking status

This study was designed to evaluate the use of salivary cotinine, salivary thiocyanate, and expired-air carbon monoxide as biochemical validation measures for assessing the smoking status of adults. The participants were 20 known non-smokers plus 216 admitted smokers and 102 proclaimed quitters participating in a clinical trial of approaches to facilitate smoking cessation. Conventional analytical procedures were utilized. By use of data from known non-smokers and admitted smokers, the sensitivity and specificity of the validation measures were as follows: salivary cotinine, 99% and 100%; expired-air carbon monoxide, 96% and 100%; and salivary thiocyanate, 67% and 95%, respectively. The salivary cotinine and expired-air carbon monoxide tests confirmed smoking cessation for 55% and 74%, respectively, of the proclaimed quitters. The length of time since quitting was significantly related to the results observed with the latter measures. Consideration of these observations along with various practical factors suggests that expired-air carbon monoxide assays may be the validation measure of choice for most clinical trials.

Kinetics of cotinine after oral and intravenous administration to man

Cotinine, the main metabolite of nicotine, was administered intravenously to healthy male non-smoking volunteers in doses of 5, 10 and 20 mg, and orally in doses of 10 and 20 mg. Intravenous administration was characterized by a dose-independent half-life of 12.2 h, mean residence time of 15.9 h, total clearance of 3.64 l h-1 and a volume of distribution of 56.5 l. Renal clearance was 0.46 l h-1 and approximately 12.0% of the dose was excreted unchanged in the urine. The mean absorption time after oral dosing ranged between 1 and 3 h, the peak concentration was reached within 45 min and the mean elimination half-lives were 12.9 and 11.7 h, respectively, after the 10 and 20 mg doses. Systemic bioavailability ranged between 0.84 and 1.11 following 10 mg and between 0.97 and 1.03 following the 20 mg dose. Mean urinary recovery and renal clearance were almost identical with the values after iv administration.

Trial of an intervention to reduce passive smoking in infancy

We tested a health education intervention program to reduce passive smoking in infancy. The aim was to develop an instrument for study of tobacco smoke exposure and childhood respiratory illness. One hundred and eighty-four women who had smoked during pregnancy were allocated by month of delivery to an intervention group, to a minimal contact group, or to a follow-up only comparison group. Exposure to smoke was assessed 3 months later by questionnaire and by measurement of cotinine in samples of maternal and infant urine. There was a reduction in maternal smoking associated with contact with research staff, but this was not statistically significant. There were no differences between the groups in the exposure of infants to tobacco smoke. Reasons for this finding may include the timing of the intervention, the heterogeneity of the target group, and the manner in which information was presented on health risks caused by parental smoking.

Passive smoking at work: biochemical and biological measures of exposure to environmental tobacco smoke

Several biochemical and biological measures of tobacco smoke intake were used to evaluate exposure of restaurant personnel to environmental tobacco smoke as compared with active smokers and non-exposed non-smokers. All of the measured parameters--carboxyhaemoglobin (COHb), thiocyanate (SCN) and cotinine in plasma, cotinine and mutagenicity in urine, total white blood cell count (WBC), and sister chromatid exchange (SCE) frequency in cultured lymphocytes--were significantly elevated in the smoker group (n = 22) compared to the non-exposed group (n = 20). Work-related passive exposure (n = 27) was seen most clearly in the cotinine values, both from plasma (mean P-cot in passive smokers 10 ng/ml vs 5.2 ng/ml in non-exposed) and from urine (mean U-cot in passive smokers 56 ng/ml vs 8.3 ng/ml in non-exposed), but significant increases were also seen in the thiocyanate levels (mean P-SNC in passive smokers 58 mumol/l vs 46 mumol/l in non-exposed) and, as a preliminary finding, in total leucocyte count (in passive smokers 8.0 X 10(9)/l vs 6.8 X 10(9)/l in non-exposed). The results demonstrate that environmental tobacco smoke may be an occupational health hazard.

Measuring problems in estimating the exposure to passive smoking using the excretion of cotinine

Quality control studies on cotinine measurements following low level environmental tobacco smoke (ETS) exposure are rare. The exposure to ETS was controlled and systematically changed in a series of experiments in a climatic chamber. Healthy nonsmoking volunteers were exposed to ETS simultaneously. The duration and level of exposure varied using high (8, 17 and 25 ppm CO), and low (2 and 5 ppm CO) exposure levels. The variation between radioimmunoassay (RIA) and gas chromatography (GC) was high as was the variation between the results of RIA laboratories. There was also a high within-laboratory-variation. A 1:10 dilution seems to be preferable over a 1:3 dilution. Freezing the urine samples immediately after collection led to the detection of higher cotinine values than freezing the samples 24 h after collection. Highly reliable data for cotinine were obtained when the urine samples were kept frozen immediately after collection and fractionated sampling over 48-72 h was used. Our data show that estimating low-level ETS exposure by measuring urinary cotinine is highly susceptible to uncontrolled variation and errors. Sufficiently reliable estimates of low-level ETS exposure can be made only when fractionated sampling over 48-72 h is used and when the urine samples are kept frozen just after collection.

Estimation of smoke dosage and mortality of non-smokers from environmental tobacco smoke

This paper shows how biochemical markers can be used to estimate smoke intake from passive smoking to complement epidemiological studies on the health risks and mortality to non-smokers. Using data from slow nicotine infusions given over 1 h, we estimated that the nicotine intake from passive smoking averages about 0.014 mg/h among urban non-smokers leading their usual daily lives. This compares with 0.23 mg/h in a smoke-filled public house, 0.36 mg/h during maximum exposure in an unventilated room, and 1.0 to 1.4 mg nicotine per cigarette taken in by active smokers. Data from several studies on urinary nicotine concentrations and those of cotinine in blood, urine and saliva were collated. The results show that the concentrations in non-smokers averaged about 0.7% (for nicotine) and 0.6% (for cotinine) of the levels found in smokers. From this we estimate that the mortality from passive smoking is about 1000 non-smokers per year in Britain and about 4000 per year in the United States, assuming that the relation of dose to risk is linear.

Smoking and passive smoking during pregnancy and early infancy: effects on birth weight, lactation period, and cotinine concentrations in mother's milk and infant's urine

The extent of smoke exposure via mother's milk and passive smoking was investigated in a prospective, longitudinal matched-pair study by comparison between children, whose mothers smoked substantially throughout pregnancy and nursing period and children whose mothers did not smoke. Our preliminary results show that not only infants of smoking mothers but also those of smoking fathers show reduction of birth weight. Smoking mothers weaned their babies earlier than non-smokers. Cotinine concentrations in breast milk depended on the number of cigarettes smoked. The highest urinary excretion of cotinine (as expressed by ng cotinine/mg creatinine ratios) were observed in infants fully breast-fed by smoking mothers. After weaning the values were in the same range as those of formula-fed infants of smoking mothers (exposed to passive smoking only). In the group of non-smokers only small or undetectable amounts of cotinine were found. Thus it is demonstrated that both nursing and--to a lower degree--passive smoking contribute to the exposure of infants to nicotine and its metabolite cotinine.

Breast feeding and smoking hygiene: major influences on cotinine in urine of smokers' infants

The determinants of urine cotinine levels were studied in a group of 101 infants aged 3 months, including 79 infants whose mothers were current smokers. At a pre-arranged home visit the infants' mothers completed an interviewer-administered questionnaire, and samples of maternal urine and breast milk and infants' urine were collected. Cotinine and nicotine levels were determined by gas-liquid chromatography. Infant urine cotinine levels ranged from 0 to 140 micrograms/l (0-1120 ng cotinine/mg creatinine). A linear dose response relation between mother's smoking rate and infant urine cotinine level was observed among breast-fed infants (r = 0.79, p less than 0.001). The relation was weaker among infants fed by both breast and bottle (r = 0.56, p = 0.01) and was not apparent among bottle-fed infants (r = 0.15, p = 0.16). In addition to mode of feeding and mother's smoking rate, mother's smoking "hygiene" (assessed by the reported frequency of smoking while feeding and with infant in same room) was independently associated with infant urine cotinine level. Father's smoking pattern and exposure to smoke outside the household did not relate significantly to infant cotinine levels. We conclude that when mothers smoke, breast feeding is the principal determinant of cotinine in infants' urine. It is likely that most of this cotinine comes from cotinine in mothers' breast milk, but further research is needed to establish how much nicotine is ingested by breast-fed infants of mothers who smoke, and to investigate possible health effects.

Contribution of passive smoking to respiratory cancer

This article reviews data from experimental and epidemiologic studies on passive smoking and makes 12 recommendations for further study. The physicochemical nature of passive smoke, the smoke inhaled by nonsmokers, differs significantly from the mainstream smoke inhaled by the active smoker. At present, measurement of urinary cotinine appears to be the best method of assessing exposures to passive smoking. Data indicate that the greater number of lung cancers in nonsmoking women is probably related to environmental tobacco smoke. Exposures in utero and very early in life to passive smoking may be important in relationship to the subsequent development of cancer and need further consideration. The short-term effects of environmental tobacco smoke on the cardiovascular system, especially among high-risk individuals, may be of greater concern than that of cancer and requires further study. Further study of increased risks of lung cancers in relation to environmental tobacco smoke exposure requires larger collaborative studies to identify lung cancer cases among nonsmokers, better delineation of pathology, and more careful selection of controls. In addition, studies of epithelial cells or specific cytology should be undertaken to determine evidence of cellular changes in relation to environmental tobacco smoke exposure. Animal inhalation studies with passive smoke should be initiated with respect to transplacental carcinogenesis, the relationship of sidestream smoke exposure with lung cancer, the induction of tumors in the respiratory tract and other organs, and the differences in the physicochemical natures of sidestream and mainstream smoke.

Determination of cotinine in biological fluids of non-smokers by packed column gas-liquid chromatography

A method is described for the analysis of cotinine in plasma, saliva and urine using packed-column gas-liquid chromatography, which is sufficiently sensitive and reproducible for quantitative study of the low levels resulting from exposure of non-smokers to other people's smoke. The lower limit of detection of cotinine in these fluids was 100 pg ml-1. The coefficient of variation over the range 0.25 to 2.0 ng ml-1 averaged 7.7%. In a sample of 85 non-smokers the concentrations of cotinine in plasma correlated 0.82 with those in urine and saliva, while the correlation between the saliva and urine concentrations was 0.91. Saliva cotinine concentrations were quantitatively related to passive exposure to parental smoking in a population study of 569 non-smoking schoolchildren.

Single-reagent polarisation fluoroimmunoassay for cotinine (a nicotine metabolite) in urine

A rapid, single-reagent, non-separation, non-isotopic immunoassay was developed for determining levels of the nicotine metabolite, cotinine, in urine. The single reagent was prepared by pre-mixing an appropriate dilution of sheep anti-cotinine serum with a fluorescein-labelled cotinine tracer. All normal reliability criteria were satisfied. The assay was found to be specific for cotinine and there was no cross reactivity with other available nicotine metabolites and structurally-related compounds. The results obtained correlated closely with those of an established radioimmunoassay. The assay was well-suited to application in the discrimination of active smokers from non-smokers (and passive smokers).

Effect of passive smoking on birth-weight

500 consecutive Danish women who had full-term babies were interviewed on the third or fourth day post partum and asked about smoking in all household members. Exposure to smoking by the mother was found to reduce birth-weight, and indirect or passive exposure to smoking by the father had nearly as large (66%) an effect. On average, birth-weight was reduced by 120 g per pack of cigarettes (or cigar/pipe equivalent) smoked per day by the father. This relation remained statistically significant after controlling for mother's age, parity, alcohol and tobacco consumption during pregnancy, illness during pregnancy, and social class and sex of the baby. The effect of passive smoking was greatest in the lower social classes.

Pre- and postnatal carbohydrate metabolism of rat lung tissue. The effect of maternal nicotine exposure

The effect of maternal nicotine exposure on fetal and neonatal lung metabolism was investigated. Nicotine (0.25 and 1.0 mg/kg body weight/day) administered subcutaneously to the mother animal from day 7 of gestation until weaning led to retarded glycogenolysis of fetal lung. This was due to an inhibition of lung glycogen phosphorylase. Exposure until 2 weeks after birth had no effect on the in vitro oxygen consumption of lung tissue, but the total glucose turnover of rat neonates exposed to 0.25 and 1.0 mg nicotine/kg body weight per day was increased to 78.96 +/- 3.92 and 121.09 +/- 7.36 mumol/g per h, respectively, as compared to controls (64.95 +/- 4.56 mumol/g per h). In contrast to the marked increase in total glucose turnover, the in vitro lactate production was significantly lowered, suggesting an inhibition of the glycolytic pathway. The lung lecithin content of control neonates (day 1 post-partum) was 1.94 +/- 0.30 mg/g wet tissue mass. Nicotine administration to the mother resulted in a 92% higher lung lecithin content (3.72 +/- 0.06 mg/g). The results suggest that although nicotine will have no effect on the incidence of respiratory distress syndrome due to a lack of lecithin, it may have a detrimental effect on the functional development of the lung as a result of its inhibitory effect on glucose oxidation via the glycolytic pathway.

Bladder cancer in nonsmokers

Potential risk factors for bladder cancer were studied in a series of 76 male and 76 female bladder cancer cases and 238 male and 254 female controls who reported never having smoked. Risk factors included usual occupation, smoking by the spouse, sidestream smoke exposure at home and at work and in transportation, coffee drinking (caffeinated and decaffeinated), artificial sweetener use, body mass index, and a history of diabetes and high blood pressure. No association was found with spouse's smoking or reported sidestream smoke exposure, coffee drinking, artificial sweetener use, or a number of other variables; however, there was some indication that several occupations were overrepresented in the cases. A positive association was found with snuff use in women, but the numbers were small (three cases and one control). Restriction of the study to lifetime nonsmokers permitted the assessment of potential risk factors in the absence of potential confounding and interactive effects of smoking. The study had adequate statistical power to detect moderately small elevated risks due to the main factors examined.

Environmental tobacco smoke: comparative characterization by mutagenicity assays of sidestream and mainstream cigarette smoke

Mainstream cigarette smoke particles were collected by means of a smoking machine, and sidestream particles were collected from the room in which the smoking took place. The particles were extracted by sonication with acetone, and the extracts were solvent-exchanged to dimethyl sulfoxide. The samples were tested for mutagenicity in the Ames Salmonella/microsome assay. The mainstream extract is preferentially mutagenic in the presence of S9, with about 30,000 revertants/cigarette in TA98, but has little or no activity in its absence. The sidestream extract is also mutagenic in the presence of S9 with TA98, and this activity is mainly due to basic compounds. Sidestream smoke is also significantly mutagenic in the absence of S9 in the strain TA100 as well as in TA97 and TA104. This "direct" activity is due to components that are labile. The response of sidestream particles is 10,000-20,000 revertants/cigarette in TA98 + S9 and TA100-S9 when the collection is performed in a room where the particle concentration is modulated by deposition to surfaces. Sidestream particles collected on glass fiber filter and by electrostatic precipitation (ESP) with a commercial air cleaning device gave essentially the same mutagenic response, showing that ESP sampling may be an alternative to filter sampling for environmental tobacco smoke (ETS) in indoor environments. ESP sampling in children's rooms in smoking and nonsmoking homes showed that 5-10% of the tobacco smoke emitted in the smoking homes entered the child's room, demonstrating that diffusion of pollutants is faster than ventilation in modern buildings with low ventilation rates.

Verification of smoking status by thiocyanate in unrefrigerated, mailed saliva samples

A simple method of obtaining an unbiased verification of smoking status was developed for use in a randomized clinical trial. At the end of smoking cessation intervention for pregnant women, each participant mailed a saliva sample to a laboratory for the determination of thiocyanate. For comparison, salivary thiocyanate also was measured by a standard collection method in a reference group of non-study women who did not smoke during pregnancy. Although there may have been up to a 1-week delay between collection and analysis, results show that thiocyanate from unrefrigerated, mailed samples of saliva distinguishes reported smokers from nonsmokers, is positively associated with the amount of smoking, and is negatively associated with the length of cessation. These study findings are consistent with results from other studies in which samples of serum or saliva were collected and shipped under conditions requiring the presence of a staff member. The ability to perform an unbiased smoking status verification using a simple, inexpensive, and noninvasive collection method expands study possibilities, as it eliminates the need for direct, face-to-face contact with study subjects, and for being at their location.

Review of epidemiology in relation to passive smoking

Large segments of the population in many countries are exposed to environmental tobacco smoke which means that health effects resulting from this exposure are of great public health concern. Acute irritation of the eyes and airways as well as annoyance are probably the most common effects of passive smoking. Children with smoking parents run an increased risk of bronchitis and pneumonia. This seems to be related primarily to the smoking habits of the mother. Pulmonary function changes have also been reported in passive smokers but the data are not consistent. There are a few epidemiologic studies showing an increased risk of lung cancer in nonsmokers married to smokers. These studies may be affected with various types of biases and the association can not at present be regarded as causal. Particular attention should be put on the acquisition of precise and accurate exposure information in future epidemiologic investigations on health effects related to passive smoking.

Nicotine and cotinine concentrations in serum and urine of infants exposed via passive smoking or milk from smoking mothers

The exposure of infants to nicotine via milk of smoking mothers or via inhaled side-stream smoke ("passive smoking") was evaluated. Newborn infants nursed by smoking mothers and unexposed to passive smoking showed measurable serum concentrations of nicotine (0.2 to 1.6 ng/ml) and its main metabolite, cotinine (5 to 30 ng/ml), and also excreted measurable amounts of nicotine and cotinine in their urine: the ratio of nanograms of nicotine/milligrams of creatinine (N/C ratio) ranged from 5.0 to 110 (median 14), and the corresponding ratio of nanograms of cotinine/milligrams of creatinine (C/C ratio) from 10 to 555 (median 110). Infants of the same age nursed by nonsmoking mothers did not excrete measurable amounts of the two substances except in one case. Older and non-breast-fed infants exposed only to passive smoking had N/C ratios in the range of 4.7 to 218 (median 35) and C/C ratios in the range of 117 to 780 (median 327 ng/mg). Infants exposed to passive smoking and to smoke via breast milk had N/C ratios in the range of 3.0 to 42 (median 12) and C/C ratios in the range of 225 to 870 (median 550). The significant serum concentrations and urinary excretion rates of nicotine in the breast-fed infants of smoking mothers suggest that nursing contributes to the nicotine exposure of these neonates. In older infants, the wide variation of cotinine excretion values did not allow separate evaluation of the two exposure routes.

Passive exposure to tobacco smoke: saliva cotinine concentrations in a representative population sample of non-smoking schoolchildren

Saliva cotinine concentrations in 569 non-smoking schoolchildren were strongly related to the smoking habits of their parents. When neither parent smoked the mean concentration was 0.44 ng/ml, rising to 3.38 ng/ml when both parents were cigarette smokers. Mothers' smoking had a stronger influence than did fathers' (p less than 0.01). In addition, there was a small independent effect of number of siblings who smoked (p less than 0.01). The dose of nicotine received from fathers' smoking was estimated as equivalent to the active smoking of 30 cigarettes a year, that from mothers' smoking as equivalent to smoking 50 cigarettes a year, and that from both parents smoking as equivalent to smoking 80 cigarettes a year. This unsolicited burden may be prolonged throughout childhood and poses a definite risk to health.

Are active and passive smoking harmful? Determining causation

Assessing the evidence regarding any causal question involves examining the strength of the studies conducted and applying a series of "diagnostic tests" for causation. We have reviewed the strength of the evidence incriminating smoking as a cause of lung cancer, and passive smoking as a cause of respiratory illness and decreased pulmonary function in children. There are eight prospective studies of smoking and lung cancer which have consistently shown a strong relationship. These studies have confirmed the temporality of the association and demonstrated a dose-response gradient. The studies addressing the effects of passive smoking in children are considerably weaker. Although they are consistent in suggesting increased infections for children less than one year of age, neither increased risk nor a dose-response gradient is consistently found in older children and the effect size, when present, is small. The rules for assessing causation applied here can be used to integrate new information concerning the health hazards of smoking.

Passive smoking under controlled conditions

Ten healthy subjects were exposed to passive smoking at a high level corresponding to 25-30 ppm CO in the ambient air for 3 h. All subjects were exposed at the same time in a climatic chamber especially designed for exposure experiments. Despite an identical exposure rate considerable interindividual variability of subsequent nicotine and cotinine levels in saliva, plasma and 24-h urine were observed. This variability was more prominent in nicotine than in cotinine levels. The kinetic pattern as reflected by saliva levels for up to 24 h was consistent with previous data found in active smokers. Nicotine levels found in saliva were markedly influenced by repeated sampling. This was not the case for cotinine levels. With regard to laboratory techniques RIA seems to be more sensitive than gas chromatography (GC). The results of this study suggest that measuring cotinine levels in 24-h urine with RIA is presently the most sensitive and reliable criterion for estimating exposure to passive smoking and for validating questionnaires or interviews about short-term exposure to passive smoking.

Cumulative effects of lifetime passive smoking on cancer risk

Cancer risk from cumulative household exposure to cigarette smoke was evaluated in a case-control study. Overall cancer risk rose steadily and significantly with each additional household member who smoked over an individual's lifetime. Cancer risk was also greater for individuals with exposures during both childhood and adulthood than for individuals with exposures during only one period. These trends were observed for both smoking-related and other sites. These findings are preliminary and must be confirmed with other studies. Nonetheless, they suggest that effects of exposure to the cigarette smoking of others may be greater than has been previously suspected.