Robert A. Greenberg

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

The effect of parental smoking on the well-being of infants and children is an important public health concern. It is necessary, however, to validate the existence of such exposure objectively before an evaluation of the effects of parental smoking behavior on the childs health can be made. We measured the concentration of nicotine and its major metabolite, cotinine, in the saliva and urine of 32 infants with household exposure to tobacco smoke, and 19 unexposed infants. The concentrations were significantly higher in the exposed group than in the unexposed group, with the best indicator of chronic exposure being the urinary cotinine:creatinine ratio; median in the exposed group, 351 ng per milligram (225.3 nmol per millimole); median in the unexposed group, 4 ng per milligram (2.6 nmol per millimole) (P less than 0.0001). There was a direct relation between cotinine excretion by the infants and the self-reported smoking behavior of the mothers during the previous 24 hours (r = 0.67, P = 0.0001). Our results indicate that infants who were exposed to tobacco smoke absorbed its constituents and that urinary excretion of cotinine is a reliable measure of such exposure in infants.

Evaluation of a home-based intervention program to reduce infant passive smoking and lower respiratory illness

We conducted a randomized controlled trial to determine whether a home-based intervention program could reduce infant passive smoking and lower respiratory illness. The intervention consisted of four nurse home visits during the first 6 months of life, designed to assist families to reduce the infants exposure to tobacco smoke. Among the 121 infants of smoking mothers who completed the study, there was a significant difference in trend over the year between the intervention and the control groups in the amount of exposure to tobacco smoke; infants in the intervention group were exposed to 5.9 fewer cigarettes per day at 12 months. There was no group difference in infant urine cotinine excretion. The prevalence of persistent lower respiratory symptoms was lower among intervention-group infants of smoking mothers whose head of household had no education beyond high school: intervention group, 14.6%; and controls, 34.0%.

Lower respiratory illness in infants and low socioeconomic status.

OBJECTIVESnInfants from families of low socioeconomic status are said to suffer higher rates of lower respiratory illness, but this assertion has not been carefully examined.nnnMETHODSnWe studied the frequency and determinants of lower respiratory illness in infants of different socioeconomic status (n = 393) by analyzing data from a community-based cohort study of respiratory illness during the first year of life in central North Carolina.nnnRESULTSnThe incidence of lower respiratory illness was 1.41 in the low socioeconomic group, 1.26 in the middle group, and 0.67 in the high group. The prevalence of persistent respiratory symptoms was 39% in infants in the low socioeconomic group, 24% in infants in the middle group, and 14% in infants in the high group. The odds of persistent respiratory symptoms in infants of low and middle socioeconomic status were reduced after controlling for environmental risk factors for lower respiratory illness. Enrollment in day care was associated with an increased risk of persistent symptoms among infants of high but not low socioeconomic status.nnnCONCLUSIONSnInfants of low socioeconomic status are at increased risk of persistent respiratory symptoms. This risk can be partly attributed to environmental exposures, most of which could be changed.

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 infants 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 mothers smoking behavior, smoke produced anywhere in the home, and household social influences on smoking behavior near the infant.

Passive smoking during the first year of life.

BACKGROUND AND PURPOSEnA description of passive smoking during the first year of life might assist planning preventive efforts.nnnMETHODSnChanges in the ecology of passive smoking were investigated in a sample of infants in central North Carolina followed from birth to one year of age.nnnRESULTSnThe prevalence of tobacco smoke absorption, indicated by excretion of cotinine, increased from 53 percent to 77 percent (95% CI of difference: 14, 35) during the first year of life. Most infants (92 percent) excreting cotinine at three weeks of age were also excreting it at one year. Moreover, 61 percent of infants not excreting cotinine at age three weeks were excreting it at one year. This increase reflected an increased exposure to household and, particularly, nonhousehold sources of smoke; the proportion of infants exposed to nonhousehold smokers increased from 14 percent to 36 percent.nnnCONCLUSIONSnThese findings suggest that prevention of the onset of passive smoking should begin very early.

Influence of training and experience on selecting criteria to evaluate medical care

To determine whether training and experience affect the selection of process criteria for evaluating medical care, three groups of physicians (family physicians, general pediatricians, and pediatricians specializing in infectious disease) were sent a questionnaire asking their opinions about various clinical actions in 125 clinical situations concerning respiratory infections in infants. Five hundred and twenty-four (54 per cent) physicians returned completed questionnaires. The three groups agreed in 93 (74 per cent) situations, especially about history taking, physical examination, and follow-up observation. Disagreements occurred most often regarding antibiotic use. Of the three groups, the family physicians selected the most extensive list of recommended actions including the greatest number of indications for antibiotics. The general pediatricians selected the fewest situations requiring history taking, physical examination and diagnostic tests. The infectious-disease pediatricians felt the greatest necessity to record history and physical-examination items but were the most restrictive in recommending antibiotics and other drugs.

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.

The constancy of parent-offspring similarity of total cholesterol throughout childhood and early adult life: The Lipid Research Clinics Program Prevalence Study

In a cross-sectional study of 11,409 white parent-offspring pairs in five North American populations we examined the effect of age of the offspring on parent-offspring total cholesterol correlations. In general there were no differences in correlations by age of the offspring for the four types (by gender) of parent-offspring pairs. This was true within each of the five populations and for the average of all populations combined. For offspring from less than 2-29 years of age, these average age-specific correlations ranged from 0.17 to 0.42. Despite the considerable physiologic and environmental changes which influence cholesterol levels from birth to early adulthood, the strength of parent-offspring similarity shows no consistent pattern of change.