Passive smoking in infants, children and adolescents. The effects of diet and socioeconomic factors

OBJECTIVES: Many studies have associated environmental tobacco smoke (ETS) exposure with an increased risk for various diseases in infants and children, and although superficially the evidence is compelling, on closer scrutiny socioeconomic factors, especially diet, could have a greater contributory effect. An analysis of this evidence was made. RESULTS: Studies which have correlated smoking during pregnancy with low birth weight have considered weight gain and cholesterol levels as a measure of nutrition in the mother, but not the micronutrient content of the diet to which low birth weights could be due. Several authors have attributed ETS exposure to the presence of abnormal lipid profiles in children and adolescents, without considering the diet of the latter, and the abnormal lipids have been linked to a subsequent increased risk for atherosclerosis. The evidence linking lower respiratory infections and bronchitis with passive smoking is strong, although it seems likely that the diet of the mother during pregnancy or breast feeding is equally important. Similarly, increased risks for asthma, otitis media and sudden infant death syndrome have been attributed to the effects of passive smoking, without adequate allowance for confounding by other socioeconomic factors. CONCLUSION: After consideration of the accumulated evidence, it seems improbable that the small exposure could produce all of the effects claimed.