PASSIVE SMOKING AS A DETERMINANT OF BRONCHIAL RESPONSIVENESS IN CHILDREN

The effect of passive smoking on the degree of nonspecific bronchial r esponsiveness (BR) in children was evaluated. In a cross-sectional sur vey of primary school children (7 to 11 yr) in Latium (Italy), a total of 1,215 methacholine challenge tests was performed. The children wer e divided into nonresponders (PC20 FEV(1) > 64 mg/ml) and responders ( PC20 FEV(1) less than or equal to 64 mg/ml), the latter including a su bgroup of strong responders (PC20 FEV(1) less than or equal to 4.0 mg/ ml). The role of passive smoking exposure was analyzed through logisti c regression models. Higher odds ratios were found among girls (for st rong responders: maternal smoking, OR 2.92; paternal smoking, OR 2.59) ; moreover, among girls there was a dose-response relationship with th e number of cigarettes smoked by the mother. An effect modification wa s also detected for father's education and household crowding: materna l and paternal smoking were strong predictors of bronchial hyperrespon siveness in families in which the head was less educated and in overcr owded houses. The results were confirmed using a continuous index of B R (slope) and after adjustment for baseline airway caliber. We suggest that the effect of parental smoking on children's bronchial responsiv eness is detectable when the conditions for a higher exposure level at home are met; females seem to be more susceptible.