A new method to evaluate nicotine exposure in infants

Abstract

Exposure of infants to parental smoking has been associated with several adverse health effects [6]. It was the aim of this study to find an easily applicable method to collect urine samples from infants and to correlate cotinine concentrations with parental smoking habits. This study was approved by the local Ethics Committee. Filter paper strips (Schleicher and Schuell, Germany) were placed in the nappies of infants. After wetting, the paper strips were air-dried, cut into small pieces, and extracted with 0.01 M phosphate buffer solution for 24 h. From this eluate, cotinine was analysed by ELISA and correlated to creatinine concentration (expressed as ng cotinine/mg creatinine, CCR). The parents’ smoking habits were evaluated by a structured questionnaire. CCR was determined in 93 infants (38 females) with a median age of 63 days (range 25–221 days). Exclusion criteria were questionnaires with incomplete information and urine creatinine levels 30 ng/mg, a cut-off level based on a previous study [2]. We found a significant correlation ( P <0.01) between maternal smoking habits and cotinine concentrations of infants (Table 1). This new method was used to avoid the inconvenience and higher failure rate of paediatric collection bags, especially in female infants [4]. A good correlation between urine collected on filter paper and native urine samples had been shown previously [5]. The method is inexpensive and therefore well suited for large series. By use of this technique, we confirmed the findings of previous reports describing a good correlation between the CCR of infants and maternal smoking habits, but not paternal smoking habits [1]. This is the first study to demonstrate this simple-touse, inexpensive way of verifying nicotine exposure in infants. The results of using filter paper strips are comparable to those using standard methods. Moreover, the method is easier to handle than any other used previously.