Tob Control：孕期应避免吸入任何形式的二手烟

　　迄今为止，通过对非吸烟孕妇尿中4 -（甲基亚硝胺）-1-（3-吡啶基）-1-丁醇（NNAL）和可替宁的浓度的研究评估，并没有表明不同来源的二手烟（SHS）导致4-（甲基亚硝胺）-1-（3-吡啶基）-1-丁酮（NNK）和尼古丁的吸收有所不同，同时已经戒烟与未戒烟孕妇相比也没有发现不同来源的二手烟造成的NNAL浓度有所差异。

　　希腊的一项研究纳入克里特岛的“瑞亚”母亲分娩队列的1317对母子，随访直至分娩，进行二次抽样，测量其中部分产妇的尿液，评估其NNAL浓度（n=117）和可替宁浓度（n=377）。

　　结果显示，怀孕期间继续吸烟的孕妇，尿中NNAL平均浓度为0.612 pmol/毫升，已经戒烟者为0.100 pmol/ ml，非吸烟但吸入二手烟者为0.0795pmol/ ml。暴露于家庭二手烟者尿中可替宁水平增加4.40ng/ml，而暴露于汽车中的二手烟者增幅甚至更高（8.73ng/ml），并且可替宁浓度增加与NNAL浓度有密切相关。在工作场所和公共场所吸入二手烟者，也显示可替宁和NNAL的浓度增加。 NNAL和可替宁之比在暴露于二手烟而本身不吸烟的孕妇中更高（P<0.001）。

　　可见，用可替宁水平作为评估怀孕期间暴露于二手烟摄入的NNK的一个指标，将会导致低估NNK的摄取量。此外，任何一个接触源均能导致可替宁水平的增加，说明避免吸入任何来源的二手烟的重要性。

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Exposure to different sources of second-hand smoke during pregnancy and its effect on urinary cotinine and tobacco-specific nitrosamine (NNAL) concentrations.
BACKGROUND
To date, no research exists on the role that different sources of exposure to second-hand smoke (SHS) have on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and nicotine uptake, assessed via urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and cotinine concentrations of non-smoking pregnant women, nor the differences in NNAL concentrations among pregnant women who quit smoking in comparison to those who do not.
METHODS
As part of the 'Rhea' mother childbirth cohort in Crete, Greece, 1317 mother-child pairs were followed-up until delivery, while among a subsample, maternal urine was assessed for its NNAL (n=117) and cotinine concentrations (n=377).
RESULTS
Pregnant women who continued to smoke during pregnancy were found to have geometric mean urinary NNAL concentrations of 0.612 pmol/ml, in comparison to the 0.100 pmol/ml of ex-smokers and 0.0795 pmol/ml of non-smokers exposed to SHS. Exposure to SHS in the home was associated with a 4.40 ng/ml increase in urinary cotinine levels, while reported exposure to SHS in cars was associated with an even higher (8.73 ng/ml) increase in cotinine concentrations and was strongly related to NNAL concentrations. Exposure to SHS in the workplace and in public places was also shown to increase cotinine and NNAL concentrations. The NNAL:cotinine ratio was found to be higher among pregnant women who were exposed to SHS but did not smoke (p<0.001).
CONCLUSIONS
Using cotinine levels as an indicator of NNK, exposure due to SHS during pregnancy leads to an underestimation of exposure to NNK uptake. Moreover, each source of exposure contributed to the increase in cotinine levels, indicating the importance of avoiding SHS exposure from any source.