Joo Hyunjoo, Lim Myung-Ho, Ha Mina, Kwon Ho-Jang, Yoo Seung Jin, Choi Kyung-Hwa, Paik Ki-Chung
Department of Public Health, Graduate School of Dankook University, Cheonan, Chungnam, Republic of Korea.
Department of Psychology, Dankook University College of Public Service, Cheonan, Republic of Korea.
Nicotine Tob Res. 2017 Jan;19(1):94-101. doi: 10.1093/ntr/ntw152. Epub 2016 Jul 7.
Secondhand smoke (SHS) is a major indoor pollutant. We examined the possible association between exposure to both SHS and low levels of lead and attention-deficit-hyperactivity disorder (ADHD) and its symptom domain in children.
This case-control study was based on the results of a community survey using the ADHD rating scale conducted in 49 elementary schools. Both cases and control subjects were confirmed by a child psychiatrist. Each case was matched with one control subject according to gender, school, and grade in school. Using a multivariate conditional logistic regression model, we analyzed 214 case-control pairs of children who ranged in age from 6 to 10 years. Urine and blood levels of cotinine and of lead were determined, and information pertaining to SHS exposure was obtained by means of a questionnaire.
Exposure to low levels of lead (geometric mean = 1.65 µg/dL) was related to ADHD, particularly inattention (odds ratio [OR] = 1.67, 95% confidence interval [CI] = 1.07-2.59), whereas SHS exposure was associated mainly with hyperactivity/impulsivity (OR = 3.85, 95% CI = 1.55-9.56). In the pathway from blood lead to hyperactivity/impulsivity, children's SHS exposure mediated and indirectly accounted for about 73% of this relationship. The combined exposure to lead and SHS synergistically increased the risk of ADHD, evident as both inattention and hyperactivity/impulsivity.
SHS, which is associated with hyperactivity/impulsivity in particular, combined with exposure to low blood levels of lead synergistically increased the risk of ADHD. Therefore, the exposure of children to both SHS and lead needs to be reduced.
Although exposure to low levels of lead has been shown to be associated with ADHD, there is little evidence of symptom domain specificity. In our study, low blood lead levels were related to inattention. In addition, prenatal or postnatal exposure to SHS increased the risk of ADHD, particularly hyperactivity/impulsivity. Combined exposure to lead and SHS synergistically increased the risk for both these ADHD symptom domains. To protect children from environmental risk factors related to ADHD, it is necessary to further reduce children's exposure to SHS and lead, even in those with low blood lead levels.
二手烟（SHS）是一种主要的室内污染物。我们研究了儿童接触二手烟和低水平铅与注意力缺陷多动障碍（ADHD）及其症状领域之间的可能关联。
本病例对照研究基于在49所小学进行的一项使用ADHD评定量表的社区调查结果。病例和对照均由儿童精神科医生确诊。每个病例根据性别、学校和年级与一名对照进行匹配。我们使用多变量条件逻辑回归模型分析了214对年龄在6至10岁之间的儿童病例对照。测定了可替宁和铅的尿液及血液水平，并通过问卷获取了与二手烟暴露相关的信息。
接触低水平铅（几何平均数 = 1.65 µg/dL）与ADHD有关，尤其是注意力不集中（比值比[OR] = 1.67，95%置信区间[CI] = 1.07 - 2.59），而二手烟暴露主要与多动/冲动有关（OR = 3.85，95% CI = 1.55 - 9.56）。在从血铅到多动/冲动的路径中，儿童的二手烟暴露介导并间接解释了这种关系的约73%。铅和二手烟的联合暴露协同增加了ADHD的风险，表现为注意力不集中和多动/冲动。
二手烟尤其与多动/冲动有关，与低血铅水平的暴露相结合，协同增加了ADHD的风险。因此，需要减少儿童对二手烟和铅的暴露。
尽管已表明接触低水平铅与ADHD有关，但几乎没有症状领域特异性的证据。在我们的研究中，低血铅水平与注意力不集中有关。此外，产前或产后接触二手烟增加了ADHD的风险，尤其是多动/冲动。铅和二手烟的联合暴露协同增加了这两个ADHD症状领域的风险。为保护儿童免受与ADHD相关的环境危险因素影响，有必要进一步减少儿童对二手烟和铅的暴露，即使是那些血铅水平低的儿童。
