美国加利福尼亚州圣迭戈大学的一个研究小组日前表示，脚趾甲可以成为诊断肺癌的先兆。
据悉，他们通过研究脚趾甲中尼古丁的含量发现，高尼古丁含量的人得肺癌的风险，比低含量的人高出三倍。
而令人震惊的是，在接受试验的人中，有些人脚趾甲中尼古丁含量高，却从未有吸烟的历史。专家称，这证明吸二手烟对人体的危害巨大。
人的脚趾甲每年只会增长一厘米，这一增长速度比手指甲要慢得多，因此，从脚趾甲中更能判断出是否受过尼古丁的侵害。
该研究小组曾花费了12年的时间用来跟踪记录850人的健康状况，他们发现脚趾甲中的尼古丁含量过高还会增加心脏病的发病率。
据世界卫生组织的统计，全球每年估计有120万以上的新发肺癌病例，死亡约110万人，平均每隔30秒就有人死于肺癌，而90%的肺癌是由吸烟引起的。（生物谷Bioon.com）
生物谷推荐原文出处：
Am. J. Epidemiol. (2011) doi: 10.1093/aje/kwq446
Toenail Nicotine Level as a Novel Biomarker for Lung Cancer Risk
Wael K. Al-Delaimy* and Walter C. Willett
Abstract
The objective of this US study was to assess the association of toenail nicotine level as a novel biomarker with lung cancer risk independent of reported smoking history. A nested case-control study of 210 male lung cancer cases and 630 matched controls aged 40–75 years participating in the Health Professionals Follow-up Study was conducted. Toenail samples collected in 1987 were analyzed for nicotine levels, and incident lung cancer cases were diagnosed between 1988 and 2000. Mean toenail nicotine level among cases was 0.95 ng/mg compared with 0.25 ng/mg among controls (P < 0.0001). In univariate analyses, the relative risk of lung cancer for the highest versus lowest quintiles of toenail nicotine level was 10.50 (95% confidence interval: 5.61, 19.64; P for trend < 0.0001). When the authors adjusted for pack-years from reported smoking history in multivariate analyses, the relative risk for toenail nicotine levels in the highest quintile was still significant in predicting lung cancer risk: 3.57 (95% confidence interval: 1.73, 7.37; P for trend < 0.0001). In conclusion, the toenail nicotine biomarker was found to be a strong predictor of lung cancer independent of smoking history, suggesting that the adverse effects of cigarette smoke may be underestimated in studies based on smoking history only.
