记载这事的文件名字是WARNING:SMOKING CAUSES MALE SEXUAL IMPOTENCE ，这个里面指出尼古丁会引起阳痿的原因。
还说US men 年龄between 20 and 39 的人每13个里面有一个impotent。
http://www.ash.org.uk/files/documents/ASH_193.pdf

The British Medical Association在2004年的报告里提出在英国有超过120000年龄在30–50 years的男性的性功能障碍是由吸烟引起的，而且认为这个数字比实际偏低。吸烟的男性在三四十岁的时候，患性功能障碍 的风险会增加50%。
http://www.bma.org.uk/images/smoking_tcm41-21289.pdf

Tulane大学的研究人员调查4,764 Chinese men -- average age 47，发现：

1、Men who smoked more than 20 cigarettes daily had a 60% higher risk of erectile dysfunction, compared to men who never smoked.

2、15% of the past and present smokers had experienced erectile dysfunction.

3、Men who currently - and formerly -- smoked were about 30% more likely to suffer from impotence.

4、Among men who had never smoked, 12% had erection problems.
http://www.webmd.com/erectile-dysfunction/news/20030307/smoking-can-lead-to-erectile-dysfunction

香港大学的研究人员通过在香港的研究验证了British Medical Association的50%的数据。
http://www.nature.com/ijir/journal/v18/n4/full/3901436a.html