Number 1. You cannot prove a negative.
Number 2. As for your five sites.
The first is the debunked EPA study. The federal courts already threw that one out.
The second site - It cites Stanton Glantz, one of the foremost anti-smokers and cites the debunked EPA study.
The third site - It cites no studies and if you look at the sentence, "Infants in the study will be followed for years to see if those exposed to the chemicals have a higher incidence of cancer than nonsmokers' babies.
The fourth site - Look at the next two sentences and tell me when you see the lie
DR. ICHIRO KAWACHI: Yes. In fact, they answered the question about passive smoking at the beginning of the study in 1982, and their exposure status was self-reported.
DR. ICHIRO KAWACHI: Basically, we took advantage of a 20-year-long ongoing study of women, and about halfway through the study, we sent out a questionnaire asking them whether they were exposed to passive smoking in the home and in the workplace, and then we just sat and waited and saw what happened to them in terms of their heart attack rates.
so we're saying that virtually everything that we know active smoking does to the circulatory system probably the same thing is happening to the bodies of people who inhale second-hand smoke.
We weren't able to precisely estimate just how much of a dose and how long one would have to be exposed to in order to get into increased--situations of increased risk, such as we observed.
The fifth site - Approximately 2 percent of lung cancer deaths each year are thought to be caused by passive smoking.
Now then, when you find scientific proof, that hasn't been debunked, we can talk about the antis having a point.