@brien
Your argument is nothing new.
Name Three - Second Hand Smoke Nannies Are Unable to Supply a Single Victim's Name Nobody's Business: Name Three Victims of Second-Hand Smoke
Valid points, but I found another answer.
The problem is in the Wiki link below. Second hand smoke doesn't necessarily cause cancer. But it can accelerate the already existing tendency for disease.
This is precisely what happened to my mother.
My grandmother has smoked for the past 60 years. Because of the nature of second-hand smoke, and because my mother helped her by doing her laundry for the past 10 years and otherwise being around her for the past 50, they think that it developed into Acute Lymphocytic Leukemia.
The trick with A.L.L. is that they don't know what causes it. 2nd Smoke is a
possible cause, but they don't know for sure.
In the end, with many cases they never really know. The cause of death is listed as the cause of death. But they never really get into what
caused the cause because they can't really know.
So to answer your question, and as evident in the links above and below, the problem is that it needs to be pursued as to what caused the cause. Not an easy thing.
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Second-hand smoke and you
The effects of second hand smoke. Fairly objective writing; not appealing to emotion or anything like that.
Passive smoking - Wikipedia, the free encyclopedia
Wiki's take on it. Notice that they don't say that 2nd Smoke causes problems so much as it accelerates the appearance of problems that were already there (genetic proclivity for certain diseases, etc.).
Secondhand Smoke Fact Sheet - American Lung Association site
Lots of "death" numbers there.
Take all the sources with as large a grain of salt as you choose, but at least there are some sources for you,
brien.