In article , Betsy -0 wrote:
Kindly cite that study about second hand smoke.

No problem.

Enstron, JE, Kabat, GC. Environmental tobacco smoke and tobacco related
mortality in a prospective study of Californians, 1960-98. BMJ. 2003
May 17;326(7398):1057.

It is a study of 35,561 never-smokers with a smoking spouse.

The full text can be found online through pubmed, or directly from
BMJ:

http://bmj.com/cgi/content/full/326/7398/1057




And, please cite all the studies that contradict it.


Read the many comments that the BMJ put online. I will
quote from two.

Perhaps the best was an editorial in the Canadian Medical Association
Journal, which addresses the general habit of obsessing about extremely
small risk factors:


_______ Polemic and public health, CMAJ 169 (3): 181 (2003)


(begin excerpt)

[snip]

The problem with the data on passive smoking (and many other potential
environmental hazards) is that the estimated risks are so close to
zero. The study published in BMJ showed that the risks of heart
disease, lung cancer and chronic obstructive pulmonary disease among
never-smokers living with a smoker compared to never-smokers living
with a nonsmoker were 0.94 (95% confidence interval [CI] 0.85?1.05),
0.75 (95% CI 0.42?1.35) and 1.27 (95% CI 0.78?2.08) respectively, all
statistically insignificant and none very large.

Fifty-three years ago BMJ published research by Doll and Hill on 649
men who had lung cancer and compared their smoking habits with a group
of 649 comparable men who did not have lung cancer.3 The risk (odds
ratio) of lung cancer among smokers compared to nonsmokers was 14.0,
meaning that smokers were 14 times more likely to develop lung cancer
than nonsmokers.

This result is interesting for 3 reasons. First, it is instructive that
this huge increase in risk was not apparent from casual observation:
because most men smoked, the effects of this behaviour were inapparent.
Second, although even these astonishingly high risks were disputed,
this study (and others that followed) marked the start of a long but
steady decline in smoking among men, followed decades later by a
decline in deaths from lung cancer. Third, from the perspective of
almost all current research on environmental hazards, in which odds
ratios of 1.2 (or an increase of risk of 20%) are considered sufficient
to prompt action by public health advocates (or social hygienists?),
perhaps we should ask if we are sometimes overzealous in our attempts
to publicize and regulate small hazards.

It is impossible to control completely for confounding variables in
observational studies. The smaller the risk estimate, the greater the
chance that confounding factors will distort it and invalidate it. This
is not to say that observational studies should be abandoned. Faced
with the results of the recent study we can, as individuals, elect to
change our behaviours and possibly our risk exposures. But, when
interpreting the results and then championing public policy and
legislation to regulate exposure, we must be doubly wary of tailoring
statistics to fit the current fashion. We must be open with our doubts,
honest in our interpretations and cautious in our recommendations.
Exaggerated claims of risk will only erode the credibility and
effectiveness of public health.


(end excerpt)



The second provides an off-the-cuff metanalysis:

Gian L. Turci "What killer? Let's call things with their name."
BMJ Rapid Responses, 19 May 2003

http://bmj.com/cgi/eletters/326/7398/1057#32320


The situation on passive smoke is quite simple. The heterogeneity of
the studies militates against a formal meta-analysis, and the general
and admitted weakness of results rather favors a simple eyeball
appraisal. Out of a total of 123 studies (excluding this last one) 16
have shown a risk elevation for cancer, 30 have shown a benefit from
exposure, all the rest failed to demonstrate either way. Out of the 16
studies mentioned above, NONE showed an elevation of risk greater than
20 percent. We all know that in this kind of epidemiology, it takes an
odds ratio elevation of 200% or more just to demonstrate that a
correlation EXISTS.

The US National Cancer Institute affirms that "Relative risks of less
than 2 are considered small and are usually difficult to interpret.
Such increases may be due to chance, statistical bias, or the effect of
confounding factors [other causes] that are sometimes not evident"- and
this is just an example.

Thus, the 16 studies could not even demonstrate unequivocally the
existence of a correlation. The evidence for other diseases attributed
to passive smoking is even weaker. What killer? Propaganda and
instigation of hysteria (whether done by public institutions or
otherwise) do not constitute proof or evidence -- unless, of course, we
want to tell the truth and use the real names: intolerance and
prohibitionism; but please do not call it scientific demonstration, for
that insults science and intelligence!


billo