HomeMy WebLinkAboutCOM 0746.041 2000-2002
http://www.davchi~t.corn/facis/who.htinl
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The World Health Organization's study is a textbook example of the right way to Y
conduct an epidemiological study. Unfortunately for them, it yielded unexpected
results.
Fact: The World Health Organization conducted a study of Environmental Tobacco
Smoke (ETS) and lung cancer in Europe.
Fact: ETS is commonly referred to as Second Hand Smoke (SHS). The two terms are
interchangeable.
Fact: This was a case control study using a large sample size.
Fact: The purpose of the study was to provide a rraore precise estimate of risk, to
discover any differences between different sources of ETS, and the effect of ETS
exposure on different types of lung cancer.
Fact: The steady was conducted from twelve centers in seven European countries over
a period of seven years.
Fact: The participants consisted of 650 patients with lung cancer and 1542 control
subjects. latients with smoking related daseases were excluded from the control
group. None of the subjects in either group had smoked more than 400 cigarettes in
their lafetime.
Fact: Three of the study centers interviewed family members of the participants to
confiirffi the subjects were not smokers.
Fact: The study found no statistically significant risk existed for non-smokers who
either lived or worked with smokers.
Fact: The only statistically significant number was a decrease in the risk of lung
cancer among the children of sflnokers.
Fact: The study foa~gad a relative Risk (liY~) for spousal exposure of 1.16, with ~
Confidence Interval (CY) of 93 - 1.44. In layffian's terflns, that means
• Exposure to the ETS from a spouse increases the risk of getting lung cancer by
16®/®.
• Where you'd norrraally find 100 cases of lung cancer, you'd find 116.
Fact: A of less than 2.0 is usually written off as an insigrrificant result, most likely
to be due to error or bias. An 1~R of 3.0 or higher is considered desirable. (See
E~r.'den~iolo~!
10.1 for more details.)
Fact: Since the CI includes 1.0, the 1~ is just as likely to be 1.0 as it is to be 1 a ~o
, ,
(Submitted by Steven Araujo) 1~ ~
any other number within the range of the CI.
Fact: The study found no Dose/I~esponse relationship for spousal ETS exposure. See
Epidemiology_ 102 for more information.
Fact: The I~1Z for workplace ETS was 1.17 with a CI of .94 - 1.45, well below the
preferred 2.0 - 3.0, and with another CI that straddled 1.0.
Fact: The RIt for exposure from both a smoking spouse and a smoky workplace was
1.14, with a CI of .88 - 1.47.
Fact: The RIt for exposure during childhood was 0.78, with a CI of .64 - .96. This
indicates a protective effect! Children exposed to ETS in the home during childhood
are 22®/0 less likely to get lung cancer, according to this study. Note that this was the
only result in the study that did not include 1.0 in the CI.
The WII® quickly buried the report. The British press got wind of it and hounded
them. for weeks.
Fact: ®n IVlarch 8, 1998, the British newspaper The Telegraph re rted "The world`s
leading health organization has withheld frorri publication a study which shows that
not only might there be no link between passive smoking and lung cancer but that it
could have even a protective effect."
Finally, the WI-IC issued a press release. Although their study showed no statistically
significant risk from ETS, their press release had the misleading h ' e °'Passive
Smoking Does Cause Lung Cancer - I?o Not Let Them Fool Yoai." (I say
"misleading" because it w®uld be impolite to call Yt an Outright lie.)
Fact: In paragraph four they admitted the facts: '°The study found that there was an
estirriated 16% increased risk of lung cancer among nonsmoking spouses of smokers.
For workplace exposure the estimated increase in risk was 17®/0. I~owever, due to
small sample size, neither increased risk ~vcrs statistically signiftccrnt." (Emphasis
added.)
Fact: The press release doesn't mention the one statistically signif cant result from the
study, that children raised by smokers were 22% less likely to get tong cancer.
Fact: The WII~ tried to blame the results on a small sample size. however, the in the
Journal of the National Cancer Institute, where the results were published, the
researchers cleanly state: "An iiriportant aspect of our study in relation to previous
studies is its size, which allowed us to obtain risk estimates with good statistical
precision..."
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An abstract of the study is available here.
The WHO's press release is located here.
This article, from the British Wall Street Journal, discusses this study and the EPA
study.
FORCES has lots of links to articles and editorials on this subject.
~ 2000 - 2001 Dave 1°iitt
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