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The case
against passive smoke (environmental tobacco smoke or ETS) is mainly based on
statements that it causes lung cancer or cardiovascular disease in non-smokers.
This short analysis examines what is considered the strongest evidence, that on
lung cancer. What follows applies equally to the risk for cardiovascular disease
and for any other disease attributed to ETS, as the methodologies of the studies
are essentially the same.
The possible
risk of ETS for lung cancer could be determined if the frequency of lung cancer
is greater in non-smokers exposed to ETS. Because it is impossible to find
persons never exposed to ETS, the only real possibility is to observe if the
frequency of lung cancer is higher or lower in non-smokers that are more or less
exposed. A study would then require a reliable measurement of both the extent of
individual exposure and of the frequency of lung cancers in different groups of
non-smokers. Because there are many other proven risks for lung cancer, a study
also must find whether individual lung cancers in non-smokers might be linked to
other risks and not to ETS.
The following
analysis reveals that no study of ETS and lung cancer has met these simple
requirements, and therefore was not capable of determining risk.
1. Nonexistent
Measurements
- Because lung cancer is a disease that develops slowly and manifests itself for
the most part at an advanced age, the exposure to ETS needs to be measured over
the lifetime of non-smokers. This is what ETS studies claim to have done, even
though it could not have been a measure of exposure starting from any person’s
birth through the 60-70 years needed for lung cancer to develop, nor a backwards
reconstruction of a person’s exposure from old age to birth, both tasks being
obviously impossible.
So impossible,
in fact, that ETS exposure has never been measured at all. Instead of an
independently objective measure, 60-to-70-year-old non-smokers have been asked
to recall what their personal exposure to ETS might have been during
their lifetimes . Typically, such people were asked to recall how many
cigarettes, cigars or pipes had been smoked in their presence since early
childhood. Their reveries – elicited in a few minutes usually over the phone, or
even provided by proxy recalls of the relatives of deceased persons -- were
recorded by the studies as precise numbers devoid of error and
uncertainty.
It is well
known how difficult it is to remember what one ate one week ago, never mind 20
years ago or during childhood; how could it be possible to remember, with an
absurd expectation of precision, the total exposure to smoke over the 50-60
years of a prior lifetime? The only compelling conclusion is that
without dependable measures of exposures, the ETS studies produced statistical
estimates of risk that are illusory.
2. Fatal Flaws
-According to summaries conducted by groups that have an interest in finding
elevated risks for ETS, the average of all studies on lung cancer and passive
smoke published up to May 2006 (about 75) claims a risk elevation of some 20 per
cent. Such a relatively low elevation is not credible because the studies have
not accounted for a whole series of other known risks of lung cancer, and
prejudices and biases that are inevitably present. Here a few examples.
It is known
that people with lung cancer are more prone to amplify their recall of exposure
(recall bias) than those who are not so affected, and for obvious emotional
reasons. Another example is that some declare of being non-smokers without
saying they have been smokers, and therefore contaminate and bias the results
(misclassification bias). Yet another one: there are over 30 risk factors for
lung cancer reported in the professional literature – over 300 of them for
cardiovascular diseases – and their very likely interference in ETS studies has
never been credibly measured and corrected for. It is therefore exceedingly
probable that the small risk elevation of 20 per cent is fictitious
because of interferences that are not and cannot be calculated.
Singly or combined, these considerations are sufficient to explain the glaring
inconsistencies of different studies, and erase the credibility of the claimed
risk of ETS.
3. The Absurd
Methodology
- The overwhelming majority of ETS studies does not define risk on the necessary
basis of higher or lower frequency of cancer in function of higher or lower
exposures to ETS, as it should be done. Rather, self-declared non-smokers all
with lung cancer and exposed to ETS have been compared to self-declared
non-smokers without lung cancer, the latter also exposed to ETS because
it is impossible to find never exposed people. To illustrate, studies may
have found that non-smokers without lung cancer recalled ETS exposure at a 100
rate, while non-smokers with lung cancer recalled exposure at a 120 rate. With
an absurd logic, the studies presume that having remembered 20 per cent more
represents 20 per cent more risk!
Such
presumption also implies the equally absurd reasoning that a 20 per cent excess
exposure – which is impossible to verify or measure in the first place –
had been responsible for all the lung cancers of the
non-smokers with the disease, while non-smokers who remember only a little less
exposure remain totally immune from lung cancer.
Conclusion -
No
study of ETS and lung cancer has provided a credible and accurate measurement of
ETS exposure. The overwhelming majority of the studies has not measured
different frequencies of lung cancer in different groups. Lacking reliable
measurements, the statistical analyses of the studies are illusory. No study can
guarantee that some of the non-smokers studied were in fact smokers or had been
smokers. No study could exclude that the lung cancers observed might have been
caused by other risks and not by ETS. The overwhelming majority of studies
adopted improper and absurd methods of risk calculations. The majority of
studies did not report differences of risk, and many claimed a reduction of
risk.
Independently or combined, these considerations negate the credibility of
claimed ETS risk for lung cancer, and are equally applicable to ETS studies of
cardiovascular and other diseases.
The statement
of the US Surgeron General is based solely on the studies discussed
above. All smoking bans are also based solely on this body of evidence.
-- The FORCES
International Board Of Directors
For detailed
information, complete bibliography and full scientific reference material up to
May 2006 visit:
www.forces.org/passivesmokefraud.htm |
