# Passive Smoking

I do not want to write about whether smoking increases the risk of lung cancer. My topic is how the wealth of cigarette companies is increased by the actions of anti-smoking campaigners, bans on advertising, the WHO and the IMF.

However, when evaluating what I write one has to also take a view about the health damage caused by cigarette smoke. This does underlie the justification for governments to ban smoking etc. Even for the WHO to interfere in the economic policies of countries.

The basis for discussion of the health effects of cigarette smoking has two foundations:

  1. The effect on the smoker,
  2. The effect on the people around the smokers (passive smoking).

There is little debate that smoking increases the chances of a smoker getting lung cancer.

However, there is also little debate about the risks of passive smoking – yet the evidence for this is not as strong as most people would believe. Even I was surprised when I read Christopher Snowdon’s book Velvet Glove, Iron Fist.

Snowdon is an investigative journalist and his books about smoking really comes across as being unbiased and very factual.

In his book he gives a summary of all the scientific studies done about passive smoking – also as a downloadable file on his blog.

Below I just quote some paragraphs from this blog:

Takeshi Hirayama conducted the first epidemiological research into passive smoking by monitoring the health of nonsmoking women married to smoking husbands and this model remains the gold standard for research of this kind. In the 25 years since Hirayama’s paper was published (1981), a further 62 similar reports have been published. Taken together they form a substantial body of evidence which, according to one Surgeon General, is ‘overwhelming’ in supporting the hypothesis that nonsmokers exposed to secondhand smoke are more likely to suffer from lung cancer than those who generally avoid exposure. After reading all of these studies,, I have not been able to endorse this interpretation.

There are only three possible outcomes in studies of this kind. The first is that the hypothesis is correct (ie. that passive exposure to tobacco smoke increases lung cancer risk). The second possibility is that there is a negative association (ie. that passive smoking reduces the risk of lung cancer). The third possibility is that there is no association either way; this is known as the ‘null hypothesis’.

A relative risk (RR) of 1.0 represents no association either way. An RR below 1.0 represents a negative association and an RR above 1.0 represents a positive association (increased risk). For example, 0.9 = 10% less risk, 1.35 = 35% greater risk and 2.0 = 100% greater risk.”

“Of the epidemiological papers that studied the effect of secondhand smoke on nonsmoking wives, 9 found a statistically significant positive association, 2 found a statistically significant negative association and the remaining 52 found no statistically significant association either way. Some within the tobacco control movement have claimed that the risk from passive smoking is too small to be demonstrated conclusively in small and medium sized studies. Only very large studies, they say, have the statistical power to meet the criteria for significance but these studies are difficult to carry out thanks, in part, to the relative scarcity of lung cancer patients who have never smoked. There is some truth in this, although it is worth pointing to the 11 findings here that have achieved statistical significance.”

“There is a natural tendency for epidemiologists to want to show a positive result if only because null studies are of little interest and are less likely to be published. This tendency is particularly strong when the issue relates to secondhand smoke and when the researcher has a personal bias. From the very outset, there was a hope and expectation that passive smoking was indeed linked to lung cancer in nonsmokers. This prevailing bias has led to studies being written up in such a way that emphasised the results that supported the passive smoking theory and ignored the vast majority that did not.”

“What follows is every peer-reviewed study of nonsmoking wives ever published with the editorialising stripped away to reveal the data in its pure form. Doctoral theses and dissertations are not included unless they have subsequently been published in a book or scientific journal. When results have been published more than once (eg. Hirayama, Fontham), the most recent version has been reviewed. Where confounding factors have been accounted for, the adjusted odds ratios have been used.

The studies are listed in descending order of size, with the studies with the largest sample group listed first. The order of the studies is important since those with the largest sample group are likely to offer the most accurate results. The reader will notice that the higher relative risks appear towards the bottom, where the smallest and least reliable studies lie. If one examines the results from the ten largest studies it is very difficult to view them as anything other than a random assortment of numbers hovering either side of 1.0. In order, they appear: 1.29, 1.11, 0.70, 1.03, 1.53, 1.10, 0.89, 1.10, 0.90 and 0.96. Between them, they give an average relative risk of 1.06 which is so close to a zero risk that if it were not so political, the issue of passive smoking would have been quietly shelved years ago. The smaller studies lift the average slightly higher – as the EPA found to their benefit – but some of these involve just 8 or 9 women and, with apologies to their authors, they are meaningless.”

 

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