‘In retrospect, it is striking’, writes epidemiologist Geoffrey Kabat in Hyping Health Risks ,‘how disposed the public [in the USA] was to believe that some form of environmental pollution – whether chemicals in the soil and water, radionuclides from nuclear reactors, or magnetic fields from power lines, or something else – must be involved in the development of breast cancer’.
However, to the disappointment of environmental activists, intensive local investigations (notably in Long Island, New York) of exposures to organochlorine compounds (including DDT) and combustion products – the major focus of suspicion – showed no evidence of a link with breast cancer. While in relation to breast cancer such negative findings have largely been accepted, in other areas – such as the alleged links between electromagnetic fields and childhood cancer – the strength of popular conviction has led to the distortion and misrepresentation of scientific studies.
What Kabat characterises as a ‘deliberate willingness to be careless with data’ is most apparent in the controversy over passive smoking, where he identifies ‘a political strategy of hyping an unrealistic risk in order to gain public support for tobacco control policies’. Kabat was co-author, with James Enstrom, of a paper published in the British Medical Journal (BMJ) in 2003 under the provocative headline ‘Passive Smoking May Not Kill’. This paper reported the results of a large, 40-year-long, rigorously conducted study of the effects of ‘environmental tobacco smoke’. It revealed a marginally increased risk of coronary heart disease (and an even smaller effect on lung cancer). The increase in relative risk was slightly smaller than in numerous similar studies, but within the same range – the sort of increase that, given the margins of error of such studies, would generally be deemed too small to be considered of significance.
Yet, as Kabat observes, anti-smoking campaigners and public health authorities have routinely manipulated the results of such studies to justify increasingly coercive policies. He details their methods of selecting positive and neglecting negative studies, overstating the significance of results and ignoring weaknesses and inconsistencies. Their key calculation is based on multiplying marginal increases in relative risk by vast population numbers to construct an estimate of the annual mortality attributable to passive smoking. Headlines proclaiming that ‘passive smoking kills’ thousands every year then provide the banners for the anti-smoking crusade.
The Kabat and Enstrom paper, published at a moment when the campaign for bans on smoking in public places had reached a critical stage in the UK, provoked a torrent of condemnation and abuse, with – (unsubstantiated) allegations of corruption and fraud. A subsequent commentary on ‘the BMJ affair’ by two sociologists, entitled ‘Silencing Science’, was based on a study of the 144 ‘rapid responses’ received by the BMJ: