 | | | | |  | An antidote to panics based on dodgy statistics and dubious arguments.
Edited by Rob Lyons. |  | | |  |  |
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| | | 21 May 2004 | Return of the mad cow
Panic: 'Thousands carrying hidden CJD timebomb', says The Times (London), reporting a new study conducted by Plymouth's Derriford Hospital and the UK CJD Surveillance Unit into infection rates for variant-Creuzfeldt-Jakob disease (vCJD). Researchers tested 12,674 appendix and tonsil samples. Three were found to contain prion proteins that could lead to the development of vCJD, often called the human form of mad cow disease. Although this is a tiny percentage, extrapolated over the whole country it could mean that 3,800 people are infected. David Hilton, the lead researcher, told the BBC, 'Our findings need to be interpreted with caution, but cannot be discounted.' Reports of the study's findings have raised new fears about the possibility of passing on the infection through blood transfusions and contaminated surgical instruments.
Don't panic: Making this a major news story on television and in the press hardly constitutes 'caution' - but does reflect the lack of reality that has been associated with the mad cow panic.
It is almost impossible to draw any conclusion from these results because the number of positive results is tiny. If this study were repeated on another 12,674 samples, it is highly likely that a different number would come out. On top of this, a number of logical steps need to be taken to conclude that thousands are at risk. Firstly, it would need to be established that these positive tests really do represent vCJD, rather than some other prion protein that causes no harm. Secondly, even if these are vCJD samples, there is no way of knowing how many people would actually develop the disease. A genetic predisposition to develop vCJD may be required.
Even if these reports are accurate, the idea that 0.02 per cent of the population might, over a period of decades, develop this nasty condition suggests there are many more pressing problems that face us. To date, there have been 141 deaths from vCJD in roughly ten years - a far cry from the 'epidemic' of hundreds of thousands that was talked about in the past. Previous research has suggested that around 540 people may die in total from the condition.
This might not matter as a passing news story, except that the effect is to increase the anxiety of patients going into hospital for treatment for real, existing health problems. For one thing, there are likely to be even greater controls on blood stocks. For another, there have been calls to look again at using disposable surgical instruments - despite the fact that these have been withdrawn as unsafe. It's not just the cows that are mad.
Read: |  | Thousands may be harbouring vCJD, | | BBC News, 21 May 2004 |
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| | | 18 May 2004 | Passive smoking and pregnancy
Panic: Researchers in the USA and China claim to have discovered a link between passive smoking and miscarriage. Their report, published in the American Journal of Epidemiology, suggests that the chance of early pregnancy miscarriage for women married to heavy smokers is significantly greater than for women married to non-smokers. The researchers believe that smoking may affect both the quality of the husband's sperm and the balance of hormones in the woman's body. Professor Alison Murdoch, president of the British Fertility Society, told BBC News: 'Everyone in a household where there is going to be a baby should stop smoking.'
Don't panic: There are some problems with this study. The first is that many pregnancies end early, often before women are even aware that they are pregnant. This study merely suggests it is a matter of degree: women with non-smoking husbands suffered pregnancy loss in 30 per cent of cases; for women with husbands who were moderate smokers the figure was 32 per cent, and for women with heavy smoking husbands it was 41 per cent. However, the numbers for the heavy smokers were skewed by a very small number of women (five) who suffered pregnancy losses on three occasions during the course of the study.
The study made no attempt to measure how much actual exposure women had to smoke. The only measure was the husband's statement of smoking habits at the start of the study - so whether the husband's smoking levels increased, decreased or stayed the same during the study is unknown. Nor do we know how often these husbands smoked in the company of their wives.
The biggest problem with the study is the naive acceptance that all these non-smoking women really are non-smokers. The report notes that in China 70 per cent of men say they smoke, compared with only four per cent of women. Clearly smoking must be rather unfashionable, or possibly frowned-upon, for Chinese women. It is hard to believe that at least some of these women do not light up from time to time; and the wives of heavy smokers may be more likely to smoke on the sly than those whose husbands do not smoke at all.
This tendency among some pregnant women to avoid admitting that they smoke can be glimpsed in a new initiative in Glasgow (previously criticised on spiked), which will test pregnant women who claim to be non-smokers as it is known that some do not disclose their smoking habits to health workers. Is China really so different?
The authors of the report admit that 'results of investigations of increased risk due to maternal exposure to passive smoke have been inconsistent'. The study does not offer much clarification on the subject of passive smoking and pregnancy. But you would never guess that there was such weak evidence from the bald comments made by some health campaigners.
Read: | | Paternal smoking and pregnancy loss, | | American Journal of Epidemiology, 2004; 159:993-1001 | | Passive smoke link to miscarriage, | | BBC News, 12 May 2004 |
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| | | 11 May 2004 | No fun in the sun
Panic: 'Over a third of parents admit sunburn slip despite warnings.' So declared Cancer Research UK on 9 May 2004, as it published a survey suggesting that, while most parents know that children should be protected from sunburn, many of them do not take the necessary precautions. Also, most parents are unaware how quickly children can start to burn, and 41 per cent think that it is desirable for children to have a tan. According to Cancer Research's press release, 'Children's skin is much more delicate than adults' and research shows that sunburn in childhood can double the risk of getting skin cancer later in life'.
Don't panic: Avoiding sunburn is a good idea for both adults and children, not least because it hurts. But it is doubtful whether avoiding the sun improves life expectancy.
The most common forms of skin cancer (basal-cell or squamous-cell carcinomas) are clearly related to sun exposure. But they are also highly treatable and rarely serious, as the Cancer Research website confirms. The relationship between malignant melanomas, which are far more serious, and sunlight is less clear. For example, melanomas tend to appear on areas of the body that are less likely to be exposed to the sun. Rates for melanoma in Japan are comparable to those in the UK, even though there is no tradition of sunbathing in Japan.
Claims of parental neglect possibly leading to the early death of their offspring are greatly exaggerated. Melanomas in the young are rare. In the case of malignant melanomas, 88 per cent of deaths in England and Wales in 2002 were in patients over 45. So if there is a link at all, it is unlikely to affect people until later in life.
What is striking is how one panic contradicts another, to the extent that it seems there is no safe course of action. Apparently if our children play in the sun they run the risk of skin cancer or abduction - but apparently if they stay indoors, watching TV or playing computer games, they can look forward to becoming obese victims of heart disease or diabetes. There is even evidence to suggest that some exposure to sunshine may be valuable in helping to counteract cancer.
The fact is that health campaigns, for the most part, have been unsuccessful in changing adult behaviour - though they have succeeded in increasing anxiety levels. So now health campaigners seem to be upping the ante, along the lines of, 'If you tolerate this, your children will be next'. Parents would be best advised to use their own judgement and ignore such scaremongering.
Read: | | Children 'at risk of skin cancer', | | BBC News, 9 May 2004 | | Don't panic: Getting burned | | Enjoy your moment in the sun, by Mick Hume | | The Times (London), 28 July 2003 | | Vitamin D may have preventive properties against cancer, | | The Scientist, 24 August 2000 |
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| | | 27 April 2004 | New scares over SARS
Panic: Severe acute respiratory syndrome (SARS), a viral chest infection that resulted in 774 deaths worldwide between November 2002 and July 2003, has hit the headlines again, with a new outbreak in China. There have been six new suspected cases of SARS in Beijing, and two cases (one of which has resulted in death) in the eastern province of Anhui. Two of these eight suspected cases are researchers at China's leading virus laboratory, the National Institute of Virology in Beijing, where the SARS virus is being studied. It is thought that this latest outbreak can be traced back to the laboratory, and there are rumours of a safety breach.
One of the laboratory researchers thought to have contracted SARS travelled by train between Beijing and Anhui, prior to being diagnosed with the disease, and it is feared that she exposed many fellow travellers to the virus. Now over 600 residents of Beijing and over 300 residents of Anhui have been quarantined, the National Institute of Virology has been closed, and safety measures have been introduced on public transport. Meanwhile, scientists in Canada and elsewhere have responded to the outbreak by calling for tighter regulation of the study of SARS.
Don't panic: SARS is a relatively contagious disease, that in about 10 percent of cases in the previous outbreak led to death. But the reaction to SARS by authorities around the world continues to be out of proportion to the problem, causing enormous and unnecessary damage to public morale and to the global economy. Discriminate quarantines, and attempts to detect unreported cases of SARS and chains of transmission, are sensible precautions in this instance. But broadening the number of people thought to be at risk from the disease to everyone who might have encountered a laboratory worker on public transport can achieve nothing other than a nationwide panic.
Some of the measures now being taken in China - for example, railway stations and airports being ordered to take the temperature of passengers, in an attempt to detect fever - seem more to be about being seen to be act than dealing with the problem. The number of train journeys that the laboratory worker in question is said to have made between Beijing and Anhui after she became infected, seems to increase depending on which reports you read. The preoccupation with public transport as a conduit for disease, and concerns that China's week-long national holiday at the beginning of May will further increase the risk of infection, demonstrate that the SARS panic has a life of its own beyond the practical matter of addressing eight suspected cases and a death.
Perhaps the saddest thing about this latest episode is that scientific research into SARS has been implicated in the spread of the disease. The most important thing, if SARS is to be dealt with effectively, is not for people to be frightened of it, but to continue with the kind of research that is conducted at the National Institute of Virology.
| | Additional patients in China under investigation for SARS; WHO team travels to Beijing, | | World Health Organisation, 26 April 2004 | | WHO's to blame for the SARS panic?, | | by Rob Lyons | | Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003, | | World Health Organisation, 21 April 2004 |
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| | | 15 April 2004 | An eggs-aggeration
Panic: 'Danger warning after increase in drug residues found in eggs', reports the Guardian, after a report from the Soil Association revealed high levels of the veterinary antibiotic lasalocid in samples of eggs. One sample contained 3450 parts per billion of the drug, and 12 per cent of eggs sampled contained reportable levels - up from just one per cent in 1999. Although lasalocid is approved for use in chickens intended for meat, it is not approved for use in egg-laying hens. Richard Young of the Soil Association said: 'We believe that eggs contaminated at the high levels found in some samples last year pose real risks to some vulnerable consumers.... [U]ntil this drug is banned, those most at risk should limit the amount of egg eaten.'
Don't panic: There is no direct evidence that lasalocid is harmful to humans, although no proper studies appear to have been carried out. The Soil Association notes in an earlier publication that: 'We have been unable to find a single scientific review of the potential toxic effects for humans of consuming lasalocid residues in food.' However, the European Union (EU) has set an acceptable daily intake (ADI) for laslocid of 0.3 milligrams per day for a 60kg person, based on laboratory testing with rats. The average of the samples taken was 414 parts per billion - or about 0.03 milligrams per egg. So a person would have to eat, on average, 10 of these contaminated eggs every day to breach the EU limit - and only one in eight eggs tested had any reportable levels of lasalocid residues at all. Moreover, the EU safety limit is set at 100 times less, weight-for-weight, than the lowest level found to cause harm in laboratory tests on rats.
Just because a substance like lasalocid is harmful to some mammals, such as horses, does not mean that it is harmful to humans. Penicillin, for example, is lethal to guinea pigs but obviously of enormous benefit to most humans. In truth, to have any likelihood of suffering harm from lasalocid, someone would have to eat so many eggs that they would no doubt expire from excessive wind or cholesterol poisoning from the eggs themselves.
There is little evidence of widespread harm from lasalocid. While more research could be done into its effects on humans, it is inappropriate to launch scare stories like this one without something more than circumstantial evidence of a problem. It would also be better if feed producers didn't accidentally contaminate their products with antibiotics not intended for egg-laying hens. On the other hand, what is clear is that the Soil Association is against intensive agriculture in principle. Digging-up half-baked panics about the food we eat seems to be a rather illegitimate way to make their case.
Read: | | Danger warning after increase in drug residues found in eggs | | Guardian, 14 April 2004 | | Millions of eggs contain drug residues shows new report | | Soil Association, 14 April 2004 | | 2003 and 2004 UK surveillance scheme results and investigations for Great Britain, Appendix 4 (pdf format) | | Veterinary Residues Committee, March 2004 |
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