Friday, July 11, 2003

The cost of GM food

A new report by the UK Prime Minister’s Strategy Unit has suggested that the economic benefits of genetically-modified (GM) crops may be limited, at least in the short-term.

The report makes three main points. Firstly, most of the currently available GM varieties are for crops not commonly grown in the UK, like soya and cotton. So, GM will only affect a small part of British agriculture initially. Secondly, where suitable GM crops are available, they may have to be kept separate from non-GM varieties from harvest through to shelf, adding considerable expense to processing and production. Thirdly, supermarkets do not appear keen to stock GM food. The report has been leapt upon by anti-GM groups as yet another reason for not planting GM crops in the UK. Thus, an economic problem caused by the irrational reaction to GM crops is utilised as a further argument against GM. For example, the BBC quotes Stewart Wells, leader of the Canadian National Farmers Union. He is against GM production in Canada. However, Wells is an organic farmer who fears that GM-free countries will steal Canada’s traditional export markets. But his concerns are mainly a reaction to the threat posed, not by GM, but the negative publicity attached to GM. The proper response is to challenge the arguments against GM, and show that it is capable of producing good food, more efficiently. Then, the economic case for GM will become much stronger.

'Little economic benefit' from GM crops, BBC News, 11 July 2003

Thursday, July 10, 2003

A watery grave

'Are you in danger of a water overdose?', asks the UK Mirror newspaper. Apparently, there are some people drinking too much water and apparently putting their lives at risk. For example, actor Anthony Andrews was rushed to hospital after drinking eight litres of water to combat the heat on-stage, while performing in My Fair Lady. A more famous example is that of Leah Betts, the teenager who died after taking ecstasy, but whose death was largely the result of consuming too much water to counteract the effect of the drug. How much should we drink? The Mirror says, 'Although there are no recommended's generally thought that it's safest to stick to no more than three litres in one day.'

This is a panic inspired by a panic. For years, we have been told by health 'experts' that we don't drink enough water. As the Mirror story notes, 'Some experts claim dehydration is to blame for everything from heart disease and cancer, to asthma and depression'. It is a fine line between drinking the two litres of water we supposedly need, and the three litres which could potentially kill us.

But, as Professor Heinz Valtin wrote in the American Journal of Physiology in 2002, it is 'difficult to believe that evolution left us with a chronic water deficit that needs to be compensated by forcing a high fluid intake'. In other words, our bodies are extremely good at controlling the amount of water in our blood at any time. While 'water intoxication' is possible, it is also very rare. If we drink too much, we are likely to spend rather longer than we need going to the toilet, but that's about it. A radical solution might be to suggest that people should drink some water when they feel thirsty. But where's the public health education programme in that?

One good thing about this story is that it puts the whole discussion about the poisons of modern life into perspective. There is no such thing as a poisonous substance, per se. Even drinking water can kill you, if you drink enough of it. It's the dose that makes the poison.

Are you in danger of a water overdose?, Mirror, 10 July 2003

Drink at least eight glasses of water a day for better health?, American Physiological Society, 12 August 2002

Star's water overdose, Sky News, 4 July 2003

Leah Betts died of drinking water to counter drug's effect, The Times, 22 November 1995, reproduced on Urban75 website

CJD rule changes: some sense at last?

The Food Standards Agency announced on Monday that the ban on the sale of cattle over 30 months old for human consumption would be ended. The slaughtering scheme was introduced to prevent the possible spread of BSE to humans as variant-CJD. However, cases of BSE have been declining and the FSA's research suggests that the increased risk due to ending the scheme would be no more than 2.5 lives lost in the next 30 years. Instead, cattle will be tested for BSE. The slaughtering scheme has cost £3 billion since 1996.

At last, signs of common sense in relation to BSE. Despite suggestions of a link between beef and vCJD, there have been only around 100 cases in the UK, much lower than the number of cattle who had BSE. At least one long-standing vegetarian managed to develop the illness, suggesting a long incubation period or another cause entirely. If there is a link between beef and vCJD, it is a very weak one, where other factors come into play to allow vCJD to develop.

However, BSE and CJD is a vivid example of how to overreact to a problem. The risk of vCJD was always small, yet a lot of people have been put out of business, and a lot of government money wasted, in the attempt to deal with it.

BSE 'old meat' ban may end, BBC News, 7 July 2003

Wednesday, July 09, 2003

Iranian twins: some things are worth dying for

Sad to hear that the operation to separate Laleh and Ladan Bijani, the twins joined at the head, failed. Complications arose, apparently, when surgeons realised that their separate brains had fused and would need to be cut apart millimetre by millimetre. The process cost the women a lot of blood and they could not be stabilised afterwards.

They showed a lot of courage, though. They did not appear to have gone into the operation out of despair but out of a desire to live a qualitatively better life apart. The procedure was risky, but hopefully much will have been learned in the process.

High death-rates are common when radically new operations are attempted, so I hope that this will not completely discourage future attempts of this kind.

Surgeons' sorrow at death of twins, BBC News, 8 July 2003

Tuesday, July 08, 2003

Counting the cost of SARS

Rosemary Righter, writing in The Times, has provided a summary of the effect that SARS has had on the leading Asian economies. One point is that there is little point in the wider world worrying about Asia dragging the world economy down because of SARS. Excluding Japan, but including China, East Asian GDP is still just seven percent of the world total.

Asia counts the cost of an outbreak of fear, The Times, 8 July 2003

Monday, July 07, 2003

What's wrong with the precautionary principle?

My Spiked colleague, Helene Guldberg, has written a very good piece which outlines the rising popularity of the precautionary principle, and what is wrong with it. Essentially, the precautionary principle does not ask us simply to weigh up the benefits of a new action or product, compared to the negative consequences. That cost-benefit analysis has always been done. Rather, it suggests that we should take a precautionary approach wherever there are conceivable negative impacts. This tends to exaggerate the likelihood of restricting innovation since it is more likely to emphasis the negative effects of doing something over the negative effects of not doing something.

The precautionary principle chimes into an outlook which is cynical about the actions and abilities of humanity, and seems to have very little to do with actually helping people, or making life better.

Challenging the precautionary principle, Spiked, 1 July 2003

Sunday, July 06, 2003

Trans service cut

The BBC reports that Nestlé are to remove hydrogenated vegetable oil and fat from some of their confectionery products. This is due to a link between these trans fatty acids and heart disease.

Here's an example of the method that has been used to obtain such findings, from a study reported in the New England Journal of Medicine in 1997:

We prospectively studied 80,082 women who were 34 to 59 years of age and had no known coronary disease, stroke, cancer, hypercholesterolemia, or diabetes in 1980. Information on diet was obtained at base line and updated during follow-up by means of validated questionnaires. During 14 years of follow-up, we documented 939 cases of nonfatal myocardial infarction or death from coronary heart disease. Multivariate analyses included age, smoking status, total energy intake, dietary cholesterol intake, percentages of energy obtained from protein and specific types of fat, and other risk factors.

So, although the initial sample size sounds good, there are problems straight away. As soon as your research involves questionnaires, it means that the results are likely to be highly variable. Furthermore, the business end of this sample is the one percent who have suffered cardiac problems. Out of this much smaller sample, it is suggested we can learn something about their risks based on diet. Were the questionnaires accurately filled in? Were there any biases in who returned questionnaires and who did not? Were the estimates of heart disease due to other causes (age, smoking etc) correct?

There are a lot of potential compounding factors here. Therefore, to be on safe ground, it is wise to look only for very strong results. So, the link between smoking and lung cancer is very strong and widely accepted. But the results here are much weaker.

It is one thing to find an association in a study. It is quite another to show that the association is actually meaningful and worth acting upon. For example, while the level of trans fat in our diets may be rising, coronary heart disease rates are falling. So, at face value, trans fat is not exactly promoting an epidemic of disease.

Here is an interesting review of the evidence about trans fat by Steve Milloy in the Wall Street Journal from September 2002.

Personally, I don't particularly care what kind of fat Nestlé put in their chocolate bars. Nobody has ever thought chocolate bars were health foods. But I do object to the way the decisions of companies and individuals are distorted by slightly dubious science.