DU radiation
I would like to comment on your excellent article on depleted uranium in Iraq (19 April, p 4).
Depleted uranium emits about 40 per cent less alpha particles than natural uranium, due to the removal of most of the uranium-235 and, more importantly, the uranium-234. Immediately after its production, that is the whole story.
However, within a few weeks of production, decay of uranium-238 re-establishes equilibrium quantities of the first two isotopes in the decay chain of uranium-238: thorium-234 and palladium-234. These are both beta emitters, and once equilibrium is established, DU emits on average two beta particles for every alpha particle. The betas from palladium-234 are particularly energetic.
These complicate the radiobiology considerably, because beta particles have much longer ranges in tissue, affecting large numbers of cells to a minor (possibly carcinogenic) extent, as opposed to the small number of cells heavily affected (probably killed) by the alpha particles.
It should be noted that the first daughter nucleus of both uranium-235 and uranium-234 is relatively long-lived, so neither contributes significantly to the radioactivity of natural uranium. Thus DU is actually quite as harmful as natural uranium in terms of beta radiation.
Finally, the Pentagon claims that uranium oxide dust is so dense that it quickly settles, and therefore poses a threat only to persons in the vicinity of the target at the time of impact. Having seen television coverage of dust storms in Iraq, I find it hard to believe that fine uranium oxide dust would somehow avoid being blown about during such storms.
Letter
Your article on the use of depleted uranium used in shells in Iraq implies that this route into the environment is unique. However, we have been dispersing natural uranium into the environment for decades via our coal-fired power stations.
Uranium, like most heavy metals, is present in coal at concentrations of a few parts per million. A large power station, such as the one at Ferrybridge in Yorkshire, burns upwards of 7 million tonnes of coal a year, containing some 10 to 20 tonnes of uranium. The coal is finely ground before burning, producing small particles of ash. The ash from these power stations is mainly tipped into open storage lagoons, with the potential for wind-blown dispersal or leakage into watercourses.
If there is any significant effect from the use of depleted uranium in shells, surely it would have manifested itself near these large power stations.
Parting of the genes
The implications of the discovery of genetic “no-go” zones between the chromosomes of proto-humans and proto-chimps might indeed be “huge” (19 April, p 15). But they are not huge enough to justify the conclusion that geographic separation was not involved in bringing about the striking differences between the two species.
They certainly do not prove that the common ancestors “gradually diverged from one another despite sharing the same habitat and territory”. They throw no light on whether they shared the same habitat or not. That assumption is based on a false premise 鈥� that increasingly separated gene pools necessarily result in increasingly dissimilar phenotypes. It is not the case.
There are two “races” of gophers living on opposite sides of the Colorado Canyon, which precludes them from interbreeding. The genetic difference between them is as wide as the genetic difference between a man and a gorilla. Yet they are not classed as different species because they are very hard to distinguish from one another without analysing their DNA. That is because the environment on the east side of the canyon is the same as the environment on the west.
In the same way, areas of incompatible chromosomes would not explain why one descendant of the common ape ancestor is hairy, knuckle-walking and dumb, while the other is naked, bipedal and a talented linguist. They could have become genetically speciated and yet remained as hard to distinguish as the gophers. The hypothesis of ecological separation is based on the phenotypes, not the genotypes, and it remains totally unaffected by these DNA discoveries.
Perchance to dream
Perhaps Joe Griffin is referring to another form of depression than the one I and many others know well, in which you dream less, not more (12 April, p 44). In fact, most depressed people do not dream at all. If Griffin does not believe me, he should read Darkness Visible by William Styron.
Also, Griffin’s assertion that depression can be cured in just a few days is both misleading and insulting to the millions of people who suffer from the illness. In fact, his ideas border on other ignorant attitudes, such as that held by those who implore depressed people to “pull themselves together”.
When people like Griffin get publicity it only serves to deepen the stigma of depression, as those not suffering from the illness then believe it can be so easily cured.
Letter
Griffin’s revelations would come as a bit of a yawn to practitioners of cognitive behaviour therapy (CBT) or neurolinguistic programming (NLP). Albert Ellis, the father of CBT, has been teaching rumination interruptions since at least the mid-1970s. NLP has been offering the therapeutic use of metaphor and storytelling since the mid-1970s, when its originators modelled it on the work of the medical hypnotherapist Milton Erickson. And the use of the metaphor of replaying a video for trauma and phobia cures has been used by NLP practitioners since the late 1970s. The reactions to Griffin’s work from the high priests of psychotherapeutic orthodoxy come as no surprise. NLP continues to receive similar reactions in spite of its proven efficacy.
Barbara Kiser writes:
鈥n the original interview, Griffin gave credit to these therapies and said that he and his colleagues integrate and take the best from existing techniques while adding to their effectiveness via his own original research into REM sleep. In our edit, we focused on his new work rather than the previous work he has drawn on.
Aluminium burns
Your article on the Columbia space shuttle disaster attracted a letter from David Harris of the Aluminium Federation regarding the supposed non-flammability of aluminium (19 April, p 24). He states authoritatively: “Your article raises the spectre of aluminium burning. This is a mythhellip;I have never seen aluminium burning in any formhellip;and nor do I ever expect to.”
This is contrary to my experience. Aluminium does burn, and surprisingly (with relevance to the shuttle) it can do so in near-vacuum conditions. Several years ago, against the accepted knowledge of experts in the field, I devised a process that achieves this, operating at a pressure of around 10鈭�3 millibars (0.1 pascals).
In a large vacuum chamber, aluminium wire is continuously melted, vaporised, and burnt in a stream of oxygen, and deposits a coating of aluminium oxide onto a web of polyethylene terephthalate (PET) film moving past at high speed from reel to reel. Counter-intuitively, the process even improves the vacuum through a “getter” effect, by mopping up any traces of water vapour present.
This is not just a laboratory curiosity. It is a large-scale industrial process. The reels are more than 2 metres wide, weighing more than a tonne and holding more than 36 kilometres of PET film. Over the years, the burning of aluminium has produced thousands of tonnes of flexible, transparent, gas-barrier packaging material for the food industry (Patent GB 2246794A).
Letter
Harris correctly states that aluminium would have melted in the Columbia disaster. But it is not impossible for aluminium to burn as he claims.
Steel wool can be ignited with a match, but there is no flame. A flame is a region of reacting gases, for which the combustible has to vaporise. Magnesium and aluminium have similar melting points, but the former ignites easily because its boiling point is only 1107 掳C. What you see in that brilliant flame is the combustion of magnesium vapour. Aluminium boils at 2467 掳C, a temperature difficult to achieve.
Harris can safely stand alongside vessels of molten aluminium because the vapour pressure of the metal is so low that there is a negligible amount in the air. But if the temperature is raised to close to the metal’s boiling point, the abundant vapour will burn.
Media reports suggested that the temperature on Columbia’s wing was only around 1500 掳C, and at that temperature I agree with Harris that combustion is most unlikely. But if temperatures were several hundred degrees higher, then ignition is a possibility and combustion would be fierce and rapid.
For the record
鈥� The article on potential SARS treatments (26 April, p 6) stated that last year AVI Biopharma developed an antisense therapy in just two weeks to protect penguins at a Milwaukee zoo against West Nile virus, but that it had not been needed. In fact, the company has since told us that three penguins suffering from West Nile disease were successfully treated. But not enough of the drug could be made in time to treat all the birds, and 10 others died.
鈥� The expected catastrophic collapse of the island of La Palma in the Canaries will take place in the eastern rather than the western Atlantic (19 April, p 31). Apologies for any alarm caused by the error, which arose during editing.
鈥� The article on the botulinum toxin referred to the “Mediterranean coral tree, Erythrina cristagalli” (19 April, p 14). In fact, the cockspur, cockscomb or crybaby tree, as it is also known, is correctly spelled E. crista-galli and is a native of Brazil, not the Mediterranean area.
Chernobyl martyr
Philip Walton’s letter maintains that the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) is the “authoritative source” of information on radiation-related mortality and disorders (22 March, p 30). But does the status of “UN scientific committee”really..confer a passport to uncritical acceptance?
UNSCEAR figures are in fact frequently questionable. For instance, the claim that no more than 31 people were killed directly by radiation from Chernobyl is unbelievable. UNSCEAR representatives also maintain that there has been no evidence of a major public health impact from Chernobyl, that the radioactive cloud did not cross the Alps, and that even if it did, precautionary measures for pregnant women or infants were unnecessary.
Epidemiological studies give different results. Belorussian scientist Yuri Bandazhevsky’s work on caesium-137 contamination in foodstuffs shows that, in child populations, contamination above 70 becquerels per kilogram of body mass leads to a 90 per cent incidence of cardiac arrhythmia, as well as other pathologies, including cataract and intestinal lesions.
UNSCEAR rejects Bandazhevsky’s figures. Why? Firstly, because they do not come from an official source (even though UNSCEAR knows that official statistics have been falsified) and, secondly, because the UNSCEAR model in principle excludes low-dose radiation as a cause of morbidity.
Clearly, the messy interface between the world of science and the world of power politics and lobbies needs investigating. But far more urgently (and without prejudging the validity of his findings), Bandazhevsky needs our support. Among the youngest PhDs in Belarus, he volunteered to work in contaminated zones. His dedicated work as rector of the Gomel Institute produced controversial results which many consider significant. After fearlessly denouncing the institutional squandering of Western aid, he was imprisoned for 8 years, supposedly for accepting bribes. Many believe that in truth he was imprisoned because of his research on Chernobyl, and Amnesty International has adopted him as a prisoner of conscience. Today, his physical and mental health are deteriorating fast. For details of Amnesty’s appeal see .