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DU has no safe threshold New Scientist 20 Jan 2001
RADIATION from one atom of depleted uranium lodged in your body could give you cancer, British scientists have found. This is the first direct evidence that a single alpha particle could do this, suggesting that no dose is too low to trigger a tumour. The risk is small, and any cancers caused will take years to develop. But experts say the revelation reinforces the need to check the levels of uranium in soldiers and civilians affected by wars in the Gulf and the Balkans (see opposite).
More than 900,000 rounds of ammunition containing a total of some 300 tonnes of depleted uranium (DU) were fired in those conflicts over the past 10 years, the vast majority by US forces in the Gulf. Arguments about the health dangers of DU contamination have been raging this month following an announcement by the UN Environment Programme that it had found radioactivity from DU munitions at 8 out of 11 sites in Kosovo. But radiobiologists reject the widely publicised suggestion that DU could have already caused leukaemia among veterans of the 1999 Kosovo campaign. Radiation takes more than two years to induce the disease. The long-term risks from DU dust lodged in the lungs are different, however. A team from the Medical Research Council's Radiation and Genome Stability Unit in Harwell in Oxfordshire and Mount Vemon Hospital in London has just revealed how a single alpha particle can damage human white blood cells. After the irradiated cells were allowed to divide a dozen times, the researchers found that a quarter of them contained pattems of broken or distorted chromosomes. They believe this phenomenon, known as "genomic instability", is a key part of the complex chain of biological events which over years can lead to cancers (New Scientist, 11 October 1997, p 36). Dudley Goodhead, director of the Harwell unit, thinks this may have important implications for assessing the dangers of cancer from alpha-emitting radionuclides inside the body. "It suggests that even the tiniest amount carries some, albeit very small, risk," he says. "This means it is important to undertake studies into the deposition and retention of DU in the body so that they can be compared with levels of naturally occurring uranium," adds Mike Thome, a uranium expert from AEA Technology, also at Harwell. Radiation is not the only danger with uranium. Goodhead and Thome both note that the chemical toxicity of DU could be more harmful. "It would be reasonable to put a moratorium on its use as a munition until we have investigated the amounts to which people have been exposed," says Thorne. And despite British government assurances ' that inhaling dust from DU weapons does not increase the risks of developing cancers, Britain's National Radiological Protection Board confirmed to Nezv Scientist that breathing in uranium dust does result in an increased risk of lung cancer. 'The doses to lymph nodes are much lower than those to the lung so the risk is much less," says the NRPB's Michael Clark. 'We are not aware of any risk of brain cancer from inhalation of DU dust, but there can be a risk if DU is taken into the body via an open wound rather than inhaled." Rob Edwards
More at: Radiation Research (vol 155, p 122)
What went wrong? New Scientist 20 Jan 2001
A tragic death has taught gene therapy some valuable lessons
A YEAR after 18-year-old Jesse Gelsinger died following experimental gene therapy, researchers are beginning to understand what went wrong. Their work may help to prevent similar tragedies in the future. Savio Woo of the Mount Sinal School of Medicine in New York opened the conference by recounting how Gelsinger died after he was injected with an adenovirus carrying a gene to treat his liver disorder. The incident sent shock waves through the field, and similar trials were quickly halted. Federal agencies criticised the leader of the trial, James Wilson of the University of Pennsylvania, for not reporting adverse reactions in other patients, for example (New Scientist, 18 December 1999, p 9). But during the investigation, the National Institutes of Health's Recombinant DNA Advisory Committee learned that many other researchers had also failed to notify them of complications in gene therapy trials. The manner of Gelsinger's death took scientists by surprise in a number of ways. Although the virus was injected directly into his liver, it infiltrated several other organs as well. And while liver inflammation was considered the most likely side effect, Gelsinger died from a widespread inflammatory reaction. Closer examination showed his blood had high levels of IL-6, a protein that promotes inflammation. Now Wilson and his colleagues have done experiments in mice and monkeys to help them understand what went wrong. They found that in both animals, the infused virus left the liver and reached high levels in the spleen, lymph nodes and bone marrow. Even within the liver, the virus tended to accumulate in the Kupffer cells, which interact with the immune system, rather than in the main kind of liver cell, hepatocytes-which were the intended targets. At least one of these unintended hosts contributed towards inflammation. Spleen cells in mice treated with the modified adenovirus produced IL-6 within hours. "They were cranking out this protein even without us tickling them to do that," says Wilson. "Unfortunately, until we saw this reaction in the human, we didn't know whitt of oc us on in the mouse or monkey." Wilson thinks that altering the viruses that deliver genes so they interact less with cells that release IL-6 and other immunostimulatory molecules could make therapy much safer. Following Wilson's talk, Woo urged his colleagues to take these lessons to heart: "We all need to learn a lot of science from this patient," he said.
Pollution purgatory, fact or fiction? New Scientist 20 Jan 2001
FREE trade is not a one-way ticket to pollution purgatory, claims a World, Bank report. Many greens, and some economists, say free trade encourages industry to relocate to countries with lax anti-pollution laws, mostly in the developing world. To maintain competitiveness, rich nations join this downward slide towards more liberal attitudes to pollution, dubbed "the race to the bottom". But last week, free-trade advocates at the World Bank hit back [email protected] research suggesting that this logic does not hold in the real world. David Wheeler of the Bank's development research group has found that the three countries to which foreign manufacturers moved in the greatest numbers in the [email protected], Mexico and Brazil-have cleaner air than before. Despite rampant industrialisation, urban air pollution in China has fallen by 40 per cent. After peaking in the early 1990s, Mexico City's air has become cleaner as the North American Free Trade Association filled the megacity with American factories. And in Brazil's industrial heartland around Sio Paulo, pollution fell by more than half between 1984 and 1998. With pollution in the US failing too, Wheeler concludes there is "no sign of a race to the bottom. Air quality seems to be improving in countries at all income levels."
The reason, he says, is almost as surprising. Despite the frequent complaints of manufacturers, the cost of cleaning up is not so great. And many companies relocating from the rich world automatically bring their higher standards with them as part of a "good neighbour" policy. However, Larry Lehmann of The Corner House, a British group fighting trade globalisation, dismisses the research as "a piece of public relations. Many of the declines he documents occurred before the boom in foreign investment," he says. And the data only covers suspended particulates-dust and soot-rather than more insidious pollutants. Some economists may be disappointed, however. "Between you and me," the World Bank's chief economist Lawrence Summers wrote in a memo leaked in 1992, "shouldn't the Bank be encouraging [email protected] of dirty industries to less developed countries?" They should be free to sell their air for polluting to the highest bidder, he argued. Summers be came Clinton's treasury secretary. Fred Pearce
More at: www.worldbank.org/nipr/work-paper/RaceWPl.pdf
Gene machine New Scientist 20 Jan 2001
Quantum computers could be speeded up with DNA, says Alik Kasumov of the University of Paris Sud. He found till a strand of DNA from an E coli bacterium became superconducting when each end was connected to cryogenically cooled electrodes (Science, vol 291, p 171). Kasumov believes this DNA-with no electrical resistance-could one day make transistors for quantum computers.
Farewell to arms control New Scientist 20 Jan 2001
In a dangerous world, Bush prefers weapons to international agreements
'THE outcome of great battles is often determined by decisions on funding and technology made decades before." So says George W. Bush in his policy statement on defence. But experts in Europe and the US fear decisions the new president must make soon will mean those battles will be fought using horrific weapons that other leaders have spent decades trying to control. Bush's policy statements highlight the threat from chemical and biological weapons. "But the response seems more likely to be in terms of Fortress America than intemational controls," says Oliver Meyer of Vertic, a pro-arms-control group in London. A key phrase in Bush's defence pronouncements has been "homeland defence", a preference for protecting American soil over international arms control efforts. Bush has made it clear that a high priority for defending American soil will be the National Missile Defense (NMD) systema scaled-down version of Ronald Reagan's 'Star Wars" programme (see opposite). @ut such a system is prohibited under the AntiBallistic Missile Treaty, signed by the US and former Soviet Union in 1972. "The idea of the treaty was that each side promised to be vulnerable, so nuclear deterrence would work," says Tom McDonald of the British American Security Information Council, an arms-control think tank based in London and Washington DC. "The US no longer wants to be vulnerable, or deterred." Defending this position in the Chicago Tribune last month, Condoleezza Rice, Bush's nominee for national security adviser, wrote that deterrence only worked during the Cold War. "Today, the principal concems are nuclear threats from the Iraqs and North Koreas of the world." To achieve NMD, Bush says he will either talk Russia into amending the treaty, or will abandon it. The danger then will be China, whose few missiles would become useless if NMD ever works. According to McDonald, "China typically retaliates against moves it doesn't like by selling missile technology to proliferation states," as it did to Pakistan recently. 'US insistence on NMD could end up aiding the rogue states it is meant to oppose." But, says Meyer, opposition to NMD is so strong in Europe that the US may need to make concessions in other areas to achieve it. One might be to ratify the Comprehensive Test Ban Treaty, a move which was narrowly defeated in the Senate last year. But the CTBT could still die, says McDonald. China, too, has not ratified. "To counter NMD, China would need missiles with multiple warheads. Now it has only single warheads." To scale up, China would have to resume testing, which in tum might prompt India and Pakistan to resume as well. The CTBT is under pressure from another direction. Nuclear weapon designers at US national labs such as Los Alamos are pressing the government to abandon the treaty so they can test a new generation of small nuclear weapons aimed at breaking hardened targets such as underground bunkers. Bush has pledged $20 billion more funding during his term for weapons research. There is even less optimism about the Biological Weapons Convention. A system for verifying the treaty, requiring countries to declare biological activities and submit to inspections of labs, is due to be agreed this year. But the US has so far blocked the most stringent measures, and a new team may be unlikely to take a softer line, says Barbara Rosenberg of the State University of New York at Purchase, an expert on the treaty. "They won't offend their friends in the biotechnology industry by agreeing to intrusive inspections," agrees McDonald. At least one area of arms control seems likely to be supported by the new administration: the Chemical Weapons Convention, a pet project of Bush's father when he was president. When the US enacted the CWC in 1998, it exempted itself from the verification inspections required by the treaty, and from the obligation to allow samples taken during inspections to be tested out of the country. "One would hope the son will fix what Washington did to his father's treaty," says Amy Smithson of the Henry L. Stimson Center, a defence think tank in Washington L)C. Debora MacKenzis
Revolution aborted? New Scientist 20 Jan 2001
Embryonic stem cell research may grind to a halt
ON PAPER, the omens look good for medical research when the Bush administration takes charge of the $20 billion budget of the National Institutes of Health, by far the biggest kitty for health research in the world. On the campaign trail, Bush promised to increase the NIH's budget to $27.3 billion, twice what it was in 1998. But Bush and the religious right of his Republican party are unlikely to stick to the priorities of the Clinton era. The proposed relaxing of rules last year on research into stem cells taken from human embryos will be under pressure from Republican proliters. And what of AIDS, whose sufferers many conservatives think of as pron-dscuous and immoral? Will research into tropical diseases, such as malaria and Ebola, be scaled back in favour of heart disease and cancer-the "diseases of the rich"? Most attention has so far focused on whether Bush will allow NIH researchers to develop "designer" tissue and organs from embryonic stem cells. "In terms of the NIH, that's the area people are most closely watching," says Kei Koizumi, head of the R&D Budget and Policy Program at the American Association for the Advancement of Science in Washington DC. Although federally funded scientists are banned from research that would involve the destruction of a human embryo, the NIH last year drafted compromise guidelines (New Scientist, 2 September, p 6). These would allow NIH researchers to work on stem cells as long as they came from a source outside the NIH, such as private industry. "Bush has said he would seek to block such research," says Koizumi. "The question now is whether he'll follow through on that." Harold Varmus, whose six-year stint as director of the NIH finished in 1999, thinks too much is being made of the stem cell controversy. Management of the rapidly growing NIH is what matters. "The real issue is getting solid scientific leadership, good budgetary growth and good stewardship of huge resources," he says. Varmus predicts a continuation of support for the NIH from moderate Republicans on the budget-setting committees in Congress. It was they who in 1998 advocated doubling the NIH budget within five years, a plan Bush has agreed to stick to. "I'm guardedly optimistic," says Varmus. He also expects these moderate voices to drown out fanatics when it comes to ideologically sensitive areas such as AIDS. "I don't think AIDS will take a hit," he says. "Everyone realises it's one of our major global health problems, and drugs are still needed to treat it," he says. Andy Coghlan
Too darn hot New Scientist 20 Jan 2001
IT IS now certain that coral reefs are being damaged by global climate change, the Bali meeting heard last week. The first waming signs came from bleaching, which occurs when warmer waters force corals to expel their symbiotic algae. During the 1997-1998 El NiAo, reefs bleached throughout the world, and there were mass deaths of coral in the Caribbean. Now cores drilled from Caribbean reefs off Belize show that nothing like this has happened for at least 3000 years. "This is the first palaeontological evidence that directly links the new bleachingrelated mass mortality to global warming," says Rich Aronson from the Dauphin Island Sea Lab in Alabama, who did the research. "It's clearly a cause for grave concern." The tropics are bearing the brunt of global warming, Aronson says. Sea surface temperatures have risen by an average of 0.5 'C a decade, according to Alan Strong of the National Oceanic and Atmospheric Administration in the US. That's almost ten times the global average. Aronson's work is supported by evidence from cores drilled at 16 reefs throughout the tropics, which have been analysed by Mark Eakin and his colleagues at the World Data Center for Paleoclimatology in Boulder, Colorado. "There is a definite increase in temperatures in the last 400 years, with warmer, wetter conditions." This must be a result of human activity, says Eakin. "The rate is extreme and we cannot explain it any other way" Although Eakin thinks we are now entering a period of reduced El Nifio activity, reefs are still vulnerable. There will be at least a doubling of atmospheric carbon dioxide, he says. "You dm't even need to believe in climate change," adds Joan Kleypas of the National Center for Atmospheric Research, also in Boulder. "You just need to believe emissions are going up. If you put more CO, into the atmosphere, you put more into the ocean. 'that reduces pH, and in tum reduces reef calcification." If current trends continue, corals may become too fragile to support reef structures as we know them, says Kleypas. There is no evidence to suggest corals are acclimatising to the changes, she says. Reefs are worth an estimated $400 billion a year. Acall for action to cut greenhouse emissions was unanimously supported by scientists at the meeting. "These results must be used immediately to make sure the Climate Change Convention is implemented properly," says Sue Wells of the World Conservation Union. Enthusiasts can help save reefs, says Paul Holthus of the Marine Aquarium Council in Hawaii. The MAC Is setting up a scheme to certify fish and corals that are ha and handled in a sustainable way. The aquarium trade is worth an estimated $300 million a year, so by buying goods labelled under this scheme, aquarium ownen will encourage local communities to protect their reefs, Holthus says. Worldwide, 15 to 20 million marine fish and 700 tonnes of live coral are taken for the aquarium trade each year, Holthus esbmates. Some fish can only be reached by prising 'away the living reef w crowbars. Others are caught by stun,ning with cyanide. up to 80 per cent cauzht in this way die. The MAC hopes to certify sustainabiflty from reef to retailer. lt is setting up pilot schemes In Indonesia, Fin and Hawaii, and plans to have the first fish labelled under the scheme In the shops by the middle of next year. "We know the road we want to travel but we have to build the vehicle," Holthus says. However, some conservationists doubt if certification can work. "The average American will go down the street to buy [another] fish if it's cheaperl says Peter Rubec of the International Marinelffe Alliance in St Petersburg, Florida. "if we don't educate the consumer we still haven't solved the problem.' And the plan may hit another hurdle in the US, the world's largest importer. Laws being drawn up by the Coral Reef Task Force would ban the import of all corals. There are plans to add f h later. Such a move could kill the aquarium trade.
GAIA lives-or at least she appears to have been fighting fit 55 million years ago.
New Scientist 4 Nov 2000
The argument that Earth's organisms regulate the global environment, and possibly even damp down global warming, received a boost this week. Global temperatures soared around 55 million years ago when volcanoes pumped huge amounts of the greenhouse gas carbon dioxide into the atmosphere. But according to Santo Bains of the University of Oxford, huge growths of plankton formed in the oceans shortly afterwards and absorbed so much atmospheric CO2 that temperatures retumed to normal within 60 000 years. Bains's evidence for a huge plankton bloom is a big increase in the amount of barium sulphate in ocean sediments laid down at that time in the North Atlantic and off Antarctica. Living organisms are the main source of barium sulphate, and modern studies show a strong link between the amount of barium sulphate and organic carbon falling to the ocean bed as plankton die. As the atmospheric CO2 levels rose, temperatures initially climbed by 6 'C over 30 000 years. The combination of these rising temperatures, extra rainfall washing nutrients into the oceans and the fertilising effect of the CO2 may have triggered a vast bloom of phytoplankton, according to Bains. "Advocates of the Gala hypothesis might view this as one of the strongest supporting pieces of evidence yet," he says. Marine geologist Birger Schmitz of the University of Gothenberg in Sweden has found similar barium sulphate peaks in Middle Eastern sediments from the same period. Schmitz points out that these results contradict the predictions of climate models, which suggest that the oceans should become less productive under greenhouse conditions. "Here the exact opposite happens," he says. "It shows the biosphere successfully regulating the climate as it goes to the extreme." The release of CO2 from volcanoes mimics fossil fuel burning today. But Bains points out that we would have to wait 60 000 years for plankton to counteract current global warming. Fred Pearce
Source: Nature (vol 407, p 171)