Jonathan Walter, Author at 91av Science news and science articles from 91av Sun, 20 Mar 2005 10:30:00 +0000 en-US hourly 1 https://wordpress.org/?v=7.0.1 242057827 US cancels Agent Orange study in Vietnam /article/1920031-us-cancels-agent-orange-study-in-vietnam-2/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sun, 20 Mar 2005 10:30:00 +0000 http://dn7146 Is Agent Orange responsible for deformities in the children and grandchildren of people exposed to it during the Vietnam war? Vietnam claims the herbicide, used by the US to reduce forest cover, is to blame. But the US has never accepted this. The chances of the issue ever being resolved receded last month when the US cancelled a multimillion-dollar research project.

Under a 2003 US-Vietnam agreement, the study would have looked at the health effects of the dioxin TCDD, with which Agent Orange was contaminated. But the US National Institute of Environmental Health Sciences cancelled the project on 25 February 2005 after “failing to receive the necessary cooperation from the Vietnamese government”.

Project head David Carpenter, director of the Institute for Health and the Environment at the University of Albany in New York, US, adds that the research “could have been definitive” in a class action brought by Vietnamese plaintiffs against US manufacturers of Agent Orange, including Monsanto and Dow Chemicals. Carpenter says the ongoing legal action would have “increased the reluctance of the US government to fund this project”.

Last week the class action was dismissed on broad legal grounds – not because of lack of evidence. But the US judge also ruled that no evidence had linked the defendants’ herbicide to the plaintiffs’ exposure to dioxin.

]]> 1920031 Largest ever field of impact craters uncovered /article/1919325-largest-ever-field-of-impact-craters-uncovered/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sun, 07 Nov 2004 10:00:00 +0000 http://dn6611 The discovery of the largest field of impact craters ever uncovered on Earth is the first evidence that the planet suffered simultaneous meteor impacts in the recent past. The field has gone unnoticed until now because it is partially buried beneath the sands of the Sahara desert in south-west Egypt.

Philippe Paillou of Bordeaux University Observatory in Floirac, France, first noticed circular geological structures in the Sahara last year, while analysing radar satellite pictures of the area.

The structures turned out to be part of a huge field of 100 craters spread over 5000 square kilometres near the Gilf Kebir plateau. The craters vary in diameter from 20 metres to 2 kilometres across. The previous largest known crater field covers a mere 60 square kilometres in Argentina.

In February, Paillou led a joint Egyptian and French mission to find the site and examined 13 of the craters, confirming that they were the result of simultaneous impacts. But accurately dating the field has been tricky. Paillou estimates that it is roughly 50 million years old, relatively young in geological terms.

The size of the field suggests that it could be the result of two or more meteors disintegrating as they entered Earth’s atmosphere, the first evidence of a multiple strike, he says.

“Because the field is so big, it can’t have been made by one meteor,” says Paillou. But more information is needed to understand the event and its effects, and Paillou plans to return to the area next month.

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