“If they get in the bloodstreams or into ground water, even if the nanoparticles themselves aren’t dangerous, they could react with other things that are harmful,” said Kathy Jo Wetter, a researcher with the ETC Group, an environmental organization that also opposes genetically modified crops. 

    In a move that researchers believe is too dramatic, ETC is asking governments to halt development of nanotechnology until environmental and health concerns are researched and assuaged. 

   Scientists say fears such as ETC consist mainly of speculation. Nanotechnology, they say, involves well-known materials such as carbon, zinc and gold — both toxic and benign. New tools simply let researchers alter those materials at the atomic level, where the particles are measured in nanometers, or billionths of a meter.

    “It may have some unexpected consequences. Some could be toxic,” said Mihail Roco, the National Science Foundation’s senior adviser on nanotechnology. “But this happens with larger particles and in other industries. The risks are very small in comparison with the benefits.”

    Nanotechnology research is one of the US government’s top science initiatives, fed by US$604 million in federal funds this year. ETC estimates worldwide research funding at US$4 billion, including government initiatives in Japan, Taiwan, South Korea and Australia. 

   The ETC, whose Canada-based group organized discussion at the UN World Summit on Sustainable Development in early September in South Africa, believes the coming industrial production of nanoparticles has not been properly scrutinized for environmental or health risks. 

   Wetter wonders what will happen if the tiny, man-made particles accumulate in the liver or lungs? Carbon nanotube molecules currently touted as a substitute for silicon in even tinier transistors closely resemble spiky asbestos fibers, she said. Although a pair of studies on mice and guinea pigs indicated that the carbon fibers probably posed little risk to humans, Wetter and other environmentalists speculate they could damage human’s lungs.

   If water is not pumped to the top of a tall tree, and if it is not pushed, to the top of a tall tree, then we may ask. How does it get there? According to the currently accepted cohesion-tension theory, water is pulled there. The pull on a rising column of water in a plant results from the evaporation of water at the top of the plant. As water is lost from the surface of the leaves, a negative pressure or tension is created. The evaporated water is replaced by water moving from inside the plant in unbroken columns that extend from the top of a plant to its roots. The same forces that create surface tension in any sample of water are responsible for the maintenance of these unbroken columns of water. When water is confined in tubes of very small bore, the forces of cohesion ( the attraction between water molecules) are so great that the strength of a column of water compares with the strength of a steel wire of the same diameter. This cohesive strength permits columns of water to be pulled to great heights without being broken.

        Rebel territory, western Nepal, is one of the most remote regions on earth. We came here to meet the insurgents who are fighting to topple the government of the Himalayan kingdom. Soon there are no roads, no bridges. The only way to cross this river to enter the rebel heartland is this box, suspended from a cable, the bridge blown up a long time ago in the fighting. 

        Here we were approached by a girl in her school uniform. It quickly becomes clear she and two friends have been hiding in the jungle since the previous day from the rebels, they say, notorious for abducting children to become insurgents.

        For the past 10 years, these Maoist rebels, among the last in the world, have been fighting to overthrow the monarchy here and establish a socialist state. More than 12,000 people have died in the fighting, but even more disturbing are the children targeted by both sides, according to human rights group --- thousands of them, by some estimates, abducted, tortured, and killed. The government says the rebels kidnap children to recruit and indoctrinate. 

        The rebels deny it, calling it slanders spread by the government, but the story of these children says otherwise. She is 16 and scared, Ganga says she thought the rebels would kill her. She worries her parents don’t know where she is. She herself doesn’t know where she is. They have no money and no food. They stay the night at the villager’s house. Khum is 15. He says that rebels beat students at his school with sticks and stones when some try to escape. Shobba says she worries about her exams, and worries that rebels will kill her.

        The children are in desperate need for help. We abandon our plans to try and meet the rebels to try to get the children home.

        We suspect there may be some rebels among the villagers here who might want to take the kids away. That’s why we have to get out of here very quickly, and this is how we are going to do it.

        But we may have already been too late. The woman in pink acts in a suspicious way, leading us to think she may be a rebel. She appeared from nowhere and has already been in deep conversation with the children, and tried to convince them to go with her. She claims to be a cousin and says she will take them home through a shortcut in the rebel territory. Out of hope or more likely out of fear, Shobha and Khum decide to go with her. But Ganga joins us in the precarious journey to safety across the river, where the government is in control. Here at the roadside café, Ganga has her first food in two days. We put her on a bus for home, a two-hour drive and then two more hours’ walk. It’s been a terrible ordeal for Ganga and she’s far from alone. Increasingly on the battlefield in Nepal between the government and the rebels are this country’s children.