Nanoparticle safety in doubt

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Lung damage in Chinese factory workers sparks health fears.

Could nanoparticles cause some lung damage? Credit: C. Juste/Miami Herald/Newscom

Claims that seven Chinese factory workers developed severe lung damage from inhaling nanoparticles are stoking the debate over the environmental-health effects of nanotechnology.

A paper published in the European Respiratory Journal claims to be the first to document cases of ill health caused by nanoparticles in humans (Y. Song, X. Li and X. Du Eur. Respir. J. 34, 559–567; 2009). Other experts are sceptical as to whether nanoparticles are actually to blame, but the paper has triggered lively discussions.

"The study raises the bar for doing appropriate research as fast as possible to find out where the dangers might lie when working with nanomaterials," says Andrew Maynard, a nanotechnology expert at the Woodrow Wilson International Center for Scholars in Washington DC.

The study describes seven women, aged 18–47 years, who worked in an unidentified printing factory in China; two of them later died. They all had pleural granulomas — ball-like collections of immune cells in the lining of the lung that form when the immune system is unable to remove a foreign body. They also had excessive, discoloured fluid in the lung lining. Particles around 30 nanometres in diameter were found in lung fluid and tissue.

The study says that the symptoms were caused by inhaling fumes produced when the workers heated polystyrene boards to 75–100 °C. The boards had previously been sprayed with a 'paste material' made from a plastic identified as a polyacrylate ester.

“We can’t say what the link is or if there are other exacerbating circumstances. ”

The workroom, of around 70 square metres, had one door and no windows. The ventilation unit had broken down five months before symptoms started to manifest, and the door had been kept closed to keep the room warm. The workers wore cotton gauze masks only on an "occasional basis".

Electron microscopy found nanoparticles around 30 nanometres in diameter in the paste and in dust particles that had collected at the inlet of the broken ventilation unit. Lead author Yuguo Song, a clinical toxicologist at Beijing Chaoyang Hospital, says "it is obvious the disease is not due to microparticles or vapours, because the pulmonary epithelial cells are full of nanoparticles".

Maynard says the symptoms seen in the patients are "similar" to those seen in animals exposed to nanoparticles. He adds that damage to the areas surrounding the lungs suggests that larger particles are not to blame, as these tend to be constrained within the lungs. But because the study does not identify what nanoparticles were involved or their concentration, he says, "we can't say what the link is or if there are other exacerbating circumstances".

Ken Donaldson, a respiratory toxicologist at the University of Edinburgh, UK, doubts that nanoparticles are to blame. He says the symptoms are more typical of chemical exposure. "I don't doubt that nanoparticles were present, but that does not mean they were the main arbiters," he says.

Donaldson says that the plastic material the patients worked with is the more likely culprit — as it would have been highly toxic at the levels they were probably exposed to given the size of the room they worked in and its lack of ventilation.

Anthony Seaton, an emeritus professor in environmental and occupational medicine at the University of Aberdeen, UK, agrees that the study does not pin down nanoparticles as the cause of the ill health. Rather than an insight into the toxicology of nanoparticles, he says, the study is an example of a "total failure in health and safety procedures".

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Gilbert, N. Nanoparticle safety in doubt. Nature 460, 937 (2009) doi:10.1038/460937a

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