Nanoparticle safety under scanner

recalling of a nanotechnology product in Germany within a week of its launch has renewed the debate on whether nanomaterials are safe. Magic Nano -- a bathroom cleaner -- was withdrawn from the market in April after about 90 people reported severe respiratory problems after using it. The product contained silicate nanoparticles, which block minute crevices on glass and ceramic surfaces to make them dirt and water repellent.

According to the Federal Institute for Risk Assessment (bfr) in Germany, which had issued warnings about the product when it was released, respiratory symptoms cleared up within 18 hours, though in some cases breathing problems persisted for days. However, bfr later "clarified" that the respiratory problems were noticed only when the aerosol spray-can form of the product was used; no problems were reported when a pump bottle containing the fluid was used. bfr officials said they assumed that inhalation of the aerosol droplets caused the reported respiratory problems. Whether the nanoparticles it contained also contributed to the problem is unclear. There are hundreds of nanotechnology products out in the market and none of them have been reported to harm anyone, add the officials.

RELATED STORY • Cover: Nanoparticle threat [Sept. 15, 2003]

However, opponents of nanotechnology are up in arms. "This case provides strong support and urgency to our calls to companies and government to develop sufficient information on the potential hazards of nanomaterials used in products and avoid dispersive (as in aerosols) uses until then," says Environmental Defense, a us advocacy organisation, in a press release.

Nanotechnology is an emerging field of materials science involving substances smaller than one-ten thousandth of the width of a human hair (see 'At an atom's level', Down To Earth, August 31, 2004). Nanomaterials are used in several cosmetics and household products, as well as in electronics, automobile and aircraft industries. "While the new technology could have huge potential benefits for industry and society as a whole, the safety implications are brushed over," says Anthony Seaton, an environmental health expert, who teaches at the Edinburgh University in the uk.

Insurance concerns Besides public health, nanomaterials present new challenges for insurance companies as well. A report released in 2004 by Swiss Re, a leading reinsurance company, had called upon the industry to assess the risks of nanotechnology. The report focused on the potential risks of nanomaterials and raised the spectre of insurers being caught unawares by a landslide of claims should nanomaterials prove dangerous.

The apprehension expressed in the report was based on the experience with asbestos, which had led to a deluge of unexpected insurance claims. When asbestos was introduced, nobody had suspected that the tiny particles it contained could enter the lungs, causing asbestosis and other serious respiratory ailments. Like asbestos fibres, the report said, nanoparticles could cause problems simply because of their size. "It is not beyond the bounds of possibility that nanomaterials can have a similar effect on human health," agrees Seaton. Nanomaterials can be extremely mobile in the environment and once airborne, can be inhaled, possibly even be absorbed through the skin and manage to pass the blood-brain barrier.

But some experts think the asbestos analogy is not fair. "The world has moved on since asbestos. I think the asbestos issue got out of hand because our industrial society at that stage did not think about risks from new materials," says P V Madhusudhan Rao of the Indian Institute of Technology, Delhi, who works on nano-machines. However, dispersive use of untested nanomaterials should be avoided, adds Rao. "A health scare can damage the reputation of an important field of research and industry needs to tread carefully," warns Seaton.

The problem seems to be of regulation and methods to test whether a particular nanoproduct is safe. "The trouble is that government scientists are themselves unsure of exactly what tests might be necessary. Thousands of products containing untested nanomaterials are reaching the shelves and the future health implications are unknown, even to the experts," says Seaton.

Physical Science Germany Nanoparticles Health Effects Health Effects Health Effects Respiratory Diseases Respiratory Diseases Research News News News US Radiation Radiation Medical Research The Fortnight The Fortnight The Fortnight The Fortnight