Tiny particles used in some sun protection creams have the potential to cause nerve damage, researchers in the US say .
It may not necessarily imply that these microscopic grains, which are also used in consumer products such as some toothpastes and cosmetics, are harmful in the human body, Nature magazine said reporting the latest findings.
But it also warned that a growing body of evidence suggests their safety cannot be taken for granted simply because larger particles of same substance have no ill-effect.
Bellina Veronesi of the US Environmental Protection Agency's research laboratories in North Carolina and her co-workers have studied the effect of nanoparticles of titania (titanium oxide) on cultures of mice cells called microglia, which protect neurons in the brain from harm.
They found the particles provoke the cells to manufacture chemicals that are protective in the short term but potentially damaging when released in the prolonged manner seen in the experiments.
Gunter Oberdwrster, a specialist in nanoparticle toxicity at University of Rochester in New York, said it was too early to say if the findings reveal a real health hazard.