Scientists are to investigate whether human-engineered nanoparticles which are found in sunscreen have any links with Alzheimer's and Parkinson's diseases.

Professor Vyvyan Howard, a pathologist and toxicologist, and Dr Christian Holster, an expert in Alzheimer's, have been awarded £350,000 from the European Union to carry out a three-year research project.

Their study at the Biomedical Sciences Institute in Coleraine, Co Londonderry, is part of a worldwide project called NeuroNano, which also involves scientists at Dublin, Cork and Edinburgh universities, among others.

The team from the University of Ulster will look specifically at the nanoparticles present in the chemicals found in sunscreens, and in an additive to some diesel fuels - titanium dioxide and cerium oxide - and consider their links to Alzheimer's and Parkinson's diseases.

Professor Howard said yesterday: "There is now firm evidence that some engineered nanoparticles entering intravenously or via lungs can reach the brains of small animals.

"Indeed, they lodge in almost all parts of the brain and there are no efficient clearance mechanisms to remove them once there."

There were also suggestions that nanoscale particles arising from urban pollution had reached the brains of animals and children living in Mexico City, he added.

"The brain itself is a very special organ. It cannot repair by replacing nerve cells - the ones you get at birth have to last all your life, which makes them peculiarly vulnerable to long-term, low-dose toxicity."

Neurodegenerative diseases affect more than 1.6 per cent of people in Europe, latest figures suggest. A dramatic rise in the incidence rates of the two diseases is, in part, the likely result of the increase in the average age of the population.

"The risk that engineered nanoparticles could introduce unforeseen hazards to human health is now also a matter of growing concern in many regulatory bodies, governments and industry," said Professor Howard.