University of Ulster scientists are to examine a link between some man-made nanoparticles, such as those found in sunscreens, and Alzheimer's disease.
Professor Vyvyan Howard and Dr Christian Holscher are leading research into whether engineered nanoparticles can induce neurodegenerative disease.
They are based at the Biomedical Sciences Institute in Coleraine.
They have been awarded £350,000 from the European Union to carry out investigations over three years.
Professor Howard said they would examine if there was a significant risk.
"The overall science and technology objective of this programme is to determine if engineered nanoparticles could constitute a significant neuro-toxicological risk to humans for two diseases - Alzheimer's and Parkinson's," he said.
Their research is part of a worldwide project call NeuroNano which includes European academic partners at the universities of Dublin, Cork, Edinburgh and Munich.
In America, the universities of California, Rochester and Rice and in Japan the National Institute of Materials Science.
Professor Vyvyan Howard and Dr Christian Holscher are to conduct the research
A nanoparticle measures between 1 and 100 nanometres. A nanometre is one millionth of a millimetre.
The experts will be looking at nanoparticles present in chemicals found in sunscreens and an additive in some diesel fuels - titanium dioxide and cerium oxide - and their connection to Alzheimer's and Parkinson's diseases.
"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," said Professor Howard.
"There are also suggestions that nanoscale particles arising from urban pollution have reached the brains of animals and children living in Mexico City.
"It has recently been discovered that nanoparticles can have highly significant impacts on the rate of misfolding of key proteins associated with neurodegenerative diseases like Alzheimer's and Parkinson's disease.
"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."
Dr Susanne Sorensen, head of research at the Alzheimer's Society, said: "We do not advise people to stop using sunscreen as it has been proven to reduce your risk of developing skin cancer however we welcome research into the long term safety of modern products.
"Alzheimer's disease is believed to be caused by interaction between life style, genetics and environmental factors and there are likely to be many routes to developing the symptoms of dementia.
"There is currently no research data directly linking the use of sun screen to development of Alzheimer's disease."
Dr Simon Ridley, Research Manager at the Alzheimer's Research Trust said: "The exact causes of Alzheimer's disease are unknown.
"It's likely that both genetic and environmental factors are involved. People should not worry about using sunscreen, which protects our skin from sun damage."