The possibility of Alzheimer's disease being induced by the sunscreen used every summer by tens of millions of holidaymakers is being investigated by academics.
Sun worshipers are constantly told of the importance of using sunscreen, but the University of Ulster said two of it experts have been given substantial funding by the European Union to explore the possible links between the sunscreen and the brain disease.
They are leading groundbreaking research into whether human engineered nanoparticles, such as those found in sunscreen, can induce neurodegenerative disease such as Alzheimer's and Parkinson's.
Professor Vyvyan Howard, a pathologist and toxicologist, and Dr Christian Holster, an expert in Alzheimer's, have been awarded £350,000 from the EU to carry out a three-year research project.
Their research at the Biomedical Sciences Institute in Coleraine, co Londonderry is part of a worldwide project called NeuroNano.
European academic partners in the project are working in universities in Dublin, Cork, Munich and Edinburgh. In the US the universities of California, Rochester and Rice - together with the Japanese Institute of Materials Science - and part of the project.
"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," said Professor Howard.
The University of Ulster experts will be specifically 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.
Professor Howard said: "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 said.
"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."
The brain had built up some protective mechanisms but a major worry was that nanoparticles seemed to be able to circumvent them, he said.
"All this adds up to a new field of investigation. This research programme is deeply challenging and entails the gathering of entirely new knowledge in a field - neuronanotoxicology.
"It requires the marshalling of unique expertise, methodologies, techniques and materials, many themselves completely new and never before brought together in the required combination, " said the professor.
Latest figures show neurodegenerative diseases currently affect over 1.6% of the European population, with dramatically rising incidence likely in part to the increase of the average age of the population.
"There is also some epidemiological evidence that Parkinson's disease is connected to environmental pollutants and it is often noted that, historically, reports of Parkinson's symptoms only began to appear after widespread industrialisation.
"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 the professor.