A note of caution as you squeeze out the last of your micronized mineral sunscreens before the fall. British scientists are beginning a study to determine whether there is a link between brain diseases, such as Parkinson's and Alzheimers, and nano particles from sunscreen. Titanium dioxide is being especially targeted for scrutiny under the microscope.

The scientists, based at a university in Ireland, said that there is existing research to prove that sunscreen nano particles have entered the brains of small animals by either intravenous means, from topical application for example, or by entering the lungs having been breathed in. The evidence has shown that the particles can become lodged in specific parts of the brain where there are no clearance mechanisms.

In the meantime, environmental group, Friends of the Earth, recently released a report claiming that nano-based sunscreens do not increase sun protection and can also pose a number of potential health problems.