Protection problems The issue hit the headlines last month when Which? magazine tested fourteen popular SPF 15 sunscreens and found that three provided an SPF of 12.5 or less. The worst offender, Marks & Spencer's Sun Formula Lotion, came out of the tests with an SPF of only 7.1, less than half its advertised level. Manufacturers must not be seen to mislead the consumer about something as important as sun protection so formulators will be looking to prevent any discrepancies between real and advertised SPF levels. Jennifer Hart, marketing manager for Croda Suncare and Biopolymers, told CosmeticsDesign.com: "The magnitude of the apparent failure in these cases would seem to rule out batch to batch variation or any difference in the SPF testing processes." Hart said industry onlookers may be inclined to conclude that these discrepencies are related to formulation stability issues or the photo-instability of some low cost organic sunscreen actives. However, recent Croda research has shone light on another problem source. Deterioration We have found that SPF levels can deteriorate over time, even when in-organics are used, said Hart. The temperature variations that sunscreen formulations endure as they go through manufacture, transportation, storage and trips to the beach may have a detrimental effect on SPF levels. Croda claims this problem can be overcome by using pre-dispersed Titanium Dioxide in sunscreen formulations. The UK-based company recently compared the SPF stability over time of an O/W formulation containing pre-dispersed Titanium Dioxide from Croda and powder grades of the compound. Hart said in several cases the measured in-vitro SPF of the powder-based formulations was only half of the initial value after three months of exposure to different temperatures. However, she said Croda's pre-dispersed Titanium Dioxide formulations maintained its SPF levels during the test period.