Protozoa are future's guinea pigs

Replacing animals with tiny organisms for testing new cosmetics products like mascara is something animal rights group may cheer about.

Scientists at the University of Liverpool are developing a new system that involves protozoa - a unicellular micro-organism - for testing cosmetic products like mascara. They have even nicknamed these micro-organisms 'slipper' and 'eyelash'.

The new system is cheaper, reliable and rules out cruelty to animals, added researchers.

"This test has great potential for reducing the use of rabbits as it is both cheap and reliable, and while the protozoa have a similar metabolism to animals, they are not classed as such," said David Montagnes from University of Liverpool who supervised the project.

The scientists from the University's Institute of Integrative Biology were able to examine potential toxicity caused by mascara, based on the growth of the protozoa when placed in experimental chambers containing the cosmetic.

Six different brands of mascara were tested, by painting it on small glass plates and placing these in the chambers. The protozoa and their food were then added.

The protozoa were chosen carefully because of their large size (Protozoa are normally 10 to 52 micrometres long but can grow as large as 1 mm), their historic use as model organisms and genetic similarities to humans, said the study published in the International Journal of Cosmetic Sciences.

Their large size enabled the scientists to visually measure population growth using a microscope, and they were able to show that this varied according to the brand of mascara and the amount in the chamber. There was a substantial difference between brands, with some killing the protozoa and others not harming them at all.

"When you can develop a simpler and cheaper alternative, there is really no need to test cosmetics on animals," added Montagnes.