Sense about Science ? equipping people to make sense of science and evidence
Parabens in cosmetics: an office experiment
Parabens are preservatives widely used in medicines and in cosmetic products. They are added to prevent deterioration and infection by bacteria and other microbes. In 2004, a report linking parabens in underarm deodorants and antiperspirants to breast cancer received a great deal of media coverage and caused much public concern.
There were several major problems with the study this report was based on. Moreover, the claim of a parabens-underarm deodorant/antiperspirant-breast cancer association was curious, as parabens are not actually used in over 99% of underarm deodorants and antiperspirants, simply because most underarm products do not require preservation. Despite this, even now, there is still a great deal of public confusion about the safety of and necessity for preservatives in cosmetics. Cosmetics that are preservative-free, or that contain "natural" preservatives are still being touted as a safer option for women.
Because the parabens family of preservatives is very effective at killing microbes, we were interested to see for ourselves what would happen to a simple body cream if it was truly preservative-free...
So, we had four pots of body butter made up. The formulations were identical, except that two of the pots contained parabens (B and D), and the remaining two were preservative-free (A and C). Then we took microscopic spores of two common contaminants that might be found on our food or fingers. We added these to one of the pots of body butter with parabens (D), and also to one without (C).
Two days later, we left all four pots open to the air, and started taking photographs.
On day zero, pot C (which had no preservatives and had been contaminated) was already showing visible mould growth. This is due to the transit time from the lab to our offices.
Day three shows little visible development in all pots.
Day six shows the appearance of fungal fruiting bodies in pot C.
|As the moisturiser was beginning to dry out, the lids were replaced from day 14|
Meanwhile...before somebody helpfully provided this body butter, we'd put the word out that we'd like to see it for ourselves and a group of scientists working in a cosmetics lab took it on as a little project and made this neat film. (We can't tell you which one because they kind of did it on company time...)