Most makeup experts will tell you to replace your mascara every three months and we are similarly cautioned about most makeup products. But according to the FDA, most of your makeup will remain uncontaminated by bacteria even if it is older than three months. In a typically related scenario, a woman putting on mascara while driving, scratches her eyeball with a contaminated wand and infection ensues. The last report of an injury like that to the FDA was in 1989.

The reason? Preservatives.

Cosmetic companies use sometimes 5 or 6 preservatives in a product and the preservatives are very efficient at keeping the bacteria at bay. Contaminated makeup is usually the result of misuse of the product or inadequate preservatives. “Cosmetics are not expected to be totally free of microorganisms when first used or to remain free during consumer use,” according to a 1989 FDA report.

Serious contamination can occur, but it’s rare. Consumers need to be aware and use good hygiene - clean hands, clean face.

Oh, and that warning about not trying to put on mascara while you drive? That’s just common sense.

* The Federal Food, Drug, and Cosmetic Act defines cosmetics as “articles other than soap which are applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance.”

Tomorrow: The risk of contamination in makeup testers