The authors state that they chose to focus on mascara for a couple of reasons:
- It goes near your eyes, one of the places you reeeeeally don't want to fuck up.
- It's one of the most popular and frequently used cosmetics products.
- It's aqueous, increasing the risk of bacterial contamination.
- People bonk their mascara wands all over the place. (You're less likely to scrape your eyeshadow palette against the bathroom counter, in other words.)
|The mascara unibrow picture you didn't know you needed.|
Although preservatives such as parabens can substantially decrease the likelihood of bacterial contamination, both improper storage of makeup and even-more-improper not-throwing-it-the-fuck-away of makeup can turn the most belovedly vicious of preservatives into something inefficient. The results can be potentially irritating or, in rarer cases, dangerous.
The authors explain, "Staphylococcus epidermidis and Staphylococcus aureus proliferate in contaminated mascaras. The most common infections caused by these microorganisms occur especially when the surface of the eyeball is damaged, in other words, traumatized. Pseudomonas aeruginosa is the main agent of eye infections like conjunctivitis, keratitis and ophthalmitis, which may threaten the integrity of the eye, destroying tissues and damaging visual acuity. Infections by P. aeruginosa have been reported to occur due to contaminated mascara, trauma to the eye or bad hygiene. Fungi can also be found in contaminated mascaras, although less frequently than bacteria, being related to immune-compromised people or those who wear contact lenses."
Brazilian standards for bacterial contamination dictate the cosmetics should have no detectible presence of P. aeruginosa, S. aureus, or coliform bacteria. Coliform bacteria usually do not cause illness themselves (with the scarier E. coli strains as an exception), but they are used as in indicator of contaminated food, water, or products, because they are easy to both detect and culture, and because their presence usually indicates fecal contamination. Other bacteria can be present in low concentrations-- less than one unit forming colony per gram.
What Did They Do?
The authors recruited participants from a cohort of female students enrolled in a college-level pharmacy class. They conducted a questionnaire on use of expired makeup, collected makeup samples (recording the condition and percentage of products that were expired), and then stole their mascara to test to for P. aeruginosa and S. aureus, compared to a 'brand new' control.
The authors found that 97.7% of their sample admitted to using expired makeup. Mascara, eyeliners, lip products, and eyeshadow (in that order) were most likely to be expired, with 86.3% of students using an expired mascara. The researchers also found that 79% of the expired mascaras contained S. aureus and 13% contained P. aeruginosa. None of the brand spanking new mascaras were contaminated (duh. I wish they'd used non-expired-but-still-used mascara as a control, personally).
What Does It Mean?
In the United States, manufacturers are not required to print specific expiration dates on cosmetic products. So, how long should you keep your mascara? The FDA recommends tossing your eyelash goop after two to four months, or any time your mascara has gotten dried up and crusty. Additionally, a 2008 study by Pack, Wickham, Enloe, and Hill found that three months of mascara use was sufficient to contaminate 36.4% of a mascara tubes with various Staphylococcus species, as well as some miscellaneous fungi. Based on this, they conclude that three months should be the absolute maximum length of time that anyone uses a tube of mascara.
You should also go ahead and toss any products that change in consistency, smell, texture, or appearance, since this can be a sign that they are way over the hill.
Additionally, the European Union does mandate that products display a "period after opening" symbol shaped like an open jar for goods that last less then 30 months, which gives an approximate expiration date. Thus, if you have cosmetics that are sold in the EU (or, you know, if you happen to live there or something), you can always use that.
|This mouthwash has a PAO symbol indicating that you should toss it after 12 months.|
(Unfortunately, not-putting-contaminated-goop-in-your-immediate-eye-area doesn't seem to be the norm. Not only did the participants in this study overwhelmingly use expired mascara, the authors cited previous research which showed that about 92% of women keep their mascara for longer than six months.)
Besides throwing out any yucky, expired crap you have sitting around in your makeup bags, the FDA has a page on their site detailing the best ways to ensure eye product safety (link here). Among their suggestions are washing your hands before applying any cosmetics, keeping your products to yourself (makeup is one of the places where not sharing is caring!), avoiding eye makeup if you have an eye infection, and keeping your makeup-y things out of damp or warm areas (which means no storing makeup in the bathroom, guys). The FDA notes, "Consumers should be aware that expiration dates are simply 'rules of thumb,' and that a product's safety may expire long before the expiration date if the product has not been properly stored."
*Maybe just sexy to me.