Learn something new every Friday. Join 2,000+ nerds and satisfy your curiosity one question at a time with topics including science, technology, history, and more.
How are expiration dates in cosmetics determined?
How are expiration dates in cosmetics determined?
π The short answer
Expiration dates in cosmetics are determined by running a "stability test" which evaluates how well a product maintains its efficacy and safety while undergoing various environmental conditions, such as changes in temperature and light, over a set period of time.
π The long answer
Why cosmetics need expiration dates
First off, why do cosmetics β such as makeup, hair dye, skin cream, and deodorant β need expiration dates in the first place? It mostly comes down to the issue of microorganisms like bacteria and fungi (yeast and mold).
Here are some fun reasons why cosmetics start to break down and become unsafe to use:
- Dipping your fingers into a product and using applicators (like mascara wands) adds microorganisms each time you use them
- Preservatives break down over time, allowing microorganisms to grow
- Exposure to moisture (like in a steamy bathroom) also make it easier for microorganisms to thrive
- Products can dry out, causing them to harden and crack
- Temperature changes and exposure to air and sunlight can cause changes in texture and color.
All of these issues (and more) can lead to your favorite cosmetic to lose their efficacy over time and become a treasure trove of bacteria, yeast, and/or mold. So it makes sense that government regulations would dictate including an expiration date on the label, like we do with food.
Government regulation (?)
Here's where it gets interesting. If you're in the United States, you might be surprised to find out that, according to the Food and Drug Administration:
However, the European Union does require all cosmetics products to undergo a standardized "stability test" to determine both the estimated shelf life and the Period After Opening.
Shelf life vs. Period After Opening
In the EU, all cosmetics are tested for shelf life and PAO. What's the difference?
- Shelf life is how long a product can be used β whether or not a consumer opens the container.
- Period After Opening (PAO) is how long a product can be used after a consumer opens the container.
If a shelf life is determined to last longer than 30 months, a manufacturer does not need to include it on the container. But they must include the PAO period. Conversely, if a shelf life is determined to be under 30 months, a manufacturer needs to include the shelf life period on the container and a PAO is not necessary.
What is a cosmetic stability test?
A stability test is an evaluation of how a cosmetic retains its efficacy and safety in a variety of environmental conditions for a set period of time. The goal is to recreate what happens to a product while it gets shipped, arrives on store shelves, and sits in consumer's bathrooms.
The product undergoes changes in light and temperature and is evaluated at set intervals to see if its physical, chemical, and performance has changed (if at all). Characteristics such as color, odor, pH value, viscosity, and microbial content are monitored.
If a product is found to have a shelf life lasting beyond 30 months, the PAO is calculated (rounded to the nearest 3-month interval) according to various parameters, such as water content, frequency of use, whether it is rinse-off vs leave-on type of product, and preservative content.
---
|
--- Thanks for reading this week's newsletter! If you have any thoughts, questions, or favorite GIFs, my inbox is always open. Just hit reply to send me a note! :) All my best, |
βSources for this week's newsletterβ
π Book of the week
π Catch up on other curious questions
- βWhat do our recyclables become?ββ
- βWhat does "natural flavors" mean?ββ
- βHow should you charge your devices to maximize battery life?ββ
P.S. π€ Do you have a question for the newsletter? Click here to submit your question. (or reply to this email!)
|
π‘ Today You Should Know
Learn something new every Friday. Join 2,000+ nerds and satisfy your curiosity one question at a time with topics including science, technology, history, and more.
Why do coconuts have water? This question came from a reader submission (thanks Akaal!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer Coconuts carry water because theyβre designed to launch a seed with an immediately usable food reserve. This liquid endosperm supports early growth, while the meat provides sustained fuel as the seedling develops. π The long answer Coconuts are an unusual fruit (yes, they are a...
Why does alcohol make you feel warm? π The short answer Alcohol feels warming because ethanol lowers the activation threshold of heat-sensitive receptors, fooling your nervous system into thinking youβre overheating. Your body then attempts to cool itself by dilating blood vessels and sending warm blood to the skinβs surface. π The long answer Normally, a beverage needs to be warm to make you feel warm β but not alcohol. Whether it's a burning sensation from taking a shot or a more gentle...
What does "feels like" temperature mean? This question came from a reader submission (thanks Nikilah!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer βFeels likeβ temperature reflects how wind and humidity change how cold or hot the air feels to the human body. Wind chill increases heat loss in cold conditions, while the heat index reflects how humidity interferes with sweating in hot weather. π The long answer...