Waterproof Sunscreen: Real or Fake News?

Confusion with Sunscreen Labels

Scientists have discovered that excessive exposure to sunlight can have deleterious effects on your skin.^[1] If you’re like most people, you know all too well the agony that comes with having a sunburn and real firsthand experience with the negative effects of sun overexposure. Fortunately, we have sunscreen to aid in protecting us.^[2] Unfortunately, there has been a lot of confusion surrounding the way sunscreens are labeled.

The title of this article is a prime example because there is no such thing as “waterproof” sunscreen.

Water Resistant vs Waterproof Sunscreen

In 2012 the Food and Drug Administration (FDA) ruled that for over-the-counter sunscreen products, manufacturers are no longer allowed to make claims such as: “sunblock,” “sweatproof,” and “waterproof.” The FDA determined such claims on sunscreen products are false and could be misleading consumers by “overstating” their effectiveness.^[3,4]

Words like “waterproof” or “sunblock” suggest that the sunscreen is completely unaffected by water or offers total protection from the sun – both of which are untrue. Instead, manufacturers are mandated now to label their products as “water resistant” and to state when swimming or sweating if the sunscreen remains effective for either 40 minutes or 80 minutes.^[3,5]

How Is Water Resistance Determined?

The FDA has put forward specific procedures/protocols that companies must follow in order to label a sunscreen as “water resistant (40 minutes)” or “water resistant (80 minutes).”^[3] For example, the sun protective factor (SPF), which is a measure of how well sunscreens can protect from the sun’s UVB sunburning rays, is determined after completing either 40 or 80 minutes of water immersion.^[6]

The set water immersion procedure is to be conducted in a whirlpool, indoor freshwater pool, and/or hot tub maintained at 23°C to 32°C. The FDA takes it as far as to also require the pool and air temperature as well as the relative humidity where the water immersion procedure is taking place.^[3]

Water resistant (40 minutes) testing requirements

1. Apply the sunscreen as designated by the FDA
2. Have subject perform moderate activity in water for 20 minutes
3. Rest out of water for 15 minutes – without toweling test site
4. Then again perform moderate activity in water for 20 minutes
5. Allow the test site to dry completely without toweling
6. Finally, apply the SPF standard and expose test site to UV doses as designated by the FDA

Water resistant (80 minutes) testing requirements

1. Apply the sunscreen as designated by the FDA
2. Have subject perform moderate activity in water for 20 minutes
3. Rest out of water for 15 minutes – without toweling test site
4. Perform moderate activity in water for 20 minutes
5. Rest out of water for 15 minutes – without toweling test site
6. Perform moderate activity in water for 20 minutes
7. Rest out of water for 15 minutes – without toweling test site
8. Perform moderate activity in water for 20 minutes
9. Allow the test site to dry completely without toweling
10. Finally, apply the SPF standard and expose the test site to UV doses as designated by the FDA.

Why Should Water Testing of Sunscreens Matter?

Well, first off, there is nothing more powerful than being an informed consumer. Knowing what labels on products both mean and represent gives you the ability to choose the product most suited to your needs.

For example, in the procedure for sunscreen companies to test water resistance, the participants dry off out of the water without toweling. However, in everyday life, people tend to dry off with a towel every time they come out of the water. Subtle nuances like these are critical to catch so consumers can recognize that they may be scrubbing off their sunscreen each time they towel and thus need to constantly reapply after they get out of the water.

Secondly, there is no requirement that the water testing is done in chlorine or in beach conditions. So the testing is not as accurate if you are having fun with the waves washing over you at the beach or if you are splashing around in the neighborhood pool. In some cases, chlorine may even change how your sunscreens perform.

Furthermore, sunscreen companies are not actually required to confirm the legitimacy of “sweat resistant” claims. "Water resistant" means that you still need to reapply sunscreen after swimming or sweating.  Reapplying sunscreens and understanding where the testing falls short is key enjoying the outdoors and reducing some of the negative effects of the sun’s UV radiation when in the water.

Practical Points

• There is no such thing as “waterproof” sunscreen, only water “resistant” sunscreen
• Water resistant testing is probably NOT relevant to how you typically use the sunscreen
• Remember to reapply your sunscreen EVERY time you get out of the water
• "Water-resistant" means 40 minutes of testing and "Very water-resistant" means there was 80 minutes of testing