This article was originally posted on Reddit on January 22, 2022. I’ve replaced links with archive links if necessary (and available) and made minor formatting changes and corrections, and integrated one comment of mine (with the testing process) into the post, but otherwise haven’t done any editing or updating.

[News] New sunscreen rating system for water resistance to be introduced in Japan starting from December 2022

According to this series of notifications, JCIA (Japan Cosmetic Industry Alliance), the organization that’s in charge of the SPF/PA rating system in Japan, is currently holding a remote briefing for their members this month to explain the introduction of their new rating system for the water resistance of sunscreens. The on-demand Zoom video of the briefing and a PDF handout are available here (password-protected, but the passwords are on that page). The video is available until February 2.

This post is based on the PDFs in the two links. I watched the first three minutes of the video but stopped because it seems like it’s a presentation based directly on the slides in the PDF handout.

Water resistance claims currently aren’t regulated in Japan. I often see the expressions “waterproof” and “super waterproof,” where the former usually means the product has passed a 40-minute water resistance test and the latter an 80-minute water resistance test, but there are also products that have passed longer (or shorter?) tests and still use these same expressions. [ETA that there are also brands that use the expressions “waterproof” and “water resistant” to indicate different levels of water resistance.] Major sunscreen brands like Shiseido Anessa and Kanebo Allie do specify what they mean, but there are many cases where it’s left ambiguous.

Disclaimer: I’m not a JCIA member, nor am I affiliated with the beauty industry in any way. I’m just a bilingual sunscreen enthusiast with no background in science. If anyone happens to know that I got something wrong, leave a comment!

The rating system

The ratings will be shown as follows, right next to the SPF ratings:

| In Japanese | Literal translation | English equivalent | What it means (in a nutshell) | | --- | --- | --- | --- | | UV耐水性☆ (or UV耐水性★) | UV Water Resistance ☆ (or UV Water Resistance ★) | Water resistant | Retained at least 50% of the full SPF rating after a 40 min. water resistance test (20 min. × 2) | | UV耐水性☆☆ (or UV耐水性★★) | UV Water Resistance ☆☆ (or UV Water Resistance ★★) | Very water resistant | Retained at least 50% of the full SPF rating after an 80 min. water resistance test (20 min. × 4) |

For those of you using screen readers, that’s “UV Water Resistance” with either one star or two stars. (Not sure whether they’re read as “stars” based on the glyphs above, so.)

Someone (rightfully) pointed out that “UV Water Resistance” is an inaccurate expression that technically refers to the water resistance of UV rays, whatever that might mean. JCIA went with the expression anyway (a) for brevity and (b) because expressions similar to “water resistant” and “very water resistant” have already been used in Japan without any standardization, and could cause confusion among consumers. (What they really mean is “water resistance of UV protection.”) They also explain that they went with stars rather than plus signs because “UV Water Resistance ++” looks like it’s somehow weaker than “PA++++.”

Rollout schedule

The new water resistance ratings will be printed on products released on December 1, 2022 at the earliest.
Sunscreens with water resistance claims that don’t have the new ratings are allowed to be shipped out until November 30, 2024 (so there’s a two-year grace period).
Products that are already on the market as of December 1, 2024 will be allowed to be sold until November 30, 2027, and are expected to be removed from the market entirely as of December 1, 2027.

ISO 18861

This new rating system (日本化粧品工業連合会紫外線防止効果に対する耐水性測定法基準〈2021年版〉) is based on ISO 18861:2020 - Cosmetics — Sun protection test methods — Percentage of water resistance and was published on October 15, 2021, following confirmations by the MHLW (Ministry of Health, Labour and Welfare) and the JFTC (Japan Fair Trade Commission). I think these are the standards that are also used/will be used in Europe (not entirely sure). The product’s water resistance is based on how much of the SPF is retained after water immersion, comparing the SPF with and without immersion.

There’s a flow chart showing the steps taken when testing for the “UV Water Resistance” ratings on the last page of the second PDF on the first link and more detailed information in the password-protected PDF on the second link, if you can read Japanese. There’s something about 90% reliability, but I’m not going to pretend I fully understand what they mean. (See next section.)

There’s also ISO 16217:2020 and the US FDA’s 21 CFR 201.327(i)(7). I think Japanese brands with more specific claims are (generally? sometimes?) currently basing their water resistance claims on the US FDA’s system, where the SPF rating is determined after either 40 minutes or 80 minutes of water immersion (see link for details). The US system will no longer be used in Japan.

This article describes ISO 16217 and ISO 18861 as follows:

ISO 16217, which specifies a procedure of water immersion for the in vivo determination of the water resistance of sunscreen products, and ISO 18861, specifying a procedure for evaluating the water resistance retention percentage, were both published this year [2020].

The testing process

I originally didn’t go into this because I didn’t want to risk making a mistake with the more technical details, but the testing process JCIA describes is basically as follows (and I’m sorry if I do get anything wrong):

Determine what would be the SPF before water immersion (“SPFis” where the “is” is in subscript) according to ISO 24444
Determine what would be the SPF after water immersion (“SPFiwr” where the “iwr” is in subscript) according to ISO 16217 and ISO 24444, I think? (I haven’t looked into ISO 16217)
In accordance with ISO 18861, the SPF retained (%WR) = (SPFiwr - 1) / (SPFis - 1) × 100. The average %WR must be greater than or equal to 50 (i.e., at least half) with at least 90% reliability (?)

And step 2 consists of the following:

Apply the product on the subject’s back and let dry for 15–30 minutes
Immerse in constantly circulating water for 20 minutes and air dry for 5–20 minutes (do not towel dry). For a 40 min. test, repeat twice. For an 80 min. test, repeat four times
Expose to UV rays and determine SPF

Step 1 (for “SPFis”) is the same thing as step 2 (for “SPFiwr”) but without the water immersion part.

I haven’t looked up the testing process in the EU, but I’m guessing it’s probably similar or the same.

Other notes

Products with SPF ratings based on ISO 24444:2010 are encouraged to retest with ISO 24444:2019 when determining the water resistance rating with ISO 18861:2020.
The ratings are specifically based on SPF retention after water immersion, and do not indicate sweat resistance. They’re also unrelated to resistance to sweat, tears, etc. in terms of maintaining the product’s appearance (as in makeup).
The JCIA is currently working on an updated version of their booklet on sunscreen (日本化粧品工業連合会編「紫外線防止用化粧品と紫外線防止効果」), as their SPF/PA rating systems are also being updated in accordance with ISO revisions.
JCIA isn’t a government organization so they can’t legally enforce these standards, but they say they’re working with the JFTC and expect all companies (including those that aren’t JCIA members) to comply in order to avoid losing consumers’ confidence in the industry as a whole.

I’ve discussed SPF and PA testing methods in Japan here.