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    Over 80% of sunscreen performed below their labelled efficacy (2020)

    (www.consumer.org.hk)
    230 points mgh2 | 11 comments | 06 Sep 25 19:57 UTC | HN request time: 0.204s | source | bottom
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    Aurornis ◴[06 Sep 25 23:11 UTC] No.45153756[source]▶
    This is a topic where the details matter a lot. A sunscreen which is labeled SPF 50 but performs at SPF 45 is such a minimal difference that it would be impossible to notice in the real world. The variance of your application technique and applied thickness would actually matter more. There is also a lot of testing variability, so if a sunscreen rated to block 98% of certain rays only gets 97% in the test that would be acceptable in the real world, but it would get counted for this clickbait headline.

    If a sunscreen comes with a high SPF rating and performs close enough in random testing (which is hard to replicate) then I wouldn’t have any concerns in the real world.

    The body of the article has some more details about how the number of majorly deficient brands was much smaller, but that makes for less clickbaity headlines:

    > The measured sunscreen efficacy of 4 models were below SPF15, of which 2 were sunscreen products with very high protection i.e. labelled with SPF50+

    Knowing which 2 brands were labeled SPF 50 but performed below 15 would have been helpful, but the article is not helpful.

    replies(5): >>45153888 #>>45154339 #>>45154418 #>>45154691 #>>45156970 #
    1. hn_throwaway_99 ◴[07 Sep 25 01:02 UTC] No.45154339[source]▶
    This is related to an article from yesterday, https://news.ycombinator.com/item?id=45145624, about the Choice Australia investigation that found that some sunscreens (named in that article) provided around SPF 4 when it was labeled as SPF 50+. It is a big deal because many people (like the 34 year old woman in the article who had skin cancer removed from her face) use a specific brand for years, believing it to be as effective as the label proclaims.
    replies(1): >>45154435 #
    2. MangoToupe ◴[07 Sep 25 01:18 UTC] No.45154435[source]▶
    As someone who burns extremely easily, I'm confused how this happens. I can feel the difference immediately; as little as ten minutes in direct sunlight makes me tinged red; and if I don't cover every inch I can tell which parts I missed the next day. If it doesn't work why would you use it?!

    I do have sympathy for those with dark(er, which is basically everyone) skin who may not be able to directly tell the efficacy.

    My concern is that mineral sunscreens are difficult to apply and leave a film on the skin (which is the entire point, I guess?); i hate that feeling, so I use chemical sunscreens. I'd bet that some of them have very nasty long-term side effects. So in the end i almost always go with trying to cover my skin with clothes/shade/whatever if at all possible.

    replies(4): >>45154694 #>>45154855 #>>45155052 #>>45156533 #
    3. daneyh ◴[07 Sep 25 01:57 UTC] No.45154694[source]▶
    Why are you confused? You can be (and are likely) doing deep, long term damage to your skin even if your skin doesn't have an immediate reaction to sun exposure (i.e sunburn). This is a key point that cancer council australia are constantly trying to drill into peoples heads.
    replies(2): >>45155056 #>>45155889 #
    4. hn_throwaway_99 ◴[07 Sep 25 02:29 UTC] No.45154855[source]▶
    > I'd bet that some of them have very nasty long-term side effects.

    Why?

    replies(1): >>45155047 #
    5. MangoToupe ◴[07 Sep 25 03:04 UTC] No.45155047{3}[source]▶
    Mineral sunscreen works very intuitively, and feeling that grime makes sense. If you have dark skin, many if not most mineral sunscreens will be quite visible. You're trying to literally cover your skin with a screen and you should be able to feel it and probably see it. You can also wash it off quite easily (to the extent it's a problem at the beach).

    Chemical sunscreen that avoids this is designed to sink into the skin like lotion. So there's something literally in your skin blocking uv or it won't work very well. I'd say this increases the odds of circulating something carcinogenic or otherwise toxic into your bloodstream.

    replies(2): >>45155432 #>>45155488 #
    6. Aurornis ◴[07 Sep 25 03:06 UTC] No.45155052[source]▶
    Many people don't burn so quickly.

    They could also have a lot of short exposures, like someone who is only outside for 5-10 minutes at a time but 2-3 times per hour every day, as was the case with one of my early jobs that involved walking between buildings a lot.

    A common mistake to make is believing that if you're not burning, you're not accumulating damage.

    7. ◴[07 Sep 25 03:07 UTC] No.45155056{3}[source]▶
    8. conradev ◴[07 Sep 25 04:36 UTC] No.45155432{4}[source]▶
    TIL that chemical sunscreen does go into the bloodstream: https://www.fda.gov/news-events/fda-brief/fda-brief-fda-anno...
    9. dkga ◴[07 Sep 25 04:52 UTC] No.45155488{4}[source]▶
    Recently I went into the whole rabbit hole of sunscreens as I moved to Brazil from Switzerland, and now need to use it everyday (ok I know, theoretically also back home would be nice!). So I bought a mineral sunscreen. It feels "healthier" but also doesn't have that good lotion-like characteristic that you can just apply and forget. I really hope sunscreen companies are able to crack this one up.
    10. ◴[07 Sep 25 06:31 UTC] No.45155889{3}[source]▶
    11. scrollop ◴[07 Sep 25 08:50 UTC] No.45156533[source]▶
    Chemical sunscreens:

    Endocrine disruption: Oxybenzone (BP-3) and related benzophenone-type UV filters have demonstrated endocrine-disrupting properties in vitro and in animal studies, with some human data suggesting possible hormonal alterations and increased risk of uterine fibroids and endometriosis.[6-7] However, most human plasma concentrations are much lower than those producing effects in bioassays, and current evidence suggests low intrinsic biological activity and risk of toxicity for most organic UV filters except oxybenzone.[8-9]

    Contamination: Benzene, toluene, and styrene have been found in a large proportion of sunscreen products, likely due to manufacturing processes rather than the UV filters themselves. Benzene contamination is a particular concern due to its established carcinogenicity.[1]