Sunscreens have frequently been attacked by various people, stirring up all sorts of controversies. In some ways, the controversy has veered off in an unhelpful direction, taking on an almost political or factional element. We want to review specific claims, and discuss which ones have evidence backing it.
Most dermatology associations, including the American Academy of Dermatology, are pro-sunscreen.1 The overwhelming majority of dermatologists believe that sunscreen is helpful and essential in protecting your skin from skin cancer and premature skin aging. However, this opinion is far from a consensus among the general public.
Time has an article questioning sunscreens, and a quick search on google “are sunscreens safe?” will net you thousands of articles that attack sunscreen. Whatever your views are on sunscreen, it’s important to focus on the issues without getting distracted by narratives and nuances.
So What’s the Issue?
There is an endless number of possible criticisms that are leveled at sunscreens (much like anything else), but some are more credible than others. We’ve compiled the concerns that come up most frequently or have some reasonable basis.
It’s unnatural: This is an alarmingly non-specific and nebulous claim but is a compelling argument for many people. This seems to be a prevalent theme among many people who are opposed to sunscreen. Appeal to nature is, indeed, appealing to many people, even though it is an arbitrary distinction. All sorts of pseudo-science and conspiracies with varying levels of credulity pop up and become mainstream (anti-vaxxers, alternative medicine), mainly due to an underlying assumption of some naturalistic fallacy.
There’s not much to say on this topic, except that there are many “natural” things that are hazardous to our health, and there are many “artificial” things that are perfectly healthy. Most of us implicitly associate substances found in nature with wholesomeness while associating synthetic substances with toxicity. To say that sunscreens are unnatural (so are vaccines) is an appeal to emotion and not a rational position itself.2
Vitamin D deficiency: This concern has some merit. Vitamin D deficiency is a legitimate concern for many people in North America, especially among African Americans.3 As humans cannot acquire sufficient vitamin D from food sources, we either need sun exposure to trigger our body to produce the necessary vitamin D, or we need to get them via vitamin supplementation.
The argument is that while sunscreens help reduce exposure, they may increase vitamin D deficiency as it blocks a requirement for the body to produce vitamin D. This makes logical sense. Some studies suggest that there may be a connection here.4 However, the current evidence is mixed.5
Most dermatology associations take the position that vitamin D should be acquired mainly via vitamins for those that are deficient. Notably, the Canadian Dermatology Association endorses this view.6
Nanoparticles: Physical blockers use titanium dioxide or zinc oxide to reflect off the sun’s rays. Some of these sunscreens use nanoparticles. Some scientists have voiced concerns about the nanoparticles potentially passing through the skin barrier into the bloodstream.
Most scientists take the charitable view that further study of the potential effects of nanoparticles is warranted. However, given the clear evidence of skin cancer risks and the impact of sunscreen in reducing this risk, the use of sunscreen is justified.7 The Environmental Working Group (EWG) also agrees that applied topically, nanoparticles used in sunscreens are unlikely to be harmful.8
Environmental Concerns: We wrote about the adverse effect of oxybenzone-based sunscreens on coral reefs. We now have a relevant update: Hawaii has taken the step to ban sunscreens containing oxybenzone and octinoxate.9 This isn’t a wholesale criticism on sunscreens – but it does highlight the importance of continuous testing.
Increasing Skin Cancer Rates: We know that skin cancer incidences are increasing for the most part. Skin cancer education is also on the rise, as well as sunscreen use. Put two and two together, and sunscreen causes skin cancer, right?
Correlation does not imply causation. Importantly, there is a delay effect – similar to global warming – which incidentally also doesn’t help. As most skin cancers predominantly affect the elderly population over 65 years old, a large proportion of skin cancers we are seeing are not from the current generation (that uses more sunscreen) but from a previous generation which was far more suntan happy.10
So is it all Fear Mongering?
Some of it surely is – especially those that take on a tone of implying (or in some cases explicitly stating) that dermatologists or skin cancer organizations are in the business of selling sunscreens knowing that they are harmful.
First, science is always questioning itself and revising its position in light of new evidence – otherwise, it’s no different from dogma. It’s a good thing that scientists continue to question sunscreens and their potential to harm humans, animals, or the environment.
Second, there is some legitimate concern about overstating the efficacy of sunscreens and becoming over-reliant on sunscreen for protection, both of which can increase harm rather than decrease it. There are many challenges with sunscreen education – and one of the more pressing concerns is people thinking that they are invincible with sunscreen on, thereby staying out longer in the sun.
- Not applying enough sunscreen (most people use 25-50% of what they should according to the American Association of Dermatology)11
- Not reapplying appropriately (very few people reapply sunscreen even after swimming or being out in the sun for hours)
- Being reckless – staying out too long in the sun
It’s important to remember that while sunscreens are an essential tool in protecting ourselves from sun exposure, it is only one aspect of sun protection. Applying sunscreen does not make you immune to sun exposure. First, you need to understand that sweat, wind, water, or simple friction can and will degrade sunscreen. When you’re out there, you need to reapply sunscreen every few hours to ensure that you are protected. It’s also important to understand that sunscreen isn’t magic – it can backfire if you allow sunscreen to be an excuse to eschew your other sun protection habits.
2This isn’t to say that artificial substances shouldn’t be tested continuously. There’s a reason to check for safety continually – especially long-term safety when we may not fully understand the consequences.