The problem with sunscreen

Most of us will slather on plenty of sunscreen when likely to be exposed to the sun’s powerful ultra violet rays. Sunshine can be a great mood-booster, and provides vital vitamin D, but without some UV protection we’re also susceptible to skin damage like wrinkles, skin discolouration and even skin cancer.

SPF: what it does (and doesn’t) mean

The sun’s UV (ultraviolet) rays can be classified as UVA or UVB. UVA has a longer wavelength and is most associated with skin aging and pigmentation changes, while UVB waves are shorter and linked to sunburn. While most skin cancers are UVB-related, both UVA and UVB have been implicated.

UVB rays reach only the epidermis (the outer layer of the skin). The SPF (Sun Protection Factor) shown on a product indicates how well it can protect skin specifically from these burning rays. Introduced in 1974, when cancer concern was focused solely on UVB, the SPF indicates the fraction of all UVB rays that will still reach the skin (i.e., SPF30 allows through only one-thirtieth).

Unlike UVB, UVA rays penetrate both glass windows and cloud cover, and can reach the deeper empidermis. Their intensity remains more or less constant all year round. UVA protection, which we now understand we all also need to avoid cancers, is not part of the SPF.  ‘UVA’ inside a circle indicates that the ratio of UVA protection is at least one third of that of the UVB, and therefore in line with EU guidance. Many products sold in the UK use a five-star rating which represents UVA protection as a percentage of the UVB protection, with five indicating that this is 90% or above. Look for four or five stars. (Outside the UK, a Japanese system is sometimes used, with a PA-rating indicating UVA protection out of four, although its reliability has been questioned.)

The term “broad spectrum” sometimes highlights sunscreens offering both types of UV protection, but it’s worth checking the details regardless. The NHS recommends choosing SPF30 or more and at least four-star UVA protection. A sunscreen with less than SPF15, or without a UVA rating, won’t necessarily protect you at all. Finally, avoid sprays: much of the sunscreen won’t even reach your skin, becoming an instant pollutant, and many ingredients are likely to pose a health risk if inhaled.

How does sunscreen work?

There are two types of sunscreen, which work in different ways. A chemical one allows UV light to be absorbed into the skin, where the active organic chemicals (most typically oxybenzone, avobenzone, octisalate, octocrylene, homosalate and/or octinoxate) convert it into infra-red heat, which then dissipates. Chemical ones tend to spread more easily onto the skin and don’t produce a visible whitening effect. However, you need to put a chemical sunscreen on well before you go outside to give it a chance to work.

The more traditional mineral type contains micronised particles of zinc oxide and/or titanium dioxide, which sit on the skin’s surface to physically block the UV rays. A mineral barrier protects you as soon as you apply it, but is harder to blend in, and can become visibly white as UV light is reflected away. Manufacturers have begun to use the mineral in a micronised form to avoid this issue.

Both types will need to be reapplied frequently to maintain protection: the mineral ones can rub of while the chemical ones disappear into the skin. Many sun products rely on a blend of various chemical and mineral screens to make up their advertised protection level, especially where legal limits apply to specific ingredients. Unfortunately, when you swim or shower, any type gets washed off, and will end up in waterways and oceans.

What’s the problem with the chemical ones?

Because of the way they work, chemical sunscreens raise the skin’s internal temperature, which can cause prickly heat, and sometimes discolouration. They also end up in the bloodstream. Oxybenzone, also called benzophenone-3 or BP-3, has been implicated in contact and photocontact allergic reactions, hives, and more seriously, endocrine disruption. Ironically, it’s also been linked to skin damage via antioxidant deactivation.

A 2008 report by the US Center for Disease Control pointed out that oxybenzone can react with chlorine, producing chloroform which is significantly more toxic and then concentrates in swimming pools. Wastewater treatment plants don’t effectively remove it from our drinking water, and it’s been found in fish, so you don’t even have to use it to be exposed. The CDC found oxybenzone in the urine of 97% of Americans. Alternatives like avobenzone or homosalates are not particularly better, but the ubiquity of oxybenzone in sun products has led it to be more widely investigated.

PABA, also called aminobenzoic acid and para-aminobenzoic acid, became a popular sunscreen in the 1970s. Now generally avoided due to its tendency to irritate skin and stain clothing, it’s been banned in both the EU and Canada due to links to thyroid-disruption, although levels are only limited in the USA. It’s sometimes replaced by derivatives like OD-PABA, however, which doesn’t itch or stain clothing so much, but has been linked to endocrine disruption.

We need to talk about coral

Despite these worrying implications, it’s the impact of chemical sunscreen on marine life that’s finally led to an outcry. Coral reefs around the world, known as ‘the rainforests of the sea’, provide a quarter of all marine species with habitat and food. Their rapid depletion is one of our planet’s major biodiversity crises. Corals stressed by rising water temperatures can throw off the symbiotic algae that naturally surround them, exposing bone white skeletons in a process known as bleaching.  Climate change is causing more and more mass-bleaching events, a problem only exacerbated by unsustainable fishing practices, land-based pollution, coastal development, diseases and invasive species. Around half the worlds’ corals may have already been lost, and reefs could disappear entirely by 2070 if current trends continue.

Chemical sunscreens contribute to this damage. While sunscreen washed off in the shower is likely to end up in the sea eventually, higher concentrations of oxybenzone are undoubtedly found in coastal areas where bathing is common. In May 2022, Stanford University researchers, publishing in Science, revealed that oxybenzone makes sunlight toxic for corals and other marine life. The anemones and corals in their trials metabolized it into a substance which then reacted with sunlight to form a potent toxin. They also demonstrated that the algae living in corals were protecting their hosts by sequestering these phototoxins within themselves. Bleached corals are therefore more vulnerable to both disease and environmental shocks, including those created by oxybenzone, which include hormone disruption leading to larva deformation. Although less well-researched, octinoxate is widely associated with similar concerns.

What about Reef Safe products?

All this has led to a number of bans on oxybenzone and octinoxate in island resorts including the U.S. Virgin Islands & Hawaii, as well as Palau and Dutch-administered Bonaire. The Hawaiian ban explicitly prohibits only oxybenzone and octinoxate, but moves are now being made to also ban avobenzone and octocrylene.  It’s worth noting that there is no independent Reef Safe or Reef Friendly certification available. Brands labelled ‘reef-safe’ or ‘reef-friendly’ may be compliant only with the limited current Hawaiian ban. The Stanford researchers, however, point out that since they work in the same way and haven’t really received the scrutiny aimed at oxybenzone, there’s no real reason to assume the other chemical sunscreens are any safer. It’s fairer to say that we don’t know for sure that they will damage coral and other marine species (or what they’re doing to us!). So what it comes down to is whether or not you’re behind the wait-and-see strategy favoured by the chemical industry lobby.

Based on existing research on coral bleaching and a local study into the effects of chemical sunscreens on marine life including jellyfish, Palau, the first whole nation to ban them, prohibits eleven types of typical ingredient, including any and all benzophenone-based chemicals, of which oxybenzone is just one of those listed. In the same way, octinoxate, octocrylene, avobenzone and homosalate are banned both individually and along with any similar chemicals scientists might formulate to replace them. PABA derivatives are subject to a similar blanket ban. Meanwhile, the chemical industry in places like the US and the EU continues to produce new variants which all need individual investigation and certification, while quibbling about tolerable levels for a human. A 2010 University of Zurich study of lactating mothers found at least one sunscreen chemical in 85% of their breastmilk samples. Palau’s response is the only one that seems to us to make any real sense.

So what can I use?

A barrier of zinc oxide has been effectively used to protect skin from burning since the 1940s. The CDC report concluded by suggesting that sunscreen actives such as micronized zinc oxide and titanium dioxide are also now ‘more effective’ than the chemical alternatives. Mineral sunscreen is also safer for people with sensitive skin, eczema or melasma. The main issue with these ‘physical’ sunscreens is that they can leave a white ‘cast’ on the skin. Now that some dermatologists recommend wearing sunscreen daily, this has been raised as a cosmetic problem, particularly for dark complexions, leading in part to the development of the chemical versions.

Nano vs. ‘non-nano’

Perhaps unsurprisingly, many brands have also sought to make their mineral sunscreens more absorbable and less likely to be visible in use. This has led to the use of micronized particles which can include nanoparticles. A nanoparticle is one small enough to be measured in nanometres (i.e., one-billionth of a metre), so smaller than 100 nanometers. Any larger particle is classified as ‘non-nano’. It’s worth noting that most research into nanoparticles in sunscreens suggests no adverse health effects. However, much about the implications of nanotechnology remains unknown. Although nanoparticles can occur naturally, synthetic ones are a very recent development. At the nanoscale, so-called quantum effects may come into play, with substances behaving more as individual atoms and molecules than as larger materials. We don’t yet know how our bodies, or those of other organisms, will interact with them. Research into the nanoparticles in diesel fumes showed them not just damaging the lungs, but crossing cell membranes, getting into the blood and reaching other sites such as the liver or heart. For some, the use of nanoparticles seems too risky for the sake of a cosmetic benefit. Non-nano particles, which are not tiny enough to penetrate the skin, may well be safer, which is why you see ‘non-nano’ highlighted on labels.

The Coral Reef Alliance recommends using a sunscreen with non-nano titanium dioxide or zinc oxide as the active ingredient. However, the Stanford scientists point out that their safety or otherwise for coral has yet to be proven. Dispiritingly, research suggests zinc oxide might contribute to coral damage by disrupting algae photosynthesis. It does seem to do slightly better at screening out UVAs, however. Titanium dioxide has been found not to cause coral bleaching, yet is linked with potential danger to other forms of marine life. Nevertheless, a non-nano mineral sunscreen seems our best option as we wait for the research to develop further. Many formulations combine zinc and titanium.

Karanja Oil

This comparatively new ingredient isn’t yet certified as an effective sunscreen, although it’s been claimed to provide a natural SPF of around 10. Since this wouldn’t be enough alone anyway, it may be used to supplement other sunscreen actives. 

Preservatives and other additives


Parabens are added as a preservative to many skincare products, as well as some processed foods and pharmaceuticals. Their many names include methylparaben and butylparaben, but always end in ‘paraben’. Findings based on studies done so far link them to hormone disruption and other health concerns. Fairly low levels of butylparaben have been shown to kill coral. For this reason, sunscreens, along with other lotions and creams, may advertise when they are Paraben Free. In 2015 the EU banned propyl- and butylparaben for personal care products after the European Commission’s Scientific Committee on Consumer Safety was unable to prove them safe. They’re therefore illegal in UK sunscreens. They’re similarly banned in the 10 Southeast Asian countries covered by the Association of Southeast Asian Nations (ASEAN), along with phenylparaben, benzylparaben and pentylparaben. Palau has explicitly banned all and any parabens.

There is a valid argument for using preservatives in sunscreen: as well as extending shelf life, they prevent the growth of mould and any bacteria contributed by the fingers. That said, there are viable natural alternatives including grapefruit seed extract. You could also consider a preservative-free cream, which is less susceptible to bacterial contamination than a similar lotion because it contains less water.

Other chemical additives

Many other typical chemical ingredients are worth avoiding where you can. Octisalate, used to stabilise chemical sunscreens and stop them washing off, has been linked to similar problems. Unsurprisingly, it’s also banned in Palau, along with all other salicylates. Use a mineral one and it won’t need octisalate.

Retinyl palmitate is a storage form of vitamin A, frequently-used in cosmetics for its demonstrated ability to improve the visible signs of aging and hyperpigmentation. Scientists have suggested it may become carcinogenic in combination with UV-A rays. The natural response would seem to be to avoid it, at least in sun products. Triclosan is a once-popular antibacterial, now widely banned from handwashes, but which could still turn up in a sunscreen as a secondary preservative.


Fragrance or Parfum is a rather worrying blind for a whole raft of potential ingredients, which manufacturers have been allowed to hide since the days when the only worry about synthetic chemicals was that a competitor would steal your formula. Potential components include phthalates, inconsistently banned worldwide and a focus for consumer concern. Fragrance-Free doesn’t actually mean that the product won’t smell nice, or at all, it simply indicates that there’s not a cocktail of dubious chemicals hiding behind the word. Sunscreens can be more transparently fragranced with natural ingredients like essential oils, although it’s worth noting that some of these can bring their own problems.

Palm oil

Palm oil may seem benign by comparison, but it’s known to be farmed in an extremely unsustainable way, and most ethical shoppers will seek to avoid it due to concerns surrounding its impact on the rainforest, wildlife and our climate. This can be trickier than you might think, though. Most palm-related ingredients in sunscreen are derivatives with names that don’t include ‘palm’. The best strategy may be to buy a brand that has a published palm oil policy. However, in June 2022, SunButter launched the first ever sunscreen product to bear the international Palm Oil Free Certification Trademark (POFCAP), introduced specifically to cut through this lack of transparency. Look out for the trademark on more products!

Animal products

As with other personal care products, sunscreens also often contain animal derived ingredients such as keratin and lanolin, as well as honey and beeswax. Many companies advertise ‘Vegan Friendly’ individual products, but for a product made by a reliably vegan company, look for the Leaping Bunny logo.

None of the above is necessary in a sunscreen. Rather than waiting for more proof of precisely how damaging these unnecessary additives really are, why not support the businesses who are leading the move away from them?


Perhaps the most obvious way that sunscreens are affecting the oceans is through plastic pollution. Sunscreen is particularly difficult to obtain without a plastic bottle or tube, at least among those products found in high-street chemists. An estimated 120 billion units of packaging are produced every year by the global personal care industry. Much of this is non-recyclable or only partially recyclable plastics. Think about how you’re going to recycle the container before you buy. Alternatives to look out for include glass, aluminium or plant-based plastic substitutes.

At least there’s no need for plastic microparticles in a sun lotion, though, right? Well, not as “exfoliating beads”, but they’re still widely used in sun protection products. Dutch campaign group Plastic Soup reviewed the ingredients of 2,042 suncare products in 2021 and found either definite or suspected plastic ingredients in 83%. Ingredient names include giveaway words like polyester, polyurethane, polyethylene and acrylate. There’s also another ingredient, UV-328, often used with plastics as a light stabiliser, which can also be used to contribute to the sunscreen effect. A widespread ban of UV-328 as a pollutant is in the pipeline, with many industries phasing it out for its persistence and toxicity, which is to say, it’s legal at time of writing. So, difficult as it may be to believe, you may also need to look out for an explicitly plastic-free suncare product.

Does sunscreen really give you cancer?

It may be time for a major rethink on sunscreen. Some argue that the confidence sunscreen gives us could be contributing to skin cancer rates, particularly among older generations. The sun has become more dangerous, and it’s not reasonable to behave as if this has been completely solved by sunscreen manufacturers.  Even an SPF50 product only claims to screen out half the sun’s rays.

A 2019 article in the Journal of the American Academy 0f Dermatology admits there’s no conclusive proof that sunscreen use prevents cancers like melanoma in otherwise healthy people. A 2000 study conducted in Sweden showed higher rates of melanoma in individuals who wore sunscreen. The authors concluded that they probably spent more time in the sun, increasing their risk, possibly also forgetting to reapply appropriately. It also seems possible that the range and number of ingredients in many modern formulations, in combination with the contribution of the sun itself, is having unanticipated consequences. Either way, this seems an argument for a change of attitude.

What to do

While it is something we all need to continue to use, if only to avoid painful sunburn, staying in the shade between 10am and 3pm is a much more reliable way to avoid all the effects of UV rays. If you do go out in the sunshine, take your own shade in the form of a broad brimmed hat or umbrella and sunglasses.

Choose a non-nano, mineral-based sunscreen with the shortest available list of other ingredients. You can reduce the amount of skin you’ll need to cover in it by wearing UPF (ultraviolet protection factor) sunwear, rash guards, or simply normal clothes. A thick T-shirt has an estimated SPF of 30, while a linen shirt is closer to 50. And at least you’ll know whether or not it’s still there.

Also think about nurturing your natural sun resistance. Staying hydrated will help. Consider your diet, and maybe investigate oral supplements like tyrosene, carotene and Vitamin E, which can increase your sun tolerance.

A final thought from Ethical Consumer: while it is definitely sensible to choose the sunscreen least likely to cause harm, you could do the coral a greater favour by not taking a flight to that tropical destination.

Unfortunately, none of this will protect you from the range of synthetic toxins already in your own environment (and body!) or the coral and other marine life from the sun products other people are using. Support any campaigns for more widespread bans – if these only happen, frustratingly, one named ingredient at a time, they’re still worth a mouse-click. And vote with your purse – if everyone suddenly stopped buying anything containing chemical sunscreens or additives, the mainstream brands would be forced to take notice.