Sunscreens - more harm than good?

Australia has a uniquely high level of regulation for sunscreens.

Primary sunscreens and secondary sunscreens with SPF15 or greater are regulated as therapeutic goods by the TGA.⁴ These sunscreens must only contain permitted sunscreen ingredients, must meet rigorous manufacturing requirements and must meet specific testing, labelling and advertising requirements. 

All other secondary sunscreens are regulated as cosmetics by the national industrial chemical regulator AICIS. Secondary sunscreens are required to list all intentionally added ingredients on the label, as regulated by the Australian Competition & Consumer Commission (ACCC).

The TGA and AICIS monitor and review the safety of sunscreens and their ingredients, as do other regulators around the world. For example, the TGA actively monitors and tests therapeutic sunscreens available on the Australian market to make sure they comply with safety, quality and efficacy requirements.

Some common sunscreen ingredients, such as oxybenzone, continue to be the target of unfounded health claims. To read more about these myths, please click see Oxybenzone – and endocrine disruption?

The TGA reviewed the safety of seven UV filters in February 2025, to see if there was any new information on skin penetration or toxicity that would change how these ingredients are used. The review identified some ‘theoretical risks’ associated with frequent sunscreen use over a lifetime but said these were ‘minimal compared with the proven dangers of prolonged sun exposure and sun burn’.⁵

‘Sun protection, which includes the use of sunscreen, remains the best way to prevent skin cancer.’⁶ 

So Australia’s main sunscreen regulator thinks we should keep using sunscreen.

Conventional (non-nano) zinc oxide and titanium dioxide have been used as sunscreens for many years. These ingredients are excellent sunscreens as they have a broad spectrum of action, blocking both UVA and UVB.

But if you have ever used one of these sunscreens, you may have noticed it left a white cast on your skin.

Nano-scale zinc oxide and titanium dioxide have the advantage of being transparent, as well as easier to apply. And their smaller size enables better skin coverage—and therefore better sun protection, according to the President of the American Academy of Dermatology.⁷

What are nanoparticles?

‘Nano’ refers to a size range.

1 nanometer (nm) is one-billionth of a metre. Although there is no internationally agreed definition of ‘nanoscale’, 1–100 nm is generally used.

For some perspective, a human hair is 80,000 nm wide. 

Click here for more general information on ‘nano’

Nano-scale zinc oxide and titanium dioxide are used in some sunscreens as highly effective broad-spectrum UV filters. These ingredients are not new. According to the TGA, ‘nanosized titanium dioxide particles have been used in sunscreens since at least 1990 and nanosized zinc oxide since 1999'.⁸ 

Imagine if everything we put on our skin went through. Skin wouldn’t be much use, would it? All kinds of things on the outside would go in (and alarmingly, things on our insides might go out).

Healthy skin is an effective barrier to many particles, chemicals and microorganisms. It has an outer protective layer of dead skin cells, under which is living tissue. You can read more on the skin barrier here.

The hypothetical concern with zinc oxide and titanium dioxide nanoparticles is that, due to their small size, they may penetrate the skin. And then they may have harmful effects on the body.

According to a 2016 article published in the Medical Journal of Australia, many studies have shown metal oxide nanoparticles (like zinc and titanium) do not readily penetrate the skin’s outer layer and that nano-sunscreens ‘are formulated to remain on the skin’s surface, which is constantly shedding its outer layer of dead cells’.⁹ A 2018 study using both human volunteers and excised human skin provided the first direct evidence that intact zinc oxide nanoparticles don't get through the human skin barrier, or cause toxicity after repeated applications.¹⁰

If most particles aren’t getting in, there is no need to worry too much about any effect on the body.

The safety of zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles used in sunscreens is continuously monitored by the Australian Therapeutic Goods Administration (TGA). Its focus is on whether these nanoparticles penetrate the skin to reach viable cells, and—if so—whether they are toxic. The TGA has published reviews on this in 2006, 2009, 2013 and 2017.

According to the TGA’s 2017 review,¹¹ ‘the majority of in vitro studies (using both animal and human skin) and in vivo studies have shown that both ZnO and TiO2 NPs [nanoparticles] either do not penetrate or minimally penetrate the stratum corneum and underlying layers of skin.’ (This was for both healthy and compromised skin.) The conclusion? ‘On current evidence, neither TiO₂ nor ZnO NPs [nanoparticles] are likely to cause harm when used as ingredients in sunscreens and when sunscreens are used as directed.’ 

‘There is no evidence suggesting that nanoparticles in sunscreen are unsafe. Evidence shows nanoparticles in sunscreens are highly unlikely to cause harm because they remain on the surface of the skin.’¹² 

The EU’s Scientific Committee on Consumer Safety (SCCS) also published, and has not revised, its 2012 Opinion that ‘there is no evidence for the absorption of ZnO nanoparticles through skin’ and ‘even if there was any dermal and/or oral absorption of ZnO nanoparticles, continuous dissolution of zinc ions would lead to complete solubilization of the particles in the biological environment.’¹³  The SCCS published a similar opinion on titanium dioxide nanoparticles in sunscreens.¹⁴ 

Several laboratory studies have shown that sunscreens can cause coral bleaching.

But these results have not been confirmed under real-world conditions—a link between sunscreen use and coral health in the environment has not been made.

The concentrations of some UV filters found to have an effect in laboratory studies were in the parts per billion to parts per million range. This is higher than the levels of these UV filters in most seawater. For example, according to coral scientists Carys Mitchelmore and Doug Fenner, environmental studies show that oxybenzone may be present in seawater samples near reefs at low parts per trillion concentrations.¹⁵

They also stressed that ‘if sunscreen were a cause of coral die-offs, we would expect to see reef damage where sunscreen concentrations are highest, but there is no data to support that’.

Reef authorities are gravely concerned about the health of coral reefs, globally. According to the Coral Reef Alliance, 75% of the world’s coral reefs are currently threatened and 100% of reefs will be threatened by 2050 if action isn’t taken now.

Action on what? Authorities are clear: climate change, land-based pollution (sediment, nutrients and chemicals from sewage, agricultural runoff and industrial waste discharge), unsustainable fishing and habitat destruction in poorly managed areas are the main threats.

Australia’s Marine Conservation Society agrees that climate change is the biggest threat to coral reefs and that the need for action on this issue is urgent. 

Australia’s Great Barrier Reef Foundation lists increasing sediment, nutrients and contaminants, combined with rising sea temperatures and ocean acidification, as the causes of damage to the Great Barrier Reef. Aha – contaminants! These must include sunscreens! No…run-off from agricultural, industrial and urban land use are called out as the cause.

The US National Ocean Service lists increased ocean temperatures caused by climate change as the leading cause of coral bleaching. Runoff and pollution (for near-shore corals), overexposure to sunlight and exposure to the air during extreme low tides (for shallow-water corals) are also listed as causes. Again, no sunscreens.

‘People make a long list of bad things that human beings do to coral reefs — I would place sunscreen at number 200.’¹⁶

Prof. Terry Hughes, former Director of the ARC Centre of Excellence for Coral Reef Studies (2005-2020)

Wait…what? Why on earth not? What more do these people want?!

Well, action on the significant causes of coral bleaching, for one thing. As mentioned in the above fact, evidence points to ocean warming (due to climate change), ocean acidification (due to climate change) and run-off from agricultural and urban activities as the main causes.

To quote coral scientists Carys Mitchelmore and Doug Fenner, ‘people are being led to believe there is extensive scientific evidence about the impact of oxybenzone on corals, and this is simply not true.’¹⁵

But hey, let’s focus on the unsubstantiated and potentially minimal risk of sunscreens rather than commit to meaningful and effective action on these big issues. Politicians sound like they are doing something. Everyone choosing ‘reef safe’ feels virtuous…forget the climate impacts of the long-haul flight to get to the reef holiday…

‘Let’s not waste more time and money fighting the right problem with the wrong solution.’¹⁵
Coral scientists Carys Mitchelmore and Doug Fenner