What the science actually says about sunscreen and the Great Barrier Reef

Key points

• Homosalate, oxybenzone and octinoxate, the ingredients this kind of campaign actually targets, aren't banned by a single major regulator anywhere in the world.
• Australia's own wastewater data puts oxybenzone at roughly 90 times below the concentration shown to cause any measurable harm to coral.
• The study behind most of the public alarm rested on one outlier water sample and a lab test on coral cells, not a finding from a living reef.
• No wastewater treatment plant discharges anywhere near the Great Barrier Reef; the nearest coral sits tens to hundreds of kilometres further out.
• The most independent reviewers in the field, a US government scientist and the US National Academies of Sciences, say there isn't enough evidence yet to know whether these chemicals harm coral at all.
• Skin cancer is the proven risk a schools policy needs to manage. This isn't.

A petition asking the Queensland Department of Education to ban certain sunscreen ingredients from schools and worksites has picked up real momentum, built on three claims: that these ingredients are banned overseas, that they're detected in wastewater and harming the Reef, and that this is backed by independent, peer reviewed science. Each claim is worth walking through properly, because the actual evidence is considerably more complicated than the petition suggests, and a schools procurement decision built on it would be resting on shakier ground than it looks.

"Banned or restricted overseas"

Take homosalate, the ingredient at the centre of Australia's own live safety review. The United Kingdom permits it up to 10 per cent for whole-body use. The European Union permits up to 7.34 per cent in face products. New Zealand and the ASEAN Cosmetic Directive both follow the EU figure. None of these regulators have banned it. Each ran its own safety review and arrived at its own concentration limit, a genuine scientific disagreement about which laboratory finding should set the ceiling, not evidence the ingredient is prohibited elsewhere while Australia lags behind.

The Therapeutic Goods Administration's 2025 safety review of seven priority sunscreen actives, part of a consultation that is still open and has not been finalised, proposed that five of the seven remain safe at current permitted concentrations, with no change recommended. Homosalate and oxybenzone are the two still under active consideration for a possible new concentration limit, the same kind of ingredient-specific process the UK and EU have already run to their own conclusions. That's a normal regulatory process working its way through, not a ban, and not a settled decision either way yet.

A small number of places, Hawaii, Palau, the US Virgin Islands and the town of Key West, do restrict sale of sunscreens containing oxybenzone and octinoxate specifically, on environmental rather than human health grounds. That's a real position worth engaging with on the science, which the next section does. It isn't evidence of a broader overseas consensus that these ingredients are unsafe for people to use.

Detected in wastewater, harming the Reef

The scientific case for reef harm from sunscreen chemicals is unusually weak for how much attention it has received. The US National Academies of Sciences, commissioned by the US EPA in 2022 to review this exact question, found the underlying coral toxicity data too inconsistent and methodologically limited to support a formal ecological risk assessment. A 2024 peer reviewed audit by an independent US EPA research scientist went further: oxybenzone, the most heavily studied UV filter in the world by a wide margin, still meets only around half the standard data requirements needed to set a defensible water quality benchmark, and less than a quarter for chronic exposure. No credible, independent reviewer currently claims to know the concentration at which real coral harm actually begins.

Much of the public alarm traces back to a single study published in 2016. It's genuine, peer reviewed science, but it rested heavily on one unusually high concentration reading from a single water sample, later treated by other researchers as a statistical outlier, and its most striking findings came from coral larvae and cultured cells in a laboratory, using a novel bioassay that has never been independently replicated, not from adult coral living on a reef. Direct toxicity testing on adult coral since has found no measurable effect at the concentrations actually detected near real reefs.

Australia's own data tells a similarly reassuring story, and it doesn't need to borrow from overseas research to make the point. The only dedicated national study of UV filters in Australian wastewater (University of Queensland and Griffith University, funded by Queensland Health and the Australian Research Council) tested treated effluent, the water actually released after treatment, from 33 plants across the country. It found oxybenzone at an average concentration around 90 times below the level shown in direct testing to cause any measurable effect on adult coral, and treatment itself removes around 70 per cent of the oxybenzone present, on average, before that water is even released. The UV filter detected most often in Australian wastewater, by a wide margin, wasn't oxybenzone, the one ingredient in this dataset still under active TGA consideration. It was an ingredient called PBSA, and the TGA's own review proposed it was safe with no change recommended, a sign that "detected in wastewater" and "a genuine safety concern" are two different things that barely overlap in Australia's own data.

Geography matters here too. Wastewater treatment plants don't discharge onto the Great Barrier Reef. Coastal Queensland plants discharge into rivers, inlets and harbours, waters connected to the Reef's broader catchment, but the actual coral structures sit anywhere from roughly 15 to 300 kilometres further offshore depending on location. That's a substantial additional distance on top of whatever dilution treatment and the receiving water already provide. A study of a heavily used Caribbean tourist beach, looking at direct sunscreen wash-off from swimmers rather than treatment plant discharge, found UV filter concentrations in the water fell exponentially with distance from the shore, from thousands of nanograms per litre right at the water's edge to a small fraction of that within a couple of hundred metres. That same study was honest about the flip side too: right next to shore, where some coral colonies actually live, concentrations were high enough to be a genuine point of concern. The pattern that emerges isn't "no risk anywhere." It's that risk, to the extent it exists at all, is concentrated at the point of direct contact, not carried kilometres out to sea in a form that could plausibly reach an offshore reef at a meaningful concentration.

What "independent, peer reviewed" science actually shows

Real science on this question exists, and Accord isn't asking anyone to ignore it. The point is that the actual, careful research, run by government scientists auditing their own field's data gaps in public, university researchers testing Australian wastewater with proper quality controls, and international expert panels reviewing everything that's been published, doesn't support a confident claim of reef harm at current sunscreen use levels. It supports a more honest, less satisfying conclusion: the data isn't good enough yet, in either direction, and treating a single contested study as settled fact does a disservice to the researchers doing the slow, real work of finding out.

What this means for a schools policy

Skin cancer, not an unresolved question about reef runoff, is the proven risk a schools sunscreen policy needs to manage. Zinc oxide and titanium dioxide mineral sunscreens are safe, legitimate products, and nothing here argues against making them available. But swapping away from effective, well-tolerated sunscreens on the strength of a "banned overseas" claim that doesn't match the regulatory record risks reducing how consistently sunscreen actually gets applied and reapplied over a school day, in exchange for a benefit to the Reef that no credible independent reviewer currently claims exists.

The ingredients in question are already subject to an active, evidence-based safety review by the Therapeutic Goods Administration, the body actually equipped to make this call, using the same kind of process the UK and EU have already run. Queensland schools would be better served waiting for that review's findings than adopting a procurement policy based on a petition whose central claims don't hold up.

"Every one of these ingredients is being assessed, or has already been assessed, in one of the most rigorous safety reviews applied to any consumer product category in Australia, and that process is still open," said Damian Mitsch, Executive Director of Accord Australasia. "Getting this right matters, for kids' sun protection and for the Reef. That's exactly why it should rest on what the evidence actually shows, not on a version of it that's been simplified past the point of being accurate, and not on treating a consultation as if it were already a final decision."

Media contact: Damian Mitsch [0403 372 900]