FDA Studies Confirm Chemical Sunscreen Ingredients Are Absorbed Into the Bloodstream

Chemical UV filters are the active ingredients in most mainstream sunscreens sold in Australia and around the world. For decades, regulators assumed these molecules stayed on the surface of the skin, acting as a barrier against ultraviolet radiation without being meaningfully absorbed into the body. A landmark clinical trial published by the United States Food and Drug Administration (FDA) has challenged that assumption, demonstrating that six common chemical UV filter ingredients are absorbed into the bloodstream at concentrations that exceed the FDA's own safety threshold — after just a single day of use.

What Did the FDA Study Find?

The study — Matta et al., published in the Journal of the American Medical Association (JAMA) in 2020 — was a randomised clinical trial involving 48 healthy participants. Researchers tested four commercially available sunscreen formulations containing one or more of the following six chemical UV filter ingredients: avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate.

Participants applied the sunscreen to 75% of their body surface area four times daily for four days — a protocol designed to simulate real-world use during outdoor activity. Blood samples were collected over seven days and analysed for each UV filter.

The key finding: all six UV filter ingredients exceeded the FDA's maximum threshold of 0.5 nanograms per millilitre (ng/mL) of plasma after just one day of application. Several ingredients reached concentrations many times above this level and were still detectable in the blood seven days after the final application. As News Medical reported at the time, oxybenzone reached the highest plasma concentrations of all six filters tested.

Does Systemic Absorption Mean Sunscreen Is Unsafe?

It is important to be precise about what this study does — and does not — show. The FDA researchers were explicit: the finding that these ingredients are absorbed into the bloodstream does not by itself mean that sunscreens are unsafe. The 0.5 ng/mL threshold is not a danger level; it is the concentration below which the FDA considers additional toxicological testing unnecessary. When ingredients exceed that threshold, the FDA requires further study to determine whether systemic exposure poses any health risk.

The authors of the study called for additional research into the potential effects of long-term, repeated systemic absorption of these UV filters — particularly given that sunscreen is widely applied to large skin surface areas, including in children, and that some of these compounds have been investigated for possible endocrine-disrupting properties in other research.

Why Does Skin Absorption Matter for UV Filters?

The relevance of systemic absorption depends on what, if anything, the absorbed compounds do once inside the body. Chemical UV filters work by absorbing UV photons and converting the energy to heat — a function that requires them to be photochemically active molecules. That same reactivity raises questions about how they behave in the bloodstream or in tissues over time.

Studies examining related questions — such as the detection of UV filter compounds in breast tissue, breast milk, and umbilical cord blood — suggest that systemic absorption is not merely a transient phenomenon (see companion ASC articles on those topics). The Matta et al. findings provide a mechanistic foundation for understanding how UV filter compounds reach these sites in the body.

The Regulatory Gap in Australia

In Australia, chemical sunscreens are regulated as therapeutic goods by the Therapeutic Goods Administration (TGA). As of the publication of this article, the TGA continues to permit all six UV filter ingredients examined in the Matta et al. study. The TGA has not publicly required manufacturers to conduct systemic absorption studies comparable to the FDA protocol.

The FDA trial used a maximal use design — 75% body surface area coverage, four applications per day — which may exceed typical consumer behaviour but is consistent with the conditions under which sunscreen labels encourage liberal reapplication. For consumers who use sunscreen daily and across large skin areas, the cumulative systemic exposure over a lifetime may be substantially higher than a single-use study would suggest.

What Should Consumers Know?

The FDA study does not advise people to stop using sunscreen. UV radiation is a well-established cause of skin cancer, and broad-spectrum sun protection remains an important part of a comprehensive UV protection strategy. However, the study does highlight a gap in the safety evidence base: the systemic absorption of chemical UV filter ingredients has not been fully characterised, and long-term effects remain under investigation.

Consumers who are concerned about systemic absorption may wish to consider mineral-based sunscreens — those using zinc oxide or titanium dioxide as the active ingredient — as these physical UV blockers are not considered to be absorbed into the bloodstream in meaningful quantities under normal use conditions.

The Matta et al. study serves as a reminder that consumer products applied to large areas of skin daily deserve the same rigorous post-market safety evaluation applied to other systemically absorbed substances.

ASC Guidance on Sun Protection

The Australian Sunscreen Council recognises that the most effective form of UV protection is physical protection: wearing sun-protective clothing, broad-brimmed hats, and UV-rated sunglasses. During peak UV times (typically 10 am to 3 pm in Australia), limiting direct sun exposure is the single most effective way to reduce UV-related skin damage.

At the same time, moderate sun exposure during early morning and late afternoon — when UV levels are lower — supports the body's natural production of vitamin D and release of nitric oxide, both of which play important roles in bone health, immune function, and cardiovascular health. Research published in Nature Scientific Reports (Hazell et al., 2023) has demonstrated that low-dose daylight exposure induces nitric oxide release in skin cells with negligible DNA damage, and the landmark Australian Sun-D Trial (British Journal of Dermatology, 2025) confirmed that daily high-SPF sunscreen use can increase risk of vitamin D deficiency.

Consumers who choose to use sunscreen should be aware of the ingredients in their products and consider mineral-based (zinc oxide and titanium dioxide) alternatives where possible. Always consult your doctor or dermatologist for personalised advice on sun protection, vitamin D status, and any concerns about specific sunscreen ingredients.

About the Australian Sunscreen Council

The Australian Sunscreen Council (ASC) is Australia's peak body for the sunscreen and SPF cosmetics industry. The ASC is made up of sunscreen manufacturers, brand owners, formulators, and raw-material suppliers committed to evidence-based sun safety. The Council's mission is not to push more sunscreen sales or position sunscreen as the sole solution to UV risk — it is to ensure that sunscreen fits into the broader health and UV protection picture, alongside physical protection, sensible sun exposure, and public education grounded in published science.

The ASC maintains an independent Scientific Advisory Committee whose members hold qualifications spanning topical and transdermal drug delivery (with U.S. FDA-funded regulatory research), occupational sun protection and skin cancer screening, paediatric and maternal sunscreen safety with over 30 years of research into chemical UV filter effects on pregnant women and children, toxicology with expertise in hazard identification and exposure-based risk assessment for topical products (BSc Biotechnology, MSc Analytical Bioscience, PhD Toxicology), and forensic ecotoxicology — including the scientific investigations that underpinned Hawaii's landmark reef-safe sunscreen legislation. Committee members hold triple board certifications (Canada, UK, USA) in relevant medical specialties and lead globally recognised research programmes.

The ASC exists to provide Australian consumers with access to the same peer-reviewed evidence that informs regulatory decisions in Europe, the United Kingdom, and the United States — so that individuals can make truly informed choices about how they protect themselves and their families from ultraviolet radiation.

For more information, visit australiansunscreencouncil.org.