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Sunscreen filters

Oxybenzone

Also listed as benzophenone-3, BP-3, BZ-3

The most absorbed and most debated sunscreen filter: effective, but a known photoallergen, restricted in the EU and banned in Hawaii. Evidence of human harm is lacking.

Moderate evidenceTypical strength: Up to 6% (US); EU 6% face/hand/lip, 2.2% body products

What it is

Oxybenzone absorbs UVB and short-wave UVA2. It has fallen out of favour: it reaches far higher blood levels than any other filter (around 258 ng/mL from lotion in the FDA trial, some 500 times the screening threshold), it was detectable in the urine of 97% of Americans tested in 2003-04, and it is a well-known cause of allergic and photoallergic rashes.

The EU limits it to 6% in face, hand and lip products and 2.2% in body products. Hawaii and the US Virgin Islands banned sunscreens containing it over reef concerns.

How strong is the evidence?

Moderate evidence

It is an effective UVB/UVA2 filter. Hormone concerns come from cell studies and rats fed very high doses; a human study with 10% whole-body application found no attributable hormone change. Reef harm rests mainly on lab studies of coral larvae, often at concentrations above those measured on most reefs; a critical 2021 review called the risk evidence incomplete. High absorption is well documented, harm at real exposures is not, and plenty of alternatives exist.

What it's used for, checked

UVB and short-wave UVA protection

Holds up

Effective, but covers little long-wave UVA1 without partners.

Hormone disruption in people

Unproven

Weak effects in cells and high-dose rat studies; not shown in the one human trial that measured hormones.

Kills coral reefs

Mixed

Toxic to coral larvae in the lab; how much it contributes to reef decline next to warming and pollution is unknown.

Causes skin allergy

Holds up

A recognised contact and photocontact allergen; about 0.5% of patients patch-tested for dermatitis react to it.

Who should be careful

  • Avoid it if you have had a rash from a sunscreen or are prone to allergic skin; ask a clinician about patch testing.
  • If you prefer to minimise absorbed filters (pregnancy, young children), oxybenzone is the one to avoid first. That is a precaution; harm is not proven.
  • Sunscreens containing it cannot be sold in Hawaii or the US Virgin Islands.

The studies

Every citation is checked against its PubMed record.

  1. Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial.
    Matta MK, Florian J, Zusterzeel R, et al. · JAMA · 2020 · RCT (pharmacokinetic)

    48 healthy adults applied one of four sunscreens to 75% of the body, up to 4 times a day for 4 days. Avobenzone, oxybenzone, octocrylene, homosalate, octisalate and octinoxate all exceeded the FDA's 0.5 ng/mL screening threshold after a single application; oxybenzone reached about 258 ng/mL from lotion. The authors state this does not mean people should stop using sunscreen.

  2. Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methyl-benzylidene) camphor after whole-body topical application and reproductive hormone levels in humans.
    Janjua NR, Mogensen B, Andersson AM, et al. · J Invest Dermatol · 2004 · Controlled clinical trial

    32 volunteers applied cream with 10% each of oxybenzone, octinoxate and 4-MBC over the whole body daily for a week. All three were absorbed (oxybenzone up to 200-300 ng/mL), but reproductive hormones showed no changes attributable to the filters.

  3. Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands.
    Downs CA, Kramarsky-Winter E, Segal R, et al. · Arch Environ Contam Toxicol · 2016 · Laboratory toxicology + field sampling

    In the lab, oxybenzone deformed and bleached coral larvae, with effects worse in light; some effect levels were in the low micrograms per litre. Water at some Virgin Islands sites measured far higher than Hawaiian sites. This is the study behind many reef bans.

  4. A Critical Review of Organic Ultraviolet Filter Exposure, Hazard, and Risk to Corals.
    Mitchelmore CL, Burns EE, Conway A, Heyes A, Davies IA · Environ Toxicol Chem · 2021 · Critical review

    Across 12 studies, UV filters near reefs were mostly found in the nanograms-per-litre range, while toxic effects in the nine coral toxicity papers appeared at micrograms to milligrams per litre, with widely varying methods. The authors list major data gaps and flawed assumptions and call for better studies before firm risk conclusions.