Oxybenzone

Being a conjugated molecule, oxybenzone absorbs light at lower energies than many aromatic molecules. As in related compounds, the hydroxyl group is hydrogen bonded to the ketone. This interaction contributes to oxybenzone's light-absorption properties. At low temperatures, however, it is possible to observe both the phosphorescence and the triplet-triplet absorption spectrum. At 175 K the triplet lifetime is 24 ns. The short lifetime has been attributed to a fast intramolecular hydrogen transfer between the oxygen of the C=O and the OH. == Production ==

Oxybenzone is produced by the Friedel-Crafts reaction of benzoyl chloride with 3-methoxyphenol. == Uses ==

Oxybenzone is used in plastics as an ultraviolet light absorber and stabilizer. Despite its photoprotective qualities, much controversy surrounds oxybenzone because of possible negative hormonal and photoallergenic effects, leading many countries to regulate use in sunscreen products. Sunscreen Oxybenzone provides a broad-spectrum ultraviolet coverage which includes UVB and short-wave UVA rays. As a photoprotective agent, it has an absorption profile spanning from 270 to 350 nm with absorption peaks at 288 and 350 nm. Due to toxicity and environmental concerns, the percentage of sunscreen products on the market containing oxybenzone in the USA dropped to 13% in 2023 from 60% in 2019. Some brands market their sunscreens as "oxybenzone free" due to the generally negative perception of benzophenones by both the consuming public and scientific researchers. == Safety ==

In vivo studies The incidence of oxybenzone causing skin eruptions is extremely uncommon, however, oxybenzone has been associated with rare allergic reactions triggered by sun exposure. In a study of 82 patients with photoallergic contact dermatitis, just over one quarter showed photoallergic reactions to oxybenzone. Evidence points to oxybenzone having contact allergen effects. In a 2008 study of participants ages 6 and up, oxybenzone was detected in 96.8% of urine samples. Humans can absorb anywhere from 0.4% to 8.7% of oxybenzone after one topical application of sunscreen, as measured in urine excretions. This number can increase after multiple applications over the same period of time. Because oxybenzone is the least lipophilic of the three most common UV filters, it is the least likely to end up trapped in the stratum corneum and the most likely to be absorbed and metabolized. When applied topically, UV filters, such as oxybenzone, are absorbed through the skin, metabolized, and excreted primarily through the urine. The method of biotransformation, the process by which a foreign compound is chemically transformed to form a metabolite, was determined by Okereke and colleagues through oral and dermal administration of oxybenzone to rats. The scientists analyzed blood, urine, feces, and tissue samples and found three metabolites: 2,4-dihydroxybenzophenone (DHB), 2,2-dihydroxy-4-methoxybenzophenone (DHMB) and 2,3,4-trihydroxybenzophenone (THB). To form DHB the methoxy functional group undergoes O-dealkylation; to form THB the same ring is hydroxylated. The major metabolite detected was DHB and very small amounts of THB were found. In 2019, the U.S. Food and Drug Administration (FDA) noted in their recommendations for future study that, "While research indicates that some topical drugs can be absorbed into the body through the skin, this does not mean these drugs are unsafe." Oxybenzone can also occur as a natural product. == Environmental effects ==

Studies have shown possible links between oxybenzone exposure and mortality in coral larvae, coral bleaching, and to genetic damage in marine invertebrates. However, some of these studies have been criticised for not having control groups or representing real-world conditions. Nevertheless, these have led to the ban of oxybenzone-containing sunscreen in many areas such as Palau, Hawaii, the Northern Mariana Islands, and Aruba. ==Health and environmental regulation==

Aruba Aruba banned the use of oxybenzone in sunscreens due to environmental concerns in 2019. Australia As of 2023, the maximum concentration of oxybenzone in a sunscreen cannot exceed 10% according to the TGA (Therapeutic Goods Administration). Bonaire As of 2019 Bonaire banned oxybenzone due to coral toxicity concerns, with regards to coral larvae Canada Revised as of 2012, Health Canada allows oxybenzone for cosmetic use up to 6%. European Union The Scientific Committee on Consumer Safety (SCCS) of the European Commission evaluated oxybenzone (benzophenone-3) in 2021. Under Commission Regulation (EU) 2022/1176, it is permitted as a UV filter at restricted concentrations: up to 6% in face, hand, and lip products, and up to 2.2% in body products (and 0.5% to protect product formulation). However, following a decade-long evaluation, the European Chemicals Agency (ECHA) officially identified benzophenone-3 as an endocrine disruptor for both human health and the environment in September 2025. Stricter regulatory controls under the EU Classification, Labelling and Packaging (CLP) regulation are expected to be formally proposed in 2026. Japan Revised as of 2001, the Ministry of Health, Labour, and Welfare notification allows oxybenzone for cosmetic use up to 5%. Mexico Nature Reserves across Mexico have banned the usage of sunscreens containing Oxybenzone Palau The Palau government has signed a law that restricts the sale and use of sunscreen and skincare products that contain oxybenzone, and nine other chemicals. The ban came into force in 2020. Sweden The Swedish Research Council has concluded that sunscreens containing oxybenzone are unsuitable for use in young children, as children under the age of two lack the fully developed enzymes necessary to metabolize and break the chemical down. Despite this clinical finding, no formal national regulations or bans have been implemented in Sweden as a result of the study. United States In 2021, the U.S. FDA issued a proposed order requesting additional safety data for several organic UV filters, including oxybenzone. Because this specific data is still lacking, the FDA currently classifies oxybenzone as a Category III ingredient—meaning it is not GRASE (Generally Recognized As Safe and Effective) due to insufficient data. However, it remains legally approved for use in sunscreen formulations while the FDA awaits further safety studies from manufacturers. At the state and local level, the Hawaii State Legislature has made the sale of sunscreens containing oxybenzone illegal since 2021 due to its environmental effects, such as mortality in developing coral, coral bleaching, and genetic damage to marine organisms. Other U.S. territories, including the United States Virgin Islands (effective 2020) and the Northern Mariana Islands, have also enacted strict bans on the ingredient to protect local reef ecosystems. Key West also attempted to ban the sale of sunscreens containing oxybenzone and octinoxate, which was to be effective January 1, 2021. However, this local ordinance was preemptively superseded by the Florida State Legislature via Senate Bill 172, which prohibits local governments from regulating over-the-counter proprietary drugs and cosmetics. The state statute became effective July 1, 2020, legally invalidating the Key West ban. == References ==