(Chemical Abstract Service Registry Number 131-57-7; IUPAC Name (2-hydroxy-4-methoxyphenyl)-phenylmethanone; Benzophenone-3, Milestab 9, Escalol 567, Eusolex 4360)

Oxybenzone Contamination in the Environment and the Public

Oxybenzone is a ubiquitous environmental contaminant – it is found in streams, rivers, lakes, and in marine environments from the Arctic Circle (Barrow, Alaska) to the beaches and coral reefs along the equator [1],[2],[3],[4].  It is considered an environmental hazard in many locations[5]. It is found in very high concentrations in swimming pools and hot tubs[6], and even in our drinking water (municipal treated and desalinated sources)[7],[8].  Swimmers directly contaminate water sources, but point and non-point sewage and treated waste-water effluent discharges are the largest source of contamination.
Oxybenzone can be absorbed directly through the skin, either from application of sunscreen product onto the skin, or by absorption from swimming in either swimming pools or along beaches[9],[10],[11].  Oxybenzone in a commercial sunscreen formulation can transfer from the lotion or spray into the body, and be detected in urine within 30 minutes to several hours of application[12],[13].  Oxybenzone body-contamination is widely prevalent in the general human population, with some nationalities having higher levels than others[14]. One study found that 96.8% of participants’ urine was contaminated with oxybenzone, indicating the almost-universal prevalence of exposure in the human population[15],[16].  Oxybenzone can contaminate semen[17], placenta and breastmilk of marine mammals and humans[18],[19],[20],[21].  Oxybenzone can both bioaccumulate, and can be biomagnified[22]. Oxybenzone has been found in bird eggs, fish, coral, humans, and other marine mammals[23],[24].

Oxybenzone Ecotoxicology

     Oxybenzone and many of its metabolites are documented mutagens, especially when exposed to sunlight[25],[26],[27],[28],[29].  They can cause genotoxicity either from induction of photo-oxidative stress or adduction to DNA directly through bio-activation by cytochrome P450 enzymes[30],[31],[32].  Oxybenzone and other benzophenones can induce pro-carcinogenic activities by inducing cell proliferation in cancer cells lines that are receptive to estrogenic compounds[33],[34],[35].  Recent studies have also documented that oxybenzone increases metastasis potential (cellular proliferation) via a non-estrogenic mechanism[36].
Oxybenzone is a photo-toxicant, especially in the presence of ultraviolent light4.  This means that the greater the light intensity, especially in the UV and near-UV spectrum, new forms of toxicity manifest, and usually in a dose-dependent manner of both oxybenzone and light.
In mammals, especially humans, oxybenzone has been shown to induce photo-allergic contact dermatitis in 16%-25% of the population[37],[38],[39].  Oxybenzone causes toxicity to sperm development and sperm viability, reduced prostate weight in mature males, and reduced uterine weight in juvenile females[40],[41]. In rodents, it reduced fecundity and induced idiopathic sudden death in lactating mothers[42].  Several recent studies have shown a strong association between urinary and seminal oxybenzone concentrations and increased reproductive diseases and reduced fecundity[43],[44]. There is a building body of evidence of the estrogenic and anti-androgenic endocrine disrupting mechanisms of oxybenzone in mammals[45],[46]. One study indicated an increased occurrence of endometriosis in women exposed to concentrations of oxybenzone, while another study showed a positive association with uterine leiomyoma[47],[48].  Oxybenzone has also been associated with altered timing of breast development in girls[49].
Oxybenzone is a notorious estrogenic endocrine disruptor, causing male fish to become feminized and inducing egg protein production in males and juveniles[50],[51],[52].  Oxybenzone causes a reduction in the number of eggs a female fish will produce[53],[54],[55]. In fish, oxybenzone is metabolized into benzophenone-1, a much more potent estrogenic disruptor[56]. Oxybenzone will also cause radical behavioral changes in fish, causing them to lose “territorial” behavior[57].
Oxybenzone can have devastating effects on invertebrates, especially on juvenile developmental stages4.  In coral, it can cause coral bleaching, DNA damage, planula deformity, mortality, and skeletal endocrine disruption4.  For coral planula, gross toxicological effects were seen as low as 6.5 ppbillion in a 24-hour period, and cellular effects were seen as low as 72 pptrillion in a 4-hour period. In bivalves, growth inhibition occurred around 2-3 ppmillion[58].  In shrimp larvae, growth inhibition was seen around 421 ppbillion49.
Oxybenzone is even toxic to microalgae, such as Isochrysis galbana, at levels comparable to coral, such as 4 ppbillion49.
Oxybenzone is also associated with several human diseases, especially of fetal-development diseases associated with prenatal exposure to oxybenzone[59],[60].  Hisrschsprung’s disease, a development abnormality thought to afflict every 1 in 2,000 births, has been linked to maternal exposure to oxybenzone, by interfering with the migration neural crest cells during embryonic development[61].

Emerging Science regarding Oxybenzone: a human-health warning.

Oxybenzone can contaminate hot-tubs and swimming pools with concentrations in the parts per billion5.  If these pools use chlorine or bromine as a disinfectant, the oxybenzone undergoes a chemical reaction and can become “chlorinated” or “brominated – meaning a chlorine or bromine is conjugated to the oxybenzone, changing its chemical structure and chemistry[62],[63].  Very recent studies show that the chlorinated forms of oxybenzone are significantly more toxic than normal oxybenzone, acting as significant DNA damage agents[57],[58],[64].  A by-product of this oxybenzone chlorination is chloroform[65].

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