Oxybenzone

Oxybenzone is a phenol that may be oxidized, creating a stressful environment for coral reefs.

General Information

IUPAC name: 2-hydroxy-4-methoxyphenyl)-phenylmethanone

Only 4% of ozybenzone in sunscreen is absorbed into the skin, the remaining 96% is washed off and enters various water ways (Dinardo, Joseph and Downs, A Craig 2018).

As a sunscreen additive, oxybenzone is less effective at protecting against UV exposure than avobenzone, titanium dioxide, and/ or zinc oxide (Dinardo, Joseph and Downs, A Craig 2018).

Adverse Effects of Oxybenzone

Several studies have reported that oxybenzone has adverse effects on reproduction and development of algae, the freshwater flea, and plarian (Kim, Sujin and Choi, Kyungho 2014). Oxybenzone is a photoxicant, genotoxicant, and a skeletal endocrine disruptor in coral. Oxybenzone has also been found in the tissue of many fish that humans consume (ex. white fish, perch, and rainbow trout). Oxybenzone inhibits reproduction of coral and fish via embryo toxicity and/or causes male fish to be feminized (DiNardo, Joseph and Downs, A Craig 2018). There is not much information on the long term ecological effects of oxybenzone in our freshwater systems, so further investigation is warranted.

Oxybenzone is also one of the top three most frequent allergens in sunscreens (DiNardo, Joseph and Downs, A Craig 2018).

Physical Properties

Names:

2-Hydroxy-4-methoxybenzophenone
Oxybenzone
Benzophenone-3 (BZ-3) <--trade naming, see other below
Eusolex 4360
Escalol 567

Molecular weight: 228.24 g/mol

Boiling point: 115°C.

Melting point: 65.5°C.

Density: 1.32 g/mL.

pKa: 7.1.

UV max: 288 and 326 nm.

Described as an off-white or light yellow powder.

Other--> Benzophenone-n

Chemical Oxidation

The following link shows an in depth explanation of the chemical oxidation of oxybenzone. This page also contains the data collected from this particular experiment.

Oxybenzone Oxidation

Chlorination of Oxybenzone

Oxybenzone can become chlorinated in swimming pools because of the chlorine in the water. Chlorine also oxidizes oxybenzone quite well. There are three major products of the chlorination of oxybenzone.

Products of chlorination of oxybenzone. Source: Chlorination of oxybenzone: Kinetics, transformation, disinfection byproducts formation, and genotoxicity changes (Chemosphere 154 (2016) 521-527)

Coral Bleaching

Coral bleaching happens when the algae living on the coral are destroyed, leaving the coral to starve. The coral then lose their bright colors, which is why the term is called "bleaching." Oxybenzone reactions can harm these algae, resulting in coral bleaching.