Plurk paste

Chemical Principles:
Oxybenzone outside of solution is described as a white or yellow-white powder. It absorbs high-frequency UVA and UVB light, then releases that energy at a lower wavelength, thus protecting the skin from deep penetration from high energy light. The same qualities that make it useful as a sunscreen make it a viable option for protecting plastic products from sun damage. Besides that, it’s used in products such as nail polish, hairspray, and other cosmetics, and is described as a “photostabilizer.” Photostabilizers help prevent other chemicals from reacting in the presence of high energy light, by absorbing the light of shorter wavelength and emitting it at a longer, lower-energy wavelength.

Oxybenzone is not an uncontroversial substance, and since it is applied topically and could have significant health impact its use is regulated by several countries. Most studies seem to indicate that oxybenzone is excreted in the urine and does not remain in the body for a significant length of time post-application, but Sweden has banned the use of oxybenzone completely, EU regulations state that sunscreen may only contain concentrations of 10% or less oxybenzone, and the FDA permits concentrations of 6% or less oxybenzone in over the counter sunscreens.

At least for now, oxybenzone is considered a useful industrial chemical and safe for humans to apply topically. With an LD-50 of 7400mg/kg, it seems unrealistic to expect that there is any serious risk to human health in the application of sunscreen containing oxybenzone. However, oxybenzone is a complex chemical, and the long-term health effects of topical application are not completely understood, especially when it’s paired with other organic chemicals. In addition, it has a measurable negative impact on the health of corals, which is a significant consideration because people are encouraged to apply sunscreen before entering the water.