The Health and environmental effects of sunscreen

Recently it has been observed that many chemical sunscreens, UV-filters, have had other negative health impacts on humans and the environment at large. A investigation of common chemical sunscreens (International Journal of Andrology 2012, 35, 424–436) cites benzophenone-3 (BP-3), 3-(4-methyl-benzylidene)-camphor (4-MBC) and 2-ethylhexyl-4-methoxy cinnamate (OMC) as chemical sunscreens with the highest health risk in humans. The harmful effects include developmental and reproductive effects caused by disruption of the endocrine system. Additionally, an investigation of benzophenone related compounds common in sunscreens (Environ. Sci. Technol., 2012, 46, 4624–4632) made a correlation between the estrogen signaling ability of benzophenones and estrogen’s ability to increase the size of endometriosis legions in women. After sampling the urine of female participants, the 25% with the highest amounts of 2,4-dihydroxy benzophenone in their urine had a significantly greater rate of endometriosis. Oxybenzone also has weak estrogen strong ant-androgenic effects. The CDC can detect oxybenzone in 96% of the population with the highest levels in those who use sunscreens. UV filter homosalate also disrupts estrogen and progesterone. Benzophenones are not just in sunscreens and other cosmetics but are also in plastics and cleaning products.

In addition to effects on human health, sunscreens have been linked to depletion of coral reefs.  UV-filters in sunscreens have been linked to the bleaching effects of corals by killing the symbiotic algae that keeps coral healthy (Environ Health Perspect. 2008, 116, 441–447). Only 10 μL/L of common chemical sunscreens began significantly bleaching corals within 18-48 hours. The results suggest sunscreens containing parabens, cinnamates, benzophenones, and camphor derivatives can contribute to coral bleaching which is further accelerated at higher temperatures. Physical sunscreens are not without affect themselves (Environ. Sci. Technol., 2014, 48 (16), pp 9037–9042.) Inorganic nanoparticle zinc and titanium oxides become photocatalytic in the presence of UV radiation which generates reactive oxygen species which yield H2O2. These articles point out the undesired effects sunscreens may have while working to prevent sunburn, premature aging and skin cancer.