Sunblock poses potential hazard to sea life

Aug 20, 2014
Sunblock poses potential hazard to sea life

The sweet and salty aroma of sunscreen and seawater signals a relaxing trip to the shore. But scientists are now reporting that the idyllic beach vacation comes with an environmental hitch. When certain sunblock ingredients wash off skin and into the sea, they can become toxic to some of the ocean's tiniest inhabitants, which are the main course for many other marine animals. Their study appears in the ACS journal Environmental Science & Technology.

Antonio Tovar-Sanchez and David Sánchez-Quiles point out that other than staying indoors, slathering on is currently the best way to protect skin from the sun's harmful rays. But when sunbathers splash into the ocean to cool off, some of their lotions and creams get rinsed into the water. The problem is that and zinc oxide nanoparticles, which are common ingredients in sunblock, can react with ultraviolet light from the sun and form new compounds, such as hydrogen peroxide, that could be toxic. High amounts of hydrogen peroxide can harm phytoplankton, the microscopic algae that feed everything from small fish to shrimp to whales. The scientists wanted to figure out just how serious of an impact beachgoers could be having on life in coastal waters.

To investigate the matter, they hit the beach. They went to Majorca Island's Palmira beach on the Mediterranean along with about 10,000 beachgoers, a small portion of the more than 200 million tourists that flock to Mediterranean shores every year. Based on lab tests, seawater sampling and tourism data, the researchers concluded that titanium dioxide from sunblock was largely responsible for a dramatic summertime spike in levels in coastal waters—with potentially dangerous consequences for aquatic life.

Explore further: Making a common cosmetic and sunblock ingredient safer

More information: Sunscreens as a Source of Hydrogen Peroxide Production in Coastal Waters, Environ. Sci. Technol., 2014, 48 (16), pp 9037–9042. DOI: 10.1021/es5020696

Abstract
Sunscreens have been shown to give the most effective protection for human skin from ultraviolet (UV) radiation. Chemicals from sunscreens (i.e., UV filters) accumulate in the sea and have toxic effects on marine organisms. In this report, we demonstrate that photoexcitation of inorganic UV filters (i.e., TiO2 and ZnO nanoparticles) under solar radiation produces significant amounts of hydrogen peroxide (H2O2), a strong oxidizing agent that generates high levels of stress on marine phytoplankton. Our results indicate that the inorganic oxide nanoparticle content in 1 g of commercial sunscreen produces rates of H2O2 in seawater of up to 463 nM/h, directly affecting the growth of phytoplankton. Conservative estimates for a Mediterranean beach reveal that tourism activities during a summer day may release on the order of 4 kg of TiO2 nanoparticles to the water and produce an increment in the concentration of H2O2 of 270 nM/day. Our results, together with the data provided by tourism records in the Mediterranean, point to TiO2 nanoparticles as the major oxidizing agent entering coastal waters, with direct ecological consequences on the ecosystem.

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Shitead
not rated yet Aug 20, 2014
Ah, but the phytoplankton love the golden sheen it leaves on their shells.

Majorca! I did my field work a hundred miles south of Winnemucca; I feel like such a fool.
kochevnik
not rated yet Aug 20, 2014
"potentially dangerous consequences for aquatic life." - In contrast to proven consequences to humans if titanium dioxide isn't used

Isn't hydrogen peroxide essential to life? These same animals are exposed to huge doses of UVA radiation being immersed only inches deep. Isn't that a million times more oxidative stress?
supamark23
5 / 5 (1) Aug 20, 2014
"potentially dangerous consequences for aquatic life." - In contrast to proven consequences to humans if titanium dioxide isn't used

Isn't hydrogen peroxide essential to life? These same animals are exposed to huge doses of UVA radiation being immersed only inches deep. Isn't that a million times more oxidative stress?


Unlike mammals, most other animals have a robust mechanism to correct UV damage to DNA. We have hair instead... H2O2 is also a strong oxidizing agent, which is why it's a good disinfectant.
alfie_null
not rated yet Aug 21, 2014
This sounds like an attractive venue of research.

How prevalent is the use of zinc and/or titanium compounds? None of the various sunscreens I have contain either.
kochevnik
not rated yet Aug 21, 2014
This sounds like an attractive venue of research.

How prevalent is the use of zinc and/or titanium compounds? None of the various sunscreens I have contain either.
Titanium dioxide is the best sunblock. The products you mention are partially transparent to UV so called "screens" in acknowledgment of their inferiority. Some are actively carcinogenic.

Isn't hydrogen peroxide essential to life? These same animals are exposed to huge doses of UVA radiation being immersed only inches deep. Isn't that a million times more oxidative stress?
Unlike mammals, most other animals have a robust mechanism to correct UV damage to DNA. We have hair instead... H2O2 is also a strong oxidizing agent, which is why it's a good disinfectant.

Right so most animals probably have strong defenses against hydrogen peroxide as well, since it is essential to immune systems