A recent report on high levels of heavy metals washing off beachgoers in Europe has called the safety of mineral-based sunscreens into question.

The biggest question, however, is what news reports didn’t mention: the sunscreen they tested was manufactured with titanium dioxide nanoparticles. These tiny particles have long been known to be less environmentally stable than the naturally occurring titanium dioxide found in products like Stream2Sea which have been fully tested and shown to be ocean-friendly.

Government agencies in the United States do not require that sunscreens identify the minerals they use as nanotized or non-nanotized. Most scientists understand the difference and clearly differentiate it in their research.  It’s unclear why this recent report failed to disclose the particle size of the minerals in its abstract, although it did note that it studied the impact of nano-sized particles in the full document, which is paywalled.

Nanoparticles, which can be up to 100,000 times thinner than a human hair, have many therapeutic properties in treatments like chemotherapy because the behavior of materials change as their size is reduced and the percentage of atoms at the surface of a material becomes significantly larger.

For some sunscreen manufacturers, the primary benefit of nanotized minerals is that they rub on “clear” making higher SPFs more attainable.  However, one of the downsides that multiple studies have shown, including the most recent published on August 15 by the American Chemical Society, show that nanoparticles are harmful to the environment, potentially increasing levels of metals, including titanium, aluminum, lead, nickel and cobalt, into waters when they are exposed to high levels of UV light.

Nanoparticles of zinc oxide, the most commonly used ingredient in mineral sunscreens, are also clearly toxic in a marine ecosystem. Even the manufacturer’s data sheet highlights that toxicity in red letters on the front page of a 12-page document.

Other reports on titanium dioxide sunscreen detailing potential damage date back several years but clearly identify the use of nanoparticles in the reports. Non-nano titanium dioxide naturally occurs in the sea bed and, to the best of our knowledge, there are no formal studies that look at the impact of it from sunscreens.  

Alternatively, not only have we thoroughly researched the literature, but we have conducted a series of safety tests starting with C. elegans, simple nematodes that are ideal for rapid, predictive screening on inflammatory ingredients. We then moved on to prove safety with  freshwater and saltwater fish species, looking at the impact on the fish’s eating behavior, swimming behavior and, of course, mortality rates. Finally, we safety tested our sunscreen on vulnerable coral larva which will not survive concentrations of oxybenzone and octinoxate as low as 62 parts per trillion – which is the equivalent of about a drop of water in six and a half Olympic-sized swimming pools.

Titanium is considered to be one of the safest and most stable minerals, and is often used in hip, knee and dental implants.  Some more recent studies have shown that people with those implants may have higher levels of metal in their blood, but most reactions have been attributed to nickel, a lower cost metal alloy used with titanium.   There have been no reports documenting damage from titanium implants.

Additionally, non-nano coated titanium dioxide is even more stable because the surface layer of titanium dioxide prevents chemical reactions. Even when the layer is damaged, it is restored rapidly in a natural process when it comes in contact with air or water.

As additional research is compiled,  we are working closely with manufacturers and scientists to ensure that Stream2Sea formulations are safe for both people and marine ecosystems.  As it stands today, we have decided NOT to use ANY clear or nano minerals in our formulas.  They may be a bit more whitening than some of the other brands on the market that are touting themselves as ‘reef safe’, but we believe that the safety of our waters is worth a little whitening.  Besides, our tinted formula addresses that issue.

Don’t forget – 30 years ago, manufacturers thought oxybenzone was safe for people and oceans – we’ve since learned otherwise.   Science changes, but we’re committed to staying at the leading edge of safety.


For our fellow science geeks who want to see the actual science, check out these links from the
National Institutes of Health library.

Sunscreens as a New Source of Metals and Nutrients to Coastal Waters, the abstract on this most recent report does not mention
the use of nano-titanium dioxide but the paywalled document notes that “the study of the behavior of metal nanoparticles included in sunscreen formulations and released in the sea is considered very important.”

Acute exposure to sunscreen containing titanium induces an adaptive response and oxidative stress in Mytillus galloprovincialis. Again the title and abstract for this report do not differentiate between nano and non-nano titanium dioxide but the paywalled document reports
that “several studies have evidenced that mussels and oysters can significantly ingest and accumulate titanium nanoparticles in their tissues.”

Effects of TiO2 nanoparticles and sunscreens on coastal marine microalgae: Ultraviolet radiation is key variable for toxicity assessment which reports that “the differential sensitivity of microalgae to sunscreens and TiO2 NPs can produce a change in the dynamics of phytoplankton populations and provoke undesirable ecological effects.”

Sunscreen products as emerging pollutants to coastal waters, noting that the use of various sunscreen ingredients, including nano titanium dioxide have become a significant source of organic and inorganic chemicals that reach the sea with potential ecological consequences on the coastal marine ecosystem.

There also is accumulating evidence that nanoparticles may cause damage in human beings as well:

Titanium Dioxide Nanoparticles: a Risk for Human Health?

Repetitive Application of Sunscreen Containing Titanium Dioxide Nanoparticles on Human Skin.

Titanium dioxide nanoparticles: some aspects of toxicity/focus on the development.

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