Why doesn't Typology use Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (MBBT)?

MBBT is a substance that is minimally absorbed but highly persistent.

According to assessments by the Scientific Committee on Consumer Safety (SCCS), MBBT exhibits very low skin absorption. A study in vitro showed that only 0.02% of the applied molecule in its nano form penetrated intact human skin, and about 0.07% on damaged skin. This implies that the systemic risk associated with skin exposure remains limited. These results are reassuring, especially since nanoparticles raise concerns due to their small size, which could allow them to cross the skin barrier.

As a precautionary measure, we do not use nanoparticles at Typology.

However, MBBT is extremely hydrophobic, with an estimated log P of 12.7, and has a very low water solubility, less than 5 ng/L. These properties account for its strong persistence in the environment. Indeed, when it is rinsed into water, for instance at the beach, MBBT tends to accumulate in sediments and aquatic organisms, thereby posing potential risks to marine ecosystems. Traces have been found in shellfish, fish, and crustaceans, suggesting a potential for bioaccumulation. Furthermore, MBBT is not biodegradable, another harmful characteristic if it ends up in the environment.

The nano form of MBBT still raises concerns.

As mentioned above, MBBT is often used in nanometric form. However, unlike the non-nano form, according to the CSSC, data on its genotoxicity remains insufficient. To remind, the genotoxicity of a substance refers to its ability to damage the DNA of a living organism. The genotoxic character of a compound is generally a good indication of its cancer-causing potential. At the moment, the committee has not been able to firmly rule on the safety of the nano form of MBBT due to the lack of currently available data. Tests in vitro on animal cell lines have not shown a clear genotoxic effect, but the results have not been conclusive enough for the CSSC to declare a lack of danger.

Inhalation tests were also conducted by the CSSC, demonstrating an absence of acute pulmonary toxicity at 0.488 mg/L with respirable particles of 1.4 µm. Despite this, the committee recommends not using the nano form in spray or loose powder formulations, due to the lack of long-term data on respiratory toxicity. This caution is all the more justified as nanometre-sized particles could theoretically reach the lung alveoli, potentially leading to entry into the bloodstream and potentially harmful effects on tissues.

MBBT is suspected to be irritating to the skin.

Several studies conducted on animals have investigated the acute, subchronic toxicity and local effects of MBBT. When applied daily to rats for several weeks at high doses (up to 2,000 mg/kg/day), MBBT did not cause any notable systemic or organic adverse effects. However, from a local tolerance perspective, the picture remains unclear. Indeed, tests were conducted on mice to which 20% MBBT was applied. A few isolated cases of skin allergy were reported, as well as the formation of scabs. Although the concentration used is twice the amount permitted in skincare products, the CSSC concluded that it would be "useful to monitor possible irritation effects via the programmes of cosmetovigilance".

That’s why we don’t use MBBT in our solar products. Despite its UV protection effectiveness, its toxicological uncertainties, environmental impact and local irritant potential have led us to prefer better documented UV filters.