Several studies were conducted to evaluate the toxicological potential of TiO2 and ZnO minerals towards marine life. Most of the results did not reveal any toxicity on the studied organisms. Only nanoparticles with sizes below 30 nm and without coating did show moderate effect on micro-algae growth, however with concentrations too high to be representative of an environmental context.
Results show that toxicity, if any, is inversely correlated to the size of particles. No study to our knowledge did reveal any toxicity of ZnO and TiO2 with sizes superior to 150 nm like the one we use.
Interestingly, the same experiments revealed that particles naturally aggregate when dispersed in aqueous media and rapidly sediment. It is worth noting that TiO2 is a common mineral that is entering composition of sand. ZnO, although less common, is also a mineral found in nature.
The Sun Protection Factor, commonly known under the acronym SPF is the main measurement of the solar protection.
It has the advantage of having the same definition in every country and measured by the same International Sun Protection Factor Test Method.
Test method: 2 mg of sunscreen is applied per cm² of skin (on the back) of volunteers, who are then exposed to UV. 24h later, the Minimal Erythema Dose (MED) is determined, which is the smallest dose of UV light causing redness. The SPF will be a the difference of MED on protected and unprotected skin. This measurement comes down to the difference between amounts of UV required to cause sunburn with and without sunscreen.
Yes, it is important to make sun protection a daily habit. Dermatologists recommend a sun protection factor year round because we are exposed to UV rays no matter what the weather is like. Even under a cloudy sky, UV rays can be harmful, especially UVA rays. It is possible to prevent and to slow down the ageing of the skin and reduce the risk of skin cancers.
Whenever you are outside for two hours, for work or for leisure, it is advisable to be protected. You need to adapt your needs to your lifestyle. For example, a person with a fair complexion who works outside needs sun protection every day, even in winter.
It is important to use a sunscreen with a high UVA protection factor, which is not the case with day creams to which a chemical sun filter has been added.
Free radicals are unstable and incomplete oxygen molecules that are set free, especially during exposure to UV rays. They attend to complete themselves by bonding with elements in our cells. But in doing this, they destroy the healthy cells. Free radicals (cell killer) cause serious damages because they trigger the oxydation of tissues and cells, a bit like rust on metal. They are toxic and attack the DNA, by modifying the cell functionning, or by killing it.
When the free radicals production becomes excessive, ouf natural antioxidants ressources can no longer neutralise the harmful effects of oxidation by free radicals in our tissues and cells.
An antioxidant is a molecule that reduces or prevents the oxidation of other chemical substances. Oxidation results in free radicals that in turn cause destructive chain reactions. Antioxidants are capable of blocking these chain reactions and preventing the action of free radicals. In fact, antioxidants bind to free radicals and create an oxidation reaction with them that renders them harmless.
These antioxidant reactions are constantly occurring in the body and they use up the antioxidants we ingest in our food. They can be supplemented with antioxidant action on the level of the skin.
Sun’s rays are classified according to their wave length. The shorter is the wave lenght, the more damaging are the rays. But they also have a lower capacity of skin penetration.
UVB rays have medium wave lenght. They don’t penetrate beyond the surface of skin’s layers. However, they cause sunburn and accelerate ageing of the skin.
UVA rays have a long wave length that penetrates the skin’s deep layers. They immediately create a tanning effect. They increase the ageing of the skin and can promote development of skin cancers.
UV rays play a very big role in the phenomenon of the ageing of our skin cells, but they are not the only factor. Additional factors are pollution, alcohol and tobacco, modified foods, food additives, pesticides as well as emotional stress, various infections, medications etc.
The choice depends mainly on the intensity of the sun’s rays and your skin type. Actually, in certain extreme situations, at the beach or at high altitude, it is advisable to choose a high protection factor (30 or 50) due to the intensity of the sun’s rays, combined with the high level of reflection from sand or snow. This concerns all skin types.
Average and low levels of protection can be used in every-day situations of sun exposure for olive and dark complexions. For milk-white and fair complexions, high and very high SPF factors are always recommended.
The mineral pigmentation powders are white. As a result, every creams based on mineral filters are white. Thin layers of the filters intercept the sun’s rays on the skin. They have a strong coverage power. These pigments are very well tolered and present not only the advantage of not causing side effects related to tolerance of toxicity, but they are also non-poulluting. These natural filters protect against the whole range of UV rays that hit the skin.
The quantity of filters is greater in the creams that provide a very high level of protection, and this is what makes them thick. Nevertheless, this is a very acceptable constraint, given the risks related to using chemical filters.
A child’s skin has a very similar structure and functions to the skin of an adult, but:
- certain functions are not mature. The pH level of a child’s skin is higher and its protective function is less developed,
- the child’s surface-to-weight ratio is almost three times higher than the adult’s: the risk of toxicity is therefore higher because the penetration is three times higher,
- certain functional anatomical characteristics are different: hyper-plasticity of the skin with a rich vascular dermal network, a thinner horny layer of the epidermis, and melanocytes that are less functional during the first year.
Therefore, creams intended for a child’s skin require a specific formulation because if it is different in its structure, it will also be different in its function. In fact, a child’s skin is more vulnerable and is less able to carry out its natural protective function.