Bronzing

Process

The mechanism of bronzing is double:

Under the action of the rays Ultraviolet S, the Kératinocyte S, cells of the surface layer of the Skin, will multiply and make it more solid and less permeable to the radiations.
the production of Mélanine by the Mélanocytes is stimulated. The mélanine with the property to absorb the very energy rays Ultraviolet S (UV-B) and thus to protect the skin. These is the process which gives to the skin this matt color, gilded, brown specific to bronzing.

Under the effect of UV, the kératinocytes secrete the hormone alpha MSH by scission of the pro-opiomélanocortine (POMC), thanks to the action of a protein called P53. Alpha MSH sticks to the mélanocytes and stimulates the production of mélanine. P53 being also a protein produced in the event of stress, that could particularly explain the hyperpigmentation which appears sometimes, in the elderly, in the event of prolonged irritation of the skin.

In addition, the formation of alpha-MSH starting from producing POMC of the Endorphin B supposed to contribute to a feeling of wellbeing, David E Fisher, director of research having highlighted the role of p53 in bronzing, proposes that the endorphin release during this process could encourage people to be exposed to the sun. The whole of the processes would support protection against cutaneous cancers. Indeed, if an exposure to the sun too long or too brutal is dangerous, a moderate and regular exposure can on the contrary constitute a protection, except at the people deprived of the capacity to bronze.

Consequences of the exposure on health

The protection offered by the skin vis-a-vis ultraviolet radiations is not perfect. Initially bronzing is a slow process, the skin thus remains very vulnerable at the time of the first hours of exposures. Then, if the mélanine makes it possible to filter 90% of the UVB, it almost does not filter the UVA which in the long run cause same the effects as the UVB: wrinkles, premature ageing of the skin, appearance of Mélanome S. Of the studies showed that each human being lays out with the birth of a capital sun which decreases throughout the life during the exposures to the ultraviolet radiation. Once this exhausted capital, bronzing does not protect the skin any more.

The independent factors of risks supporting cancers of the skin are:

heredity;
the abuse exposure to the sun before the adulthood;
the low pigmentation, at the russet-red ones and the fair with milky dye;
the compounds of tar, creosotes, of arsenic and/or radium when côtoyés regularly;
the use of the tobacco and food modes rich in fat.

However a measured bronzing is good for the fixing of the vitamins, the consolidation of the osseous mass, for the sleep and the moral one. Finally of very many and recent studies, indicate that the benefit of the solar exposures would be much larger than the risks, as well on a medical level as economic. Thus, in the United States as in England, the specialists affirm that an adequate exposure to UV would make it possible to prevent 10 to 20% of all the cancers mortals and in particular to decrease the invoice of public health.

Reference

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