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Studies suggest sunscreens provide only partial UV protection against moles

09-May-2013

Two separate studies carried out by scientists in Europe suggest that chemical sunscreens only provide partial UV protection against moles.

The studies were both published in the May edition of the peer reviewed JAMA Dermatology and stress the fact that individuals with skin that is prone to moles should take extra precautions when protecting the skin against UV rays and could also point to the need for precautionary labelling on products or sunscreens that have been developed specifically to protect individuals prone to moles.

The first study was headed by Cristina Carrera of the Hospital Clinic of Barcelona, in Spain, and the results are said to show that both physical barriers and sunscreens can partially prevent UV-B effects on moles (nevi) sampled in a group patients.

Meanwhile, a second recently published study headed up by Rainer Hofmann-Wellenhof, M.D. at the Medical University of Graz, Austria, examined the effects of UV rays on the characteristics of melanocytic nevi and also found that the effects of sunscreen protection was limited.

First study showed darkening of moles even with sunscreen

Carrera’s study included nevi from 20 patients. Half of each nevi was protected by either a barrier or a sunscreen, while the legions were then irradiated by a single dose of UV-B, with the outcomes determined by vivo examinations carried out before the radiation and seven days after.

The results showed that pigmentation was the most frequent documented change following the UV-B exposure, with both barrier and sunscreen protected nevi showing some signs of enhanced melanocytic activation, though this was more pronounced in the sunscreen protected samples.

“Both physical barriers and sunscreens can partially prevent UV-B effects on nevi. Subclinical UV radiation effects, not always associated with visible changes, can develop even after protection. Sunscreens are not quite as effective as physical barriers in the prevention of inflammatory UV-B-induced effects,” the Carrera study noted.

Second study also showed changes in mole pigmentation

The Hoffman-Wellenhof research selected 26 melanoctyic nevi from 26 patients  with a mean age of 31, and a UVA/UVB sunscreen with an SPF of 6.2 was applied to one half of the nevus.

Using digital camera equipment with a polarised dematascope, the nevi were measured before UV exposure, then again three and seven days after irradiation.

At seven days, the scientists noted an almost identical increase in pigmentation activity in both halves of the nevi, with an increase in brown to black globuli, brown dots, bluish white veil, atypical network, and increased vessels.

However, the research also noted that HMB-45 stain – the anatomic pathology tool used as a marker for melanomas - was significantly stronger in the unprotected halves.

“In summary, we extended the dermoscopic findings observed by Carrera et al into the field of solar-simulated UV radiation, and we agree that not all UV-induced changes are confined to unprotected areas,” the Hoffman-Wellenhof research notes.

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