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    Sunburn with Sunscreen - A Case Study
    By Chanda Siddoo-Atwal | April 20th 2011 11:15 AM | 11 comments | Print | E-mail | Track Comments
    About Chanda

    Post-doctoral Fellow, Medical College Wisconsin, Ph.D. [Simon Fraser University], B.Sc. Biochemistry [University College London]...

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    The subject of this case-study is a 44 year old female of Indian [Asian] origin with no past history of immunodeficiency. Currently, she is in reasonable health for her age and shows no signs or symptoms of any serious illness. A genetic predisposition to sunburn rather than to tan upon exposure to the sun runs in both her mother’s and father’s families.

    The experimental design was identical in each trial such that the subject sat upon a park bench at noon facing the direct sunlight on a clear, sunny day. Each experiment lasted between 30 and 60 minutes following the application of sunscreen ranging from 15 to 30 spf. The control experiment was performed under the same conditions without the application of any sunscreen or sun lotion.

    Photographs of the face were taken starting 24 hours from the time of commencement of initial sun exposure which was deemed as 0 hours at noon on the previous day. All experiments were conducted between the winter and spring months of February and May at Ambleside beach in West Vancouver, British Columbia (Canada). A control subject who did not get sunburnt under the same conditions was also included in the study. These same results were repeatedly observed several times under similar conditions.

    The study shows that sunburn can occur despite the use of sunscreen (15 spf) containing titanium dioxide, zinc oxide, octyl methoxycinnamate, or, benzophenone-3 during winter months in a temperate climate. Indeed, it may even cause burns to be more severe or to occur in regions in which they are not ordinarily seen, for example, in the area immediately surrounding moles. However, as one would expect in areas of melanin concentration, moles themselves remain unsusceptible to apoptosis [programmed cell death]. Moreover, melanin itself is known to be a good conductor once coated with metal and two of the foremost sunscreen ingredients are titanium dioxide and zinc oxide.

    In addition, sunburn can still occur while wearing stronger sunscreens (30 spf) containing titanium dioxide, zinc oxide, or, octinoxate. Although they may attenuate or even eliminate redness and inflammation, peeling of the damaged skin may not be prevented. As it is this last apoptotic phase that has been linked to carcinogenesis, this would appear to reflect an inherent weakness in the general composition of many sunscreens available to the consumer.

    It also brings into question the efficacy and safety of sunscreens which effectively block inflammation, but are unable to prevent peeling following sun exposure in providing protection against skin cancer. In the experience of this subject, the natural human sunburn cycle (without the use of any sun lotions or sunscreens) is approximately one week in length (7 days) from start to finish. Macroscopically, it consists of three phases including inflammation, new tissue formation, and apoptosis (visible peeling).

    The inflammatory phase consists of redness and inflammation commencing 20-30 minutes from the time of initial sun exposure. It spans roughly 2-3 days. New tissue formation is stimulated some time after initial exposure and it is complete within one week. In the last apoptotic phase, the top layer of dead skin cells sloughs off to reveal a new tissue layer beneath. This process directly follows on from the inflammatory phase and is complete approximately 7 days following exposure. While there is some redness and inflammation following initial exposure and on day 1, the inflammatory reaction seems to peak on day 2.

    The onset of apoptosis (visible peeling) occurs between day 2 and day 3 while there is an accompanying decrease in redness and inflammation. The peak of apoptosis, visible as peeling, is seen on day 4 which declines gradually on day 5 and 6 as the dead cells fall away from the skin. By day 7, recovery is usually complete and the old cells have been replaced by new ones.  Thus, this case-study suggests that modifying cultural habits such as minimizing sun exposure and covering exposed parts of the body may still play an important role in cancer prevention. 


     Octyl Methoxycinnamate

    +

    Benzophenone-3

    +

    Titanium Dioxide

    Comments

    MikeCrow
    I remember seeing a graph of the rise in skin cancer and the sales of sunscreen, and they were quite similar.
    Never is a long time.
    Chanda
    Are you sure that those studies you mention were plotting the correlation between skin cancer and sunscreen and not suntan lotions? i.e. the latter are notorious for containing tumour initiators and promoters whereas I have not come across any such studies with sunscreen before. If you are sure it is sunscreens, I would be interested in having the reference. Sorry for the delay in replying, but I am still new to science blogging!   Chanda
    MikeCrow
    Sorry, I'm pretty sure it was suntan lotions.
    Never is a long time.
    vongehr
    "Moreover, melanin itself is known to be a good conductor once coated with metal and two of the foremost sunscreen ingredients are titanium dioxide and zinc oxide."
    ???
    You might be interested into these guys here.
    Chanda
    Firstly, there is no known link between vitamin D deficiency and increases/decreases in apoptosis. Moreover, anyone who drinks 2 or more glasses of milk a day will not be D-deficient because it is vitaminzed in North America. Secondly, since you are a physicist, I understand that titanium dioxide and zinc oxide retain some of their metallic properties such as conductivity. I imagine it is this property which makes melanin a good conductor once coated with a metal, so why not a conductive metal oxide if it is provided in the optimal form for performing this function? I apologize for the delay.  Chanda  
    vongehr
    Vitaminized with the wrong form of VD, specifically not D3. Apart from that metal oxides are insulators, I did not question the conductivity, I question what on earth the conductivity of melanin coated with whatever has to do with anything at all.
    Chanda
    Perhaps, this picture will anwer your question about metal oxides partly; this episode of sunburn occurred in late October.
    Dear Chanda Siddoo-Atwal
    If you are looking to do some test for natural extract for sunscreen. please contact me.

    Chanda
    What do you mean by a "natural sunscreen"? Titanium dioxide and zinc oxide are both "natural products". Sorry for the delay.  Chanda   
    I do not tan, I burn. People that know me no longer tell me to use sunscreen or sunblock because they have seen me burn worse while using it. I have to wear long sleeves and a hat while I living out here in the Arizona Desert.. Thank You for exposing that non-organic stuff as a waste of money. I agree the efficacy needs to be challenged. Keep up the good work.

    Chanda
    Currently, I am working on some sunscreen that should be more effective. Hopefully, I will be successful in posting the inital results soon. So look out for this short study as it may be of some interest to you. In the meantime, cover up and try to stay out of the midday sun!   Chanda