Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Sun’s infrared-A is not detrimental to the skin

15.07.2010
Recent scientific publications refute concerns regarding the infrared-A (IRA) component of the Sun’s radiation. Specific protection against the Sun’s infrared-A is therefore unnecessary. As far as ultraviolet in Sun's radiation is concerned, an adequate protection is still required.

Two new publications from the Berlin Charité and the University Medical Centre Mainz [1] and from the University of Stuttgart-Hohenheim [2] confirm earlier studies concerning the harmlessness of infrared-A [3] and its usefulness to humans. They refute concerns regarding possible detrimental effects of infrared-A, which is the main part of the Sun’s thermal radiation. In the Earth’s moderate climate zones, the infrared A-radiation reaches the Earth’s surface after being filtered by the water vapour in the Earth’s atmosphere, and is thus especially well tolerable.

The publication from the Charité Berlin and the Mainz University Medical Center has demonstrated numerous systematic methodological errors in publications claiming to show the dangers of the infrared-A component of the Sun’s radiation. In cell culture studies, irradiances were partly used which were much more than 10-fold greater than that of the maximum possible infrared-A irradiance of the Sun in the moderate climate zones or even in the tropics.

These studies ignored the fact that cells in a cell culture (which are not covered by overlying skin cells and have no connection to a blood circulation) should not be exposed to the same level of irradiance as human skin (with an intact blood perfusion, a layer of overlying cells and a horny layer), if meaningful conclusions relevant to the situation in the skin of a person are to be drawn.

An earlier publication has also brought attention to the differences in effects seen when identical irradiances are used to irradiate inanimate material having no blood circulation (resulting in a surface temperature of approx. 100°C) and human skin capable of heat dissipation via the circulation (resulting in a surface temperature of approx. 38°C) [4].

In the studies in which supposed dangers were reported, no consideration at all was given to the fact that the results seen are dependent not only on the dose of irradiation, but also on the irradiance level: Effects seen following short exposures to very high irradiances can not be interpreted as suggesting that the same result will occur if irradiation is carried out over hours using a lower irradiance level.

Additionally, some of the studies were carried out using foreskin cells obtained from infants, which are known to behave differently to skin cells.
A specific effect of infrared-A exposure which was independent of a pure temperature increase could not be identified as the reason for effects interpreted as being undesirable in the critical studies. Instead, the publication from the University of Stuttgart-Hohenheim showed that certain effects could be seen in cell cultures even in the complete absence of infrared-A exposure when only the temperature of the water bath was increased, whereas these effects were not seen even with high infrared-A irradiance levels as long as the cells were maintained under physiological temperature conditions.

Ultimately, the interpretation of possible effects and the avoidance of miss- or overinterpretations are of considerable importance: Even when, as claimed in the critical reports, an upregulation of enzymes capable of degrading collagen (e.g., the matrix metalloproteinases) or their gene expression were to occur, this can not automatically be interpreted as being detrimental in the sense of a promotion of skin ageing or even more far-reaching skin changes, since these effects are also seen during other processes such as wound healing.

Even a purported increase in free radicals can not categorically be considered as being unfavourable; the ambivalent relevance of free radicals has already been pointed out in an earlier publication [5]: in the case of special white blood cells (granulocytes), the generation of free radicals is an important mechanism of action in the defence against bacteria.

Consequently, there is no reason for specific measures against the Sun’s infrared-A (e.g., in the form of special Sun protection products), especially when the fact that infrared-A has been shown to provide some protection against the unwanted effects of the Sun’s ultraviolet radiation is considered [6]. At the same time, there is no cause for any reservations concerning the beneficial medical application of infrared-A (IRA) or water-filtered infrared-A (wIRA) radiation. However, the necessity for adequate skin and eye protection against ultraviolet (UV) in Sun's radiation remains valid, e.g., in the form of protection through textiles, sunglasses or sun protection products.

Publications:
[1] Piazena H, Kelleher DK. Effects of infrared-A irradiation on skin: discrepancies in published data highlight the need for an exact consideration of physical and photobiological laws and appropriate experimental settings. Photochem Photobiol. 2010; 86: 687-705. DOI: 10.1111 ⁄ j.1751-1097.2010.00729.x
[2] Jung T, Höhn A, Piazena H, Grune T. Effects of water-filtered infrared A irradiation on human fibroblasts. Free Radic Biol Med. 48; 2010: 153-160. DOI: 10.1016/j.freeradbiomed.2009.10.036
[3] Gebbers N, Hirt-Burri N, Scaletta C, Hoffmann G, Applegate LA. Water-filtered infrared-A radiation (wIRA) is not implicated in cellular degeneration of human skin. GMS Ger Med Sci. 2007; 5: Doc08. Online available from: http://www.egms.de/pdf/gms/2007-5/000044.pdf (PDF) and http://www.egms.de/en/gms/2007-5/000044.shtml (shtml).
[4] Mercer JB, Nielsen SP, Hoffmann G. Improvement of wound healing by water-filtered infrared-A (wIRA) in patients with chronic venous stasis ulcers of the lower legs including evaluation using infrared thermography. GMS Ger Med Sci. 2008; 6: Doc11. Online available from: http://www.egms.de/pdf/gms/2008-6/000056.pdf (PDF) and http://www.egms.de/en/gms/2008-6/000056.shtml (shtml).
[5] Meffert H. Antioxidants – friend or foe? GMS Ger Med Sci. 2008; 6: Doc09. Online available from: http://www.egms.de/pdf/gms/2008-6/000054.pdf (PDF) and http://www.egms.de/en/gms/2008-6/000054.shtml (shtml).

[6] Menezes S, Coulomb B, Lebreton C, Dubertret L. Non-coherent near infrared radiation protects normal human dermal fibroblasts from solar ultraviolet toxicity. J Invest Dermatol. 1998; 111(4): 629-33. DOI: 10.1046/j.1523-1747.1998.00338.x

Wolfgang Müller | idw
Further information:
http://awmf.org

More articles from Health and Medicine:

nachricht Unique brain 'fingerprint' can predict drug effectiveness
11.07.2018 | McGill University

nachricht Direct conversion of non-neuronal cells into nerve cells
03.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>