Non ionizing radiations are part of natural light and produce both beneficial and malignant effects, depending on several factors, such as exposure, wavelength and intensity. In addition those radiations can be also generated in artificial form in a wide range of wavelengths and with different optical properties (Chan et al., 2007). Of special relevance in many aspects of the human activity is the ultra-violet region of the spectrum, which comprises wavelengths in the range 500 - 100 nm. They are
usually classified according to their wavelengths in three types, denominated UVA (400-315 nm), UVB (315-280 nm) and UVC (280-100 nm). Radiation in these regions can be produced by a number of devices, from the ordinary low energy continuous lamp to high energy superradiant pulsed laser.
The laser is a light source that produces coherent electromagnetic radiating energy. A widely used laser in medicine is the Xe-Cl excimer laser, obtained from the emission of electronically excited XeCl, whose spectrum shows two main emission bands, cantered at 308 nm and 367 nm. Although their relative intensities depend of the conditions of the excitation, emission at 308 nm is much more intense. Commercially available Xe-Cl lasers operate at 308 nm with pulses of 10 - 20 ns, energies up to 1 J and
variable repetition rates from 1 to 500 Hz o even more (Spencer & Hadi, 2004). In addition to the laser, from 1995 it has also been available a device that emits at 308 nm, called intense pulsed light (IPL) which is basically a Xe-Cl lamp that has proved
to be a useful tools for the treatment of the changes of the skin.
The IPL provides high energy pulsed excitation consisting of 85% of ultraviolet radiations UV B and 15% of radiations UV A. This technology is also known as “Photoderm”. Although the active medium of this lamp is also XeCl, the emission is polychromatic but also non coherent; therefore is not a laser. However, the use in medicine and the risks associated with it are comparable to the medical lasers of the high energy (class 3b and 4) and therefore their use should be subject to the same security guidelines (Reed et al., 1994; Nahavandi et al., 2008).
The IPL is used in a similar way to the excimer laser in the treatment of various pathologies of the skin: psoriasis, vitiligo, etc. Clinically it is also used to stimulate the regeneration of the cartilage in degenerative processes. It has been postulated that its action is based on the activation of the cell division, collagenous and elastic fibers formation, regeneration of blood vessels, cicatrisation of bone tissue and reepithelization of damaged tissue (Moseley, 1994; Garrigo & Valiente, 1996; Baumanna et al., 2006; Town et al., 2007).
Nevertheless, there are some discrepancies in results obtained with experimentation animals on the medical use of not-ionizing radiations (Reed et al.). In a previous study, we irradiated chick embryos and new born chickens with He-Ne laser, infrared and ultraviolet radiation, finding post irradiation histopathologic changes (Avila et al., 1994; Reed et al.; Samar et al., 1993).However, the biological effect of the 308 nm IPL has not been investigated using the oral cavity of chick embryos as sensor.
Therefore, it seems important to study the optical characteristics of the filtered and unfiltered light emitted by the Intense pulsed light (Xe-Cl) and its biological effects using the lingual cartilage of the chick embryo as a sensor, in order to obtain information about security measures on patients and medical staff.
Skipping to the results of the study:
To our knowledge, this is the first report on the biological effects of the 308 nm radiation of intense pulsed light from
excimer Xe-Cl in buccal cavity of chick embryo. For this reason we investigated the histopathologyc changes produced in the
tongue of chick embryos, specially in the cartilage.
With respect to the test group, we present a few representative results, obtained with three different filters. The most relevant findings consisted in degenerative changes in the cartilage with pleomorphic chondrocytes, which in some cases presented nuclei with progressive chromatin condensation (hyperchromasia) and in others vacuolated nuclei, with macro and anisokaryosis. These results are presented in Fig 3- B and correspond to irradiation using filter F5 (Orange acetate). In samples corresponding to irradiation though filter F10, we observed chondrocytes with pycnotic and hyperchromic nuclei with poorly defined limits (apoptosis) and in some cases total destruction. The cartilaginous matrix presented a reduced stained affinity
(Fig.3- C). The example shown in Fig 3- D corresponds to a study green using filter. Here we observed distal glandular necrosis, leucocyte infiltrate, thickening of the blood vessel walls to the expense of the tunica media, with perivascular edema in the subepithelial and perichondrium connective tissue. Fig. 3. A: Control, cartilage is in center of the tongue with
hematoxylin and eosin stain, 5 X. B: Irradiation using the orange acetate filter. In the upper part it is observed the hyaline cartilage with degenerative changes: pleomorphic chondrocytes, nuclei with progressive condensation of the chromatin
(hipercromasia), and vacuolated nuclei, with macro and anisokaryosis. Lower part: mucous glands with leucocyte inflitrate and necrosis. Hematoxylin and eosin stain. 10 X.
The Xe-Cl IPL system used in this work resulted in histological alterations in the tissue of chick embryos, demonstrating that his procedure by its simple methodology and availability can be used as a model to study the effect of non ionizing radiation on human health. In addition, the high energy, highly monochromatic emission at 308 nm provided by this lamp suggests that these effects could be similar to those produced by the excimer Xe-Cl laser, operating at the same wavelength. It should be noted that the IPL is routinely used for the treatment of several skin problems, and therefore, the spectroscopy characterization
reported here indicates that care should be exercised when using this kind of light sources. The filters used acted as attenuators of the light intensity and provide information about the optical properties of materials to be used as protective barriers for patients and medical staff, when employing this and related techniques.