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Asunto:[dxcolombia] NORMAS DE SEGURIDAD DE RF
Fecha:Sabado, 30 de Junio, 2007  04:00:50 (+0000)
Autor:HK1AA . <hk1aa @.......com>

 
> > [http://www.citel.oas.org/newsletter/common/bullet.gif]http://www.citel.oas.org/newsletter/2007/junio/jun-07_e.asp#chou > Norma de seguridad de RF del IEEE: Su relación con las inquietudes planteadas en cuanto a la seguridad de estaciones base y teléfonos móviles > Por C-K. Chou, Ph.D., Presidente, Comité Técnico 95, IEEE > Esta nueva "Norma del IEEE para niveles de seguridad con respecto a la exposición de seres humanos a los campos electromagnéticos de frecuencia radioeléctrica, de 3 kHz a 3000 kHz", publicada el 19 de abril de 2006, es una revisión de la C95.1-1991 (edición 1999) y C95.1b-2004 "Enmienda 2: Límites de tasa de absorción específica (SAR) para el pabellón auditivo". La revisión está basada en documentos científicos y médicos publicados hasta diciembre de 2003, pero también se incluyen varias disertaciones de 2004 y 2005. El documento contiene un examen global de unas 1300 referencias, entre ellas estudios relativos a exposiciones de bajo nivel, en las que no podían medirse o no se esperaban aumentos de temperatura (efectos "no térmicos"). La norma revisada refleja el nuevo conocimiento obtenido de métodos experimentales y numéricos mejorados, y una mejor comprensión de los efectos agudos y crónicos de la exposición a campos electromagnéticos de radiofrecuencia (RF) en animales y seres humanos. > más información > [http://www.citel.oas.org/newsletter/common/bullet.gif]Seguridad y riesgos de las comunicaciones de RF – La perspectiva de la industria de Wi-Fi > Por John Roman, Presidente, Task Group on Health and Science, Wi-Fi Alliance > Wi-Fi® es una tecnología de baja potencia que emplea las ondas radioeléctricas para crear una red de área local (LAN, por sus iniciales en inglés) entre equipos electrónicos de computación y consumo. El uso de Wi-Fi está muy difundido para proporcionar acceso inalámbrico a la Internet en lugares públicos tales como aeropuertos, hoteles, y cafés, así como en las oficinas y los hogares. Se calcula que unos 300 millones de personas utilizan Wi-Fi en todo el mundo. > Recientemente, algunas personas han planteado cuestiones respecto de los efectos que tendría en la salud humana el uso de Wi-Fi. La Wi-Fi Alliance tiene debidamente en cuenta esas inquietudes. Aunque se han planteado ciertas cuestiones, las diversas investigaciones científicas realizadas hasta la fecha concluyen que no hay pruebas confirmadas de que los campos electromagnéticos de RF por debajo de los indicados por las directrices de seguridad internacionales vigentes (directrices ANSI/IEEE C95.1-2006 y ICNIRP 1998) causen efectos adversos a la salud. La tecnología Wi-Fi debe proyectarse y ensayarse para cumplir con todos los requisitos de seguridad nacionales e internacionales. Las redes Wi-Fi emiten señales que típicamente están entre cientos y miles de veces por debajo de los límites de seguridad requeridos. > más información > Nota del editor: Este documento sólo está disponible en inglés. > This new "IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz" published on April 19, 2006 is a revision of C95.1-1991 (1999 edition) and C95.1b-2004 "Amendment 2: Specific Absorption Rate (SAR) Limits for the Pinna." The revision is based on scientific and medical literature published through December 2003, but several 2004 and 2005 papers are included. The document includes a comprehensive review of about 1300 references, including studies that involve low level exposures where increases in temperature could not be measured or were not expected (i.e., "non-thermal" effects). The revised standard reflects new insights gained from improved experimental and numerical methods and a better understanding of acute and chronic radiofrequency (RF) electromagnetic field exposure effects on animals and humans. > The weight of evidence approach was used for the standard development. This process includes evaluation of the quality of test methods, the size and power of the study designs, the consistency of results across studies, and the biological plausibility of dose-response relationships and statistical associations. C95.1 Standard's major revision includes the new recommendation of peak spatial average SAR of 2 and 10 W/kg averaged over 10 g tissue for the lower and upper tier, respectively. This revision resolves a major harmonization issue with RF standards. > RF Safety concerns started in the 50s with exposure to radars, then radio and TV broadcasting in the 60s, microwave ovens in 70s, police radar in 80s and then most recently wireless communications. Although mobile phones are a new concern, remember that two-ways radios with much higher power have been used by security professionals for more than 40 years. The major difference in ionizing and non-ionizing radiation can be seen from the electromagnetic spectrum. The well known cumulative damaging effects of ionizing radiation do not occur at wavelengths longer than those in the UV, including the sunlight. > Over the past more than 50 years, large data base has been accumulated. Currently there are about 1600 peer-reviewed articles in the WHO database relating to the RF biological effects. On the mobile telephony alone, there have been about 500 papers published and another 200 to be published. The research subjects consist of epidemiological, human, animal and in vitro cell studies. The complexities of both engineering and biological studies are pointed out in the C95.1 Standard, which are the major reasons why there is so much noise in research results. The WHO stated that scientific knowledge in this area is now more extensive than for most chemicals, and concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields. > > In terms of research, WHO estimated $250 M already spent on mobile telephony bioeffect research, and $130 M more are for on going and future studies. The strongest evidence is from animal cancer studies. The weight of scientific evidence in 41 studies shows that RF exposure up to lifetime exposure (2 years) does not adversely affect carcinogenic processes (initiation, promotion or co-promotion) at whole-body dose rates up to 4 W/kg and localized dose rates up to 2.3 W/kg. Long term animal studies provide no supportive evidence of low-level non-thermal effects. Short term animal and in vitro studies showing positive effects, even if proven repeatable, are not consistent with the lifetime exposure studies. > In the past 10 years, there have been more than 20 independent expert group reviews globally. The general conclusion of reviews is that there is no credible evidence that RF exposures within internationally accepted limits cause any adverse health effects, but more research is needed. However, it was pointed out that one can never prove the null hypothesis and thus one can never prove that something is absolutely safe. Basically, there is no known mechanism for adverse health effects of RF exposure other than thermal. Due to the current extensive database, it is unlikely that results of ongoing studies will shift the weight of evidence on health effects. > International measurement methods for measuring mobile phone emission are available. With proper regulation, all phones should comply with international exposure limits. Residential and office building RF exposures are in general lower than 1% of ICNIRP or IEEE limits, similar to that of radio and TV broadcast. Roof top antenna installation does not beam energy downward and therefore there is no need for concern. WHO Fact Sheet #304 (May 2006): Electromagnetic fields and public health: Base stations and wireless technologies, states "Considering the very low exposure levels and research results collected to date, there is no convincing scientific evidence that the weak RF signals from base stations and wireless networks cause adverse health effects." > In conclusion: 1) RF electromagnetic waves are not nuclear radiation, 2) The only proven RF interaction mechanism is thermal effect, 3) Exposure levels near base stations are very low, 4) Both ICNIRP and IEEE standards provide ample protection for all populations. > This new "IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz" published on April 19, 2006 is a revision of C95.1-1991 (1999 edition) and C95.1b-2004 "Amendment 2: Specific Absorption Rate (SAR) Limits for the Pinna." The revision is based on scientific and medical literature published through December 2003, but several 2004 and 2005 papers are included. The document includes a comprehensive review of about 1300 references, including studies that involve low level exposures where increases in temperature could not be measured or were not expected (i.e., "non-thermal" effects). The revised standard reflects new insights gained from improved experimental and numerical methods and a better understanding of acute and chronic radiofrequency (RF) electromagnetic field exposure effects on animals and humans. > The weight of evidence approach was used for the standard development. This process includes evaluation of the quality of test methods, the size and power of the study designs, the consistency of results across studies, and the biological plausibility of dose-response relationships and statistical associations. C95.1 Standard's major revision includes the new recommendation of peak spatial average SAR of 2 and 10 W/kg averaged over 10 g tissue for the lower and upper tier, respectively. This revision resolves a major harmonization issue with RF standards. > RF Safety concerns started in the 50s with exposure to radars, then radio and TV broadcasting in the 60s, microwave ovens in 70s, police radar in 80s and then most recently wireless communications. Although mobile phones are a new concern, remember that two-ways radios with much higher power have been used by security professionals for more than 40 years. The major difference in ionizing and non-ionizing radiation can be seen from the electromagnetic spectrum. The well known cumulative damaging effects of ionizing radiation do not occur at wavelengths longer than those in the UV, including the sunlight. > Over the past more than 50 years, large data base has been accumulated. Currently there are about 1600 peer-reviewed articles in the WHO database relating to the RF biological effects. On the mobile telephony alone, there have been about 500 papers published and another 200 to be published. The research subjects consist of epidemiological, human, animal and in vitro cell studies. The complexities of both engineering and biological studies are pointed out in the C95.1 Standard, which are the major reasons why there is so much noise in research results. The WHO stated that scientific knowledge in this area is now more extensive than for most chemicals, and concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields. > > In terms of research, WHO estimated $250 M already spent on mobile telephony bioeffect research, and $130 M more are for on going and future studies. The strongest evidence is from animal cancer studies. The weight of scientific evidence in 41 studies shows that RF exposure up to lifetime exposure (2 years) does not adversely affect carcinogenic processes (initiation, promotion or co-promotion) at whole-body dose rates up to 4 W/kg and localized dose rates up to 2.3 W/kg. Long term animal studies provide no supportive evidence of low-level non-thermal effects. Short term animal and in vitro studies showing positive effects, even if proven repeatable, are not consistent with the lifetime exposure studies. > In the past 10 years, there have been more than 20 independent expert group reviews globally. The general conclusion of reviews is that there is no credible evidence that RF exposures within internationally accepted limits cause any adverse health effects, but more research is needed. However, it was pointed out that one can never prove the null hypothesis and thus one can never prove that something is absolutely safe. Basically, there is no known mechanism for adverse health effects of RF exposure other than thermal. Due to the current extensive database, it is unlikely that results of ongoing studies will shift the weight of evidence on health effects. > International measurement methods for measuring mobile phone emission are available. With proper regulation, all phones should comply with international exposure limits. Residential and office building RF exposures are in general lower than 1% of ICNIRP or IEEE limits, similar to that of radio and TV broadcast. Roof top antenna installation does not beam energy downward and therefore there is no need for concern. WHO Fact Sheet #304 (May 2006): Electromagnetic fields and public health: Base stations and wireless technologies, states "Considering the very low exposure levels and research results collected to date, there is no convincing scientific evidence that the weak RF signals from base stations and wireless networks cause adverse health effects." > In conclusion: 1) RF electromagnetic waves are not nuclear radiation, 2) The only proven RF interaction mechanism is thermal effect, 3) Exposure levels near base stations are very low, 4) Both ICNIRP and IEEE standards provide ample protection for all populations. > C-K. Chou, Ph.D. > Presidente, Comité Técnico 95 > Institute of Electrical and Electronics Engineers > International Committee on Electromagnetic Safety > ck.chou@... > Información adicional: CCP.II tiene un Grupo Relator sobre Aspectos Técnicos y Regulatorios Relativos a los Efectos de las Emisiones Electromagnéticas no Ionizantes que está considerando estas cuestiones. El Relator es el Sr. Héctor Carril (hcarril@...). > © Derechos Reservados 2007. Comisión Interamericana de Telecomunicaciones > Organización de los Estados Americanos. > 1889 F St., N.W., Washington, D.C. 20006 - Estados Unidos > Tel. (202)458-3004 | Fax. (202) 458-6854 | citel@... |p://citel.tel.oas.org > Para cancelar la subscripción ir al siguiente link citel@... 
 
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