RESUMEN
In response to mounting radiofrequency health concerns, this study was constituted to provide critical scientific data and assess any potential exposure from global system for mobile communication mobile phones. Specific absorption rate (SAR) from phones approved by the regulator and untested/unapproved phones were measured with a ComoSAR system. The maximum 10 g SAR (0.51 W/kg) and 1 g SAR (0.99 W/kg) measured were 25 and 62% of the International Commission on Non-Ionizing Radiation Protection and Federal Communication Commission limits, respectively. The approved phone produced statistically significant higher SAR values relative to the untested phone. SAR values of the right ear were relatively higher. All maximum SAR values were recorded on the right ear. The regulatory approval status of the phone, phone's orientation to the head, operating frequency channel and in which ear (right or left) the phone is used influenced the SAR measured. The SAR values of the approved phone compared favourably with similar studies while the unapproved phone does not.
Asunto(s)
Teléfono Celular , GhanaRESUMEN
The protection of man and his environment from undue exposure from radio frequency electromagnetic field requires identification of the location where exposures are likely to be higher than safe levels established by international safety standards. A wideband measurement with a spectrum analyzer and a log-periodic antenna in conjunction with the three-point spatial average method was used. The results ranged from 16.21 to 2907.00 mVm-1 and complied with a maximum of 1.08% of the ICNIRP reference level. Private frequency modulation (FM) sources were identified as the major source of exposure to the public with a mean value of 337.70 ± 133.70 mVm-1 against 122.30 ± 36.47 mVm-1 for the public FM transmitters. Even though the result was lower than a workplace assessment, it was, however, higher than similar works conducted in Africa and Palestine. Finally, four sensitive locations were identified for further research work.
Asunto(s)
Monitoreo de Radiación , Campos Electromagnéticos/efectos adversos , Exposición a Riesgos Ambientales/análisis , Ghana , Humanos , Ondas de Radio/efectos adversosRESUMEN
A radiofrequency (RF) electromagnetic radiation safety assessment had been carried out at public access points within the compound of a teaching hospital. The frequency band investigated ranged from 87.5 MHz to 2.6 GHz. Eighty-eight measurements were made using a spectrum analyser coupled with a log-periodic antenna. The objective was to determine the level and nature of RF fields within the immediate premise of the facility where patients of health conditions are kept and treated. Results complied with the International Commission of Non-Ionising Radiation (ICNIRP) guidelines. The values of the resolved electric field at four spatial heights ranged from 1.00 ± 0.144 mV/m to 1.174 ± 0.169 V/m. Power densities varied from 2.65 ± 0.38 nWm-2 to 3.66 ± 0.528 mWm-2. There were relatively high contributions from frequencies above 900 MHz compared with contributions from lower frequency bands.
Asunto(s)
Campos Electromagnéticos , Exposición a Riesgos Ambientales/análisis , Hospitales de Enseñanza , Monitoreo de Radiación/métodos , Ghana , HumanosRESUMEN
This paper describes an effort to respond to the suggestion in World Health Organization (WHO) research agenda to better quantify potential exposure levels from a range of radiofrequency (RF) sources at 200 public access locations in Ghana. Wide-band measurements were performed-with a spectrum analyser and a log-periodic antenna using three-point spatial averaging method. The overall results represented a maximum of 0.19% of the ICNIRP reference levels for public exposure. These results were generally lower than found in some previous but were 58% (2.0 dB) greater, than found in similar work conducted in the USA. Major contributing sources of RF fields were identified to be FM broadcast and mobile base station sites. Three locations with the greatest measured RF fields could represent potential areas for epidemiological studies.
Asunto(s)
Radiación Electromagnética , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación/métodos , Ondas de Radio , Ghana , HumanosRESUMEN
The analysis of channel power and electric field strength at various locations from mobile base stations using power sensor, spectrum analyzer and log-periodic antenna revealed maximum potential exposure between the range of 61.1 and 254.7 m. Generally, the potential exposure values ranged from 0.0717 to 0.8950 mW m-2 with a maximum deviation of 22.22%. GSM900 was found to be more pronounced than GSM1800 and UMTS2100. Though the results complied with ICNIRP reference levels with a wide margin of 0.01%, it was higher than some previous work and South African mean value of 0.16 mW m-2, agreed with similar work elsewhere but lower than a global average value of 0.730 mW m-2.
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Teléfono Celular , Radiación Electromagnética , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación/instrumentación , Diseño de Equipo , GhanaRESUMEN
An inter-comparison study was conducted to assess the capability of dosimetry systems of individual monitoring services (IMSs) in Gabon and Ghana to measure personal dose equivalent Hp(10) in photon fields. The performance indicators assessed were the lower limit of detection, linearity and uncertainty in measurement. Monthly and quarterly recording levels were proposed with corresponding values of 0.08 and 0.025 mSv, and 0.05 and 0.15 mSv for the TLD and OSL systems, respectively. The linearity dependence of the dosimetry systems was performed following the requirement given in the Standard IEC 62387 of the International Electrotechnical Commission (IEC). The results obtained for the two systems were satisfactory. The procedure followed for the uncertainty assessment is the one given in the IEC technical report TR62461. The maximum relative overall uncertainties, in absolute value, expressed in terms of Hp(10), for the TL dosimetry system Harshaw 6600, are 44. 35% for true doses below 0.40 mSv and 36.33% for true doses ≥0.40 mSv. For the OSL dosimetry system microStar, the maximum relative overall uncertainties, in absolute value, are 52.17% for true doses below 0.40 mSv and 37.43% for true doses ≥0.40 mSv. These results are in good agreement with the requirements for accuracy of the International Commission on Radiological protection. When expressing the uncertainties in terms of response, comparison with the IAEA requirements for overall accuracy showed that the uncertainty results were also acceptable. The values of Hp(10) directly measured by the two dosimetry systems showed a significant underestimation for the Harshaw 6600 system, and a slight overestimation for the microStar system. After correction for linearity of the measured doses, the two dosimetry systems gave better and comparable results.
Asunto(s)
Dosis de Radiación , Monitoreo de Radiación/instrumentación , Gabón , Ghana , Humanos , Límite de Detección , Fotones , IncertidumbreRESUMEN
A survey of the radiofrequency (RF) radiation was undertaken within the premises of two television (TV) stations, TVA and TVB, in Accra, Ghana. The primary objective of this study was to determine the level of RF exposure to workers in the TV stations. A spectrum analyser, a bi-conical antenna (30-300 MHz) and a log-periodic antenna (200 MHz-2.0 GHz) were used. Results obtained indicated that the wideband electric field strength levels recorded in this work vary between 0.006 and 58.5 V m(-1) at TVA and between 0.007 and 28.5 V m(-1) at TVB. Compared with the results from TVB, TVA recorded relatively higher values in the 30-400 MHz range, whereas TVB produced relatively higher values in the 400 MHz-1.7 GHz range. Generally, results obtained were found to be below the occupational reference levels of the International Commission on Non-Ionizing Radiation Protection, but at some locations, the field intensity was 4.3 times higher than the reference levels for the general public.
Asunto(s)
Campos Electromagnéticos/efectos adversos , Exposición Profesional/análisis , Monitoreo de Radiación , Ondas de Radio/efectos adversos , Televisión , Ghana , HumanosRESUMEN
Heightened awareness of the ever-expanding use of radiofrequency (RF) techniques and technology has led to mounting concerns from the general public and the scientific community regarding the possible health effects that may arise as a consequence of exposure to RF radiations and has drawn the attention of many researchers the world over. A survey of the RF electromagnetic radiation at public access points in the vicinity of 20 frequency-modulated (FM) radio stations has been made in Accra, Ghana. The fundamental object was to determine the levels of RF fields from FM broadcast antennae within 10-200 m radius about the foot of the FM base station and at a height of 1.5 m above the ground at selected locations. A spectrum analyser and a bi-conical antenna element sensitive and effective within the frequency band of 30-300 MHz were used. Results obtained indicated that the levels of electric field strength ranged from 5.4E-04 V m(-1) at FM station 'O' to 7.4E-08 V m(-1) at FM station 'D'. At a transmission frequency range of 88-108 MHz, the variation of power densities is from 2.5E-10 to 1.5E-17 Wm(-2). These values are very low and are far below the reference level set by the International Commission on Non-Ionizing Radiation Protection and therefore do not pose any known hazard to the inhabitants of Accra, Ghana. The electric field levels presented in this work are comparable with those reported from epidemiological studies conducted elsewhere.
Asunto(s)
Radiación Electromagnética , Monitoreo de Radiación/métodos , Ondas de Radio , Campos Electromagnéticos , Exposición a Riesgos Ambientales , Sistemas de Información Geográfica , Geografía , Ghana , HumanosRESUMEN
Analyses of the results of calibration of survey meters carried out at the Secondary Standards Dosimetry Laboratory (SSDL) in Ghana over a period of 4 y (2008-2011) are reported. The calibration factors (CFs) of the set of survey meters indicated that â¼91.04 % were within the acceptable limit of ± 20.0 %. A higher percentage of the survey meters indicated CFs in the range of 0.95-1.15 except a few of them which indicated values <0.55. Some of the survey meters also recorded CFs >1.15. The degree of uncertainty in the measurements ranged from 0.03 to 17 % with the majority of them ranging from 0.03 to 6.0 % and a few of them >6.0 %. The results show that most of the survey meters calibrated were within the requirements of the regulations and may provide data for future development of calibration techniques in the country.
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Radioisótopos de Cesio/análisis , Monitoreo de Radiación/instrumentación , Monitoreo de Radiación/métodos , Radiometría/métodos , Algoritmos , Calibración , Ghana , Humanos , Rayos Láser , Protección Radiológica/métodos , Reproducibilidad de los ResultadosRESUMEN
A radiofrequency (RF) electromagnetic radiation safety survey had been carried out at public access points in 46 towns with 76 Global Systems for Mobile communication cell sites in two major cities in Ghana. The objective was to determine the levels of RF field in residential areas, schools and market places, and compare the measured results with the guidelines set by the International Commission of Non-Ionising Radiation (ICNIRP). Measurements were made with log-periodic antenna coupled with spectrum analyzer. The results varied from 0.85 to 1.07 mW m(-2) and 0.78 to 1.19 mW m(-2) for the transmission frequencies of 900 and 1800 MHz, respectively. The result generally shows a compliance with the ICNIRP limit of 0.024 % but was 108 times higher than a similar survey carried out in Ghana 2 y ago.
Asunto(s)
Teléfono Celular , Radiación Electromagnética , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación , Ondas de Radio , HumanosRESUMEN
Occupational exposure to radiation in medical practice in Ghana has been analysed for a 10-y period between 2000 and 2009. Monitored dose data in the medical institution in Ghana from the Radiation Protection Institute's database were extracted and analysed in terms of three categories: diagnostic radiology, radiotherapy and nuclear medicine. One hundred and eighty medical facilities were monitored for the 10-y period, out of which ~98% were diagnostic radiology facilities. Only one nuclear medicine and two radiotherapy facilities have been operational in the country since 2000. During the 10-y study period, monitored medical facilities increased by 18.8%, while the exposed workers decreased by 23.0%. Average exposed worker per entire medical institution for the 10-y study period was 4.3. Annual collective dose received by all the exposed workers reduced by a factor of 4 between 2000 and 2009. This is seen as reduction in annual collective doses in diagnostic radiology, radiotherapy and nuclear medicine facilities by ~76, ~72 and ~55%, respectively, for the 10-y period. Highest annual collective dose of 601.2 man mSv was recorded in 2002 and the least of 142.6 man mSv was recorded in 2009. Annual average values for dose per institution and dose per exposed worker decreased by 79 and 67.6%, respectively between 2000 and 2009. Average dose per exposed worker for the 10-y period was least in radiotherapy and highest in diagnostic radiology with values 0.14 and 1.05 mSv, respectively. Nuclear medicine however recorded average dose per worker of 0.72 mSv. Correspondingly, range of average effective doses within the diagnostic radiology, radiotherapy and nuclear medicine facilities were 0.328-2.614, 0.383-0.728 and 0.448-0.695 mSv, respectively. Throughout the study period, an average dose per medical institution of 3 mSv and an average dose per exposed worker of 0.69 mSv were realised. Exposed workers in diagnostic radiology primarily received most of the individual annual doses >1 mSv. The entire study period had 705 instances in which exposed workers received individual annual doses >1 mSv. On thermoluminescent dosemeter (TLD) return rates, facilities in Volta and Eastern Regions recorded highest return rates of 94.3% each. Ashanti Region recorded the least TLD return rate with 76.7%.
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Exposición Profesional/análisis , Dosis de Radiación , Monitoreo de Radiación/métodos , Radiografía/métodos , Dosimetría Termoluminiscente/métodos , Recuento Corporal Total/métodos , Bases de Datos Factuales , Ghana , Humanos , Medicina Nuclear/métodos , Radioterapia/métodos , Irradiación Corporal TotalRESUMEN
The dose management system (DMS) is a computer software developed by the International Atomic Energy Agency for managing data on occupational exposure to radiation sources and intake of radionuclides. It is an integrated system for the user-friendly storage, processing and control of all existing internal and external dosimetry data. The Radiation Protection Board (RPB) of the Ghana Atomic Energy Commission has installed, customised, tested and using the DMS as a comprehensive DMS to improve personnel and area monitoring in the country. Personnel dose records from the RPBs database from 2000 to 2009 are grouped into medical, industrial and education/research sectors. The medical sector dominated the list of monitored institutions in the country over the 10-y period representing â¼87 %, while the industrial and education/research sectors represent â¼9 and â¼4 %, respectively. The number of monitored personnel in the same period follows a similar trend with medical, industrial and education/research sectors representing â¼74, â¼17 and â¼9 %, respectively. Analysis of dose data for 2009 showed that there was no instance of a dose above the annual dose limit of 20 mSv, however, 2.7 % of the exposed workers received individual annual doses >1 mSv. The highest recorded individual annual dose and total collective dose in all sectors were 4.73 mSv and 159.84 man Sv, respectively. Workers in the medical sector received higher individual doses than in the other two sectors, and average dose per exposed worker in all sectors is 0.25 mSv.
Asunto(s)
Comités de Monitoreo de Datos de Ensayos Clínicos , Sistemas de Administración de Bases de Datos , Bases de Datos Factuales , Exposición Profesional/análisis , Monitoreo de Radiación , Protección Radiológica/métodos , Programas Informáticos , Ghana , Agencias Gubernamentales , Regulación Gubernamental , Humanos , Exposición Profesional/estadística & datos numéricosRESUMEN
Institutions in the education, research and industrial sectors in Ghana are quite few in comparison to the medical sector. Occupational exposure to radiation in the education, research and industrial sectors in Ghana have been analysed for a 10 y period between 2000 and 2009, by extracting dose data from the database of the Radiation Protection Institute, Ghana Atomic Energy Commission. Thirty-four institutions belonging to the three sectors were monitored out of which â¼65% were in the industrial sector. During the 10 y study period, monitored institutions ranged from 18 to 23 while the exposed workers ranged from 246 to 156 between 2000 and 2009. Annual collective doses received by all the exposed workers reduced by a factor of 2 between 2000 and 2009. This is seen as a reduction in annual collective doses in education/research and industrial sectors by â¼39 and â¼62%, respectively, for the 10 y period. Highest and least annual collective doses of 182.0 man mSv and 68.5 man mSv were all recorded in the industrial sector in 2000 and 2009, respectively. Annual average values for dose per institution and dose per exposed worker decreased by 49 and 42.9%, respectively, between 2000 and 2009. Average dose per exposed worker for the 10 y period was least in the industrial sector and highest in the education/research sector with values 0.6 and 3.7 mSv, respectively. The mean of the ratio of annual occupationally exposed worker (OEW) doses for the industrial sector to the annual OEW doses for the education/research sector was 0.67, a suggestion that radiation protection practices are better in the industrial sector than they are in the education/research sector. Range of institutional average effective doses within the education/research and industrial sectors were 0.059-6.029, and 0.110-2.945 mSv, respectively. An average dose per all three sectors of 11.87 mSv and an average dose per exposed worker of 1.12 mSv were realised for the entire study period. The entire study period had 187 instances in which exposed workers received individual annual doses >1 mSv, with exposed workers in the education/research sector primarily receiving most of this individual dose.
Asunto(s)
Exposición Profesional/análisis , Monitoreo de Radiación , Radiación Ionizante , Recuento Corporal Total , Centros Médicos Académicos , Investigación Biomédica , Femenino , Ghana , Humanos , Industrias , Masculino , Dosis de Radiación , Dosimetría TermoluminiscenteRESUMEN
Organ and effective doses to 90 patients undergoing some selected fluoroscopic examinations at the Korle-Bu Teaching Hospital were estimated using the Monte Carlo-based program (PCXMC version 1.5). Radiation dose was estimated from free-in-air measurements. The mean effective doses were found to be 0.29 +/- 0.07, 0.84 +/- 0.13, 3.15 +/- 0.44, 6.24 +/- 0.70 and 0.38 +/- 0.05 mSv for urethrogram, barium swallow, barium meal, barium enema and myelogram examinations, respectively. The dose area product was estimated to be 3.55 +/- 0.95, 16.44 +/- 2.60, 50.81 +/- 7.04, 99.69 +/- 10.85 and 9.32 +/- 0.99 Gy cm(2) for urethrogram, barium swallow, barium meal, barium enema and myelogram examinations, respectively. Optimisation of procedures is required for barium enema and barium meal examinations.
Asunto(s)
Carga Corporal (Radioterapia) , Exposición a Riesgos Ambientales/análisis , Fluoroscopía/estadística & datos numéricos , Recuento Corporal Total/estadística & datos numéricos , Ghana/epidemiología , Humanos , Dosis de Radiación , Medición de RiesgoRESUMEN
A survey of the radiofrequency electromagnetic radiation at public access points in the vicinity of 50 cellular phone base stations has been carried out. The primary objective was to measure and analyse the electromagnetic field strength levels emitted by antennae installed and operated by the Ghana Telecommunications Company. On all the sites measurements were made using a hand-held spectrum analyser to determine the electric field level with the 900 and 1800 MHz frequency bands. The results indicated that power densities at public access points varied from as low as 0.01 microW m(-2) to as high as 10 microW m(-2) for the frequency of 900 MHz. At a transmission frequency of 1800 MHz, the variation of power densities is from 0.01 to 100 microW m(-2). The results were found to be in compliant with the International Commission on Non-ionizing Radiological Protection guidance level but were 20 times higher than the results generally obtained for such a practice elsewhere. There is therefore a need to re-assess the situation to ensure reduction in the present level as an increase in mobile phone usage is envisaged within the next few years.