Effects of exposure to 2100 MHz GSM-like radiofrequency electromagnetic field on auditory system of rats / Efeitos da exposição a um campo eletromagnético na radiofrequência de 2100 MHz, similar ao sistema GSM, no sistema auditivo de ratos

Abstract Introduction: The use of mobile phones has become widespread in recent years. Although beneficial from the communication viewpoint, the electromagnetic fields generated by mobile phones may cause unwanted biological changes in the human body. Objective: In this study, we aimed to evaluate the effects of 2100 MHz Global System for Mobile communication (GSM-like) electromagnetic field, generated by an electromagnetic fields generator, on the auditory system of rats by using electrophysiological, histopathologic and immunohistochemical methods. Methods: Fourteen adult Wistar albino rats were included in the study. The rats were divided randomly into two groups of seven rats each. The study group was exposed continuously for 30 days to a 2100 MHz electromagnetic fields with a signal level (power) of 5.4 dBm (3.47 mW) to simulate the talk mode on a mobile phone. The control group was not exposed to the aforementioned electromagnetic fields. After 30 days, the Auditory Brainstem Responses of both groups were recorded and the rats were sacrificed. The cochlear nuclei were evaluated by histopathologic and immunohistochemical methods. Results: The Auditory Brainstem Responses records of the two groups did not differ significantly. The histopathologic analysis showed increased degeneration signs in the study group (p = 0.007). In addition, immunohistochemical analysis revealed increased apoptotic index in the study group compared to that in the control group (p = 0.002). Conclusion: The results support that long-term exposure to a GSM-like 2100 MHz electromagnetic fields causes an increase in neuronal degeneration and apoptosis in the auditory system.

Resumo Introdução: O uso de telefones celulares tornou-se generalizado nos últimos anos. Embora benéfico do ponto de vista da comunicação, os campos eletromagnéticos gerados por celulares pode causar alterações biológicas indesejáveis no corpo humano. Objetivo: Nesse estudo, o objetivo foi avaliar os efeitos do campo eletromagnético na frequência de 2.100 MHz, similar à modulação do Sistema Global para Comunicações Móveis, produzido por um gerador de campo eletromagnético, sobre o sistema auditivo de ratos usando os métodos eletrofisiológico, histopatológico e imunohistoquímico. Método: Foram incluídos no estudo catorze adultos ratos albinos Wistar. Os ratos foram divididos aleatoriamente em dois grupos de sete animais cada. O grupo de estudo foi exposto continuamente por 30 dias a um campo eletromagnético em 2100 MHz com um nível de sinal (potência) de 5,4 dBm (3,47 miliwatts) para simular o modo de conversação em um celular. O grupo controle não foi exposto ao campo eletromagnético acima mencionado. Após 30 dias, o potencial evocado auditivo de tronco encefálico de ambos os grupos foi gravado e os ratos foram sacrificados. Os núcleos cocleares foram avaliados pelos métodos histopatológico e imunohistoquímico. Resultados: Os registros do potencial evocado auditivo de tronco encefálico dos dois grupos não diferiram significativamente. A análise histopatológica mostrou aumento dos sinais de degeneração no grupo de estudo (p = 0,007). Além disso, a análise imuno-histoquímica revelou aumento do índice de apoptose no grupo de estudo em comparação com o grupo controle (p = 0,002). Conclusão: Os resultados confirmam que a exposição a longo prazo a um campo eletromagnético em 2100 MHz similar à modulação do sistema global para comunicações móveis causa um aumento na degeneração neuronal e apoptose no sistema auditivo.

Effects of exposure to 2100MHz GSM-like radiofrequency electromagnetic field on auditory system of rats.

INTRODUCTION: The use of mobile phones has become widespread in recent years. Although beneficial from the communication viewpoint, the electromagnetic fields generated by mobile phones may cause unwanted biological changes in the human body. OBJECTIVE: In this study, we aimed to evaluate the effects of 2100MHz Global System for Mobile communication (GSM-like) electromagnetic field, generated by an electromagnetic fields generator, on the auditory system of rats by using electrophysiological, histopathologic and immunohistochemical methods. METHODS: Fourteen adult Wistar albino rats were included in the study. The rats were divided randomly into two groups of seven rats each. The study group was exposed continuously for 30days to a 2100MHz electromagnetic fields with a signal level (power) of 5.4dBm (3.47mW) to simulate the talk mode on a mobile phone. The control group was not exposed to the aforementioned electromagnetic fields. After 30days, the Auditory Brainstem Responses of both groups were recorded and the rats were sacrificed. The cochlear nuclei were evaluated by histopathologic and immunohistochemical methods. RESULTS: The Auditory Brainstem Responses records of the two groups did not differ significantly. The histopathologic analysis showed increased degeneration signs in the study group (p=0.007). In addition, immunohistochemical analysis revealed increased apoptotic index in the study group compared to that in the control group (p=0.002). CONCLUSION: The results support that long-term exposure to a GSM-like 2100MHz electromagnetic fields causes an increase in neuronal degeneration and apoptosis in the auditory system.

Ototoxicity evaluation in medulloblastoma patients treated with involved field boost using intensity-modulated radiation therapy (IMRT): a retrospective review.

BACKGROUND: Ototoxicity is a known side effect of combined radiation therapy and cisplatin chemotherapy for the treatment of medulloblastoma. The delivery of an involved field boost by intensity modulated radiation therapy (IMRT) may reduce the dose to the inner ear when compared with conventional radiotherapy. The dose of cisplatin may also affect the risk of ototoxicity. A retrospective study was performed to evaluate the impact of involved field boost using IMRT and cisplatin dose on the rate of ototoxicity. METHODS: Data from 41 medulloblastoma patients treated with IMRT were collected. Overall and disease-free survival rates were calculated by Kaplan-Meier method Hearing function was graded according to toxicity criteria of Pediatric Oncology Group (POG). Doses to inner ear and total cisplatin dose were correlated with hearing function by univariate and multivariate data analysis. RESULTS: After a mean follow-up of 44 months (range: 14 to 72 months), 37 patients remained alive, with two recurrences, both in spine with CSF involvement, resulting in a disease free-survival and overall survival of 85.2% and 90.2%, respectively.Seven patients (17%) experienced POG Grade 3 or 4 toxicity. Cisplatin dose was a significant factor for hearing loss in univariate analysis (p < 0.03). In multivariate analysis, median dose to inner ear was significantly associated with hearing loss (p < 0.01). POG grade 3 and 4 toxicity were uncommon with median doses to the inner ear bellow 42 Gy (p < 0.05) and total cisplatin dose of less than 375 mg/m2 (p < 0.01). CONCLUSIONS: IMRT leads to a low rate of severe ototoxicity. Median radiation dose to auditory apparatus should be kept below 42 Gy. Cisplatin doses should not exceed 375 mg/m2.

Audiological findings in patients treated with radiotherapy for head and neck tumors.

UNLABELLED: Radiotherapy has been widely used given its increase in the successful outcomes and cure of some cancers. AIM: To evaluate the functionality of the auditory system in patients who underwent radiotherapy treatment for head and neck tumors. MATERIALS AND METHODS: From May 2007 to May 2008, otorhinolaryngological and audiological evaluation (Pure Tone Audiometry (air and bone conduction), Speech Audiometry, Tympanometry, Acoustic Reflex testing and Distortion Product Otoacoustic Emissions) were performed in 19 patients diagnosed with head and neck neoplasia and treated with radiotherapy. Prospective case series study. RESULTS: 10.5% left ears and 26.3% right ears had bilateral hearing loss soon after radiotherapy according to ASHA criteria. CONCLUSIONS: Radiotherapy treatment for head and neck cancer has ototoxic effects. Early programs of auditory rehabilitation should be offered to these patients.

Achados audiológicos em pacientes tratados com radioterapia para tumores de cabeça e pescoço / Audiological findings in pacients treated with radiotherapy for head and neck tumors

A radioterapia é uma modalidade terapêutica muito utilizada, uma vez que o aumento de resultados satisfatórios e a cura de algumas neoplasias através deste tipo de tratamento estão sendo observados. OBJETIVO: Avaliar a funcionalidade do sistema auditivo em pacientes submetidos ao tratamento radioterápico em região de cabeça e pescoço. MATERIAL E MÉTODO: Estudo realizado no período de maio de 2007 a maio de 2008. Foram realizadas avaliações otorrinolaringológicas e audiológicas como audiometria tonal limiar por via aérea e óssea, audiometria vocal, timpanometria, pesquisa do reflexo do estapédio e Emissões Otoacústicas Evocadas por Produto de Distorção em 19 pacientes com diagnóstico de neoplasia em região de cabeça e pescoço e indicação do tratamento radioterápico. Estudo de série prospectivo. RESULTADOS: 10,5 por cento orelhas esquerdas e 26,3 por cento orelhas direitas apresentaram diminuição dos limares auditivos tonais logo após o término do tratamento radioterápico, segundo os critérios da ASHA. CONCLUSÃO: O tratamento radioterápico apresentou efeitos ototóxicos quando realizado em região de cabeça e pescoço. Programas de monitoramento audiológico e reabilitação auditiva precoce devem ser oferecidos aos pacientes submetidos a esse tipo de tratamento.

Radiotherapy has been widely used given its increase in the successful outcomes and cure of some cancers. AIM: To evaluate the functionality of the auditory system in patients who underwent radiotherapy treatment for head and neck tumors. MATERIALS AND METHODS: From May 2007 to May 2008, otorhinolaryngological and audiological evaluation (Pure Tone Audiometry (air and bone conduction), Speech Audiometry, Tympanometry, Acoustic Reflex testing and Distortion Product Otoacoustic Emissions) were performed in 19 patients diagnosed with head and neck neoplasia and treated with radiotherapy. Prospective case series study. RESULTS: 10.5 percent left ears and 26.3 percent right ears had bilateral hearing loss soon after radiotherapy according to ASHA criteria. CONCLUSIONS: Radiotherapy treatment for head and neck cancer has ototoxic effects. Early programs of auditory rehabilitation should be offered to these patients.

Estudo das amplitudes das emissões otoacústicas em indivíduos expostos ao ruído de trios elétricos / Distortion product otoacoustic emission analyses after exposure to loud sound of \"truck bands\"

Os autores estudaram trinta indivíduos, adultos, portadores de audição normal, avaliada através da audiometria tonal, imitanciometria e análise de emissões otoacústicas produto de distorção. Foram estudados antes e depois da exposição sonora a trios elétricos por um período de quatro horas. Este estudo focalizou, especialmente, as frequências de 1,2,3,4e6 kHz.Todos os indivíduos submetidos a este procedimento tiveram as amplitudes das emissões otoacústicas diminuídas após a exposição ao som de alta intensidade, mostrando, assim, a alteração funcional da cóclea, os autores propõem a possibilidade de utilizar esse parâmetro como um indicativo para a prevenção da perda auditiva induzida pelo ruído

Effects of cranial radiation on hearing in children with acute lymphocytic leukemia.

We serially assessed the hearing sensitivity of 61 children with acute lymphocytic leukemia who were admitted to our Total Therapy IX study between December, 1975, and July, 1977. Their treatment included combined chemotherapy, 2,400 rads of cranial radiation, and intrathecal methotrexate. Subjects initially received an otologic examination and middle ear function testing. Audiometric testing was not done until ears were free of outer or middle ear pathology. If the child had no outer or middle ear disease, audiometric thresholds were obtained for the test frequencies: 500, 1,000, 2,000, 4,000, 6,000, and 8,000 Hz. Pure-tone thresholds were obtained before irradiation (61 patients) and at 6, 12, and 36 months thereafter (49, 46, and 22 patients, respectively). The median age at time of baseline testing was 10 years, 2 months. A paired sample test based on group data was used to test whether there were any significant changes from the threshold values at 6, 12, and 36 months after irradiation. Thresholds were not significantly affected for any test frequency at any test time. Assessments of individual audiograms indicated that none of the children had any significant reductions in hearing levels at the end of the third year after cranial irradiation.