Estudo sobre a exposição combinada entre ruído e vibração de corpo inteiro e os efeitos na audição de trabalhadores
acreditar, estimular e pelo imenso apoio. Aos professores ANTONIO REGGIANI e 10LE PINTO pela solidariedade manifesta no esforço para contribuir para a realização da avaliação de exposição à vibração e ao Prof. MASSIMO BOVENZI pelo gentil auxílio, com valiosas sugestões, na análise de regressão. A Prof.a. Dra. MARIA REGINA ALVES CARDOSO por indicar rumos seguros na análise de regressão. Às fonoaudiólogas CAROLINA MOURA DE SOUZA, DEOllNDA DO CARMO DE JESUS, ELLEN REGINA SOLA, PAULA ASCENCIO
... AULA ASCENCIO FERRAZ, SIMONE ALVES DOS SANTOS por conduzirem com segurança e profissionalismo as avaliações audiológicas e, em especial, à MÁRCIA TIVERON DE SOUZA. Aos promotores de justiça JORGE LUIZ USSIER e CARLOS ALBERTO SALLES pelo sustentáculo para a execução do trabalho. Ao CEREST-SP, representado pela coordenadora MARIA MAENO, pela cessão de sua estrutura para o desenvolvimento da pesquisa. À minha esposa ANA e à minha filha BEATRICE pela tolerância e compreensão. À colega TERESA CRISTINA MACHADO pelos comentários e sugestões pertinentes. SUMMARV SILVA LF Estudo sobre a exposição combinada entre ruído e vibração de corpo inteiro e os efeitos na audição de trabalhadores. [Study on combined exposure to noise and whole-body vibration and its effects on workers' hearing]. São Paulo; 2001. [Tese de Doutorado -Faculdade de Saúde Pública da USP]. Objectives. The purposes of this study, a cross-sectional one, were defined as a quantitative assessment of occupational exposure to noise and wholebody vibration (WBV); an analysis on the possibility of an association between these two hazards in the production of noise-induced hearing loss (NIHL); and, a discussion on feasible means of prevention. Methods. This cross -sectional study was carried out in a population of 141 bus drivers of the City of São Paulo. The prevalence of noise-induced hearing loss (NIHL) was established through an audiometric examination of ali workers. The audiograms were classified according to audiometric criteria formulated by Merluzzi and cols. (1979). The whole group of bus drivers was classified and stratified internally in subi;1roups of "exposed" and "controls", according to the cumulated length of working time as bus driver. A questionnaire was designed and applied in order to retrieve the occupational history and other relevant information. The methodology for noise exposure evaluation was based on the procedures established in the international standard ISO 1999 (1990), as well as in the European Economic Community (EEC) Directive (1986). The methodology for whole-body vibration (WBV) exposure evaluation was based on the principies established in the international standard ISO 2631 (1985). The association between the dependent variable and the set of explanatory variables was analyzed through the technique of non-conditional multivariable logistic regression. Outcomes. It was found that these bus drivers were exposed to noise leveis of 83.6 ± 1.9 dB(A) (week average) in buses with front engines; bus drivers that work in buses with rear engines were exposed to noise leveis of 77.0 ± 1.1 dB(A). Also, the average of noise exposure equivalents (LAeq) fnr bus drivers in front-engines buses was 83.1 ± 1.9 dB(A), whereas the average LAeq for drivers of rear-engine buses was 76.2 ± 1.7 dB(A). This difference was statistically significant. The average of the vibration acceleration found in the five different bus types analyzed, weighted according to the number and length of use of vehicles, was O.85/m 2 . The NIHL prevalence rates were 46% and 24% for the "exposed" group and the "reference" group, respedively. It was found that the odds ratio (OR) for NIHL prevalence, according to the univariable analysis, was 2.68 (1,31 -5.48, for a 95% confidence interval) for the "exposed" group, when compared with the referrals. For the best adjusted model, the multivariable analysis has shown that age (44 years old or more), reference to diabetes, and levei of noise exposure (above 86.8 dB(A» were risk factors, relevant for the development of NIHL. Exposure to WBV, when represented by doses, was not significant for NIHL development. Conclusions. The bus drivers analyzed in this cross-sedional study were exposed to relevant WBV leveis, higher than the permissible exposure leveis established by the international standard ISO 2631 (1985). Also, the noise exposure leveis found at the drivers' work-posts in front-engine buses were higher than the noise exposure leveis observed at the drivers' work-posts in rear-engine buses. No association between WBV exposure and NIHL prevalence was observed in this study. Also, this study could not found any interaction between WBV exposure and noise exposure. However, further studies are required, because other logistic regresion models were analyzed, showing that an association between WBV and NIHL could occur, thus aggravating the potential risk of adverse health effects to workers.