RESUMEN
OBJECTIVE: Evaluating the correlation between otoacoustic emission levels, styrene exposure, and oxidative stress biomarkers concentration in styrene-exposed subjects, to investigate the role of oxidative stress in outer hair cell damage. DESIGN: Distortion product otoacoustic emissions were measured in the exposed workers and in a control group. Separation between the distortion and reflection otoacoustic components was performed by time-frequency-domain filtering. The urinary concentration of the DNA and RNA oxidation products, namely 8-oxo-7,8-dihydroguanine (oxoGua), 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxodGuo), and 8-oxo-7,8-dihydroguanosine (oxoGuo), were evaluated. STUDY SAMPLE: Nine subjects exposed to styrene in a fiberglass factory, eight control subjects. The two groups were statistically equivalent in mean age. RESULTS: Statistically significant differences were found in the distortion component levels between the exposed and the control group. High levels of the oxidative damage biomarkers were found in the workers exposed to high levels of styrene. Significant negative correlation was found between the otoacoustic emission distortion component levels and the concentration of the oxoGuo biomarker. CONCLUSIONS: Exposure-induced damage of the cochlear amplifier is shown in the mid-frequency range, confirming animal experiments, in which hair cells in the cochlear middle turn were damaged. Hearing damage is consistent with the outer hair cell apoptosis pathway associated with oxidative stress.
Asunto(s)
Células Ciliadas Auditivas Externas/efectos de los fármacos , Pérdida Auditiva Provocada por Ruido/inducido químicamente , Ruido en el Ambiente de Trabajo/efectos adversos , Enfermedades Profesionales/inducido químicamente , Exposición Profesional/efectos adversos , Salud Laboral , Emisiones Otoacústicas Espontáneas/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Estireno/efectos adversos , 8-Hidroxi-2'-Desoxicoguanosina , Acústica , Adulto , Apoptosis/efectos de los fármacos , Biomarcadores/orina , Estudios de Casos y Controles , Daño del ADN , Desoxiguanosina/análogos & derivados , Desoxiguanosina/orina , Femenino , Guanina/análogos & derivados , Guanina/orina , Guanosina/análogos & derivados , Guanosina/orina , Células Ciliadas Auditivas Externas/metabolismo , Células Ciliadas Auditivas Externas/patología , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pruebas Auditivas , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Profesionales/diagnóstico , Enfermedades Profesionales/fisiopatología , Factores de RiesgoRESUMEN
The ototoxic effect of the exposure to styrene is evaluated, also in the presence of simultaneous exposure to noise, using otoacoustic emissions as biomarkers of mild cochlear damage. Transient-evoked and distortion product otoacoustic emissions were recorded and analyzed in a sample of workers (15 subjects) exposed to styrene and noise in a fiberglass manufacturing facility and in a control group of 13 non-exposed subjects. Individual exposure monitoring of the airborne styrene concentrations was performed, as well as biological monitoring, based on the urinary concentration of two styrene metabolites, the Mandelic and Phenylglyoxylic acids. Noise exposure was evaluated using wearable phonometers, and hearing loss with pure tone audiometry. Due to their different job tasks, one group of workers was exposed to high noise and low styrene levels, another group to higher styrene levels, close to the limit of 20 ppm, and to low noise levels. A significant negative correlation was found between the otoacoustic emission levels and the concentration of the styrene urinary metabolites. Otoacoustic emissions, and particularly distortion products, were able to discriminate the exposed workers from the controls, providing also a rough estimate of the slope of the dose-response relation between otoacoustic levels and styrene exposure.
Asunto(s)
Contaminantes Ocupacionales del Aire/efectos adversos , Cóclea/efectos de los fármacos , Pérdida Auditiva Provocada por Ruido/etiología , Ruido/efectos adversos , Emisiones Otoacústicas Espontáneas/efectos de los fármacos , Estireno/efectos adversos , Adulto , Contaminantes Ocupacionales del Aire/orina , Audiometría de Tonos Puros , Biomarcadores/orina , Biotransformación , Estudios de Casos y Controles , Cromatografía Líquida de Alta Presión , Cóclea/lesiones , Cóclea/fisiopatología , Relación Dosis-Respuesta a Droga , Monitoreo del Ambiente/métodos , Femenino , Cromatografía de Gases y Espectrometría de Masas , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/fisiopatología , Humanos , Perfil Laboral , Masculino , Persona de Mediana Edad , Exposición Profesional/efectos adversos , Salud Laboral , Saliva/metabolismo , Estireno/orina , Espectrometría de Masas en TándemRESUMEN
This study is aimed at testing the cochlear functionality using otoacoustic emissions, analyzing the synergistic effects of simultaneous exposure to noise and organic solvents EBTx on workers of a glass-reinforced plastic products factory. Exposure to organic solvents was assessed using ambiental measurements and evaluation of the salivary concentration. Biological monitoring was performed evaluating the urinary concentration of the styrene metabolites. Statistical analysis shows that otoacoustic tests can discriminate between different exposure groups. Significant differences were found between controls and subjects exposed to high styrene and low noise levels, showing the ototoxic effect (at sub-clinical level) of the styrene exposure.
Asunto(s)
Cóclea/efectos de los fármacos , Cóclea/fisiopatología , Ruido en el Ambiente de Trabajo/efectos adversos , Exposición Profesional/efectos adversos , Estireno/efectos adversos , Adulto , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.