Med Pr
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The analysis of the epidemiological data indicates that exposure to noise is widespread and it is one of the most common causes of tinnitus, estimated at about 20.7% according to Hazell; 28% according to Axelsson; and 42% according to Palmer. Bearing in mind the scantiness of reliable data on the incidence and nature of tinnitus in persons exposed to industrial noise, and especially the need for the objectivity of this subjective symptom, the authors have decided to undertake the study aimed at assessing the interrelation between tinnitus, the magnitude and kind of hearing impairment, and otoacoustic emission. The study group included 191 persons aged 42.5 +/- 7.6 years (range, 25 to 65), occupationally exposed to noise at the levels of 88-92 dB(A) for 26.9 +/- 4.6 years (range, 9 to 30) who had reported hearing disorders and tinnitus. ⋯ Interestingly, the differences in measurements of both types of evoked emissions (EOAE and DPOAE), expressed by the lowered amplitude, narrowed spectrum, reduction of emission or its complete fading in a limited area of high frequencies, were demonstrated in the ears with tinnitus only in retrocochlear hearing impairment, as compared to those free from tinnitus. The evaluation of the EOAE and DPOAE measurements seems to prove that this method may be useful in assessing the contribution of the cochlear mechanisms to the incidence of tinnitus and in distinguishing between tinnitus generated in cochlea and tinnitus with the source at other levels of the hearing organ or beyond it. Our study failed to determine the interrelation between tinnitus and spontaneous emissions as the emission was registered only in about 12% of persons exposed to noise, including 2% of those with normal hearing.
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The objective of this work was to select optimal methods for determination of toxic gases (NOx, NO2, CO, CO2, O3) and to evaluate occupational exposure of welders to those gases. The survey covered workers employed in shipyards, and other metal product fabrication plants engaged in welding mild and stainless steel by different techniques (manual metal are, metal active gas, tungsten inert gas welding; gas, plasma, laser cutting and resistance welding). Personal and stationary air samples were collected to determine time weighted average (TWA) and short-term concentrations of gases. ⋯ The average NO2 i NOx ratio was 1:4. According to Polish regulations regarding the MAC value for nitrogen oxides the analytical method should enable determination of total NOx by either direct or indirect simultaneous determination of both NO and NO2. The applicability of the spectrophotometric method of analysis of atmospheric NOx to determination of low NOx concentrations at welders working posts has been confirmed.