Ruído ocupacional e seus efeitos na saúde auditiva do pescador industrial

Abstract

Commercial fishing is considered one of the most dangerous occupations in the world. Its continuous high noise exposures associated with the working conditions contributes to increased risk of noise-induced hearing loss in fishermen. A typical industrial worker has a regular work day of 8 hours during 5 days a week, while industrial fishermen often remain on-board their boats 24 hours over a period of 28 to 50 days, depending on the type of fishing. There are few studies about on-board noise exposures, and the damage it may cause to commercial fishermen's hearing. This paucity of data is due to the difficulty of conducting noise measurements and monitoring the working day at sea, as well as the relatively scant attention that has been applied toward fishermen's occupational health issues. This study aimed to investigate the relationship between the occupational noise exposure of industrial fishermen and its effects on their hearing. This was an observational, retrospective, quantitative cohort, approach, over the period of 2007-2013. Data collection consisted of questionnaires, measurement of noise in different types of fishing vessels, noise dosimetry in all fishing job functions and audiological tests. The questionnaires were applied to characterize the socio-demographic profile, working conditions and occupational audiological history. The evaluation of sound pressure levels in dBA was performed in the compartments of 15 fishing vessels which largely represented the types most often used in Santa Catarina State, South of Brazil, in ocean waters. These vessels ranged from 17 to 28 meters in length, and employed purse seines, trawls, gillnets, and live bait types of fishing. In addition to the localized vessel compartment noise measurements, noise dosimetry was performed on individual fishermen from five of these fishing boats. The result of noise measurements in the compartments and noise dosimetry on the fishermen both indicated sound pressure levels above the threshold limits recommended by the Brazilian labor legislation, Norm NR 15 Annex 1, from Ministry of Labor and Employment of Brazil, by the legislation applied to international vessels, International Maritime Organization, and by the technical standards from FUNDACENTRO/Ministry of Labor and Employment of Brazil and American Conference of Governmental Industrial Hygienists. The sound pressure level in dBA obtained via noise dosimetry, 24-hour equivalent level, was transformed to an exposure level normalized to 8 hours, the criterion level was 80 dBA for 8 hours of exposure, and the exchange rate was 5 dBA. This 8-hour normalization and 5 dB exchange rate yielded Time-Weighted Average (TWA) exposure data. The 8-hour TWAs were between 81.2 dBA to 97.3 dBA. Although the first value is below the threshold limit value established by Brazilian labor legislation, it is above the Brazilian action level of 80 dBA and there is no break or rest from the exposure. In the noise measurements for each vessels’ compartments, the exchange rate used was 3 dB, and the resultant sound pressure levels were above the threshold limit value for 24 hours of exposure. These results identified a high risk of noise-induced hearing loss to all workers in the vessels. The audiometric tests were performed on 466 commercial fishermen, having a predominant age group of 40-49 years, and the results indicated 315 (68%) had hearing loss. Of this total, 267 (57%) showed symptoms associated with noise-induced hearing loss and 48 (10%) other hearing problems. Noise-induced hearing loss appeared to occur after 10 years of exposure, confirming the high risk of such loss in the fishing industry. The prevalence ratios indicated 78.8% of noise-induced hearing loss for the engineer, followed by the boatswain (65%), cooker (61.5%), master (57.6%), fishermen (53.8%), pilot of the auxiliary boat for purse seine (47.1%) and the skipper (46.7%). In the analysis of hearing loss by type of fishing, there is no statistically significant difference (p>0.05) between the average hearing thresholds of fishermen at all frequencies. The use of hearing protection is not feasible in most fishing jobs; however, the use in the machine room is obligatory. Furthermore, the implementation of other control measures is needed, especially in the sleeping room.