A longitudinal study of noise exposure and its effects on the hearing of olive oil mill workers

In occupational health and safety, noise is one of the biggest worldwide risk factors and it is a particularly big problem in industry. Olive oil mills play an important role in Spanish industry since they account for 45% of the world's olive oil production. Although noise is a serious occupational hazard in this industrial sector, scientific literature does not seem to contain any research study on the subject. The aim of this paper is to analyse noise exposure levels and their effects on the hearing of olive oil mill workers. For this purpose, a retrospective longitudinal observational study was conducted over the course of a decade, using a sample of 115 olive oil mill workers and analysing their exposure to noise and hearing levels. Among the main results it must be highlighted that, during the period under study, there was a notable rise in the noise levels to which these workers are exposed, although the results of the Early Loss Index (ELI), which measures hearing loss in each ear separately only at a frequency of 4000 Hz and adjusted for presbycusis by age and sex, for olive oil mill factory managers with the highest noise exposure, underwent an improvement in contrast with reception yard workers, whose ELI index did not.