Attributable fraction of work accidents related to occupational noise exposure in a city in southeastern Brazil

Noise is the most frequent occupational exposure agent and may induce the development of both auditory and extra-auditory dysfunctions, as well as increase the risk of work accidents. The purpose of this study was to estimate the fraction of accidents attributable to noise occupational exposure in Piracicaba, a city of 345,000 inhabitants located in southeastern Brazil. Based on a hospital-based case-control study including 600 cases and 822 controls, the odds ratio controlled for several covariables was obtained by correlating occupational noise exposure classified into four levels (absent, low, average, and high) with the occurrence of work accidents, as well the exposure prevalence. Considering noise exposure as absent, OR was estimated as 1 (not statistically different from the basal level), 1.630 and 2.294, for reported low, average and high exposure levels, respectively.

Based on these data, the attributable fraction was estimated as 0.3041 (CI95% = 0.2341-0.3676), i.e., 30% of the work accidents that took place in the study site were statistically associated with occupational noise exposure. It is important to point out that the traditional expression developed for homogeneous exposures was herein adapted by the authors to express the fraction attributable to occupational noise exposure at distinct levels. Thus, the causal relationship between occupational noise exposure and the occurrence of work accidents was discussed so that the control of this highly prevalent occupational agent is included as a strategy for the prevention of work accidents.