Occupational hearing loss among selected farm tractor operators employed on large multiproduction farms in Poland.

A specially selected group of 45 farm tractor drivers were examined in order to estimate the degree of occupational hearing loss. The drivers, aged 21-50 years, were employed on multiproduction farms. The study showed that the operators under study had statistically worse hearing within the range of high frequencies (3-6 kHz), especially those aged over 30 years, compared to the control group of the same age. An intolerable hearing loss (over 20 dB) was noted among 56% of operators within the highest frequency range (3, 4 and 6 kHz), and among 22% of operators in the range of medium frequencies (0.5, 1, 2 and 3 kHz), with no hearing loss observed in the control group. Based on analysis of data concerning all operators it was noted that age and the period of employment in agriculture were highly correlated with hearing loss (r = 0.45-0.57). A series of correlations and linear regression analyses, conducted in two age intervals, showed that in the group of young operators (under 35 years) a statistically significant, strong correlation was observed between hearing loss and the period of employment (right ear: r = 0.60-0.65), whereas in the older age group (over 35 years) hearing loss was more strongly correlated with age than with the period of employment, although this correlation was not statistically significant. The results obtained confirmed that the detected hearing loss among operators of farm tractors was caused by exposure to occupational noise present on farms.