[Risk of noise-induced hearing loss in farm tractor operators]. / Ryzyko utraty sluchu wsród operatorów ciagników rolniczych spowodowane halasem.

Studies of noise at work site of tractor operators showed that this parameter exceeds allowable values. In order to evaluate the risk of hearing loss in this occupational group, noise-induced permanent threshold shift (NIPTS) values were determined. This parameter is a function of the audiometric frequency, duration of occupational exposure and noise exposure level (LEX,8 h). The procedure recommended by ISO-1999/1990 was used for calculations. The study covered two groups of operators: operators of ZM "Ursus" medium-power tractors (noise exposure level: LEX,8 h = 96.6 dB) and operators of high-power tractors of the same manufacture (LEX,8 h = 89.6 dB) The risk of hearing impairment was determined for the group of men aged 50 years, occupationally exposed to noise for a period of 30 years. The calculation was based on the mean value of expected hearing loss for three selected audiometric frequencies: 1000; 2000; and 4000 Hz. The study showed that the average (median; N0.50) expected hearing loss, excluding that associated with age, after 30 years of employment was 15 dB for operators of medium-power farm tractors, and 6 dB for operators of high-power tractors. The risk of hearing impairment due to occupational exposure to noise (exceeding the maximum allowable hearing loss of 27 dB; according to ISO-1999/1990) that may cause an acoustic trauma was 37.9% for medium-power tractors and 13.0% for high-power tractors. The results of the study show that noise at workplaces of farm tractor operators creates a high risk of hearing impairment.

Duration of exposure to noise among farmers as an important factor of occupational risk.

Occupational exposure to noise is determined by the value of acoustic energy and the duration of exposure - a parameter which is especially important while considering exposure to noise among private farmers. In order to describe the duration of exposure to noise, time-schedule measurements were carried out of occupations performed by a selected group of 30 self-employed farmers during the whole year. Three calculated time values were analysed: mean total monthly time of exposure (t(t)); mean daily time of exposure (t(d)) and mean monthly time of daily exposure (t(m)). The results of the study showed that the highest time values of exposure to noise were observed during the months of intensive field and transport occupations associated with harvesting of cereals and root crops, i. e. in August, September and October; as well as during soil cultivation and chemical treatment activities in April. This was connected with a greater number of workdays in conditions of exposure to noise - 20-21 days on average - and a greater duration of such workdays, often up to 11 hours a day.

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.

[The effect of occupational exposure to noise among tractor drivers: assessment based on 'noise threshold']. / Ocena skutków zawodowej ekspozycji na halas operatorów ciagników rolniczych w zaleznosci od dawki stazowej.

The effects of occupational exposure to noise was analysed among operators of agricultural tractors (n = 172). The assessment was based on a parameter called 'noise immission level' (dose connected with the period of employment). The study showed that the correlation between hearing loss and noise immission dose was stronger than that between hearing loss and the period of employment. Equations of simple regression presented in this paper allow us to make a prognosis concerning the risk of occupational deafness and to develop the system of the prevention interventions. The results obtained indicated that the parameter of hygiene evaluation of exposure to noise, called 'noise immission level' should be used more frequently for the noise measurement, especially in the prevention of occupational diseases.

Effect of impulse vibration and noise on vasomotor function of peripheral blood vessels among pneumatic forge hammer operators.

An evaluation of the effect of impulse vibration and noise on vasomotor function of blood vessels among pneumatic forge hammer operators has been presented based on thermal tests (cooling). The study covered the following groups of workers; pneumatic forge hammer operators (I), pneumatic forging hammer operators (II), hammer operator's assistants (III), operators of forging presses and machines (IV) and the control group. The results of the study showed that in groups I and III it was impulse noise not vibration that caused changes in the functioning of peripheral blood vessels.

Studies on the transmission of vibrations in human organism exposed to low-frequency whole-body vibration.

Investigations were carried out in a group of 20 males with a definite morpho-physiological type, at two selected ranges of acceleration values chosen according to ISO criteria in the range of 2-20 Hz. In the subjects exposed to vibration the values of vibration acceleration were measured in different points along the spine at the levels of S3, L3, Th7, C3 and at the vertex. The investigations demonstrated that the frequency is the parameter of crucial significance for the propagation of vibrations in the human organism. Vibration within the frequency range up to 12 Hz affects the whole human organism, while the vibrations above 12 Hz have only a local effect.