Exposição a agrotóxicos e alterações auditivas em trabalhadores rurais

Abstract

Rural work is one of the most dangerous occupations currently due to the intensive use of pesticides. Frequent exposure to these substances may harm rural workers’ health. Studies show that pesticide exposure can be harmful to hearing, and hearing loss might be an early sign of pesticide intoxication. Thus, the aim of this study was to analyze the relationship between exposure to pesticides and hearing changes among rural workers. The research was characterized as quantitative, with a descriptive and explicative scope and a cross-sectional design. It was carried out with 71 male rural workers exposed to pesticides residing in the municipality of Santa Rosa, in the northwest region of RS who were evaluated at a Basic Health Unit located in the rural area. The sample selection was based on a stratified random sample proportional to the age group size. Data collection was threefold: (i) a questionnaire to get information about pesticide exposure and previous and current clinical history of rural workers; (ii) hearing screening using an air-conduction test of frequencies from 250Hz to 8,000Hz; and (iii) measurement of cholinesterase levels in plasma and in erythrocyte. This study respected ethical procedures and was approved by the Human Research Ethics Committee of the Universidade Federal da Fronteira Sul. Data analysis was done through univariate and bivariate analysis and using a multivariate regression model. Results showed that 78.9% of the workers did not complete elementary school and 36.6% were from the age group of 50 to 59 years. Regarding the use of pesticides, the mean time use was 27.6 ± 13 years and most workers did not effectively wear Individual Protection Equipment. The most commonly used pesticides were herbicides, toxicological class III, and chemical group glycine. In the hearing screening, 31 (43.7%) rural workers had hearing loss in both ears, 28 (39.4%) had normal hearing, and 12 (16.9%) had unilateral hearing loss. There was a statistically significant difference between the mean of the high and low frequencies in both ears, showing a greater impairment of the high frequency thresholds. Auditory thresholds by air-conduction proved to be worse as the years of exposure to pesticides increased. The multivariate regression model showed hearing outcomes to be best predicted by age. Normal levels of erythrocyte cholinesterase were found in all rural workers. Regarding the plasma cholinesterase level, only one participant had below normal values. There was no significant correlation between hearing screening results and cholinesterase values. In this study, a large number of workers were found to have hearing loss and the largest contributing factor was age. However, it is necessary to consider that hearing loss can result from multiple factors, such as pesticide ototoxicity and noise. In fact, it is believed that the interaction between pesticides and noise enhances auditory damage. Ultimately, it is clear that the occupation of these workers is linked to a risk of hearing loss.