The LD50 is used to establish the safety measures to be followed to reduce the risks that the product may present to human health

The interviewees were also asked about the impression they had about their auditory health, in regards to right ear hearing, 87% reported it being good; 8.7% that is regular and another 4.3% that is bad. In regards to left ear hearing, 100% of respondents stated that it was good.. In addition to the noises inherent in their activity in the coffee and tomato plantations, it was sought to know if they are exposed to other types of noise outside work noise and 100% said they are not exposed. In order to have a better view on the auditory health of these workers, meatoscopy and audiometry exams were performed, the results of which are presented in Table 3. According to Table 3, it can be observed that no rural worker presented lesion of the auricular pavilion, thus presenting normal diagnosis for meatoscopy. In relation to the audiometry, auditory loss was found in 34.78% of the patients evaluated, of whom 21.74% had a conductive type lesion and 13.04% had sensorineural auditory loss. As for the affected ear, it was found that in 21.74% of the sample both ears were affected, 8.69% presented auditory loss only in the right ear and 4.35% in the left ear. Considering the audiological opinion, it wasobserved that in 65.22% normal results were obtained, in those who presented some lesion, 17.39% were diagnosed with mild auditory loss in both ears, only in the right ear  or only in the left . Other degrees of impairment were also diagnosed as severe auditory loss in the right ear  and profound auditory loss in both ears . Considering the data obtained in the audiometry referring to the frequency in HZ and the possible involvement among those rural workers exposed to the pesticide, the results shown in Figure 1 were obtained.

According to the data recorded in Figure 1, considering the initial observation in the loss of the conductive type, it is observed that for the right and left ears, low sound frequencies  percentages were greater than when compared to what was seen in the higher sound frequencies . Considering also the conductive loss and the impairment of the frequencies nft growing system, it is observed that the right ear presents greater percentages for alterations in the higher frequencies than the left ear. Analyzing the results of the workers with neurosensory loss, the impairment of lower frequencies for both right and left ear was not recorded; however, 100% of them had a higher frequency, ranging from 4 kHz to 8 KHz for the right ear and, from 3 kHz to 6 kHz for the left ear. The possible associations between several factors such as socioeconomics, the use of PPE, the working period, the auditory loss and the signs and symptoms reported by the workers are recorded in Table 4. Considering the socioeconomic factors, only significant associations between age and the symptom of intoxication were observed, with higher percentages  in individuals aged over 30 years when compared to those under 30 years of age . Another association established through statistical analysis was between the use of PPE and the occurrence of ringing in ears and dizziness, with a higher percentage  for the absence of these symptoms among workers who claimed to use the equipment. The presence of ringing in the ears and dizziness was reported with percentages  in the group of those who stated that they did not use PPE and those that used it sometimes . The time of work and the otorrhea symptom were also significantly associated, with greater frequency  among those with less than 3 years of work in comparison with the other scales of working time, since the absence of this complaint was more frequent in individuals with time worked greater than 15 years . Otorrhea is also significantly associated with auditory loss, being more frequent in those diagnosed as having hearing loss , however, the same percentage is observed in other workers who had hearing loss, but who did not report otorrhea .The sample of rural male workers who were evaluated in the present study, were characterized by the mean age of 36.7 ± 9.3 years, with a low level of schooling, with a monthly income of minimum wage, with a daily working period of 8 hours and with work time greater than 15 years, being that the majority do not smoke despite the predominance of alcohol among them. Nunes when analyzing the occupational-environmental and health conditions of vegetable farmers exposed to pesticides in the district of Patrocinio de Caratinga  which stated that they were all males, predominantly from 15 to 21 years of age , education from 1 to 4 years , service time from 61 to 120 months  and the salary range up to a current minimum wage .

These results suggest that olive growers are younger than the individuals surveyed here, which is possibly related to a shorter service life when compared to the sample in this study; however, the educational level and salary range are similar to our findings .Considering also the presence of young people in the application of pesticides in crops, small and medium-sized farmers seem to have knowledge about the risks of pesticides to their health. So, they admit that in a few years of applying the products, it is necessary to hire younger employees for the activity, because they do not feel able to do so any more. According to this author, these young people are “hired” at around 17 and when they turn 25, or 26, they are no longer able to continue in the “service” . Rural workers of Teresópolis were analyzed in a sample of 18 individuals in a study on ototoxicity promoted by pesticides. In the socioeconomic profile, the authors describe the study population as composed of individuals with a mean age of 39.6, similar to the one described here, who worked for more than 21 years and with a workday of 10 hours or more . In the case of tobacco producers from Povoado Colônia Treze, Lagarto County  exposed to pesticides, the mean age was 33 ± 12.045 years and a working period of 16 years . This is similar to that found in our results. The findings regarding the use and management of pesticides along with the use of PPE and the hygiene measures of the interviewees show a disturbing picture. It is observed that the association of Roundup®, mainly, or Vertmec®, classified as class III, with others characterized as class I such as Manzate®, Meotrin® and Tamaron® is common. The toxicity of most pesticides is expressed in terms of the oral average Lethal Dose , represented by milligrams of the active ingredient of the product per kilogram of live weight, required to kill 50% of the rat or other animal population test.According to this classification the pesticides belonging to class I are considered extremely toxic. Those in class II are highly toxic, those in class III are moderately toxic and those in class IV are fairly toxic . The rural workers of Piedade de Caratinga expose themselves to the deleterious effects of these products when preparing and applying them with the use of the manual knapsack applicator and most of them prefer not to use or to use only sometimes the PPE. This fact represents a great risk for this population, which is consistent with that described in another study that investigates the risks determined by the inappropriate use and management of pesticides for the rural worker . The effects of prolonged use of pesticides have been well established in numerous national and international studies that describe chronic adverse effects, depression and suicide , immunological alterations  , impairments in reproductive function  , neurotoxic effects, gastrointestinal effects , genotoxic , neurotoxic , and cancer. Our results suggest a high incidence of auditory loss in the population surveyed with a percentage of 34.8%, considering conductive and sensorineural loss. The relationship between sensorineural auditory loss and ototoxicity promoted by pesticides is already well established by other studies    and, when considering only rural workers with sensorineural loss, the incidence is 13.04%. The comparison between the findings found in our study and those found in similar studies may become difficult, since studies of the prevalence of hearing impairments in Brazil are still scarce and, nft hydroponic system when they are performed, follow different methodologies .

In a study of 18 rural workers, aged 16 to 59 years, occupationally and environmentally exposed to organophosphorus pesticides from the city of Teresópolis , they observed that the incidence of sensorineural hearing loss in this population was 38.9%, above that observed in our findings. This difference may be conditioned by inequalities in the methodology used here, since we do not work with individuals over 50 years of age and do not use the vectoelectronystagmography test . As a way of confirming that the hearing loss presented by the individuals of this study is directly related to the use of organophosphorus pesticides, we opted to exclude those workers who handled heavy machinery, due to the noises, those that presented changes in the meatoscopy, as well as those with age range over 50 years. Teixeira et al  carried out a study of prevalence with 98 workers exposed to organophosphorus and pyrethroids pesticides used in vector control campaigns. The workers were divided into 2 groups. Group 1 reported no exposure to noise in current and past work and/or leisure life, and group 2 reported exposure to noise in current or previous work and/or leisure life. Of those exposed only to insecticides, 63.8% had hearing loss; for the group with simultaneous exposure to insecticides and noise, hearing loss was 66.7%. The authors concluded that there is evidence that exposure to pesticides induces peripheral auditory damage, and that noise is a factor that interacts with pesticides, optimizing their ototoxic effects. Similar studies have concluded that chemicals can induce hearing loss, regardless of the presence of noise, but this could act as an intensifier of hearing loss. The results described here suggest that the impression of the auditory health of the rural workers interviewed did not always correspond to what was observed through the diagnostic exams. This fact can be understood by the possible association with the impairment of sound frequencies, since among individuals with sensorineural loss, the fact that there is no compromise in the lower frequencies, which correspond to the sound of speech, could contribute to the sensation of everything being well, since they would not have limitations to communicate. Among those with conductive loss, the impression that the right ear presented less acuity than the left can also be understood by the audiometry results, since the right ear had a higher percentage of involvement in the frequencies of 250 to 500 Hz than the left one, which compromises the audition in the speech exercise.

The perception of loss of auditory acuity between those diagnosed with sensorineural loss and conductive loss, where it was observed that the first claim to not have auditory problems, possibly related to bilateral loss among those who had the compromised bone pathway, thus allowing their adaptation. As carriers of conductive losses often have unilateral involvement, this difference in acuity from one ear to the other is better perceived. Other work also report a study done with individuals exposed to various types of pesticides, among them organophosphates, the presence of sensorineural loss with bilateral impairment and alterations in their auditory thresholds for the highest frequencies from 3 kHZ to 6 kHZ, 8 kHZ, which is consistent with our results . Sensorineural hearing loss is similar to that seen in the loss caused by medication and other drugs or by noise, where a bilateral, symmetrical and irreversible lesion of the hair cells is installed, with changes in hearing thresholds of 3 kHz to 6 KHz, which also coheres with our results.  The results that indicate that all individuals sampled in this study present normal meatoscopy can be explained by the presence of alterations in this test was exclusion criterion defined in the methodology for definition of the sample. This criterion was established due to the importance of the meatoscopy in the identification of the functional integrity of the middle ear, considering possible lesions such as obstruction of the external acoustic conduit, perforated tympanic membrane and auditory deficiency of non-occupational origin already diagnosed .