Hearing health of workers exposed to noise and insecticides

OBJECTIVE: To examine the peripheral auditory disorders in a group of workers exposed to organophosphate and pyrethroid insecticides, used in vector control campaigns. METHODS: The prevalence study examined a population of 98 individuals who sprayed insecticides in campaigns for the prevention of Dengue, Chagas disease and Yellow fever. The sampling approach was finalistic, and included the workers in a health district of Pernambuco, during the year 2000. A questionnaire was used to collect data on occupational and non-occupational risks, safety measures utilized, family history of auditory problems and health symptoms. Previous noise exposure history was also investigated, since noise can be a confounding factor for hearing loss. Hearing sensitivity and middle ear function were assessed by pure tone audiometry. RESULTS: Among those exposed to insecticides, 63.8% demonstrated a hearing loss. For the group of workers exposed to both noise and insecticides, hearing loss was observed in 66.7% of the cases. The median exposure time necessary to detect high-frequency losses was 3.4 years for workers exposed to both agents and 7.3 years for workers exposed to insecticides only. Hearing thresholds were poorest among workers exposed to both agents. Auditory damage for those with combined exposures to the two factors was more severe than the hearing losses observed among those exposed only to insecticides. CONCLUSIONS: There is evidence that exposure to insecticides was associated with peripheral sensorioneural hearing loss and that noise exposure can potentiate the ototoxic effects of insecticides. It is necessary to evaluate this possible association through epidemiological studies.OBJETIVO: Avaliar as alterações auditivas periféricas em um grupo de trabalhadores exposto a inseticidas, organofosforados e piretróides, utilizados em campanhas de controle de vetores. MÉTODOS: Estudo de prevalência de uma população de 98 indivíduos que pulverizavam venenos nas campanhas de prevenção do dengue, da febre amarela e da doença de Chagas. A amostra foi de tipo finalística, considerando o universo dos trabalhadores de um distrito sanitário, em Pernambuco, no ano de 2000. Utilizou-se questionário contendo questões de identificação de riscos ocupacional e não ocupacional, medidas de segurança utilizadas, antecedentes de problemas auditivos e sintomas referidos. Foi investigada a historia pregressa de exposição ao ruído, por ser um fator de confusão para a perda auditiva. Todos os indivíduos foram avaliados pelo teste de audiometria tonal. RESULTADOS: Dos expostos apenas aos inseticidas, 63,8% apresentaram perda auditiva. Para o grupo com exposição concomitantemente aos inseticidas e ao ruído, a perda auditiva foi de 66,7%. O tempo mediano para o desenvolvimento de alterações auditivas nas freqüências médias altas, para as exposições combinadas de inseticidas e ruído, foi de 3,4 anos e para as exposições apenas aos inseticidas foi de 7,3 anos. A perda auditiva para as exposições concomitantes aos dois fatores foi de maior intensidade nessas freqüências, do que o observado na exposição apenas aos inseticidas. CONCLUSÕES: Há evidência de que a exposição aos inseticidas induz dano auditivo periférico e que o ruído é um fator que interage com os inseticidas, potencializando seus efeitos ototóxicos. Faz-se necessário avaliar essa possível associação através de estudos epidemiológicos de caráter analítico

142. Occupational exposure to chemicals and hearing impairment.

Research conducted over the last two decades has brought attention to the ototoxicity of chemicals in the workplace and their interaction with noise. Chemicals that have been specifically studied for their ototoxicity include solvents, metals, asphyxiants, PCBs and pesticides. Noise exposure is particularly damaging to the cochlea, a part of the peripheral auditory system, whereas chemicals tend to affect both the cochlear structures and the central auditory system. Reduced blood flow and free radical formation are important ototoxic mechanisms shared by noise and chemical exposures. Solvents and asphyxiants may also disrupt intrinsic anti-oxidant defences and make the ear more vulnerable to the effects of e.g. noise exposure. The chemicals reviewed in the present document have all been associated with auditory effects in animals. Some of the solvents and the asphyxiants interact synergistically with noise or potentiate noise effects on the auditory system. Combinations of chemical exposure with noise and other stressors such as physical activity during exposure may lower the concentration of the chemical exposure necessary for induction of an auditory effect. Auditory effects have also been indicated in humans for all agents covered in this document for which there are data. Noise is often present in the occupational arena, which makes prediction of the outcome challenging. As combined exposure (e.g. chemical and noise) is currently not taken care of in the regular occupational exposure limit (OEL) setting procedure, a noise notation can be used to indicate an increased risk of hearing loss after exposure to the chemical at a level close to the OEL with concurrent noise exposure. The strength of evidence for ototoxicity differs between the agents but falls basically into three categories, i.e. agents for which: 1) human data indicate auditory effects under or near existing OELs and robust animal data support an effect on hearing from exposure (styrene, toluene, carbon disulphide, lead, mercury and carbon monoxide), 2) human data are lacking whereas animal data indicate auditory effects under or near existing OELs (p-xylene, ethylbenzene and hydrogen cyanide), 3) human data are poor or lacking and animal data indicate an auditory effect well above the existing OELs (chlorobenzene, trichloroethylene, n-hexane, n-heptane, some solvent mixtures, trimethyltin, acrylonitrile, 3,3'-iminodipropionitrile, pesticides and PCBs)

Audiology in Brazil

The profession of audiology took root in Brazil nearly a half a century ago and has since blossomed into a flourishing, well-developed field. Currently, audiologists in Brazil work at private institutions, including private medical practices and dedicated speech and hearing clinics. They are also employed in a wide array of public institutions, including community clinics, elementary schools, colleges, and universities. In both the private sector and health clinics, audiologists perform diagnostic evaluations of auditory and vestibular disorders, select and fit hearing aids, and provide aural rehabilitation. At the public level, they assist with workers` health programs, dispense hearing aids, and aural rehabilitation. There is always room to grow, however, and the future of audiology in Brazil holds both challenges and opportunity. The following article will sketch the development of audiology training and practice in Brazil, provide a picture of how the field stands today, and summarize the unique challenges which the profession faces in this large and diverse nation

Saúde auditiva de trabalhadores expostos a ruído e inseticidas

OBJETIVO: Avaliar as alterações auditivas periféricas em um grupo de trabalhadores exposto a inseticidas, organofosforados e piretróides, utilizados em campanhas de controle de vetores. MÉTODOS: Estudo de prevalência de uma população de 98 indivíduos que pulverizavam venenos nas campanhas de prevenção do dengue, da febre amarela e da doença de Chagas. A amostra foi de tipo finalística, considerando o universo dos trabalhadores de um distrito sanitário, em Pernambuco, no ano de 2000. Utilizou-se questionário contendo questões de identificação de riscos ocupacional e não ocupacional, medidas de segurança utilizadas, antecedentes de problemas auditivos e sintomas referidos. Foi investigada a historia pregressa de exposição ao ruído, por ser um fator de confusão para a perda auditiva. Todos os indivíduos foram avaliados pelo teste de audiometria tonal. RESULTADOS: Dos expostos apenas aos inseticidas, 63,8% apresentaram perda auditiva. Para o grupo com exposição concomitantemente aos inseticidas e ao ruído, a perda auditiva foi de 66,7%. O tempo mediano para o desenvolvimento de alterações auditivas nas freqüências médias altas, para as exposições combinadas de inseticidas e ruído, foi de 3,4 anos e para as exposições apenas aos inseticidas foi de 7,3 anos. A perda auditiva para as exposições concomitantes aos dois fatores foi de maior intensidade nessas freqüências, do que o observado na exposição apenas aos inseticidas. CONCLUSÕES: Há evidência de que a exposição aos inseticidas induz dano auditivo periférico e que o ruído é um fator que interage com os inseticidas, potencializando seus efeitos ototóxicos. Faz-se necessário avaliar essa possível associação através de estudos epidemiológicos de caráter analítico

Interventions to prevent occupational noise-induced hearing loss: a Cochrane systematic review

To assess the effectiveness of interventions for preventing occupational noise exposure or hearing loss compared to no intervention or alternative interventions. We searched biomedical databases up to 25 January 2012 for randomized controlled trials (RCT), controlled before-after studies and interrupted time-series of hearing loss prevention among workers exposed to noise. We included 19 studies with 82 794 participants evaluating effects of hearing loss prevention programs (HLPP). The overall quality of studies was low to very low, as rated using the GRADE approach. One study of stricter legislation showed a favorable effect on noise levels. Three studies, of which two RCTs, did not find an effect of a HLPP. Four studies showed that better use of hearing protection devices in HLPPs decreased the risk of hearing loss. In four other studies, workers in a HLPP still had a 0.5 dB greater hearing loss at 4 kHz (95% CI - 0.5 to 1.7) than non-exposed workers. In two similar studies there was a substantial risk of hearing loss in spite of a HLPP. Stricter enforcement of legislation and better implementation of HLPPs can reduce noise levels in workplaces. Better evaluations of technical interventions and long-term effects are neede