Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Final Activity Report Summary - NOISEHEAR (Noise pollution effects on auditory organ - pathogenesis, risk assessment, prevention and treatment)

The mission of NOISEHEAR Transfer-of -Knowledge programme was to strengthen the international position of the Nofer Institute of Occupational Medicine (NIOM), Lodz, Poland in the field of occupational and environment-related hearing loss and shift its research and development potential toward advanced field of molecular biology and genetics. Research activities focused on developing methods of estimating individual risk of noise-induced hearing loss (NIHL) while comprising several intrinsic and extrinsic factors influencing hearing threshold shift; advancing research and summarising knowledge on ototoxicity of organic solvents; searching for susceptibility genes for NIHL; and finally developing advanced methods of molecular genetics for future studies in pharmacological prevention and gene-based therapy of NIHL.

The objectives were implemented by recruitment to the Institute 9 experienced researchers of different specialities from abroad (Belgium, Great Britain, Finland, Portugal, USA, India, Hong Kong and Ukraine) and training 10 own staff researchers in five European and one US research centres. In total 94 person/months were used by both parties. In addition 21 foreign scientists were visiting Poland to deliver training courses and lectures. The analysis of a large Polish database of workers exposed to noise allowed to elaborate a method of individual risk prediction of noise-induced hearing loss. The model includes the factors that were shown to increase the risk of hearing threshold shift, such as co-exposures to organic solvents, smoking, elevated blood pressure, in addition to aging and level of noise, as well as efficiency of using hearing protectors. Standardised method for prediction of NIHL from ISO 1999:1990 was modified by including penalties for the mentioned above risk factors; these modifications make predictions of NIHL closer to actual hearing threshold levels.

Developed research on organic solvent ototoxicity showed that occupational exposure to styrene may induce central dysfunction characterised by auditory temporal processing disorders which can impact daily listening activities. Such exposure can also impair balance function. The current knowledge on organic solvent ototoxicity was summarised at the international workshop organised by NIOM, and thereafter in a consensus paper.

One of the main scientific highlights of the collaborative projects was to discover some susceptibility genes for NIHL and excluding some others. The positive results in the association studies were obtained for Protocadherin 15 (PCDH15) gene, Cadherin 23 (CDH23) gene, Myosin 14 (MYH14) gene, Heat-shock protein 70 (HSP70) gene, Catalase (CAT) gene and some potassium ion recycling genes (KCNQ1, KCNQ4, KCNJ10, GJB2, GJB6); on the other hand 35delG mutation heterozygosity in Connexin 26 has been excluded from candidate gene mutations for noise susceptibility. The structure of Cadherin 23 gene has been examined in detail, what provided the framework for future genetic studies on this gene.

An original mice model was established allowing to develop studies on pharmacological prevention and therapy of NIHL. It was shown that time dependent alterations in scavenging enzymes facilitate the production of free radicals, and D-methionine was effective in attenuating the noise-induced oxidative stress and associated functional hearing loss in mice.

The results of the collaborative research were presented at 34 conferences and workshops as 56 oral and 8 poster presentations; 20 articles were published and submitted to peer-reviewed international journals. Deliverables of the project comprise 4 Ph.D. theses, 1 habilitation thesis, organisation of 2 workshops and 1 scientific session for occupational physicians, hygienists and sanitary inspectors. The results of the study should have an influence on the health policy makers for improving the standards of protection of worker's hearing according to the new knowledge on individual risk factors for NIHL.

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