The permissible exposure limit in many industrial countries is 85 dB(A) for an 8 hours working day. However, a daily noise exposure at 85 dB(A) is responsible for “auditory fatigue”, a temporary decrease of hearing sensitivity at the end of the day that has been largely ignored so far. When combining recreational and occupational noise exposures, approximately 13% of people are exposed to a cumulative daily dose of noise equal to, or exceeding, 85 dB(A). First, even transient hearing loss could have effects on cognitive performance through increased stress levels, learning difficulties, or the modulation of distraction and vigilance by the noise. Second, it was recently shown that a noise-induced temporary decrease in hearing sensitivity could underlie neural and synaptic alterations in the peripheral auditory system, and that this can coexist with long-term normal auditory thresholds. From that perspective, auditory fatigue could be an early sign of damage to the peripheral auditory system. The FATIGAUDIT proposal will investigate the risks of hidden damage to the auditory system and of impairment to auditory perceptual abilities at the workplace due to prolonged noise exposure. Investigations will be done in humans and gerbils, which have a peripheral auditory system very similar to humans from the perspective of its anatomy, its hearing range and, importantly, its sensitivity to daily noise exposure. We will study damage to the cochlea at the cellular level and changes in the functional organization of the auditory cortex due to single or repeated daily noise exposure. We will also test whether the ability to identify and discriminate complex sounds in noise are impaired by auditory fatigue. These results will allow us to design methods to easily and quickly diagnose auditory fatigue at places where it occurs, including the workplace. In particular, innovative methods giving access to the activity of the auditory nerve, even in humans, will be tested and validated. Finally, preventing auditory fatigue by resting periods will be explored. The FATIGAUDIT proposal brings together four complimentary fundamental, clinical and work-related research teams. The Institut de l’Audition (IdA, Institut Pasteur, coordinator) will provide expertise in noise-induced disorders and functional changes in animals’ central auditory system; The Institut des Neurosciences (INM, Montpellier) will bring its world-renowned expertise in the structure of the peripheral auditory system; The Centre Hospitalier Universitaire (CHU) in Montpellier will perform clinical tests and validation of auditory fatigue diagnosis in humans; the Institut National de Recherche et Sécurité (INRS, Nancy) will bring its unique expertise in measuring effects of occupational noise exposure directly at the workplace. This ideally tailored consortium will be able to assess the cellular, functional, and cognitive aspects of auditory fatigue. Better understanding of this neglected risk for hearing and health will help to prevent the risk of long-term hearing disorders, and premature auditory ageing, in a significant part of the population, as well as reduce the social and financial burden of noise. This proposal also aims at questioning current occupational regulations as preliminary data from this consortium shows that these regulations do not prevent temporary hearing loss from occurring in many professions.

A definitive conclusion about the dangers associated with human or animal exposure to a particular nanomaterial can currently be made upon complex and costly procedures including complete NM characterisation with consequent careful and well-controlled in vivo experiments. A significant progress in the ability of the robust nanotoxicity prediction can be achieved using modern approaches based on one hand on systems biology, on another hand on statistical and other computational methods of analysis. In this project, using a comprehensive self-consistent study, which includes in-vivo, in-vitro and in-silico research, we address main respiratory toxicity pathways for representative set of nanomaterials, identify the mechanistic key events of the pathways, and relate them to interactions at bionano interface via careful post-uptake nanoparticle characterisation and molecular modelling. This approach will allow us to formulate novel set of toxicological mechanism-aware end-points that can be assessed in by means of economic and straightforward tests. Using the exhaustive list of end-points and pathways for the selected nanomaterials and exposure routs, we will enable clear discrimination between different pathways and relate the toxicity pathway to the properties of the material via intelligent QSARs. If successful, this approach will allow grouping of materials based on their ability to produce the pathway-relevant key events, identification of properties of concern for new materials, and will help to reduce the need for blanket toxicity testing and animal testing in the future.

Ochratoxin A (OTA) is the most common mycotoxin found in our temperate regions that contaminates food commodities prior to harvest or more commonly during storage. OTA inhibits protein synthesis and lipid peroxidation by oxidative processes. These mechanisms may generate nephrotoxic, neurotoxic and immunotoxic effects. After its ingestion or its inhalation, OTA reaches blood streams and is transported to kidney that ensured its biotransformation in metabolites that are responsible of its toxicity and that are present in biological fluids. Therefore, there is an important request for fast, reliable and low-cost analytical methods for the monitoring of OTA in food. Moreover, inhalation in the workplace could be considered as a route of exposure additional to the consumption. The conventional method used for the identification of OTA is based on the use of liquid chromatography and fluorescence detection (LC/Fluo), the native fluorescence of OTA favoring the development of a very sensitive method. An immunoaffinity column (IAC) for the sample treatment is currently associated to LC/Fluo to remove matrix components. The study of the impact of OTA in inhalation studies requires a very sensitive method. It also requires a method of sampling adapted to small-size samples preventing the use of IACs. Moreover, underestimation of OTA contamination in food has been already reported. At last, antibodies involved in IAC are not adapted to the selective extraction of the OTA metabolites and of OTA DNA adducts that have to be studied in biological fluids and tissue to understand the action mode of OTA and then explain its toxicity. So, the lack of powerful methods for these OTA analogues constitutes a real limitation for toxicological studies. The aim of MYCODIAG is to propose more powerful and less expensive extraction devices as an alternative to IAC by developing molecularly imprinted polymers (MIP) and aptamer based sorbents for the selective extraction of OTA and its structural analogs from complex samples. Both approaches will be developed in conventional format to be evaluated and compared with IAC and also in miniaturized formats (pipet tips, strips, microsystems) to circumvent the drawbacks of IAC for small-size samples and to develop analytical devices that can be directly applied on field. MIPs are obtained by the polymerization of monomers in the presence of a template molecule, i.e OTA or an analogue, in the presence of cross-linking agent. The non-covalent bonds taking place between the monomers and the template allows the removal of the template after the polymerization and thus to obtain a polymer that possesses cavities complementary in term of shape and functionalities to the template. Different templates will be envisaged for obtaining a MIP with the properties to trap OTA but also its structural analogues. The aptamers are composed by a well defined nucleotides sequence that is able to bind selectively the target analyte but also structural analogues. Moreover, the highest capacity already demonstrated for MIPs (developed for other molecules and compared to IAC) and expected for oligosorbents (because of the smaller size of the oligonucleotides compared to the size of antibodies thus allowing higher binding ratio) makes them very attractive for the development of miniaturized devices. Moreover, the retention process on these chemical and biological tools should be different thus rendering them complementary for the trapping of target compounds. These tools will be evaluated for the analysis of OTA in well-defined airborne particles and be used for estimating workers exposure and in the future to inhalation studies. They will be also evaluated for toxicological studies in biological fluids (blood, urine) from animal submitted to OTA ingestion to analyze OTA and also metabolites and DNA adducts. This evaluation in real biological matrices also constitutes an important point before to start inhalation studies.