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Background: Hyperbaric exposure (HE) is proven to be a stressor to several mechanisms in living cells. Even if after homeostasis restoration, harmful effects are expected, in particular a presence of free radicals. These latter are the stimulus to negative phenomenon as inflammation or cancer. In Italy, with 7500 km of sea shores, a large quantity of workers is exposed to HE during occupational activities. A deep knowledge of HE and bodily effects is not well defined; hence a multidisciplinary assessment of risk is needed. To detect one or more indicators of HE a research group is organised, under the INAIL sponsorship. The research project focused on the oxidative stress (OxS) and this paper details on the possible protocol to estimate, with a large amount of techniques on several human liquids, the relationship between OxS and HE. Specific attention will be paid to identify confounding factors and their influence. Methods: Blood and urine will be sampled. Several lab techniques will be performed on samples, both targeted, to measure the level of well-known biomarkers, and untargeted. Regard the formers: products of oxidation of DNA and RNA in urine; inflammation and temperature cytokines and protein carbonyles in blood. Untargeted evaluation will be performed for a metabolomics analysis in urine. Confounding factors: temperature, body fat, fitness, allergies and dietary habits. These factors will be assessed, directly or indirectly, prior and after HE. The final scope of the project is to determine one or more indicators that relates to HE in hits twofold nature: depth and duration. Conclusion: The relationship between OxS and HE is not deeply investigated and literature proposes diverging results. The project aims to define the time dependence of biomarkers related to OxS, to rise knowledge in risk assessment in workers exposed to HE.

This present study is devoted to investigate the vibration transmissibility of the elbow along the forearm direction as a function of hand grip force. The vibration was from 6 to 500 Hz, which was generated on a single-axis electric shaker. It was transmitted to the elbow from an instrumented handle fixed on the shaker through the hand-arm system. 34 healthy adults participated in the measurement experiment. Each of them applied a constant grip force while maintaining the forearm in horizontal direction with a 90° elbow angle. The grip force was controlled in terms of the percent maximum voluntary contraction and three levels (20%, 30% and 40%) most frequently observed at workplaces were used in the experiment. A laser vibrometer was used to measure the vibration on the bony surface of the elbow along the forearm direction. The measured vibration transmissibility spectrum was expressed in an equal frequency band with a resolution of less than 1 Hz. This study found that increasing the grip force did not significantly change the first resonant peak at 8 Hz but it increased the second resonant frequency and the vibration transmissibility at higher frequencies. Relevance to industry The effect of the grip force on the elbow vibration transmissibility can be used to enhance the understanding of the vibration-induced disorders. The force-specific transmissibility can also be used as a frequency-weighting factor to quantify the exposure. They may help improve the method for the risk assessment of vibration-induced elbow injuries and disorders.

An experimental study has been performed on the effect of exposure to noise (N), vibration (V), and combined noise and vibration (NV), on the distortion product otoacoustic emission (DPOAE) level. The aim of the study is investigating the possible synergistic effect of noise and vibration, increasing the risk of damage to the hearing function due to noise only. Twelve normal-hearing volunteers were randomly exposed to hand arm vibration (HAV) only, noise only, and HAV and noise simultaneously. The exposure consisted of five consecutive sessions interspersed with quiet periods. DPOAEs were recorded during the quiet intervals following each exposure session, and during recovery, and compared to their baseline level, and among different test treatments. An ad hoc acquisition system developed in Labview was used to record high frequency-resolution DPOAE spectra in a suitably short time. Time-frequency filtering, based on the wavelet transform, was used to separate the DPOAE components coming from different generation mechanisms. The three test treatments, N, V, and NV, yielded significantly different results. The condition affecting most significantly all DPOAE component levels was the exposure to vibration only, causing a statistically significant increase of the signal level during all the exposure periods, with a decreasing trend during recovery. Also the exposure to noise only, N, caused a DPOAE level increase, statistically significant for the long latency (LL) DPOAE component. Only when exposure to noise was in combination with vibration, the zero-latency (ZL) component was clearly suppressed during the exposure. The results suggest a synergistic adverse effect of noise and vibration on the cochlear function. Relevance to industry The simultaneous exposure to noise and hand arm vibration is a very common industrial scenario. The risk that exposure to mild noise levels could interfere with the exposure to vibration, enhancing the adverse effect on the hearing function, should be considered to optimize prevention strategies at the workplace.

Introduction Walking on vibrating floor causes a complex exposure pattern and the superimposition of walk and vibration may induce early muscular fatigue.1 The problem is relevant is many field, as sea platform or railway transports. The present study studies the leg muscular activation and stride phases during walking under vibration to derive a muscle model in these circumstances. Methods Subjects walked on a treadmill positioned on a 6-DOF vibrating table. Vibration was imposed at four frequencies (4, 8, 12, 16 Hz) along vertical and transversal direction. The walking speed was set at 1.25 m/s. Surface electromyography (sEMG) of four muscles was recorded. Stride phases were recorded using accelerometers and stride length was calculated. Acceleration signals were acquired in several body districts (foot, knee and hip). All measurements were related to the walking condition without the vibration. Result Preliminary results showed that vibration does not affect stride length and step phases. The muscular activation patterns exhibit frequency related modification, in terms of sEMG bursts amplitude and timing. There is a linear correlation between 8 Hz frequency and muscular activation. Discussion Transmitted vibration triggers a tonic vibration reflex (TVR) that is related to mechanical frequencies.2 TVR is also related to the motor task because of the mechanical coupling between vibrator and biological apparatus.3 These facts could explain the modifications in leg muscle activation revealed with sEMG. References . Fattorini L, Tirabasso A, Lunghi A, Di Giovanni R, Sacco F, Marchetti E. Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations. J Electromyogr Kinesiol2016;26:143–148. . Eklund G, Hagbarth KE. Normal variability of tonic vibration reflexes in man. Exp Neurol1966;16:80–92. . Fattorini L, Tirabasso A, Lunghi A, Di Giovanni R, Sacco F, Marchetti E. Muscular synchronisation and hand-arm fatigue. Int J Ind Ergon2017.

The purpose of this paper is to evaluate the muscular activation of the forearm, with or without vibration stimuli at different frequencies while performing a grip tasks of 45s at various level of exerted force. In 16 individuals, 9 females and 7 males, the surface electromyogram (EMG) of extensor carpi radialis longus and the flexor carpi ulnari muscles were assessed. At a short latency from onset EMG, RMS and the level of MU synchronization were assessed to evaluate the muscular adaptations. Whilst a trend of decay of EMG Median frequency (MDFd) was employed as an index of muscular fatigue. Muscular tasks consists of the grip of an instrumented handle at a force level of 20%, 30%, 40%, 60% of the maximum voluntary force. Vibration was supplied by a shaker to the hand in mono-frequential waves at 20, 30, 33 and 40Hz. In relation to EMG, RMS and MU synchronization, the muscular activation does not seem to change with the superimposition of the mechanical vibrations, on the contrary a lower MDFd was observed at 33Hz than in absence of vibration. This suggests an early muscular fatigue induced by vibration due to the fact that 33Hz is a resonance frequency for the hand-arm system.

This article presents the new Italian database of physical agents, which is available at http://www.portaleagentifisici.it. It supports in risk assessment employers who have to comply with Italy's Legislative Decree 81/2008 (transposing into law European Union Directives 2003/10/EC, 2002/44/EC, 2004/40/EC and 2006/25/EC). The database currently contains measurements and declared European Community (EC) values from over 2540 machines; in particular, the database hosts data on mechanical vibration from over 1430 hand-held power tools (e.g., pneumatic and electric hammers, chainsaws, grinders, drills, sanders and saws) and from over 1020 whole-body machines (e.g., buses, fork lifts and wheel tractors). The database is continuously updated as soon as new experimental and declared data are acquired.