الفهرس 
Introduction and overviewOnly 14 pages are availabe for public view
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Abstract
Occupational hearing loss is a common work related problem that can be attributed to an offending agent in the workplace. With the increasing complexity of the industrial society, the exposure to different agents as noise or chemicals in the workplace represents a serious threat to the hearing system. The biological basis of NIHL is a combination of mechanical and metabolic factors: chronic excessive noise exposure damages cochlear hair cells and metabolic changes result from hypoxia caused by noise-induced capillary vasoconstriction. Exposure to excessive occupational noise is associated with many adverse effects besides loss of hearing as annoyance and fatigue and to serious health conditions such as hypertension.
An effective occupational hearing conservation program particularly in developing countries is highly recommended. It consists of identification of noise production sources, implementing standard rules and regulations, expansion of training programs and performing periodic hearing evaluation of those who are exposed to excessive sound levels. The pharmacological prevention and treatment of NIHL has been under preclinical investigation for the past 20 years. Promising treatments have now been identified and entered into clinical development. Within the next five years, safe and effective drugs could be approved as the first generation of otoprotectants.
The information currently available indicates that several chemicals, including organic solvents such as xylene and toluene have noxious neurotoxic, and ototoxic effects. These substances and their mixtures are common in industrial environments.
Organic solvents, known to be hazardous chemical substances, can induce both central and peripheral neurotoxicity as injury to sensory cells and peripheral nerve endings of the cochlea, and affect the auditory pathways in the brain.
When assessing for CIHL, a standard test battery should include acoustic reflex testing, otoacoustic emissions, and evoked potentials in order to cover the entire auditory tract. Risk-management measures aimed at decreasing exposure to ototoxic industrial chemicals should be supported.
Barotitis media is known to be an adverse effect of altitude changes. It occurs in aviation and diving when the ambient pressure changes rapidly and pressure in the middle ear fails to equilibrate with external pressure damage to both the eardrum itself and the middle ear mucosa. Preventing barotrauma requires appropriate selection of time of travelling and rates of pressure change.
Hand-arm vibration syndrome consists of disturbances in the circulation of the fingers, peripheral nerves of the hands and arms, and possibly muscle, joint and autonomic nervous system disorders and SNHL. Vibration can be reduced by the use of preventive managerial, technical and individual measures.
Radiations emitted from broadcasting stations are one of the most silent causes of hearing loss. It is recommended to decrease the use of mobile phones and to build radiation towers away from residential areas.