difficulties caused by occupational noise, with 8% affected by tinnitus, and 4% having both hearing difficulties and tinnitus. Ototoxic chemicals including solvents, metals, compounds, asphyxiants, nitriles, and pharmaceuticals, may contribute further to hearing loss. Exposure management and controls The hierarchy of control defines the approach used to reduce exposure risks protecting workers and communities. These methods include elimination, substitution, engineering controls (isolation or ventilation), administrative controls and personal protective equipment. Occupational hygienists, engineers, maintenance, management and employees should all be consulted for selecting and designing the most effective and efficient controls based on the hierarchy of control. Professional societies The development of industrial hygiene societies originated in the United States, beginning with the first convening of members for the American Conference of Governmental Industrial Hygienists in 1938, and the formation of the American Industrial Hygiene Association in 1939. In the United Kingdom, the British Occupational Hygiene Society started in 1953. Through the years, professional occupational societies have formed in many different countries, leading to the formation of the International Occupational Hygiene Association in 1987, in order to promote and develop occupational hygiene worldwide through the member organizations. The IOHA has grown to 29 member organizations, representing over 20,000 occupational hygienists worldwide, with representation from countries present in every continent. Peer-reviewed literature There are several academic journals specifically focused on publishing studies and research in the occupational health field. The Journal of Occupational and Environmental Hygiene (JOEH) has been published jointly since 2004 by the American Industrial Hygiene Association and the American Conference of Governmental Industrial Hygienists, replacing the former American Industrial Hygiene Association Journal and Applied Occupational & Environmental Hygiene journals. Another seminal occupational hygiene journal would be The Annals of Occupational Hygiene, published by the British Occupational Hygiene Society since 1958. Further, The National Institute for Occupational Safety and Health maintains a searchable bibliographic database (NIOSHTIC-2) of occupational safety and health publications, documents, grant reports, and other communication products. Occupational hygiene as a career Examples of occupational hygiene careers include: Compliance officer on behalf of regulatory agency Professional working on behalf of company for the protection of the workforce Consultant working on behalf of companies Researcher performing laboratory or field occupational hygiene work Education The basis of the technical knowledge of occupational hygiene is from competent training in the following areas of science and management: Basic Sciences (Biology, Chemistry, Mathematics (Statistics), Physics); Occupational Diseases (Illness, injury and health surveillance