title: Influence of well-known risk factors for hearing loss in a longitudinal twin study.
abstract: The aim was to investigate the influence of environmental exposures on hearing loss in a twin cohort.
  
  
  
  Male twins born 1914-1958, representing an unscreened population, were tested for hearing loss at two occasions, 18 years apart.
  
  
  
  Clinical audiometry and a questionnaire were performed at both time points in this longitudinal study. Noise and solvent exposure were assessed using occupational work codes and a job exposure matrix. Hearing impairment was investigated using two different pure tone averages: PTA4 (0.5, 1, 2, and 4 kHz) and HPTA4 (3, 4, 6, and 8 kHz).
  
  
  
  Age affected all outcome measures. Noise exposure between time point one and two affected the threshold shifts of PTA4 and HPTA4 more in participants with a pre-existing hearing loss at time point one. Lifetime occupational noise exposure was a risk factor especially for the low-frequency hearing threshold PTA4. Firearm use was a statistically significant risk factor for all outcome measures.
  
  
  
  Pre-existing hearing loss can increase the risk of hearing impairment due to occupational noise exposure. An increased risk for NIHL was also seen in the group with exposures below 85 dB(A), a result that indicates awareness of NIHL should be raised even for those working in environments where sound levels are below 85 dB(A).
authors.affiliation: a Department of Clinical Science, Intervention and Technology, Unit of Audiology , Karolinska Institutet , Stockholm , Sweden.
authors.forename: Ann-Christin
authors.initials: AC
authors.lastname: Johnson
authors.affiliation: a Department of Clinical Science, Intervention and Technology, Unit of Audiology , Karolinska Institutet , Stockholm , Sweden.|b Department of Audiology and Neurotology , Karolinska University Hospital , Huddinge , Sweden.
authors.forename: Renata
authors.initials: R
authors.lastname: Bogo
authors.affiliation: c Department of Monitoring and Evaluation, Public Health Agency of Sweden , Stockholm , Sweden.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Farah
authors.affiliation: b Department of Audiology and Neurotology , Karolinska University Hospital , Huddinge , Sweden.
authors.forename: Kjell K
authors.initials: KK
authors.lastname: Karlsson
authors.affiliation: a Department of Clinical Science, Intervention and Technology, Unit of Audiology , Karolinska Institutet , Stockholm , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Muhr
authors.affiliation: d Department of Occupational Medicine , Karolinska Institutet , Stockholm , Sweden , and.
authors.forename: Mattias
authors.initials: M
authors.lastname: Sjöström
authors.affiliation: a Department of Clinical Science, Intervention and Technology, Unit of Audiology , Karolinska Institutet , Stockholm , Sweden.
authors.forename: Eva B
authors.initials: EB
authors.lastname: Svensson
authors.affiliation: a Department of Clinical Science, Intervention and Technology, Unit of Audiology , Karolinska Institutet , Stockholm , Sweden.|b Department of Audiology and Neurotology , Karolinska University Hospital , Huddinge , Sweden.
authors.forename: Åsa
authors.initials: Å
authors.lastname: Skjönsberg
authors.affiliation: e Department of Medical Sciences , Uppsala University , Uppsala , Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Svartengren
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001299:Audiometry; D001309:Auditory Threshold / Q000187:drug effects*; D005389:Firearms; D006309:Hearing / Q000187:drug effects*; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009623:Noise, Occupational / Q000009:adverse effects*; D009784:Occupational Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology; D016273:Occupational Exposure / Q000009:adverse effects*; D016272:Occupational Health; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D012997:Solvents / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D012997:Solvents
keywords: Aging; demographics/epidemiology; hearing conservation; noise; tinnitus