Improved Hearing Protection Regulations in the Prevention of

Military NIHL and Tinnitus

Roderik Mrena, MD

University of Helsinki, Finland

February 26, 2010

Rosen Plaza Hotel, Orlando, FL

Occupational NIHL in Finland

Occupational NIHL severity

• occupational NIHL cases are reported to the National Insurance Board

• mostly mild

Occupational NIHLMrena, Ylikoski M, Mäkitie A, Pirvola, Ylikoski J. Occupational NIHL reports and tinnitus in Finland.

Acta Otolaryngol 2007, Vol. 127, No. 7, p.729-735.

– hearing loss = compensation– tinnitus ≠ compensation

Background

• military proffessional are at risk of NIHL• awareness ↑ • EU Directive 2003/10/EC (effective 2006)

– lower exposure action value: 80 dB(A), 135 dB(C)• protectors available, possibility for AG

– upper exposure action value: 85 dB(A), 137 dB(C)• protectors mandatory, noise cancellation program

– exposure limit value: 87 dB(A), 140 dB(C)• exposure may not exceed

Regulations in the FDF

• 1968– hard ammunition

• 1979– muffs in firing range, plugs in combat training

• 1985– also with blanks

• 1989, 1991– supervisor must order usage (but own responsibility)– education

• still, annually 1-2% of conscripts suffer AAT– consequences

• effective in preventing hearing loss / tinnitus?

Subjects

• 246 military personnel ending active duty

• Period 1 (1984-1986): n=123• Period 2 (2003-2005): n=129

• retrospective review of medical records– AG– exposure time– ear symptoms

Subjects

Results – Hearing LossMrena R, Ylikoski J, Kiukaanniemi H, Mäkitie A, Savolainen S. The effect of improved hearing

protection regulations in the prevention of military NIHL. Acta Oto-Laryngol 2008;128:997-1003.

• hearing generally worse in the left ear

• NCOs– improvement in both ears– statistically significant

• Officers– improvement, but statistically insignificant

NCOs – Right Ear

NCOs – Left Ear

Regulations & TinnitusMrena R, Savolainen S, Kiukaanniemi H, Ylikoski J, Mäkitie A. The effect of tightened hearing

protection regulations on military noise-induced tinnitus. Int J Audiol 2009;48:394-400.

Results – Tinnitus Prevalence

• Total Tinnitus Prevalence– Period I (1984-1986): 71%– Period II (2003-2005): 68%

• Officers– Period I: 68%– Period II: 63%

• NCOs– Period I: 76%– Period II: 72%

• significance

Results – Severe Tinnitus

• division:– no tinnitus / mild / constant or disturbing

– constant or disturbing tinnitus Period II vs. I: • Cox regression analysis:• HR 0.6, 95% CI 0.37-0.96, p=0.032

Results – Tinnitus Questionnaire

• available only during Period II (2003-2005)• localization: left 46% right 30% both 23%• high-pitched 90%

Tinnitus – Related Problems

Conclusions

• regulations are effective in reducing hearing loss

• regulations are effective in reducing serious tinnitus

• tinnitus prevalence did not improve in direct relation to hearing loss improvement

• retiring military professionals are young– NIHL & tinnitus are a serious threat to the

quality of life - preventable !

Significance of Long-Term TinnitusMrena R, Savolainen S, Kuokkanen J, Ylikoski J. Characteristics of tinnitus induced by acute acoustic

trauma: a long-term follow-up. Audiol Neurotool 2002;7:122-130.

• 418 conscripts with AAT: 100% tinnitus• 15 years later: 65% tinnitus

Results – Possible Factors

• actual use of protectors– reasons?

• leisure activities?

Always Wear Hearing Protection!

Thank you !Thank you !