Occupational Noise-Induced Hearing Loss L Mirza, DO, D

Home , Occupational medicine, Occupational noise, Ototoxicity

8 6 s and greater than 7 8000 Hz is usually better 5 8 CHARACTERISTICS The principal characteristics of exposure. This,effects together of withprominence aging, of the may thefore, ‘‘notch.’’ in reduce There- older individuals,of the the noise effects mayguish be from difficult age-related(presbycusis) to hearing without distin- loss accessvious to audiograms. pre- The exactdepends on location multiple factors including the of frequency of the theand damaging size notch noise of theIn ear canal. earlythresholds at NIHL, theof average lower 500, 1000, frequencies and hearing 2000than Hz are better average4000, thresholds and 6000 Hz, atlevel and the 3000, at hearing than the deepestThis part notching of is in thebycusis, contrast notch. which to also pres- frequency produces high- hearingdown-sloping pattern loss without recov- butery at in 8000 Hz. Although a OSHAaudiometric does not testinginclusion require of this at frequencyrecommended is to assist highly 8000 infication Hz, the of the identi- noiseage-related notch hearing as loss. well as This notch typically developsof at these frequencies one and affectscent frequencies adja- with continued noise not produce ain loss high greater than frequencie 40 dB 75 dB in lowerless, frequencies. individuals with Neverthe- as non-NIHL, such presbycusis,threshold may levelsvalues. have in excess hearing of these Noise exposure alone usually does It isaffecting always the cochlear sensorineural,inner hair ear. primarily cells inIt is the typically bilateral,exposures since most noise affectcally. both earsIts symmetri- firstaudiogram sign at is the3000, a 4000, high ‘‘notching’’ or frequencies ofat 6000 8000 Hz of Hz. the with recovery occupational NIHL are as follows: Volume 60, Number 9, September 2018 2 JOEM TATEMENT regarding the S 4 The Role of the Profes- UIDANCE PROGRAM DEFINITION Responsibilities include inter- 3 . This statement clarifies current best Occupational NIHL develops gradu- The OEM physician also plays a OF THE AUDIOMETRIC THE OEM PHYSICIAN AS HEARING CONSERVATION PROFESSIONAL SUPERVISOR TESTING COMPONENT OF A College of Occupational andtal Environmen- Medicine (ACOEM) believes thatphysicians OEM should understandnoise exposure a history worker’s cient and in become the profi- earlyof detection NIHL. and prevention pretation of audiograms,determinations, work-relatedness referral ofquality problem cases, oversightand of determination audiometric ofthe testing, the hearing effectiveness conservation program. of practices in the diagnosisbasis of NIHL. of On current the knowledge,previous ACOEM it statement updates the supervisor can beposition statement found insional the Supervisor in ACOEM theing Audiometric Component Test- ofPrograms Hearing Conservation The responsibilities of the professional distinguishing featuresNIHL. of occupational ally over time and isous a or function intermittent of noise continu- in exposure. contrast This to occupational is acousticwhich trauma is characterized byin a hearing sudden as change a result ofa a sudden single burst exposure to ofsive sound, blast. such The as diagnosis anby of explo- the NIHL OEM is physician, made account by the worker’s first noise taking exposure history into and then by considering the followingacteristics. char- critical role intional the NIHL prevention by ofsupervisor serving of occupa- as the ament audiometric professional testing of ele- The hearing conservation OccupationalAdministration programs. (OSHA) defines Safety ament require- for and professional1983 Hearing Health supervisors Conservation in Amendment. the ACOEM G The under 1 ACOEM Task Force on Occupational Hearing Loss Occupational Noise-Induced Hearing Loss l Mirza, DO, D. Bruce Kirchner, MD, Robert A. Dobie, MD, and James Crawford, MD, ´ Rau 2018 American College of Occupa- ß oise-induced hearingcontinues loss to be one (NIHL) of the most prev- Elk Grove Village, IL 60007 ([email protected]). tors to itscompeting interests, documents which toered. are disclose ACOEM carefully any consid- expressed emphasizes potential herein that represent thedence the best at available judgments evi- theconsidered the time position ofindividual of opinions publication ACOEM of contributing and and authors. not shall the be ACOEM, 25 Northwest Point Blvd, Suite 700, Environmental Medicine, Elk Grove, Illinois. Task Force on Occupationalthe Hearing auspices Loss of the CouncilIt of Scientific was Advisors. reviewedProcedures, and by Public theby Positions, the Committee ACOEM and Board on2018. approved of ACOEM Policy, Directors requires on all April substantive 28, contribu- tional and Environmental Medicine with management,hygiene, engineering, and safety, human resources to industrial ensure thatloss prevention all programs are components in place. of hearing alent occupational conditionsacross a and wide spectrum occurs of industries.pational hearing Occu- loss is preventable through a hierarchy of controls, whichuse prioritize the of engineeringtrative controls over controls adminis- equipment. and The occupational personal andmental environ- medicine protective (OEM) physician works Copyright e498 The authors declare noAddress conflicts correspondence to: of Marianne interest. Dreger, MA, From the American College ofThis Occupational position and paper was developed by the ACOEM (OEM) physician playsprevention of a occupational critical noise-induceding loss role hear- (NIHL). This in position statementcurrent clarifies the best practices in the diagnosistional of NIHL. occupa- N Occupational hearing loss is preventable through a hierarchy of controls,of which engineering prioritize controls the over use administrativetrols con- and personaloccupational protective equipment. and The environmental medicine DOI: 10.1097/JOM.0000000000001423 periodic performance audits rather than just conducting audiometric testing.less, Neverthe- audiometricmenting testing, the besidescan permanent docu- be loss ofhearing of loss at value a hearing, time when inintervention early preventive the is identification possible. of The American OEM physicianemployers the should criticalventing importance hearing emphasize of loss pre- through to controls and Copyright © 2018 American College of Occupational and Environmental Medicine. Unauthorized reproduction of this article is prohibited Copyright © 2018 American College of Occupational and Environmental Medicine.

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Hearing loss due to continuous or inter- hazardous noise exposure continue.19 hierarchy of primary prevention controls mittent noise exposure increases most Barring an ototraumatic incident, work- should be implemented in order to miti- rapidly during the first 10 to 15 years ers will always develop temporary gate the risk of an acquired dose to of exposure, and the rate of hearing loss threshold shift before sustaining perma- workers, or others, potentially exposed then decelerates as the hearing threshold nent threshold shift.1 to ototoxic chemicals. increases.9 This is in contrast to age- Individual susceptibility to the auditory related loss, which accelerates over time. ADDITIONAL effects of noise varies widely.28 The Available evidence indicates that previ- CONSIDERATIONS IN biological basis for this remains unclear. ously noise-exposed ears are not more In addition, the contribution of comorbid sensitive to future noise exposure. EVALUATING THE WORKER conditions such as cardiovascular dis- There is insufficient evidence to con- WITH SUSPECTED NIHL ease, diabetes, and neurodegenerative clude that hearing loss due to noise will The OEM physician evaluating pos- disease to hearing loss is unclear.29 progress once the noise exposure is dis- sible cases of NIHL should consider the There are a number of other causes of continued.8 This is primarily based on a following issues: sensorineural hearing loss besides occu- National Institute of Medicine report pational noise. Of primary concern is which concluded that, on the basis of Unilateral sources of noise such as sirens non-occupational noise exposure from available human and animal data, it was and gunshots can produce asymmetric a variety of sources, especially recrea- felt unlikely that such delayed effects loss, as can situations in which the work tional noise, such as loud music, weap- occur.9,10 However, recent animal involves fixed placement of the affected ons firing, motor sports, etc. Other experiments indicate although there ear relative to the noise source. When causes include a wide variety of genetic appears to be threshold recovery and evaluating cases of asymmetric loss, disorders, infectious diseases (eg, laby- no loss of cochlear cells following noise referral to rule out a retrocochlear lesion, rinthitis, measles, mumps, syphilis), exposures to rodents, there is evidence of such as an acoustic neuroma,20 is war- pharmacologic agents (eg, aminoglyco- cochlear afferent nerve terminal damage ranted before attributing the loss to sides, diuretics, salicylates, antineoplas- and delayed degeneration of the cochlear noise. The physician should consult cri- tic agents), head injury, therapeutic nerve, thus suggesting that delayed teria, such as from the American Acad- radiation exposure, neurologic disorders effects could be seen in the future.11 emy of Otolaryngology—Head and (eg, multiple sclerosis), cerebral vascu- Although the OSHA action level for Neck Surgery, which can assist in mak- lar disorders, immune disorders, bone noise exposure is 85 dB (8-hour time- ing referrals for further evaluation.21,22 (eg, Paget disease), central nervous sys- weighted average), the evidence sug- Animal exposure data suggest that the tem neoplasms, and Menie`re’s disease. gests that noise exposure from 80 to addition of very intense and frequent A medical history can help in determin- 85 dB may contribute to hearing loss impulse/impact noise to steady-state ing whether any of these conditions in individuals who are unusually suscep- noise can be more harmful than could contribute to an individual’s hear- tible. The risk of NIHL increases with steady-state noise of the same A- ing loss.30 Nevertheless, the Genetic long-term noise exposures above 80 dB weighted energy exposure. (A-weight- Information Nondiscrimination Act in and increases significantly as exposures ing is the most common noise some instances precludes the OEM phy- rise above 85 dB.12,13 measurement scale. A-weighting best sician from obtaining a family history,31 Continuous noise exposure throughout approximates the way the human ear which could give insight into genetic the workday and over years is more perceives loudness at moderate sound disorders such as Alport syndrome. damaging than interrupted exposure to levels and it de-emphasizes high and There is an exception for when the fam- noise, which permits the ear to have a low frequencies that the average person ily medical history is collected for diag- rest period. At the present time, mea- cannot hear.) Nevertheless, human data nostic or treatment purposes. In such sures to estimate the health effects of are currently too sparse to derive an cases, when genetic or any other non- such intermittent noise are controversial. exposure metric, which can practically occupational condition noted earlier is Real world attenuation provided by estimate such a hazardous noise suspected, a referral to an otolaryngolo- hearing protective devices may vary risk.23,24 gist or other appropriate specialist widely between individuals. The noise- Animal models suggest that exposure to is recommended. reduction rating of hearing protective ototoxic agents, such as solvents (nota- Individuals with NIHL may experience devices used by a working population bly ethylbenzene, methylstyrene, n-hex- significant morbidity due to hearing loss, is expected to be less than the laboratory- ane, n-propylbenzene, p-xylene, styrene, concomitant tinnitus, and/or impaired derived rating.14,15 Hearing protective trichloroethylene, and toluene), may act speech discrimination. On the job, such devices should provide adequate attenu- in synergy with noise to cause hearing hearing loss can impact worker commu- ation to reduce noise exposure at the loss. Asphyxiants (carbon monoxide and nications and safety. Other conditions eardrum to less than 85 dB time- hydrogen cyanide), some nitriles (such associated with noise exposure and/or weighted average. In addition, technol- as acrylonitrile), and metals (lead, mer- hearing loss are hypertension, depres- ogy is now available, which can provide cury, and tin) have also been implicated sion, dementia,32 social isolation,33 an individualized attenuation rating for as causing ototoxicity. The involvement increased risk of accidents,34–36 and hearing protective devices and continu- can be seen as damage to cochlear hair retrocochlear lesions.37–41 Workers with ous monitoring of noise at the ear- cells, central nervous system, or both. evidence of hearing loss require an indi- drum.16–18 Although the scientific understanding of vidualized evaluation that takes into The presence of a temporary threshold the role of all these chemicals in human account both the need to communicate shift (ie, the temporary loss of hearing, ototoxicity is still evolving, a thorough safely and effectively and the need for which largely disappears 16 to 48 hours exposure history to these chemicals protection from additional damage due after exposure to loud noise) with or should be obtained and taken into con- to noise. without tinnitus is a risk indicator that sideration when evaluating sensori- Because hearing loss due to noise permanent NIHL will likely occur if neural hearing loss.25–27 Further, the is irreversible, early detection and

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intervention is critical to prevention of exposure in the workplace, non-occupa- 15. Berger EH, Franks JR, Behar A, et al. Devel- this condition. Ensure baseline audio- tional sources of noise, chemicals known opment of a new standard laboratory protocol grams are obtained for new hires and/ for estimating the field attenuation of hearing to be ototoxic, comorbidities impacting protection devices. Part III. The validity of or employees newly identified as work- hearing, and the pathophysiology of NIHL using subject-fit data. J Acoust Soc Am. ing within a noise-laden environment. A and its clinical and audiometric character- 1998;103:665–672. 10-dB confirmed threshold shift from istics. Making a diagnosis of NIHL is an 16. Hager LD. Fit-testing hearing protectors: an baseline in pure-tone average at 2000, important step in preventing further hearing idea whose time has come. Noise Health. 2011;13:147–151. 3000, and 4000 Hz (OSHA standard loss in the affected worker and for identi- threshold shift or STS), while not nec- 17. Michael K, Tougaw E, Wilkinson R. Role of fying the potential for NIHL in coworkers. continuous monitoring in a hearing conserva- essarily resulting in significant The OEM physician must work with man- tion program. Noise Health. 2011;13:195–199. impairment, is an important early indi- 42 agement and other safety and health pro- 18. Schulz TY. Individual fit-testing of earplugs: a cator of permanent hearing loss. A fessionals to evaluate the workplace for review of uses. Noise Health. 2011;13:152–162. temporary threshold shift is an important noise exposure, educate the workers regard- 19. Moshammer H, Kundi M, Wallner P, Herbst A, early and reversible indicator that poten- ing the risk of noise exposure (occupational Feuerstein A, Hutter HP. Early prognosis of tial cochlea hair cell damage can prog- noise-induced hearing loss. Occup Environ and non-occupational), and reduce the Med. 2015;72:83–84. ress to an STS, unless preventive potential for noise exposure. interventions occur. Tinnitus is another 20. Zapala DA, Shaughnessy K, Buckingham J, 8 Hawkins DB. The importance of audiologic early warning symptom for NIHL. red flags in patient management decisions. J Other early warning flags, such a 10- REFERENCES Am Acad Audiol. 2008;19:564–570. 1. NIOSH. Criteria for a Recommended Standard: dB non-age-corrected STS or an 8-dB 21. Suter AH, Berger EH. Hearing Conservation Occupational Noise Exposure. Cincinnati, OH: Manual. Milwaukee, WI: Council for Accredi- age-corrected STS, may have a higher National Institute for Occupational Safety and tation in Occupational Hearing Conservation; positive predictive value in identifying Health; 1998:98–126. Available at: https:// 2002. those individuals who will progress to www.cdc.gov/niosh/docs/98-126/pdfs/98- 43 126.pdf. Accessed March 26, 2018. 22. American Academy of Otolaryngology Head impaired hearing. Therefore, individu- and Neck Surgery. Policy Statement: Red flags- 2. Occupational Health and Safety Administra- als in hearing conservation programs warning of ear disease [website.]. Available at: tion. 1910.95 CFR occupational noise exposure: who exhibit such shifts on serial audio- http://www.entnet.org/?q=node/912. Accessed hearing conservation amendment (final rule). May 14, 2018. metric testing should be carefully evalu- Fed Reg. 1983;48:9738–9785. 23. Qiu W, Hamernik RP, Davis B. The kurtosis ated and counseled regarding avoidance 3. Rabinowitz P. ACOEM Position Statement. The of noise and correct use of personal metric as an adjunct to energy in the prediction role of the professional supervisor in the audio- of trauma from continuous, nonGaussian noise metric testing component of the hearing con- hearing protection. exposures. J Acoust Soc Am. 2006;120: servation program. [website.]; 2007. Age correction of audiograms is a 3901–3906. 4. Kirchner DB, Evenson E, Dobie RA, et al. method of age standardization, which 24. Goley GS, Song WJ, Kim JH. Kurtosis cor- ACOEM guidance statement. Occupational rected sound pressure level as a noise metric for allows comparisons of hearing loss rates noise-induced hearing loss. J Occup Environ risk assessment of occupational noises. J Acoust among working populations. OSHA Med. 2012;54:106–108. Soc Am. 2011;129:1475–1481. allows, but does not require, the use of 5. McBride D, Williams S. Audiometric notch as a 25. Morata TC. Chemical exposure as a risk factor 2 sign of noise induced hearing loss. Occup Envi- an age-correction procedure. Age-cor- for hearing loss. J Occup Environ Med. 2003; ron Med. 2001;58:46–51. rection factors are averages for a popu- 45:676–682. 6. Consensus Conference. Noise and hearing loss. lation—some individuals will exhibit 26. European Agency for Safety and Health at JAMA. 1990;263:3185–3190. more age-related loss and some less. Work. Combined Exposure to Noise and Oto- Therefore, the application of age correc- 7. Coles R, Lutman M, Buffin J. Guidelines on the toxic Substances; 2011. Available at: https:// diagnosis of noise-induced hearing loss for osha.europa.eu/en/tools-and-publications/pub- tion to the surveillance audiograms of a medicolegal purposes. Clin Otolaryngol Allied lications/literature_reviews/combined-expo- noise-exposed population can result in Sci. 2000;25:264–273. sure-to-noise-and-ototoxic-substances. fewer confirmed 10-dB shifts being 8. Dobie RA. Medical-Legal Evaluation of Hear- Accessed May 14, 2018. reported. Thus, when applying age cor- ing Loss. 3rd ed. San Diego, CA: Plural Pub- 27. Campo P, Morata TC, Hong O. Chemical expo- rection to the audiometric results of an lishing; 2015. sure and hearing loss. Dis Mon. 2013;59:119. individual who has experienced a thresh- 9. Durch JS, Joellenbeck LM, Humes LE, eds. 28. Stucken EZ, Hong RS. Noise-induced hearing old shift, the OEM physician should Noise and Military Service: Implications for loss: an occupational medicine perspective. Hearing Loss and Tinnitus. Washington, DC: Curr Opin Otolaryngol Head Neck Surg. consider whether, in that individual, a National Academies Press; 2005. 2014;22:388–393. preventable noise component of hearing 10. Lee FS, Matthews LJ, Dubno JR, Mills JH. 29. Ward WD. Endogenous factors related to sus- loss could play a role. Longitudinal study of pure-tone thresholds in ceptibility to damage from noise. Occup Med. Any assessment of hearing loss requires older persons. Ear Hear. 2005;26:1–11. 1995;10:561–575. the review of all previous audiograms, as 11. Kujawa SG, Liberman MC. Adding insult to 30. Arts H. Sensorineural hearing loss in adults. In: well as noise exposure records, hearing injury: cochlear nerve degeneration after ‘‘tem- Otolaryngology: Head and Neck Surgery, 5th porary’’ noise-induced hearing loss. J Neurosci. ed. Philadelphia, PA: Mosby Elsevier; 2010. protection data, and clinical history, to 2009;29:14077–14085. assist in the diagnosis of NIHL. A refer- 31. US Equal Employment Opportunity Commis- 12. American National Standards Institute. Determi- sion/US Congress. The Genetic Information ral for a comprehensive audiology eval- nation of Occupational Noise Exposure and Esti- Non-Discrimination Act; 2008. Available at: uation, including bone conduction mation of Noise-Induced Hearing Impairment, https://www.eeoc.gov/laws/statutes/gina.cfm. testing, can assist in verifying the nature ANSI S3.44. Acoustical Society America; 1996. Accessed May 14, 2018. 44 of hearing loss. 13. National Institute for Occupational Safety and 32. Lin FR, Metter EJ, O’Brien RJ, Resnick SM, Health (NIOSH). Comments from the National Zonderman AB, Ferrucci L. Hearing loss and THE OEM PHYSICIAN’S ROLE Institute for Occupational Safety and Health on the incident dementia. Arch Neurol. 2011;68: Occupational Safety and Health Administration’s 214–220. IN DIAGNOSING NIHL Request for Comments on Determining the Work- Relatedness of Occupational Hearing Loss. 33. He´tu R, Getty L, Quoc HT. Impact of occupa- The OEM physician plays a major tional hearing loss on the lives of workers. 14. Lusk SL, Kerr MJ, Kauffman SA. Use of hearing Occup Med. 1995;10:495–512. role in the prevention of NIHL, and to make protection and perceptions of noise exposure and an evidence-based clinical diagnosis, must hearing loss among construction workers. Am Ind 34. Zwerling C, Sprince NL, Davis CS, Whitten PS, understand factors contributing to noise Hyg Assoc J. 1998;59:466–470. Wallace RR, Heeringa SG. Occupational injuries

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among older workers with disabilities: a prospec- and risk of acoustic neuroma. Am J Epidemiol. 41. Schlehofer B, Schlaefer K, Blettner M, et al. tive cohort study of the Health and Retirement 2006;163:327–333. Environmental risk factors for sporadic acoustic Survey, 1992 to 1994. Am J Public Health. 38. Hours M, Bernard M, Arslan M, et al. Can loud neuroma (Interphone Study Group, Germany). 1998;88:1691–1695. noise cause acoustic neuroma? Analysis of the Eur J Cancer. 2007;43:1741–1747. 35. Girard SA, Leroux T, Courteau M, Picard M, INTERPHONE study in France. Occup Environ 42. Dobie RA. Audiometric threshold shift defini- Turcotte F, Richer O. Occupational noise exposure Med. 2009;66:480–486. tions: simulations and suggestions. Ear Hear. and noise-induced hearing loss are associated with 39. Preston-Martin S, Thomas D, Wright W, Hen- 2005;26:62–77. work-related injuries leading to admission to hos- derson B. Noise trauma in the aetiology of acous- 43. Rabinowitz PM, Galusha D, Ernst CD, Slade pital. Inj Prev. 2015;21:e88–e92. tic neuromas in men in Los Angeles County, MD. Audiometric ‘‘early flags’’ for occupa- 36. Lin FR, Ferrucci L. Hearing loss and falls 1978–1985. Br J Cancer. 1989;59:783–786. tional hearing loss. J Occup Environ Med. among older adults in the United States. Arch 40. Prochazka M, Feychting M, Ahlbom A, et al. 2007;49:1310–1316. Intern Med. 2012;172:369–371. Occupational exposures and risk of acoustic 44. Lasak JM, Allen P, McVay T, Lewis D. Hearing 37. Edwards CG, Schwartzbaum JA, Lo¨nn S, Ahl- neuroma. Occup Environ Med. 2010;67: loss: diagnosis and management. Prim Care. bom A, Feychting M. Exposure to loud noise 766–771. 2014;41:19–31.

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