Chemicals And Hearing Loss
Upcoming SlideShare
Loading in...5
×
 

Chemicals And Hearing Loss

on

  • 1,519 views

 

Statistics

Views

Total Views
1,519
Slideshare-icon Views on SlideShare
1,434
Embed Views
85

Actions

Likes
0
Downloads
17
Comments
0

1 Embed 85

http://bi2016.wikispaces.com 85

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Chemicals And Hearing Loss Chemicals And Hearing Loss Presentation Transcript

    • Chemicals and Hearing Loss California Industrial Hygiene Conference December 4, 2006 LT Anne M. Jarrett, M.A., CCC-A Occupational Audiologist, MSC, USN Hearing Conservation Program Naval Medical Center San Diego
    • Hearing in the Work Environment
      • Important for understanding:
        • Individually and others in the work environment
          • critical orders
          • warning and alerting signals (including listening to equipment sounds)
        • Productivity
          • general directions
          • Job related communication between coworkers
      • Hearing can be difficult in the work environment
        • poor acoustical environments
          • noise, distance, reverberation, distractions
          • work space, intercoms, meetings, telephones, walkie-talkie
        • Compounded by any underlying hearing loss
    • Workers in the United States
      • 30 million individuals in the labor force who are exposed to hazardous noise
      • 9.5 million individuals who may be exposed to organic solvents
      • 1988 – Nat. Institute for Occup. Safety & Heath (NIOSH)
        • began studying the solvents and HL
      • 1998 - National Occupational Research Agenda (NORA)
        • included noise + chemicals topic
      • 2001 - NIOSH
        • made available grants for investigating
      • 2002 - NIOSH Best Practices Workshop
      • (Effects of Chemicals & Noise on Hearing)
    • Work Environments with Solvents
      • Painting
      • Printing
      • Boat Building
      • Construction
      • Furniture Making
      • Manufacturing of metal, leather, and petroleum products
      • Cause: Spills, explosions/fires, industrial wastes, water contamination, occupational environment, etc.
    • Ototoxins
      • Organic solvents
        • ** Toluene (printing)
        • ** Xylenes (plastics)
        • ** Styrenes (plastics)
        • ** Trichloroethylene (degrease)
        • * Carbon Disulfide (textile)
        • * Stoddard/white spirits
        • * N-hexane
        • Fuels (JP-8 fuel)
        • Ethyl benzene
        • Perchloroethylene
        • Butyl Nitrite
        • Methylene chloride
      • Metals
        • * Mercury and derivatives
        • * Lead and derivatives
        • * Arsenic (atoxyl)
        • * Manganese
        • Trimethyltin (organic tin)
        • Cobalt
      • Asphyxiants
        • ** Carbon Monoxide
        • * Cyanide
      Army ID: * potential ** high-priority
      • Drugs
        • Aminoglycosides
        • Loop diuretics
        • Anti-neoplastic agents
        • ASA
        • Quinine compounds
      • Others
        • Chem. warfare nerve agents
        • Organophosphate (pesticide)
        • Paraquat (pesticide)
    • Morata,TC., Dunn,DE., Kretschmer, LW., Lemasters, GK., Keith, RW., Scandinavian Journal of Work, Environment & Health, 19(4): 245-54, 1993 Aug.
      • Paint and print industries - risk of hearing loss
        • Unexposed (no noise or solvent)
        • Noise exposed only – hearing loss risk 4x
        • Toluene solvent only – hearing loss risk 5x
        • Toluene solvents and noise –hearing loss risk 11x
        • Controls: previous exposure to noise and/or chemicals, medical and audiological history, age, length of employment, recreational exposure, and military service
        • Tests: puretones, immittance (tympanograms, reflexes, reflex decay)
    • Problems caused by solvents
      • Hearing Loss
        • Sensorineural Hearing Loss - Inner Ear
          • Tuning (clarity and loudness)
          • Testing: common audiometric procedures (Puretones, Speech, Other)
        • Central/Retrocochlear Hearing Loss - Brainstem and Cortex
          • Processing (transmission, cognition, varying degrees of tuning and loudness)
          • Testing:
            • Speech Processing (interrupted speech, speech in noise, temporal integration)
            • Evoked Potentials (brainstem or cortical potentials),
            • DPOAE: Contra-lateral suppression (efferent testing)
            • Reflex and Reflex Decay
            • Modified Puretone: masking level difference, gap detection, duration pattern, pitch pattern, temporal integration, high frequency audiometry, step size less 5dB
            • Questionnaire on speech discrimination difficulties or other auditory problems that are inconsistent with thresholds
      • Disequilibrium, Headaches, Vision Problems, Neurological
    • Many other causes of Hearing Loss
      • Accumulative noise exposure
        • occupational and recreational
      • Disease Processes
        • outer, middle, inner ear and combinations
      • Accidents
      • Ototoxic exposure that are medical
      • Aging
      • Genetics: anatomical and sensitivity/susceptibility
      • Medical contributions to poor hearing health
    • Hearing Conservation Programs (HCP)
      • Most HCP have no mandate for chemical exposure
        • American Conference of Industrial Hygienists (ACGIH)
          • Advise Monitoring
        • US Army (1998):
          • Initiation enrollment when there is excessive exposures to ototoxins (1 of 13 solvents)
          • Monitoring (same as noise exposure)
    • Questions with integrating into solvent exposure in HCP
      • Which solvents to include?
      • Excessive exposure levels?
      • Best audiometric test battery?
        • Location of damage - Retrocochlear hearing loss
        • Efficient Monitoring Program
    • 2002 Best Practices Workshop Comb. Effects of Chem. & Noise on Hearing
      • NORA – Nat. Occupational Research Agenda
      • NIOSH – Nat. Institute for Occupational Safety and Health
      • NHCA – Nat. Hearing Conservation Association
      • Goal:
        • Review current knowledge
        • Determine how to address chemical exposures in hearing loss prevention efforts
      • Next Slides:
      • Main Results of the Workshop
    • Current knowledge
      • Yes, enough evidence that solvents alone and solvents combined with noise exposure cause hearing, but more research is needed
      • Research does not capture all conditions/questions to outline a new national guideline for Hearing Conservation Programs
    • Mechanistic Research guide research to determine auditory risk - affect
      • Understand the mechanisms by which chemicals affect the auditory system. Lead to a prediction of which chemicals to target by preventive efforts
      • Issues:
        • Species respond differently – clues to the mechanism of ototoxicity
        • Toxic interactions – manipulate exposure parameters
        • Physical or other factors considerations
          • Health status, genetics, and age of participants
    • Rationale for Inclusion of Chemicals guide research on specific solvents and establish recommendations for best practices
      • Magnitude of exposed population
      • Evidence of chemical's ototoxicity, general toxicity, and neurotoxicity
      • Chemical produces reactive oxygen species (free radicals) or glutathione depletion -cellular injury
        • Glutathione –antioxidant that limits cell damage
    • Exposure Issues
      • Methods for administering chemicals
        • inhalation, dermal, injection sites
      • Methods for evaluating exposures
        • Task-based exposures assessments
          • experienced, specifically trained control variables)
        • Comprehensive noise measurements
        • Biomarkers for type of cell damage in the ear
        • Personal protective use
        • Target workers who have held their jobs
      • Methods for assessing auditory effects
        • Approach that discerns peripheral vs. central systems
        • No gold standard auditory test battery
    • Response Level and Action
      • Concentration level at which protective action (i.e.. enrolled in HCP) should be initiated
        • What actions for various solvents
          • Intervals between testing
            • HCP= annually
          • Alert/Criteria signal
            • HCP = puretones significant threshold shift
          • Alternatives Evaluation/control exposure
            • HCP = NIOSH 8 hour TWA =>85dB A SPL, hearing protection, remove from noise
          • New training needs for exposed population
            • HCP = initial and annual (effects, purpose testing & protection)
    • Other Issues Identified
      • Information Dissemination
      • Database (IH, HCP)
      • Other research questions
        • Development of standardized case history
        • Interactions that modify the effects (smoking)
        • Occurrence of tinnitus
        • Incorporating neurological tests periodical medical evaluations
        • Antioxidant therapy impact on preventive strategies
    • Key points – Take home message
      • Keep updated on new research findings and guidelines
      • Review exposures in current work area and workers
      • No standard yet but it is coming
      • Hearing is:
        • Complex (when damaged causes many problems)
        • Painless (often taken for granted)
        • Effects others (not just the hearing impaired)
        • Permanent (except for many OM and ME problems)
        • Accumulative and Progressive
        • Often preventable