DR MOHAMAD SABRI MOHD SHAFFI

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OCCUPATIONAL HEALTH STANDARDS

• DR MOHAMAD SABRI MOHD SHAFFI

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Occupational Health Standards

• PURPOSE OF STANDARDS
• Protection of workers
• Guidance
• (i) Employers and Employees
• (ii) Safety and Health professionals
• (iii) Medical practitioners
• (iv) Engineers

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Occupational Health Standards

• BASIS FOR STANDARDS
• Health effects
• Practicability
• DEFINITION OF PEL - Maximum airborne
  concentration of a contaminant to which an
  employee be exposed
• SOURCES OF EXPOSURE STANDARDS
• USA- OSHA(PEL) U.K. (OEL MEL )
• Germany ( MAC ) Sweden Others.

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ACGIH TLVs

• ESSENTIAL FEATURES
• Refers to airborne concentration.
• Protects almost all workers.
• Over working life (8 hour day, 40 hour week).
• BASIS
• Industrial experience.
• Animal experiments.
• Human studies.
• Combination.

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ACGIH TLVs

• Airborne concentration of substance and
  represent condition under which it,believed that
  nearly all worker may be repeatedly exposed day
  after day without adverse effect. Because of wide
  variation in individual susceptibility, however ,
  a small percentage of worker may experience
  discomfort from such substance at concentration
  at or below the threshold limit, a smaller
  percentage may be affected more seriously by
  aggravation of preexisting condition or by
  development of an occupational illness

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• CAUTION
• Not a fine line - safe / unsafe.
• Guide only.
• Refer documentation for justification
• DEFINITIONS
• (a)Time weighted average (TLV - TWA)
• time weighted average concentration
• normal 8 hour
• 40 hour week
• (b) Short term exposure limit (TLV - STEL)
• 15 minute TWA
• Supplements TLV - TWA
• Not independent

ACGIH TLVs
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DEFINITIONS CONTINUED

• c)TLV- Ceiling ( TLV-C)
• should not be exceeded
• mostly applied to irritants.
• d)Carcinogens (ACGIH)
• AI are confirmed human.
• A2 suspected human.
• Note ACGIH classification not same as IARC

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The classification of carcinogens-

• Group 1 Carcinogenic to humans.
• Group 2a Probably carcinogenic to humans with
  sufficient evidence from
  animal studies.
• Group 2b Possibly carcinogenic to humans but
  absence of sufficient evidence from
  animal tests.
• Group 3 Not classifiable as carcinogenicity
  to humans.
• Group 4 No evidence of carcinogenicity to
  humans or animals.

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LIMITATIONS OF EXPOSURE STANDARDS

• Limited data on which to base TLVs
• Variations between individual workers
• Difficulty in measuring a representative exposure
• Difficulty in acquiring a truly representative
  breathing zone sample
• Uncertainties concerning the extent of absorption
  of the amount inhaled

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OTHER CONSIDERATIONS

• UNLISTED SUBSTANCES
• Many don't have TLVs.
• Not necessarily harmless.
• Data does not exist or not reliable.
• WORKLOAD AND CONDITIONS
• TLVs may not apply if
• (i) very heavy work
• (ii)excessive humidity or heat
• (iii)high altitude.
• EXPOSURE DURATION
• TWA applies to 8 hour shifts.
• May need to be reduced if longer than 8 hours.
• Not necessarily reduced if less than 8 hours.

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BIOLOGICAL STANDARDS

• FUNCTION
• Indicates body burden (dose).
• Useful if absorption by more than one route.
• Used in conjunction with air monitoring.
• Measures contaminant or metabolite in
• (i) tissue
• (ii)body fluids (blood, urine sputum)
• (iii)exhaled air.

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BIOLOGICAL EXPOSURE INDICES

• BEls established by ACGIH.
• Limited number of substances (mostly solvents
  metals).
• Measures concentration - blood, urine, exhaled
  air
• Assesses overall exposure.
• Refer to documentation for rationale.
• DEFINITION - BEls represent the, level of
  determinant (contaminant, metabolite, enzyme etc
  )which is most likely to be found in specimens
  from healthy workers with inhalation exposure to
  the TLV.

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LEGISLATIVE REQUIREMENTS

• PELs
• Mandatory eg lead, asbestos.
• TLVs
• Voluntary, guidance.

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THE END