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PURPOSE OF STANDARDSProtection of workersGuidance(i)Employers and Employees(ii)Safety and Health professionals(iii)Medical practitioners(iv) Engineers. Occupational Health Standards. BASIS FOR STANDARDSHealth effectsPracticabilityDEFINITION OF PEL - Maximum airborne concentration of
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1. DR MOHAMAD SABRI MOHD SHAFFI
2. PURPOSE OF STANDARDS
Protection of workers
Guidance
(i) Employers and Employees
(ii) Safety and Health professionals
(iii) Medical practitioners
(iv) Engineers
3. 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.
4. 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.
5. “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”
6. 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
7. 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
8. 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.
10. 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
11. 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.
12. 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.
13. 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.
14. PELs
Mandatory [eg lead, asbestos].
TLVs
Voluntary, guidance.