Transcript Threshold Limit Values (TLVs) - Dave's Safety Page | Your

Threshold Limit Values (TLVs)
TLV® Definition
concentrations … which it is
airborne concentrations … which it is
believed that nearly all workers may be
repeatedly exposed … without adverse
health effects believed that nearly all workers
may be
repeatedly exposed … without adverse
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Industrial Hygiene
TLVs
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How to apply…
Trained professionals
Guides and recommendations
Not for community air pollution
Not for proving disease
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TLVs
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Why TLVs?
OSHA Standards
NIOSH RELS
Other Sources
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PEL
Concentrations that
healthy individuals
can normally tolerate
for eight hours a day,
five days a week
without harmful
effects
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TLVs
• OSHA Standards. Permissible Exposure Limits (PELS)
• Established in 1970
– 1910.1001 Z Tables
• Updated in 1989 but not since.
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OSHA PELS
Chemical
• Acetylaldehyde
• Acetic Acid
• Acetone
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PEL
200 ppm
10 ppm
1000 ppm
Industrial Hygiene
TLV (2007)
25 ppm
10 ppm
500 ppm
TLV
Response
LD50
ED
TWA
Threshold
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Dose
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NIOSH RELS
Chemical
• Acetylaldehyde
• Acetic Acid
• Acetone
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RELs
18 ppm
10 ppm
250 ppm
Industrial Hygiene
TLV (2007)
25 ppm
10 ppm
500 ppm
German MAKs
In the work-place environment MAK values
(maximum allowable workplace concentrations)
haven been fixed as time-integrated averages
relatively early in order to avoid adverse health
effects to workers exposed to air pollution during
their working shift.
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GERMAN MAKs
Acetaldehyde 5 mg/m3
Acetanilide
6 mg/m3
Acetic acid 15mg.m3
Acetic anhydride 10mg/m3
Acetone
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200 mg/m3
Industrial Hygiene
TLVs
Data points
Extrapolation of Data
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Activity
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Activity
Given: 10 mg/kg
LD50 Rats for Chemical X
Using Linear scaling: The LD50 for a 2 kg rate would
be 20 mg/kg
For a 10 kg dog would be 100 mg
What would the LD50 for a 50 kg person be?.
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Non-linear response
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TLVs
• Basis:
– Benzene: Leukemia
– Beryllium: Lung Cancer
– Toluene: Visual impairment, female reprod.
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Industrial Hygiene
TLVs
• Other Chemicals based:
• Animal Studies
• Epidemiology Study
– Ames Study
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TLVs
Because of wide variations in individual
susceptibility, exposure of an individual at, or
even below, the TLV may result in annoyance,
aggravation of a pre-existing condition, or
occasionally even physiological damage.
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Industrial Hygiene
TLVs
2007
Substance [CAS No.] (Documentation No.) TWA STEL NOTATION
Toluene
20 ppm - A4 BEI
Time Weighted Average
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Not classified as Carcinogen
TLV
TWA – Time Weighted Average
TWA = (C1T1) + (CnTn)
Total Time
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TLV - STELS
• Short Term Exposure Limits
– 15 minutes
– Never exceeded at any time
– STEL Is the level one can be exposed to
without
• Irritation, chronic effects or dose related toxic
effects
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TLV - Ceiling
• Not exceeded during any time of exposure
• Sample to ensure they can not be exceeded.
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Calculate TWAs
Activity:
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TWA
• Sample 1. 100 mg/m3 100 minutes
• Sample 2. 160 mg/m3 150 minutes
• Sample 3. 200 mg/m3 150 minutes
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Extended Work Hours
• Do TLVs need to be adjusted?
• Why and how?
• What type work would need it?
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Extended Work Hours
• Half-Life:
• Toluene: 8 hours
½ Dose
8 Hours
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Time
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Extended Work Hours
> BEI
> 8 hrs
BEI
Day 1 Day 2
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Day 3
Day 4
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Day 5
Biological Exposure Indices
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BEIs To control Exposure
Indicators
Various fluids are monitored
Various Times (Critical)
– What are times based on?
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Biomarkers
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XYLENE
BEI: Methylhippuric acid in urine (Methip)
Specimen collection: A post-shift urine sample (20
mL) obtained after at least two consecutive days of
exposure.
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Industrial Hygiene
Physical Agents
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Noise
RF
Lasers
Vibration
Ultraviolet Radiation
IR
Heat/Cold
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TLV – Physical Agents
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TLV Questions?
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Industrial Hygiene