Safety 5120Industrial Hygiene Threshold Limit Values (TLVs) TLV ® Definition concentrations …...
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Transcript of Safety 5120Industrial Hygiene Threshold Limit Values (TLVs) TLV ® Definition concentrations …...
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
TLVs• How to apply…• Trained professionals• Guides and recommendations• Not for community air pollution• Not for proving disease
TLVs
• Why TLVs?
• OSHA Standards
• NIOSH RELS
• Other Sources
PEL
Concentrations that healthy individuals can normally tolerate for eight hours a day, five days a week without harmful effects
TLVs
• OSHA Standards. Permissible Exposure Limits (PELS)
• Established in 1970– 1910.1001 Z Tables
• Updated in 1989 but not since.
OSHA PELS
Chemical PEL TLV (2007)
• Acetylaldehyde 200 ppm 25 ppm
• Acetic Acid 10 ppm 10 ppm
• Acetone 1000 ppm 500 ppm
TLV
Dose
Res
pons
e
LD50
ED
TWA
Threshold
NIOSH RELS
Chemical RELs TLV (2007)
• Acetylaldehyde 18 ppm 25 ppm
• Acetic Acid 10 ppm 10 ppm
• Acetone 250 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.
GERMAN MAKs
Acetaldehyde 5 mg/m3
Acetanilide 6 mg/m3
Acetic acid 15mg.m3
Acetic anhydride 10mg/m3
Acetone 200 mg/m3
TLVs
Data points
Extrapolation of Data
Extra
polat
ed
Activity
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?.
Non-linear response
TLVs
• Basis:– Benzene: Leukemia– Beryllium: Lung Cancer– Toluene: Visual impairment, female reprod.
CH3
TLVs
• Other Chemicals based:
• Animal Studies
• Epidemiology Study– Ames Study
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.
TLVsSubstance [CAS No.] (Documentation No.) TWA STEL NOTATIONToluene 20 ppm - A4 BEI
2007
Time Weighted AverageNot classified as Carcinogen
TLV
TWA – Time Weighted Average
TWA = (C1T1) + (CnTn)Total Time
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
TLV - Ceiling
• Not exceeded during any time of exposure
• Sample to ensure they can not be exceeded.
Calculate TWAs
Activity:
TWA
• Sample 1. 100 mg/m3 100 minutes
• Sample 2. 160 mg/m3 150 minutes
• Sample 3. 200 mg/m3 150 minutes
Extended Work Hours
• Do TLVs need to be adjusted?
• Why and how?
• What type work would need it?
Extended Work Hours
• Half-Life:
• Toluene: 8 hoursD
ose
Time8 Hours
½ Dose
Extended Work Hours
Day 1 Day 2 Day 3 Day 4 Day 5
BEI
> 8 hrs
Bui
ld u
p
Purge
> BEI
Biological Exposure Indices
• BEIs To control Exposure
• Indicators
• Various fluids are monitored
• Various Times (Critical)– What are times based on?
Biomarkers
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.
Physical Agents• Noise
• RF
• Lasers
• Vibration
• Ultraviolet Radiation
• IR
• Heat/Cold
TLV – Physical Agents
TLV Questions?