Guidelines for Safe Handling
and Use of
Polymeric MDI
Polymeric MDI - Safe Handling/Use
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Isocyanates/Diisocyanates are reactive
chemicals.
Many specific compounds in this family of
chemicals - characterized by -NCO functional
groups.
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Chemical/Physical properties of specific compounds vary
Used for over 40 years to make a variety of
polyurethane products in home & industry.
Used since the mid 1980s in the forest products
industry to make OSB.
Polyurethane Products
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Paints, varnishes
Automobile parts (bumpers, dashboards,
headliners, armrests, seats, carpet
underlayment,)
Binder for wood products (OSB, MDF, etc.)
Insulation in home appliances, buildings (roofs,
walls).
Footwear, sports equipment.
Pillows, mattresses, clothing
Physical Properties of PMDI/MDI
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Brown liquid having consistency of motor oil.
Reacts with water for form solid polyureas and
carbon dioxide.
Poor odor warning properties (odors are
however subjective).
Very low vapor pressure (VP)
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VP of water ~1.8 million times greater
Polymeric MDI - Safe Handling /Use
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Prevent exposures - prevent risk of injury
Use a combination of effective control
measures
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Engineering - enclosures, local exhaust ventilation
Administrative - work practices, controlled access
Personal Protective Equipment - gloves, respirators etc.
Control measures must be properly maintained
for them to be effective.
Engineering - - - PPE (least preferred)
Exposure Limits
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Airborne concentrations of substances…
To which nearly all workers may be repeatedly
exposed..
Day after day for a working lifetime..
Without adverse health effects.
Philosophy Behind Setting Exposure
Limits
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Based on acceptable risk
All chemicals are toxic at some
concentration
A concentration exists at which no
significant injurious effect should occur
Routes of Exposure to Chemicals
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Inhalation - breathing the air in which the
chemical is suspended
Skin and eye contact
Ingestion (least significant route of exposure)
Exposure Limits - MDI
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OSHA Permissible Exposure Limit (PEL) - USA
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ACGIH Threshold Limit Value (TLV) - USA
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0.2 mg/M3 = 0.020 ppm, ceiling (legally binding)
0.051 mg/M3 = 0.005 ppm, 8-hr TWA (good recommended
practice)
For comparison, vapor pressure of MDI at room
temperature is about 0.006 ppm, with no ventilation
Effects of Overexposure - MDI
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Irritation of the respiratory tract, eyes, nose
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Symptoms may include sore throat, chest tightness,
wheezing, coughing
Respiratory sensitization - occupational asthma
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Difficulty breathing, asthmatic symptoms
Symptoms may be immediate or delayed or both
Exposure limits may not be protective
To prevent symptoms, avoid exposures
If early diagnosis, good chance of recovery; however, there
are no guarantees
Agents Which Can Cause
Occupational Asthma
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Naturally Occurring Products
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Animal dander, latex proteins, insect debris, flour, tobacco
dust, moldy compost, rosin(fluxes), soybean dusts, wood
dusts, mushroom dusts….
Synthetic Products
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Metal salts (Ni, Cr, Pt), Persulfates, Penicillin, Tetracycline,
Amines, Formaldehyde, Diisocyanates,...
Effects of Overexposure - MDI
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Eye Contact
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Skin Contact
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Pain, irritation, possible corneal burns if not treated
Brown discoloration - hardens, eventually peels off
Skin rash - prolonged, repeated contact - skin sensitization
Respiratory sensitization?? - data inconclusive - avoid skin
contact
Ingestion
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Irritation of digestive tract
Practically non-toxic by this route (= table salt)
Air Monitoring for MDI
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Direct Reading Methods - Screening
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Paper tape technology - color change
Interpret results with caution
Results at best semi-quantitative
Indirect Methods
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Treated filter papers or impingers
Requires laboratory analysis
Highly accurate and precise
Scott Bacharach SureSpot Monitor
Scott Bacharach AutoStep Plus Direct
Reading Monitor
Polymeric MDI - Safe Handling/Use
Medical Surveillance
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Medical history with emphasis on the
respiratory tract
Pulmonary Function Testing (PFT)
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Baseline
Periodic (if symptoms of over exposure occur)
Recommended by all suppliers of MDI/PMDI
Not required by law
Personal Protective Equipment - PPE
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Gloves - nitrile, butyl, or neoprene rubber
Coveralls - Tychem SL (Saranex) or Tyvek QC
(PE) laminated
Respirators
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Supplied-air (historically) - if airborne levels warrant use
Recent change in OSHA respirator standard
 May be OK to use air-purifying respirators for some
applications if certain conditions are met.
Boots - same materials as gloves
Engineering controls most preferred
Personal Protective Equipment:
Appropriate Use
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Disposable gloves are sufficient for most
production situations
Coveralls, boots and respirators typically only
required when loading large storage tanks or
cleaning up very large spills (more than 20
gallons)
Spills
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Don protective equipment
If needed, monitor to evaluate airborne levels
Contain spill with absorbent material (sand, dirt,
spill kit, etc.)
Mix well and shovel into containers - move
outside, do not seal
Add decon solution and mix well - let stand
Dispose of solids/liquids per State or local
regulations
Decontamination solutions
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Type A
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Water (90%)
Concentrated Ammonia (8%)
Liquid detergent (2%)
Type B
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Water (90-95%)
Sodium Carbonate (5-10%)
Liquid detergent (0.2-0.5%)
MDI Under Fire Conditions
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Not readily ignitable (35 kg)
Heptane (1L) added to enable MDI to burn
Mass burned for several minutes after ignition
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Fire subsided, then ceased leaving behind a dark residue
~80% of original sample weight.
Offgassing products - CO2 (47%); CO (180 ppm): Nox (30
ppm); HCN (15 ppm); MDI (1.8 ppm)
Concern for responders - use same PPE as for
typical structural fires
Comparison:
Gaseous Combustion Products of
Untreated and Treated Wood (mg/g)
Com. untreated 6% PMDI
Products
10% PF
8% UF
CO
137
124
173
131
CO2
383
339
402
384
HCN
0.6
0.75
0.5
1.55
NOx
0.24
0.12
0.10
0.26
Re-evaluation of Diisocyanates Data
for Cancer Classification - IARC
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Status of TDI and MDI reviewed in 1998
Data made available for both
Human evidence inadequate to change
classification for TDI - remains category 2B
- possibly carcinogenic to humans.
Insufficient new data available to warrant a
full scale review for MDI - remains category
3 - not classifiable as to carcinogenicity to
humans.
IARC Classification Scheme for
Cancer
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Category 1: Sufficient evidence of cancer in
humans - asbestos, wood dust, VC
Category 2: probably carcinogenic to humans
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2A - Limited evidence to humans: Be, acrylonitrile,
2B - Sufficient evidence in animals, inadequate data in
humans - Cd, DDT, TDI, formaldehyde,
Category 3: not classifiable as to
carcinogenicity to humans - Cyclamates,
Saccharin, MDI,
Environmental Issues
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MDI is listed as a Hazardous Air Pollutant (HAP)
MDI invalidated by court of appeals as a high
risk pollutant under the US Clean Air Act.
MDI removed from EPA’s Urban Toxics listing of
chemicals presenting the “greatest threat to
public health”.
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Overestimated emissions reporting by industries
Improper assumptions in calculating emissions by
consultants.
Petition filed in 8/98 with EPA to exempt MDI as
a VOC - inhibits ozone formation (CA study).
Environmental Fate of MDI*
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The half-life of MDI is short (0.6 - 32 hours) and
will have a limited tendency to accumulate in
environment due to air emissions.
Spills are not likely to release MDI in either
vapor or aerosol form; therefore, significant
airborne levels are not expected.
The reactions that occur after spills (solids and
water insoluble polyureas) limit further
exposure to airborne MDI.
* Manitoba Environment, Report 96-08
Polyol Formulations
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High molecular weight polyester and polyether
polyols - major component
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Generally regarded as non-toxic and non-hazardous
Catalysts and mold release agents - minor
component in polyol formulation (0.1- 5%
typically)
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Occasionally caustic (irritants, corrosives, skin absorption
for some but not many
Occasionally odorous
Use local exhaust ventilation and PPE to prevent exposure,
if indicated by MSDS
The Bottom Line:
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Use common sense when handling all kinds of
chemicals. Maintain a sense of perspective.
All chemicals have some degree of toxicity.
Any chemical is toxic if the amount consumed
(dose) is large enough.
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Toxicity and hazard are not the same
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People drown in water, suffocate in pure nitrogen
Toxicity - ability to cause damage in living systems
Hazard - risk/likelihood of injury - depends on how used
Exposure doesn’t necessarily mean harm depends on dose.
The Bottom Line:
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Benefits are provided by end products made
from isocyanates/diisocyanates.
There are risks associated with any activities
we undertake
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Handling/using chemicals - no exception
All chemicals can produce adverse health effects and be
hazardous - depends on how they are handled/used.
Risk of injury can be real or perceived.
Risk is minimized or eliminated when chemicals
are properly handled.
For further information, contact…
Harry D. Coffee
Nautilus Composites LLC
575 Walnut Ridge Trail
Aurora, OH 44202
(330) 995-2636 office
(216) 496-8921 cell
[email protected]