Presentation on theme: "Guidelines for Safe Handling and Use of Polymeric MDI."— Presentation transcript:
Guidelines for Safe Handling and Use of Polymeric MDI
Polymeric MDI - Safe Handling/Use Isocyanates/Diisocyanates are reactive chemicals. Many specific compounds in this family of chemicals - characterized by -NCO functional groups. 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 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 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) VP of water ~1.8 million times greater
Polymeric MDI - Safe Handling /Use Prevent exposures - prevent risk of injury Use a combination of effective control measures 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 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 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 Inhalation - breathing the air in which the chemical is suspended Skin and eye contact Ingestion (least significant route of exposure)
Exposure Limits - MDI OSHA Permissible Exposure Limit (PEL) - USA 0.2 mg/M3 = ppm, ceiling (legally binding) ACGIH Threshold Limit Value (TLV) - USA mg/M3 = ppm, 8-hr TWA (good recommended practice) For comparison, vapor pressure of MDI at room temperature is about ppm, with no ventilation
Effects of Overexposure - MDI Irritation of the respiratory tract, eyes, nose Symptoms may include sore throat, chest tightness, wheezing, coughing Respiratory sensitization - occupational asthma 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
Effects of Overexposure - MDI Eye Contact Pain, irritation, possible corneal burns if not treated Skin Contact Brown discoloration - hardens, eventually peels off Skin rash - prolonged, repeated contact - skin sensitization Respiratory sensitization?? - data inconclusive - avoid skin contact Ingestion Irritation of digestive tract Practically non-toxic by this route (= table salt)
Air Monitoring for MDI Direct Reading Methods - Screening Paper tape technology - color change Interpret results with caution Results at best semi-quantitative Indirect Methods 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 Medical history with emphasis on the respiratory tract Pulmonary Function Testing (PFT) Baseline Periodic (if symptoms of over exposure occur) Recommended by all suppliers of MDI/PMDI Not required by law
Personal Protective Equipment - PPE Gloves - nitrile, butyl, or neoprene rubber Coveralls - Tychem SL (Saranex) or Tyvek QC (PE) laminated Respirators 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 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 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 Type A Water (90%) Concentrated Ammonia (8%) Liquid detergent (2%) Type B Water (90-95%) Sodium Carbonate (5-10%) Liquid detergent ( %)
MDI Under Fire Conditions Not readily ignitable (35 kg) Heptane (1L) added to enable MDI to burn Mass burned for several minutes after ignition 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)
Re-evaluation of Diisocyanates Data for Cancer Classification - IARC 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 Category 1: Sufficient evidence of cancer in humans - asbestos, wood dust, VC Category 2: probably carcinogenic to humans 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 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”. 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* The half-life of MDI is short ( 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 High molecular weight polyester and polyether polyols - major component Generally regarded as non-toxic and non-hazardous Catalysts and mold release agents - minor component in polyol formulation (0.1- 5% typically) 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: 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. People drown in water, suffocate in pure nitrogen Toxicity and hazard are not the same 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: Benefits are provided by end products made from isocyanates/diisocyanates. There are risks associated with any activities we undertake 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 (330) office (216) cell