January 29, 1999 ITEC 041 1

Health and Safety

Professor Joe Greene

CSU, CHICO

January 29, 1999 ITEC 041 2

Topic

• Physical Hazards• Biomechanical Hazards• Chemical Hazards• Sources of Chemical Hazards• MSDS

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Physical Hazards

• Machine Motions• Clamping Devices• Heavy Items• Electrical Systems• Hydraulic/Pneumatic Pressure Systems• Noise • Thermal• Radiation

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Biomechanical Hazards

• Repetitive Motions• Injury not immediate but occurs over days, weeks,

or months.• Causes

– Poor ergonomics in workplace

– Incorrect computer position for hand, eyes, and legs

– Poor design of machine causing reaching or twisting

• Proper Ergonomics can lead to healthier workplace• Proper lighting, protective equipment, safe

operating procedures

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Chemical Hazards• Materials

– Resins (See MSDS)• Thermoplastic resins- low toxicity and low health hazard

• Thermoset resins- moderate toxicity and moderate health hazard

– Reinforcements- low toxicity and moderate health hazards (dust)

– Fillers- low toxicity and moderate health hazards (dust)

– Solvents- moderate to high toxicity with moderate to high health hazards

– Catalyst- moderate to high toxicity with moderate to high health hazards

– Plasticizers- low toxicity and moderate health hazards

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Chemical Hazards

• Processing (example of molding machine)– Closed Mold (2 mold halves that have resin injected)

• Thermoplastic- low health hazard with most materialsfor– Injection Molding– Blow Molding– Extrusion– Compression Molding

• Thermoset- some health hazards when filling tanks– Polyurethanes- Isocyanate– Polyesters- Catalyst– Catalyst- MEK– Promoters– Inhibitors

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Chemical Hazards

• Processing– Open Mold (1 mold half that has resin poured or rolled)

• Thermoplastic- none• Thermoset- some health hazards when mixing and applying resin

– Polyurethanes- Isocyanate– Polyesters– Phenolics– Catalyst- MEK– Promoters– Inhibitors

– Additives• Metal pigments• Inorganic dyes

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Chemical Hazards• Processing

– Reinforcements: low toxicity and moderate health hazards (dust)

• Glass fiber

• Glass bubbles or microspheres

• Mica

• Mineral fiber

– Fillers• Calcium Carbonate

• Talc

• Gypsum

– Solvents- Variety of alcohol based products

– Plasticizers- low toxicity and moderate health hazards

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Chemical Hazards

• Post molding operations– Sanding- dust– Grinding- dust– Polishing- dust– Surface Prep- chemical wipe– Bonding- 2 component adhesives– Tool cleaning- solvents– Tool prep- mold releases– Waste products– Scrap products– Painted plastics

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Material Safety Data Sheet(MSDS)

• Hazardous materials are common in the plastics industry

• MSDS are required to accompany any purchased hazardous industrial raw material.

• Plastics are defined as potentially hazardous because in the course of normal use, plastics may produce dusts, mists, gases, fumes, vapors, or smokes which are dangerous.

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Material Safety Data Sheet(MSDS)

• Section I: General Information• Section II: Composition• Section III: Physical Properties• Section IV: Fire and Explosion Hazard Data• Section V: Health Hazard Data• Section VI: Reactivity Data• Section VII: Spill or Leak Procedure• Section VIII: Occupational Protective Measures• Section IX: Special Precautions• Section X: Transportation

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Section I: General Information• Product name• Manufacturer’s Identity• Emergency telephone numbers• Trade name of chemical• Chemical family name of the material• Example

– Lexan– General Electric– 1-800-gecares– Lexan PC Resin– Poly(Bisphenol-A carbonate)

– Chemical Abstracts Services (CAS) Number- Unambigous identification of materials. Lexan= 25971-65-5 (same as Merlon)

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Section II: Composition

• Hazardous Ingredients– Major constituents

– hazardous additives, fillers, or colorants

– Example for ABS• 3 % Carbon black (solid- trapped in polymer)

• 0.2% residual styrene monomer (gas- released during processing)

CAS # ChemicalName

OSHAPEL Units

ACGIHTLV Units

763-86-9 Silica 0.05 mg/m3 0.05 mg/m3

100-42-5 Styrene 50.0 ppm 50.0 ppm1333-86-4 Carbon Black 3.5 mg/m3 3.5 mg/m3

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Section II: Definitions

• Definitions• OSHA- Occupational Safety and Health Administration

• ACGIH- American Conference of Governmental Industrial Hygienists

• PEL- Personal Exposure Limits (TWA)

• TWA- Time weighted average. Exposure level considered acceptable in an 8 hour day as part of a 40 hour week.

• REL- Recommended exposure

• TLV- Threshold Limit Value. Recommended by the American congress of Governmental industrial Hygienist. (TWA for 8 hours)

• STEL- Short term exposure limit. Acceptable exposure for 15 minutes and should not be exceeded any time during the 8 hour work day.

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Section II: Styrene• Styrene as a health hazard

• Building block for thermoplastic styrenics, e.g., polystyrene, ABS, SAN, and others.

• Cross-linking building block for thermoset styrenics, e.g., polyesters, vinyl esters.

• ABS has 0.2 % residual styrene plus other sources (styrenic plastics)

• One study found a range of 1 to 7 ppm styrene in an injection molding plant

• Thermosets

– Manufacturing of large boat hulls, boats, large tanks, tubs, shower stalls, body panels for cars and trucks.

– Polyester is 35% styrene by weight.

– Processing methods include fiber spray with resin in stream, handlayup by roller, closed mold RTM operations, compression molding of polyester sheet.

• Ventilation is essential to keep exposure within limits.

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Section III: Physical Properties

• Properties of material as one substance– Evaporation Rate

– Melting point

– Boiling point

– Specific gravity

– Solubility in water

– Physical form

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Section IV: Fire and Explosion Hazard Data

• Section for fire fighting• Most plastics are not explosive

• Upon burning most plastics will yield water and CO2

• Many plastics are self-extinguishing • All thermosets are self-extinguishing • Water is recommended as the best medium for

extinguishing fires• Toxic fumes from plastics include

– black smoke, CO, hydrogen cyanide, and ammonia

• Flash point is very high for many plastics

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Section V: Health Hazard Data

• Routes of entry of toxic substances– Ingestion

• Oral LD-50 in rats. Lethal Dose 50 percentile of fatalities in rats

• Many pelletized plastics are rather inert.

• Extremely toxic: LD-50 less than 1 mg/kg or 10 ppm

• Highly toxic: LD-50 less than 50 mg/kg or 100 ppm

• Moderately toxic: LD-50 less than 500 mg/kg or 1000 ppm

• Slightly toxic: LD-50 greater than 500 mg/kg or 1000 ppm

• Example

– LD-50 for guinea pig is 264mg/kg (264mg x mass of pig)

– Assuming equal response from human: 264mg x 70kg for mass of human = 18480mg or 18.48g to be ingested.

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Section V: Routes of Entry• Routes of entry of toxic substances

– Inhalation• Thermosets reactants can be inhaled since they are in liquid form and have a

vapor pressure that indicates relative volatility.• Example: Isocyanates used in polyurethane production

– TDI (toluene diisocyanate) used in foams for seats or paints.– MDI (methylene diisocynate) used in RIM body panels or in paints.– Construction projects use foamed polyurethane for interior walls and roofs. – TLV is 0.005 ppm– STEL for TDI is 0.02 ppm.

• Local and general ventilation are extremely important when working with urethanes

• Effects are asthma symptoms

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Section V: Routes of Entry• Routes of entry of toxic substances

– Inhalation• LC for lethal concentration (normally for a vapor or gas)

• Unlikely for peletized plastics

• Heated plastics yield hydrocarbons

• Example

– Overheated PET releases acetaldehyde

– STEL of 25 ppm

– Odor threshold is 0.050 ppm.

• Example

– PVD polymerization uses Vinyl chlorine gas

– TLV of 5 ppm

– Odor threshold of 3000 ppm (no odor warning)

– Known human carcinogen

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Section V: Routes of Entry• Routes of entry of toxic substances

– Dermal (Skin)• Most pelletized plastics do not affect dermal• Isocyanates can cause rashes and blistering of skin• Isocyantes can cause discoloring of skin.• Hot plastic materials can cause skin burns• Catalyst materials can cause skin abrasions• Example

– Diethylene Triamine (catalyst) CAS# 111-40-0– ACGIH

» TLV STEL» 1 ppm (skin) NE

– OSHA» PEL STEL» 1 ppm NE

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Section V: Routes of Entry• Routes of entry of toxic substances

– Eyes• Injured by objects landing in the eye

– glass fibers, fillers, additives, colorants, particles of plastic– liquids and gases can cause severe damage– Example

» methylene- hardener for epoxy» Causes irreversible blindness in cats and visual impairment in cattle.

– Carcinogenicity• Pelletized plastics are often not regulated as carcinogenic• Residual monomers have links to cancer (vinyl acetate, a residual monomer from PVA and

EVA is present at 0.3%) at levels of 600 ppm caused some cancer in some animals (bears A3 notation)

• Some liquid polymers and catalysts can cause cancer in some animals

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Section VI: Reactivity Data

• Pelletized plastics are very stable and non-reactive• Thermo-oxidative degradation can yield hazardous gases

– PVC: at 100 ºC releases HCl

– PMMA: at 100 ºC releases MMA

– POM: at 230 ºC releases formaldehyde

– Teflon (other fluoroplastics): at 250 ºC release HF

– PET: at 300 ºC releases acetaldehyde

– Nylons: at 300 ºC nylons release CO and ammonia

– Nylon 6: at 340 ºC releases e-caprolactam

– Thermoset resin degrade to toxic fumes of CO, formaldehyde, isocynates (for urethanes)

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Section VI: Reactivity Data_PVC and POM• Thermal degradation of PVC

– PVC degradation is a serious problem• Can decompose catastrophically if overheated in barrel.

• Remaining materials is tightly packed carbon

• Fumes contain high concentrations of HCl

• Response team must wear air respirator, turn off machine, tear down after cooling, remove nozzle and end cap.

• Thermal degradation of POM (poly actetal or polyoxymethylene)

• Thermally degrades (>230 ºC )and releases formaldehyde

• Exposure can occur at purging of machine

• Local exhaust is essential to minimize exposure

• Thermal degradation of Phenolics• Major uses in adhesive applications (plywood & particleboard)

• Compression and transfer molding operations

• Can release small amounts of ammonia, formaldehyde, and phenol

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Section VI: _Phenolics, Nylon 6, & PMMS

• Thermal degradation of Phenolics• Major uses in adhesive applications (plywood & particleboard)• Compression and transfer molding operations• Can release small amounts of ammonia, formaldehyde, and phenol

– Phenol: TLV of 5 ppm, LD-50 of 414mg/kg, and LC-50 of 821 ppm.– Formaldehyde: ceiling of 0.3 ppm

• Thermal degradation of Nylon 6• Degrades into monomer_ e-caprolactam, and residual caprolactam

– Caprolactam vapor: TLV is 5 ppm, LD-50 (rat) is 2.14 mg/kg– Molding operation release some caprolactam vapor, with more produced during purging and

extrusions

• Thermal degradation of PMMA (acrylic)_ Plexiglass• PMMA degrades into MMA (methyl methacrylate)• TLV for MMA is 100 ppm (410 mg/m3)

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Section VII: Spill or Leak Procedure

• Pelletized materials are swept up.• Liquid chemicals use absorbent materials• For isocyanates the absorbent materials need to

allow reaction of the isocyanate with the water in the air. The reacted materials is then disposed of according to specified government regulations.

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Section VIII: Occupational Protective Measures

• Workplace protection– Adequate ventilation

– Personal protective devices include• safety glasses or goggles for eye and face protection

• gloves, long sleeves, face shields, ear plugs

• respirators

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Section IX: Special Precautions

• Handling • Storage

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Section X: Transportation

• Special instructions for transporting liquid chemicals

• Most pelletized plastics have no special restrictions