SAFETY EDUCATION Department of Chemistry Minnesota State University Moorhead Lecture 2 (continued) Pyrophoric Materials A pyrophoric material is one that, even in a small quantity, without an ignition source, can ignite within 5 min. after coming in contact with air. Finely divided metals: calcium (Ca), lead (Pb), titanium (Ti), zirconium (Zr), etc. Alkali metals: sodium (Na), potassium (K) Metal and nonmetal hydrides: diborane (B 2 H 4 ), sodium hydride (NaH), Lithium aluminum hydride (LiAlH 4 ) White phosphorus (P 4 ) Preventing Fires and Explosions, review Know the flammability of the chemicals you use. Keep the fire triangle in mind. Store and transport solvents safely. Beware of ignition sources. Electrically ground flammable liquid containers before making transfers. Fire Extinguishers - Fire Types Extinguishers are based on the area of coverage and the type of fire. Type A: Wood, paper rubber, plastic Water or water/foam, dry chemical, carbon dioxide Type B: Flammable liquids and greases Foam (non-water), carbon dioxide, dry chemical Type C: Electrical equipment Carbon dioxide, dry chemical Type D: Active/combustible metals Sand and special powders Fire Extinguishers Many common extinguishers are ABC type which means they will work on types A, B, and C fires, but not on type D fires Carbon dioxide extinguishers must not be used to try to put out type D (metal) fires. CO 2 will actually increase the intensity of metal fires because the metal reacts with CO 2 2Mg(s) + CO 2 (g) 2MgO(s) + C(s) + heat
What To Do When a Fire Occurs If the fire is large or compressed gases are nearby or toxic fumes are present, you should LEAVE immediately! Your first concerns should be: Sound an alarm Evacuate the area Summon assistance What To Do When a Fire Occurs If a person s clothing is on fire, use the safety shower. If this is not available, wrap the person in a fire blanket. Place clean, wet, cold cloths on burned areas. Wrap the person to avoid shock. Get medical attention promptly. Oxidizing and Reducing Agents Oxygen is the oxidizing agent and the organic material (fuel) is the reducing agent. Very vigorous reactions or even explosions can occur when oxidizing and reducing agents are combined. Common oxidizing agents A more general definition of an oxidizing agent is a chemical substance in which one of the elements has a tendency to gain electrons. The following common materials are oxidizing agents by this definition: O 2, Halogens: F 2, Cl 2, Br 2 Peroxides, H 2 O 2, Na 2 O 2, etc. Nitric acid, HNO 3 ; Nitrate Salts, e.g., NaNO 3 Chlorate salts, e.g., KClO 3 Percholoric Acid, HClO 4 ; Perchlorates salts, e.g. KClO 4 Permanganates, e.g. KMnO 4 Common Reducing Agents A more general definition of a reducing agent is any chemical substance which has atoms with a tendency to loose electrons. The following are common examples: H 2 (g), hydrocarbons, e.g.c 2 H 6, and their derivatives including alcohols, e.g.,c 2 H 5 OH, oils, greases, organic acids (CH 3 COOH) Metals and many metal salts,e.g., Na, LiH Ammonia, NH 3 and ammonium salts, (with NH 4 + ion) Carbon
Incompatibilities, examples Nitric acid(ox.agent) and alcohol(red.agent) Ammonia soln.(red.agent) and bleach(sodium hypochlorite,ox. agent) This is a very common household error. toxic chloramines are given off Do not store incompatibles together Heat & Shock Sensitive Compounds (explosives) Some compounds have reducing groups and oxidizing groups in the same molecule. These tend to be heat and shock sensitive. Examples: Chlorites, chlorates, perchlorates, nitrates, e.g. NH 4 NO 3. The NO 3- is the oxidizing agent; the NH 4+ is the reducing agent. Organic nitrates and nitro compounds, (e.g., TNT, trinitrotoluene, CH 3 C 6 H 2 (NO 2 ) 3. The nitro groups are oxidizing agents; the carbon atoms are reducing agents Corrosives Living tissue as well as equipment is destroyed on contact with corrosives. The following are common laboratory reagents that are corrosive: Ammonia soln., NH 4 OH Hydrochloric acid, HCl Nitric acid, HNO 3 Phosphoric acid, H 3 PO 4 Sulfuric Acid, H 2 SO 4 Sodium hydroxide, NaOH Potassium Hydroxide, KOH Glacial acetic acid, CH 3 COOH Potassium chromate, K 2 CrO 4 Acid and Base safety Always use proper personal protective equipment including proper goggles when working with concentrated acids and bases. Store acids and bases separately. Know how to handle acid/base spills. Acid and Base safety When diluting a concentrated acid: Add the acid to water! Why? Lots of heat is generated when acids and bases are diluted. If you add water to the concentrated acid or base, the heat may be enough to boil the water and splash the concentrated solution on you. If you add the acid or base to water, the bulk of the water can absorb the heat fairly quickly without getting hot enough to boil. (That is if you don t add too much too fast.)
Precautions with Corrosives Do not breathe chemical vapors. Avoid contact with skin, eyes, and clothing (Safety Goggles). Carefully clean equipment that comes in contact with corrosives. Use suitable protective equipment. Use secondary containment devices when storing, transporting, or dispensing corrosives. Water Reactive Compounds Materials that by contact with water become spontaneously flammable or give off a flam-mable or toxic gas presenting a health hazard. Alkali metals, e.g., Li, Na, K (detonation, heat, hydroxide formation, H 2 liberated) Alkaline earths, e.g. Be, Mg, Ca, Ba (detonation, H 2 (g) liberated) NaOH, KOH, H 2 SO 4 (gives off lots of heat, splash hazard) Toxic Chemical Exposure to Toxic Chemicals Review Acute poisoning: Brief exposure that may have sudden and severe effects. Chronic poisoning: Prolonged or repeated exposure over a period of time (months, years). Low level exposure that does not produce immediate observed health change. Exposure to Toxic Chemicals Review Cumulative exposure: Materials that tend to build up in the body as a result of numerous chronic exposures. Substances in Combination (synergistic effects): Two or more hazardous materials present at the same time resulting in greater effect then predicted based on individual substances.
Agencies that publish limits, OSHA Occupational Safety and Health Administration (OSHA) sets Permissible Exposure Limits (PEL s) for 550 chemicals. PEL s are the allowable limit for an air contaminant to which nearly all workers may be repeatedly exposed day after day without adverse health effects. Permissible Exposure Limits Each of these limits may be expressed as: Time-weighted averages, TWA s. This is an average exposure weighted for an 8 hour work day. Ceiling (C) limits, not to be exceeded during any part of the work day. Short-term Exposure Limits (STEL), usually a 15-min. time-weighted average exposure. How are limits determined? Toxicity data is obtained by tests on laboratory animals. Since animal and human metabolisms differ, expert interpretation and judgment are needed to apply this data to human exposure. Toxicity data is also obtained through industrial experience of workers health and by the analysis of accidents. Toxicity Data LC 50 lethal concentration 50 The concentration of a material in air that is expected to kill 50% of a group of test animals when administered as a single respiratory exposure. LD 50 lethal dose 50 The single dose of a substance that causes the death of 50% of an animal population from exposure to a substance by any route other than inhalation. Specific Hazards, Carcinogen Carcinogen: Substance that is suspected or known to cause cancer. The following are agencies responsible for evaluation and regulation of carcinogenic materials: International Agency for Research on Cancer (IARC) National Toxicology Program (NTP) Occupational Safety and Health Administration (OSHA) International Agency for Research on Cancer (IARC) This agency was established by the World Health Organization and evaluated materials into three carcinogenic groups: Group 1: Material that are carcinogenic to humans Asbestos, Benzene, Hepatitis B and C virus (chronic infection with), Human papillomavirus types 16 & 17, Mustard gas, Oral contraceptives, Radon, Solar radiation, Alcoholic beverages, coal tar, Tobacco products and smoke, Wood dust, furniture and cabinet making, Painter, occupational exposure, Sulfuric acid mists
International Agency for Research on Cancer (IARC) Group 2A: Material that are probably carcinogenic to humans: Ultraviolet radiation, Diesel engine exhaust, Non-arsenical insecticides, Hairdressing or barber occupational hazard, Sunlamps and sunbeds, use of. Group 2B: Materials that are possibly carcinogenic to humans: Acetaldehyde, Carbon tetrachloride, Chloroform, Glasswool, Lead and its compounds, Saccharin, Coffee, Engine exhaust, Fuel oils, gasoline, Welding fumes, Dry cleaning fumes Groups 3 & 4: Not known to be carcinogenic or not studied. Other Agencies Regulating Carcinogenic Materials National Toxicology Program (NTP) Prepares an Annual report of materials that are listed as known carcinogens and another list of reasonably anticipated to be carcinogen. Occupational Safety and Health Administration (OSHA) OSHA does not maintain a list of known carcinogen, but it regulates specific carcinogenic materials through standards. Other Toxic Descriptions Lachrymator: Substances that have an irritant or burning effect on skin, eyes, or respiratory tract. Mutagen: Chemical or Physical agents causing genetic alterations. Teratogen: Substances that cause the production of physical defects in a developing fetus or embryo. Sources of Information on Chemical hazards, Labels OSHA requires that all hazardous chemicals be labeled with known immediate and delayed hazards and that each label contain: The identity of the material. The name and address of a responsible person from whom information can be obtained if necessary. Precautionary hazard warnings. Sources of Information on Chemical hazards, Labels Signal Words. Only three words are used to indicate degree of hazard. DANGER!- the most serious hazard WARNING! - for moderate hazard CAUTION! - for lesser degree of hazard Only one of these words is used on a label. The most serious word is used if two words apply. POISON! - is used for any toxic material either alone or in addition to one of the above words.
Sources of Information on Chemical hazards, Labels (Examples) Iodine, I 2 POISON! DANGER! CORROSIVE. CAUSES SEVERE IRRITATION OR BURNS TO EVERY AREA OF CONTACT. MAY BE FATAL IF SWALLOWED OR INHALED. VAPORS CAUSE SEVERE IRRITATION TO SKIN, EYES, AND RESPIRATORY TRACT. STRONG OXIDIZER. CONTACT WITH OTHER MATERIAL MAY CAUSE FIRE. AFFECTS THE CARDIOVASCULAR AND CENTRAL NERVOUS SYSTEMS. MAY CAUSE ALLERGIC SKIN OR RESPIRATORY REACTION. Sources of Information on Chemical hazards, Labels (Examples) Carbon tetrachloride, CCl 4 MAY BE FATAL IF SWALLOWED, INHALED OR ABSORBED THROUGH SKIN. CAUSES IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. SUSPECT CANCER HAZARD. MAY CAUSE CANCER. Risk of cancer depends on level and duration of exposure. AFFECTS CENTRAL NERVOUS SYSTEM, LUNGS, LIVER, AND KIDNEYS. Hazardous Chemical Graphics Graphics used on DOT labels are standards used for hazardous chemicals labeling. Carcinogenic Corrosive Explosive NON-FLAMMABLE GAS 2 Non-flammable gas He, N 2, NH 3 W Flammable Solid 4 Flammable Liquid Gasoline, Ether Flammable Solid Dangerous when wet K, CaC 2 Flammable 3 Flammable Oxidizer Toxic Poison 6 Corrosive 8 Radioactive Water Reactive Poisonous Solid or liquid Arsenic, insecticides Corrosive liquid or solid H 2 SO 4, NaOH National Fire Prevention Association (NFPA) Labels A hazard rating system for materials developed by the National Fire Protection Association (NFPA). Particularly relevant to fire prevention, exposure, and control. A: Health B: Flammability B C: Reactivity D: Special A C D A: Degree of health hazard 0=No significant hazard 1=Slightly hazardous 2=Hazardous 3=Highly toxic 4=Deadly B: Flammability 0=Non-Combustible 1=Slightly combustible 2=Combustible 3=Flammable 4=Extremely flammable A B D C
C: Reactivity, Instability 0=Stable 1=Unstable if heated 2=Violent chemical change (or reacts violently with water) 3=Shock or heat may detonate 4=May detonate D: Special Hazard OX = Oxidizer A W = Use no water, reacts ACID = Acid ALK = Alkali COR = Corrosive P = Polymerization = Radiation B D C Fire Diamond examples Fe(NO 3 ) 3 Mg metal 1 1 0 OX HCl 3 0 COR 1 1 3 W 0 Fire Diamond examples Acetic Acid, glacial CH 3 COOH Acetone CH 3 COCH 3 2 2 0 _ 3 1 0 _ Pitchblende 0 1 0 Sources of information Material Safety Data Sheets What do MSDS s provide? Name, address and phone number of the manufacturer. The date the MSDS was prepared or revised. Sources of information What s MSDS? Sources of information What s MSDS? Material Identification Hazard Identification First Aid Measures Fire Fighting Measures Accidental Release Measures Handling and Storage Exposure Controls/Personal Protection Stability and Reactivity
Sources of information What s MSDS? Toxicological Information Ecological Information Disposal Considerations Transportation Information Regulatory Information Other Information When Reading an MSDS Note that: only minimum precautions may be outlined. Do not assume a substance is hazard free if no particular health effects are cited. In many MSDSs, the first aid procedures and handling precautions assume a worst case scenario. Use your common sense. Think AND Act Safely! Think AND Act Safely! Act on the knowledge you have acquired in this course. If you have knowledge of a hazardous situation, respectfully report it to your instructor or the person responsible for the lab. All accidents predict themselves. Analyze all close calls to avoid the accident. Step back when an accident occurs; take time to gather your wits. Safety Examination Exam is 91 questions, most True/False, some multiple choice, some fill in the blank (acronyms). Resources Safety lecture notes Safety Videos Good luck on the test.