Prudent Practices in the Laboratory Handling and Management of Chemical Hazards, Updated Version (2011) / Chapter Skim
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4 Evaluating Hazards and Assessing Risks in the Laboratory
4 Evaluating Hazards and Assessing Risks in the Laboratory
Pages 45-82
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From page 45... ...
47 4.B.3 Globally Harmonized System for Hazard Communication 49 4.B.4 Laboratory Chemical Safety Summaries 50 4.B.5 Labels 51 4.B.6 Additional Sources of Information 51 4.B.7 Computer Services 52 4.B.7.1 The National Library of Medicine Databases 53 4.B.7.2 Chemical Abstracts Databases 53 4.B.7.3 Informal Forums 53 4.B.8 Training 53 4.C TOXIC EFFECTS OF LABORATORY CHEMICALS 53 4.C.1 Basic Principles 53 4.C.1.1 Dose-Response Relationships 54 4.C.1.2 Duration and Frequency of Exposure 56 4.C.1.3 Routes of Exposure 57 4.C.2 Assessing Risks of Exposure to Toxic Laboratory Chemicals 58 4.C.2.1 Acute Toxicants 59 4.C.3 Types of Toxins 60 4.C.3.1 Irritants, Corrosive Substances, Allergens, and Sensitizers 60 4.C.3.2 Asphyxiants 62 4.C.3.3 Neurotoxins 62 4.C.3.4 Reproductive and Developmental Toxins 62 4.C.3.5 Toxins Affecting Other Target Organs 63 4.C.3.6 Carcinogens 63 4.C.3.7 Control Banding 64 4.D FLAMMABLE, REACTIVE, AND EXPLOSIVE HAZARDS 65 4.D.1 Flammable Hazards 65 4.D.1.1 Flammable Substances 65 4.D.1.2 Flammability Characteristics 65 4.D.1.3 Classes of Flammability 68 4.D.1.4 Causes of Ignition 69 4.D.1.5 Special Hazards 69 4.D.2 Reactive Hazards 70 4.D.2.1 Water Reactives 70 4.D.2.2 Pyrophorics 70 4.D.2.3 Incompatible Chemicals 70 4.D.3 Explosive Hazards 70 4.D.3.1 Explosives 70 4.D.3.2 Azos, Peroxides, and Peroxidizables 72 45
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From page 46... ...
46 PRUDENT PRACTICES IN THE LABORATORY 4.D.3.3 Other Oxidizers 73 4.D.3.4 Powders and Dusts 73 4.D.3.5 Explosive Boiling 73 4.D.3.6 Other Considerations 73 4.E PHYSICAL HAZARDS 74 4.E.1 Compressed Gases 74 4.E.2 Nonflammable Cryogens 74 4.E.3 High-Pressure Reactions 74 4.E.4 Vacuum Work 75 4.E.5 Ultraviolet, Visible, and Near-Infrared Radiation 75 4.E.6 Radio Frequency and Microwave Hazards 75 4.E.7 Electrical Hazards 76 4.E.8 Magnetic Fields 76 4.E.9 Sharp Edges 76 4.E.10 Slips, Trips, and Falls 77 4.E.11 Ergonomic Hazards in the Laboratory 77 4.F NANOMATERIALS 77 4.G BIOHAZARDS 79 4.H HAZARDS FROM RADIOACTIVITY 79
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From page 47... ...
However, most ciples that form the foundation for evaluating hazards CHPs provide only general procedures for handling for toxic substances. The remainder of this section de chemicals, and prudent experiment planning requires scribes how trained laboratory personnel can use this that laboratory personnel consult additional sources understanding and the sources of information to assess for information on the properties of the substances that the risks associated with potential hazards of chemical will be encountered in the proposed experiment.
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From page 48... ...
and the OSHA Laboratory Standard (29 toxic effects is quite lengthy and includes every CFR § 1910.1450) , the audience for MSDSs has ex possible harmful effect the substance has under panded to include trained laboratory personnel in the conditions of every conceivable use.
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From page 49... ...
As a result, trained laboratory personnel may not distinguish highly hazard ous materials from moderately hazardous and relatively harmless ones. 4.B.3 Globally Harmonized System (GHS)
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From page 50... ...
LCSSs In addition to the labeling requirements, GHS re- also contain a concise critical discussion, presented in quires a standard format for Safety Data Sheets (SDS) a style readily understandable to trained laboratory that accompany hazardous chemicals.
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From page 51... ...
Entries are organized into effects of chemical substances. Although MSDSs and chapters according to functional group classes, LCSSs include information on toxic effects, in some and each chapter begins with a general discussituations laboratory personnel should seek additional sion of the properties and hazards of the class.
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From page 52... ...
It also contains pages long and written clearly at a level readily immediately dangerous to life or health (IDLH) understood by trained laboratory personnel, levels for approximately 1,000 chemicals, and each set of guidelines includes information on for laboratory personnel it is a useful reference physical, chemical, and toxicological properties; for checking the accuracy of an MSDS and a signs and symptoms of exposure; and consider valuable resource in preparing a laboratory's able detail on control measures, medical surveil own LCSSs.
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From page 53... ...
DIALOG, 800-334-2564; Questel, 800-456-7248; 4.C TOXIC EFFECTS OF STN, 800-734-4227; LABORATORY CHEMICALS SciFinder, 800-753-4227. 4.C.1 Basic Principles Additional information can be found on the CAS Web site, www.cas.org.
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From page 54... ...
Among the thousands of laboratory chemicals, a greater than the toxic effect of either substance alone is wide spectrum of doses exists that are required to proimportant. Because most chemical reactions produce duce toxic effects and even death.
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From page 55... ...
De- quick guide for assessing biological hazards in the laboratory. termine the potential routes of exposure for each chemical.
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From page 56... ...
low-dose exposures. Some toxic effects occur only afAlthough lethal dose values may vary among animal ter long-term exposure because sufficient amounts of species and between animals and humans, chemicals chemical cannot be attained in the tissue by a single that are highly toxic to animals are generally highly exposure.
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From page 57... ...
haled gases and vapors include the solubility of the gas Even very low vapor pressure chemicals are dangerin body fluids and the reactivity of the gas with tissues ous if the material is highly toxic. A classic example is and the fluid lining the respiratory tract.
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From page 58... ...
of other chemicals through the skin by increasing its permeability. 4.C.2 Assessing Risks of Exposure to Toxic Contact of chemicals with the eyes is of particular Laboratory Chemicals concern because the eyes are sensitive to irritants.
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From page 59... ...
Acute toxicity is the ability of a chemical to cause Laboratory chemicals are grouped into several a harmful effect after a single exposure. Acutely toxic classes of toxic substances, and many chemicals dis- agents cause local toxic effects, systemic toxic effects, play more than one type of toxicity.
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From page 60... ...
refers to the concentration safe for exposure institutions assist trained laboratory personnel in meaduring an entire 8-hour workday; the TLV-STEL is a suring the air concentrations of chemicals. Examples of Compounds with a High TABLE 4.3 Level of Acute Toxicity 4.C.3 Types of Toxins Acrolein Methyl fluorosulfonate 4.C.3.1 Irritants, Corrosive Substances, Allergens, Arsine Nickel carbonyl and Sensitizers Chlorine Nitrogen dioxide Diazomethane Osmium tetroxide Lethal dose and other quantitative toxicological paDiborane (gas)
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From page 61... ...
allergic reaction due to uroshiol. Also, just as people vary widely in their susceptibility to sensitization by 4.C.3.1.2 orrosive Substances C environmental allergens such as dust and pollen, indi Corrosive substances are those that cause destruc- viduals also exhibit wide differences in their sensitivity tion of living tissue by chemical action at the site of to laboratory chemicals.
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From page 62... ...
Although retrospective studies the structure or function of the central or peripheral of the teratogenic risk in women of childbearing age nervous system, which can be permanent or reversible. of occupational exposure to common solvents have The detection of neurotoxic effects may require special reached mixed conclusions, at least one such study of ized laboratory techniques, but often they are inferred exposure during pregnancy to multiple solvents defrom behavior such as slurred speech and staggered tected increased fetal malformations.
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From page 63... ...
cases, trained laboratory personnel must evaluate the Compounds that are known to pose the greatest car- potential risk that the chemical in question is a carcicinogenic hazard are referred to as select carcinogens, nogenic substance. This determination is sometimes and they constitute another category of substances made on the basis of knowledge of the specific classes that must be handled as PHSs according to the OSHA of compounds and functional group types that have Laboratory Standard.
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From page 64... ...
Trained laboratory person- By considering the physical and chemical characternel must decide whether the amount and frequency of istics and hazards posed by the material (e.g., toxicity) , use, as well as other circumstances, require additional the quantity used, the intended use or application, and precautions beyond the basic prudent practices of the mode of exposure (e.g., inhalation)
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From page 65... ...
Also important EXPLOSIVE HAZARDS are the relative density and solubility of a liquid with In addition to the hazards due to the toxic effects of respect to water and of a gas with respect to air. These chemicals, hazards due to flammability, explosivity, characteristics can be evaluated and compared in terms and reactivity need to be considered in risk assess- of the following specific properties.
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From page 66... ...
hazards associated with laboratory chemicals, see Box 4.1. For a quick guide for assessing biological Consider the changes in pressure, heat, flammabil hazards in the laboratory, see Box 4.3.
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From page 67... ...
, Boiling Points (bp) , Ignition TABLE 4.4 Temperatures, and Flammable Limits of Some Common Laboratory Chemicals Flammable Limits NFPA Flash Boiling Ignition (% by volume)
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. These materials can be of a number of common laboratory chemicals are given hazardous in the common laboratory environment.
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From page 69... ...
4.D.1.4.2 gnition Sources I Liquid nitrogen standing for a period of time may have Potential ignition sources in the laboratory include condensed enough oxygen to require careful handling. the obvious torch and Bunsen burner, as well as a When a liquefied gas is used in a closed system, pres number of less obvious electrically powered sources ranging from refrigerators, stirring motors, and heat guns to microwave ovens (see Chapter 7, section 7.C)
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From page 70... ...
the explosive polymerization of acrolein, and many Although trained laboratory personnel question the metal ions can catalyze the violent decomposition of necessity of following storage compatibility guidelines, hydrogen peroxide. Shock-sensitive materials include the reasons for such guidelines are obvious after read- acetylides, azides, nitrogen triiodide, organic nitrates, ing descriptions of laboratories following California nitro compounds, perchlorate salts (especially those of earthquakes in recent decades [see Pine (1994)
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From page 71... ...
. Reprinted from Hazardous Chemicals Handbook (Second Edition)
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From page 72... ...
Users should be familiar Class C: Unsaturated monomers that may autopolymerize as a with the hazards of these materials and trained in their result of peroxide accumulation if inhibitors have been removed proper handling. or are depleteda Certain common laboratory chemicals form per- Acrylic acid Styrene oxides on exposure to oxygen in air (see Tables 4.8 Butadiene Vinyl acetate Chlorotrifluoroethylene Vinyl chloride and 4.9)
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From page 73... ...
Even if the 4.D.3.3 Other Oxidizers material does not explode directly, the sudden forma Oxidizing agents may react violently when they tion of a mass of explosive or flammable vapor can be come into contact with reducing materials and some- very dangerous. times with ordinary combustibles.
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From page 74... ...
4.E PHYSICAL HAZARDS In many cases, barricading is not necessary if the ap propriate reaction vessel, fittings, and other equipment 4.E.1 Compressed Gases are used. However, the laboratory environment must Compressed gases can expose the trained laboratory be designed to accommodate the failure of the equippersonnel to both mechanical and chemical hazards, ment: ventilation must be adequate to handle discharge depending on the gas.
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From page 75... ...
Health hazards associated tered light. In addition to these skin and eye hazards, with vacuum gauges have been reviewed (Peacock, Class IV (4)
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From page 76... ...
instruments, tools, and other equipment are almost The magnitude of these large static magnetic fields falls eliminated by taking reasonable precautions, and the off rapidly with distance. Many instruments now have presence of electrically powered equipment in the internal shielding, which reduces the strength of the laboratory need not pose a significant risk.
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From page 77... ...
For example, laboratory personnel are often inchance of anyone changing the trash receiving a cut. volved in actions such as pipetting and computer work Other cut hazards include razors, box cutters, knives, that can result in repetitive-motion injuries.
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nanoparticle, example, NIOSH has proposed special exposure limits a nano-object with all three external dimensions at the nanoscale. for nano-size titanium dioxide that are significantly Nano-objects are commonly incorporated in a larger matrix or more restrictive than for larger particles of titanium substrate referred to as a nanomaterial" (HHS/CDC/NIOSH, 2009a)
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have demonstrated risks from biohazards in the laboratory. that conventional laboratory chemical hoods may Certain biological toxins and agents are classified create turbulence that can push the materials back as select agents under 42 CFR Part 73 and have addiinto the laboratory space.
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6. Consider the transgenes expressed by the hazards associated with laboratory chemicals, see organism.
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For γ rays and X rays, rad and rem are virtually equivalent. Examples of β Emitters TABLE 4.10 Damage may occur directly as a result of the radia tion interacting with a part of the cell or indirectly by Extremely High-Energy Low-Energy Low Energy the formation of toxic substances within the cell.
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From page 82... ...
. Exposure limits are lower in facilities operated by the Embryo/fetus of 500 NA U.S.
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