CHAPTER 8: Hazardous Substances: Categories, Examples, and Stanard Operating Procedures for Proper Use

8.0 Introduction
This Chapter (modified from the University of Minnesota Department of Chemistry Chemical Hygiene Plan) includes the Categories & Definitions of hazardous chemicals, and Standard Operating Procedures (SOPs) that are necessary when working with hazardous chemicals. 

8.0.a    IMPORTANT – Read CHAPTER 7 before continuing. 
Before consulting the appropriate Standard Operating Procedure presented in this chapter, the “Basic Rules and Procedures for Working with Chemicals” (Chapter 7) MUST be read and understood.
8.0.b   Follow the SOPS. 
The SOPs describe fundamental safety precautions and measures beyond the general laboratory safety practices (Chapter 7) that the laboratory worker must follow to minimize the risk associated with potential hazards.  These SOPs must be familiar to all laboratory workers, and must be followed at all times.
8.0.c    Enforce the Exposure Limits. 
Many substances can be hazardous simply by being exposed to the atmosphere because the toxic vapors can then come in contact with or be absorbed into a person’s body.  Therefore most materials used have some guidelines for exposure, such as ACGIH’s Threshold Limit Values (TLV) and OSHA’s Permissible Exposure Limits (PEL).  The exposure guidelines are presented in Chapter 5.  It is the responsibility of the laboratory supervisor to ensure that the PEL or TLV for a specific chemical is not exceeded.


8.1    Categories of Hazardous Chemicals (This section is reproduced from Section 5.1)
8.1.a    Definition of “Hazardous Chemical”
(1)  The OSHA Laboratory Standard defines a hazardous chemical as a chemical “for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed employees” (29 CFR 1910.1450(b)).
(2)  In addition, the worker should be aware that it is possible that a substance may be both a potential physical and health hazard.
(3)  The OSHA list of Hazardous Chemicals can be found online at

8.1b    Physical Hazards
The OSHA Laboratory Standard (29CFR 1910.1450(b)) considers a chemical a physical hazard if it falls into one of the following categories.  Refer to Section 8.2-8.11 for Definitions and SOPs.
(1)  Oxidizers (Section 8.2)
(2)  Combustible Liquids, or Flammables (Section 8.3)
(3)  Explosives (Section 8.4)
(a)   Shock- Sensitive (Section 8.4)
(b)  Organic Peroxides & Peroxide-Forming Substances (Section 8.5)
(c)   Dusts, Explosive Boiling (Section 8.6)
(4)  Reactives
(a)   Incompatibles (Section 8.7)
(b)  Pyrophorics (Section 8.8)
(c)   Water-Reactives (Section 8.9)
(5)  Compressed Gases (Section 8.10)
(6)  SOPs for Cryogens and Liquified Gases are included in Section 8.11.

8.1c     Health Hazards
The OSHA Laboratory Standard (29 CFR 1910.145(b)) considers a chemical a health hazard if it falls into one of the following categories.  Refer to Section 8.12-8.17 for Definitions and SOPs.
(1)  Corrosives (Section 8.12)
(2)  Irritants (Section 8.13)
(3)  Sensitizers & Allergens (Section 8.14)
(4)  Carcinogens (Section 8.17)
(5)  Toxic or Highly Toxic Substances (Section 8.17)
(6)  Reproductive Toxins (Section 8.17)
(7)  Hepatotoxins (Section 8.16)
(8)  Agents which act on the hemotopoietic systems (various sections)
(9)  Agents which damage the lungs, skin, eyes, or mucous membranes (various sections)
(10) SOPs for Asphyxiants are included in Section 8.15.

8.1.d    Health Hazards – Additional Information
Prior to using substances classified as health hazards, it is essential that the risks associated with these chemicals be well understood:
(1)  All such substances can potentially have adverse effects on living systems depending on the duration of exposure, frequency of exposure and the inherent toxicity of the particularsubstance.
(2)  Toxic effects can be acute, causing damage after a single short duration exposure, or chronic, causing damage either after repeated or long duration exposure or a long latency period.  Some chemical s may have both acute and chronic toxic effects.
(3)  It is highly possible that a specific chemical may exhibit several adverse health effects, and it is then necessary to consult all appropriate procedures.
(4)  It is the responsibility of the laboratory supervisor to ensure that the PEL or TLV for a specific chemical is not exceeded.  See Chapter 5 for details.

8.1.e    Particularly Hazardous Substances
The OSHA Laboratory Stand (29 CFR 1910.14450(e)(3)(vii)) considers certain classes of Health Hazards to be “Particularly Hazardous.” These three classes of substances are ‘Select Carcinogens,’ ‘Reproductive Toxins,’ and ‘Substances that have a High Degree of Acute Toxicity.’ 
(1)  Provisions for additional protection for personnel working with these substances are required. 
(2)  Refer to Section 8.17 for Definitions & SOPs.

8.1.f    The “Dirty Dozen” Substances
According to “Prudent Practices” it is generally recognized that certain substances tend to be responsible for more than their share of accidents.  These substances have earned the nickname of the “Dirty Dozen.”
(1)  See Section 5.3.c for a list of the Dirty Dozen and their most common harmful effects.
(2)  Inappropriate mixing or handling of certain compounds can also produce hazardous toxic gases.  Individual laboratories are encouraged to prepare their own list of additional “Dirty Dozen” substances as part of their laboratory-specific Standard Operating Procedures.


8.2 – 8.11        Physical Hazards

    • Oxidizers

8.2.a    Definitions and other Important Information
(1)  Oxidizer.  A “chemical other than a blasting agent or explosive [as defined in 29 CFR 1910.109(a)] that initiates or promotes combustion in other materials, thereby causing fire either of itself or through the release of oxygen or other gases.”                          20 CFR 191.1450(b).
(2)  Perchloric Acid and Perchlorates.  These are particularly powerful oxidizing agents.  Perchloric acid has the potential for undergoing explosive reactions with organic compounds and reducing agents. perchloric acid, perchlorate esters and transition metal perchlorates are capable of exploding.
(3)  Oxidizing agents are potential fire and explosive hazards.  They may react violently when in contact with reducing materials.  Sometimes they also undergo a violent reaction with ordinary combustibles and trace metals.
(4)  Corrosive Properties.  Oxidizers tend to be corrosive.  See Section 8.11 for information.

8.2.b   Examples
(1)  Refer to Table 2 (Appendix A) for an incomplete list of oxidizers.

8.2.c    Standard Operating Procedures

  • Know the reactivity of the materials being used in the process.
  • If the reaction is potentially violent or explosive a safety shield must be used, or the reaction must occur in a hood with the sash pulled own completely.
  • Use the minimum amount of material necessary for the procedure.
  • Segregate oxidizers from flammable or combustible materials and from reducing agents.
  • Liquid oxidizers should be stored in a secondary container that is large enough to hold the contents of the reagent container.
  • Oxidizers must be labeled, dated and inventoried when received.  The label should state:  DANGER!  OXIDIZING AGENT HIGHLY REACTIVE.
  • Perchloric acid should only be used in a water wash-down perchloric acid fume hood.
  • Perchloric acid should not be used near wooden tables or benches.
  • When adding perchloric acid to organic material, the organic matter should first be digested with nitric acid.
  • Do not heat perchloric acid with sulfuric acid.  Heating with sulfuric acid may produce anhydrous perchloric acid which is explosive.
  • Store perchloric acid properly.


8.3    Flammables and Combustibles
Flammable and combustible substances are routinely used in most laboratories, and may be solids, liquids, or gases.  These substances release vapors, and it is the vapors that can ignite and are therefore a common source of fire hazard.  Gases pose special hazards since leakage or escape of the gas can produce an explosive atmosphere in the laboratory.

8.3.a    Background Information and Examples
(1)  Flash PointThe flash point is the lowest temperature at which an ignition source can cause the chemical to ignite momentarily.  Although the lowest temperature at which the chemical will catch fire with an ignition source is called the “fire point,” it is rarely more than one or two degrees greater than the “flash point.”  Many common solvents have flashpoints that are lower than room temperature, making them potentially dangerous.  Therefore, the flash point will be used as the reference of Fire Hazard at St. Olaf College.
(2)  Conditions that will Cause a Fire. In order for a fire to occur, the following conditions must be met:
(a)   The concentration of the vapor must be between the upper and lower explosion limit (UEL, LEL).
(b)  An oxidizing material (e.g. oxygen in the room) must be present.

  • A source of ignition must be present.  (e.g. with a standard hot/stir plate, every time the controls are turned on/off a small spark is emitted).

(d)   Spontaneous Combustion.  As defined in “Prudent Practices” autoignition can take place when a substance reaches its ignition temperature without the application of external heat.  Examples of materials susceptible to spontaneous combustion include oily rags, dust accumulations, organic materials mixed with strong oxidizing agents (e.g., nitric acid, chlorates, permanganates, peroxides, and persulfates), alkali metals (e.g., sodium and potassium), finely divided pyrophoric metals, and phosphorus.
(3)  Refer to Table 3 (Appendix A) for a list of chemicals with low flash points (< 32 °C; < 89.6 °F).

8.3.b   Primary Guidelines
(1)  Chemicals with either of the following conditions will be considered a fire hazard:
(a)   An NFPA rating of ≥ 2 in the red category.
(b)  A flash point < 200° F (93.3°C) if the NFPA rating is not given.
(2)  Chemicals that are considered a fire hazard will be:

  • Stored in a flammable solvent storage area or flammable storage cabinet, and
  • Used in a vented fume hood, away from sources of ignition.
  • Open “Immediate Use” containers (e.g., beakers) with small quantities of flammables (≤ 250 ml) that have an NFPA rating of ≤ 3 can be used on the laboratory countertops.

(3)  Proper PPE must be worn at all times, and might include a flame retardant lab coat and face shield (over the safety goggles) if the conditions warrant.

8.3.c    Definitions.  NFPA and OSHA have definitions to determine when a chemical is considered flammable or combustible.  These guidelines are herein adopted for use in the laboratory.
(1)  NFPA 704 Fire Hazard Ratings.  Probably the quickest way to assess the risk associated with flammable substances is to use the NFPA fire hazard ratings.  These ratings are based on the severity of the fire hazard and the following criteria apply:

    • 0    Substance will not burn under typical fire conditions.
    • 1    Flashpoint ≥ 93.4°C

            Flashpoint ≥ 200°F
            Substance requires considerable preheating, under ambient temperature conditions,
            before ignition and combustion can occur.

    • 2    93.4°C > Flashpoint ≥ 37.8°C

            200°F > Flashpoint ≥ 100°F
            Substance must be moderately heated or exposed to relatively high ambient temperatures
            before ignition can occur.

    • 3    37.8°C > Flashpoint ≥ 22.8°C  or [(22.8°C > Flashpoint) and (Boiling Point ≥ 37.8°C)]

            100°F > Flashpoint ≥ 73°F  or [(73°F > Flashpoint) and (Boiling Point ≥ 100°F)]
            Substance can be readily ignited under almost all ambient temperature conditions.

  • 4    22.8°C > Flashpoint and 37.8°C > Boiling Point

73°F > Flashpoint and 100°F > Boiling Point
            Substance will rapidly or completely vaporize at ambient temperature and will burn readily.
(2)  OSHA Definitions.  The following definitions from the OSHA Laboratory Standard will also be followed:
(a)   flammable liquid – any liquid having a flashpoint below 100°F (37.8°C), except any mixture having components with flashpoints of 100°F or higher, the total of which make up 99 percent or more of the total volume of the mixture.
(b)  flammable solid – a solid that is liable to cause fire through friction, absorption of moisture, spontaneous chemical change, or retained heat from processing, or which can be ignited readily and when ignited burns so vigorously and persistently as to create a serious hazard.
(c)   flammable gas – a gas that, at ambient temperature and pressure forms flammable mixture with air at a concentration of 13 percent by volume or less, or forms a range of flammable mixtures with air wider than 12 percent by volume, regardless of the lower limit.
(d)   combustible liquid – a liquid having a flashpoint at or above 100°F (37.8°C) but below 200°F (93.3°C), except any mixture having components with flashpoints of 200°F or higher, the total volume of which make up 99 percent or more of the total volume of the mixture.
(e)   flash point – the lowest temperature at which a liquid has a sufficient vapor pressure to form an ignitable mixture with air near the surface of the liquid.

  • ignition temperature – the minimum temperature required to initiate or cause self-sustained combustion independent of the heat source.
  • limits of flammability – the range of concentrations in mixtures of air that will propagate a flame and cause an explosion.

8.3.d    Standard Operating Procedures.  The following SOPs must be followed when working with flammable or combustible substances:
(1)  Know the flammability properties of the chemicals being used.  Pay particular attention to substances with NFPA fire hazard ratings of 3 or 4.
(2)  Containers must have the required identifying labels.  See Section 7.4
(3)  The amount of flammable/combustible materials in the open in the laboratory shall be kept to the minimum necessary for the work being conducted.  Never exceed the storage limits imposed by NFPA Standard No. 45 (“Standard on Fire Protection for Laboratories Using Chemicals, 2000 Edition”) and 29 CFR 1910.106 (“Flammable and Combustible Liquids”).
(a)   Within laboratories, storage of flammable liquids (including wastes) outside of approved flammable storage cabinets or safety cans (i.e., open shelves) must not exceed 10 gallons per 100 square feet of laboratory space.
(b)  For the maximum amounts allowed in a laboratory see Table 4 (Appendix A).
(4)  Eliminate ignition sources from areas where flammable substances are handled or stored.  Ignition sources include electrical equipment, open flames, static electricity, and hot surfaces.
(5)  When heating flammable materials:
(a)   Never use an open flame.
(b)  Use heat sources such as steam baths, water baths, oil baths, heating mantles or hot air baths.
(c)   Never heat a closed container (even in a microwave).

  • Heat open containers only in a fume hood, with the sash pulled down completely.

(6)  When transferring flammable liquids from one container to another:

  • The preferred method is to transfer substances within a fume hood.
  • If transferring from one metal container to another metal container, ground both containers (to avoid static sparks).
  • Avoid transferring from one plastic container to another plastic container since they require special grounding techniques.

(7)  Before introducing flammable gases into a reaction vessel, the equipment should be purged either by evacuation or with an inert gas.


8.4    Explosives 
Special precautions must be taken in handling explosive materials.  Explosions result when a substance undergoes a rapid reaction resulting in a violent release of energy.  Explosive materials are those substances that either detonate or deflagrate.  Many factors including heat, light, mechanical shock, and certain catalysts may initiate explosive reactions.  Gases and fumes resulting from explosions may also have health hazards associated with them.

8.4.a    Definition
(1)  Explosive.  A “chemical that causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden shock, pressure, or high temperature.”                                                                                                                   (29CFR 1910.1450(b))

8.4.b   Examples
(1)  Refer to Table 5 (Appendix A) for an incomplete list of classes of explosive compounds and their associated functional group.
(2)  Refer to Tables 6 & 7 (Appendix A) for examples of shock-sensitive compounds.

8.4.c    Standard Operating Procedures.  If it is necessary to work with explosive or highly reactive materials, the following guidelines must be adhered to:
(1)  Prior Approval must be obtained.

  • Before working with explosive or potentially explosive substances, the hazards associated with the substances and any specific safety precautions must be known.
  • Relevant literature must be consulted, and the procedures must be discussed/”walked thru” before any activities takes place.

(3)  Explosive chemicals should be brought into the laboratory only as required.
(4)  Use the minimum amounts necessary for the procedure.
(5)  Potentially explosive substances should be labeled, dated and inventoried when received.  The label must include:  DANGER! EXPLOSIVE MATERIAL
(6)  All potentially explosive liquids must be stored in secondary containment trays large enough to hold the contents of the container.
(7)  Proper PPE, including a flame retardant lab coat, face shield (over goggles), and heavy leather gloves must be worn at all times.  A portable safety shield must also be used.


8.5    Organic Peroxides and Peroxide Forming Substances

8.5.a    Definition and other Important Information
(1)  Organic Peroxide.  An “organic compound that contains the bivalent –O-O- structure and which may be considered to be a structural derivative of hydrogen peroxide, where one or both of the hydrogen atoms has been replaced by an organic radical.”             (29CFR 1910.1450(b))
(2) Organic peroxides are one of the more hazardous classes of chemicals commonly found in the laboratory.  Generally they are low-power explosives, but they are extremely sensitive to shock, sparks, and other forms of accidental ignition.
(3)  Organic peroxides are highly flammable.
(4)  There are also many potentially hazardous compounds that auto-oxidize when exposed to air and form hydroperoxides and peroxides.

8.5.b   Examples
(1)  The most commonly used peroxide-formers in use at St. Olaf are Tetrahydrofuran (THF) and Diethyl Ether.
(2)  Refer to Table 8 (Appendix A) for an incomplete list of compounds that are known to form peroxides.

8.5.c    Standard Operating Procedures

    • Write the Date Opened on the jar.  Any jar found without such a date will be promptly processed for disposal.
    • Purchase and use only chemicals that contain peroxide-inhibitor additives (St. Olaf recognizes that there is a limited need for small quantities of ultra-pure chemicals that do not contain peroxide-inhibiting additives).
    • Purchase substances in small enough jar sizes that, when opened, will be used in less than 3 months.
    • Do not return unused chemicals to the original container.
    • All spills involving peroxides should be cleaned up immediately.  Solutions of peroxides can be absorbed on vermiculite or other absorbing material.
    • Inert solvents can be used to dilute peroxides, which reduces their sensitivity to shock and heat.  Do not use aromatic solvents.
    • Metal spatulas must not be used when handling peroxides.
    • Sources of heat are not allowed near peroxides.
    • Avoid forms of impact near peroxides.
    • Do not use chemicals that have reached their expiration date; take these substances to the stockroom manager for prompt stabilization and disposal.

8.5.d    Storage of Peroxide-Forming Chemicals
(1)  Store the containers in a tightly closed, properly labeled container.
(2)  Store in a flammables cabinet, away from light, heat, sources of ignition, oxidizers, and oxidizing acids.

8.5.e    Testing for Peroxides
(Use the test strips that are kept in the Chemistry Stockroom freezer; follow the directions)
(1)  Chemicals stored in the stockrooms and the Chemical Storage Facility will be tested by the stockrooms managers. 
(2)  Laboratory Supervisors are responsible for testing for peroxides in their research laboratories.
(3)  For bottles with inhibiting agents added by the manufacturer:
(a)   Once a bottle is opened, it must be tested monthly for peroxides.
(4)  For bottles without inhibiting agents added by the manufacturer: 
(a)   Once a bottle is opened, it must be tested every two weeks for peroxides.
(5)  Any jar found to have peroxide formation will have Hydroquinone or Butylated Hydroxy Toluene (BHT) added to the bottle (these are stabilizing agents), and monthly testing will continue.
(6)  The following concentration guidelines apply: 
(a)   If peroxide levels are < 50 ppm, then the solution is still ok to use.
(b)  If peroxide levels are ≥ 50 ppm, then the solution will be stabilized and processed for disposal.
(b)  Do not use the substance if there is any signs of crystal formation inside the jar; immediately inform the stockroom manager & CHO and do not move the jar.


8.6    Dusts, Explosive Boiling (taken from “Prudent Practices”)

8.6.a    Dusts
Suspensions of oxidizable particles (e.g., flour, coal dust, magnesium powder, zinc dust, carbon powder, and flowers of sulfur) in the air can constitute a powerful explosive mixture.  These materials should be used with adequate ventilation and should not be exposed to ignition sources.  Some solid materials, when finely divided, are spontaneously combustible if allowed to dry while exposed to air.  These materials include zirconium, titanium, Raney nickel, finely divided lead (such as prepared by pyrolysis of lead tartrate), and catalysts such as activated carbon containing active metals and hydrogen.

8.6.b   Explosive Boiling
Not all explosions result from chemical reactions. A dangerous, physically caused explosion can occur if a hot liquid or a collection of very hot particles comes into sudden contact with a lower-boiling-point material. Sudden boiling eruptions occur when a nucleating agent (e.g., charcoal, ''boiling chips") is added to a liquid heated above its boiling point. Even if the material does not explode directly, the sudden formation of a mass of explosive or flammable vapor can be very dangerous.


    • Incompatible Chemicals

8.7.a    Pay close attention to the combination of chemicals that are being used.
Incompatibles must be separated, since an inadvertent mixing/spill may result in the formation of substances that have a combination of both physical and health hazards associated with them.

8.7.b   Examples
(1)  Refer to Table 9 (Appendix A) for an incomplete list of incompatible chemicals.

8.7.c    Standard Operating Procedures
(1)  Know the hazards associated with incompatible substances used in the procedure, and know the possible characteristics of any new substance that could result from the inadvertent mixing/spill of original chemicals.
(2)  Storing Incompatibles.  Store incompatible chemicals properly as suggested in Table 10 (Appendix A).
(3)  Use the minimum quantities necessary in the process.


    • Pyrophorics 

8.8.a    Definitions and other Important Information
(1)  Pyrophorics.  Pyrophorics are substances that ignite spontaneously in contact with air or moisture.

8.8.b   Examples
(1)  Refer to Table 11 (Appendix A) for an incomplete list of Pyrophorics.  Examples of pyrophorics include many finely divided metals, metal hydrides, alloys of reactive metals, low-valent metal salts and iron sulfides.

8.8.c    Standard Operating Procedures
(1)  Avoid contact with air or water
(2)  Work in inert environments
(3)  Store pyrophorics in inert environments and away from flammables
(4)  Pyrophorics should be labeled, dated an inventoried when received.  The label should state:  DANGER! PYROPHORIC MATERIAL HIGHLY REACTIVE.


    • Water Reactives

8.9.a    Definitions and other Important Information
(1)  Water Reactives.  Substances that are classified as water reactive are those that react violently with water.
(2)  Typically these materials result in a large evolution of heat when in contact with water, decompose in moist air and may violently decompose in liquid water.

8.9.b   Examples
(1)  Water Reactives include alkali metals, many organometallics, some hydrides, some anhydrous metal hydrides, nonmetal oxides and halides.  Refer to Table 12 (Appendix A) for an incomplete list of Water Reactives.

8.9.c    Standard Operating Procedures
(1)  Keep away from moisture; store in air-tight containers in a dark, cool, dry place.
(2)  Work in a fume hood.
(3)  Wear protective acid resistant rubber or plastic clothing along with gloves and a face shield.
(4)  The Class D fire extinguisher (in Chemistry Stockroom Office) must be readily available.
(5)  Water reactive materials should be labeled, dated and inventoried when received.  The label should state:  DANGER! WATER REACTIVE MATERIAL HIGHLY REACTIVE.


    • Compressed Gases & Cylinders

(adapted from the University of West Virginia Chemical Hygiene Plan,

Depending on the identity of the compressed gas, it can be both a possible physical and health hazard.  The compression of a gas results in a large amount of potential energy.  Therefore, compressed gas cylinders are high-energy sources that can act as a rocket or fragmentation bomb.  If the gas is flammable there is also the possibility for a fire or explosion to occur.

The contained gases may also be reactive, corrosive, or toxic, so these properties must be considered when developing experimental procedures and designing apparatus. 

The primary hazards of inert gas systems are ruptures of containers, pipelines, or other systems, and the potential of an inert gas to asphyxiate if released into a confined space in high concerntrations.

8.10.a  Definition
(1)  Compressed Gas.  Any material or mixture having in the container either an absolute pressure greater than 276 kPA (40 lif/in2) at 21° C, or an absolute pressure greater than 717 kPA (104 lbf/in2) at 54° C, or both, or any liquid flammable material having a Reid vapor pressure greater than 276 kPA (401 lbf/in2) at 38 °C.                 (29 CFR 1910.1450(b))

8.10.b  Standard Operating Procedures
(1)  Know and understand the physical/health hazards, uses, and safety precautions of the gas and associated equipment before using a cylinder.  Consult the MSDS or other appropriate reference material.
(2)  The contents and hazard level of every cylinder must be clearly identified with a durable label.  If the contents and hazard level are not clearly labeled, then you must not handle or use the cylinder.
(3)  Do not remove or deface the product identification labels or decals, or change the cylinder color.
(4)  No cylinder should be accepted that is not clearly identified.
(5)  Leather gloves and safety glasses are recommended for handling cylinders; chemical splash-resistant goggles may be necessary depending on the contents.
(6)  The Laboratory Supervisor must develop plans to cover any emergency situation that might arise; do not move or use a cylinder unless you have received proper training.
(7)  The Laboratory Supervisor must provide proper training and instruction for all personnel who handle compressed gases (see Sections 8.10.c-f).
(8)  Identify empty cylinders by using the ring tags, or by writing the letters “EMPTY” or “MT” near the top of the cylinder.

8.10.c  While working with compressed gases that are flammable, corrosive, irritating or toxic, the following additional SOPs must be observed:
(1)  Cylinders of all gases having a Health Hazard Rating of 3 or 4 and those having a Health Hazard Rating of ≥ 2 with no physiological warning properties must be stored and used in a continuously mechanically ventilated hood or enclosure.
(2)  Wear chemical splash resistant goggles and (if appropriate) a full face shield. 
(3)  Do not store or use incompatible cylinders next to each other.
(4)  When opening valves on irritating or toxic gases, it must be done in a fume hood or specially designed cabinet.
(5)  The relief valve on cylinders of hazardous gases must vent to a hood or other safe location.
(6)  Cylinders of flammable gases and cylinders of toxic or corrosive gases must be stored and used in a ventilated area as required by the NFPA Standard 45.
(7)  No more than three gas cylinders with Health Hazard Ratings of 3 or 4 may be kept in a ventilated hood or enclosure.
(8)  Use soapy water or approved explosimeters to detect for flammable gas leaks.

8.10.d  Handling and Moving Cylinders
(1)  Handle all cylinders with care.  Have a firm grip before moving cylinders, and never underestimate the cylinder’s weight or momentum.
(2)  When moving cylinders:
(a)   Make sure the valve is closed and the cap is securely placed over the valve.
(b)  Use a cylinder cart, and do not drag or slide cylinders, even for short distances.  Make sure cylinder is securely fastened to cylinder cart with the supplied strap or chain.
(c)   Use only the 4-wheel cylinder carts; do not use a 2-wheel hand-truck or dolly since this is an inherently risky method of transporting a cylinder.

  • Never drop cylinders or permit them to strike each other violently. 
  • Do not allow others to ride with you in an elevator with a cylinder.
  • Return all empty cylinders to the designated storage area by the SC loading dock doors.   Secure the empty cylinders to the wall with the chain.  All empty cylinders must be identified by writing the letters “EMPTY” or “MT” near the top of the cylinder, or by using a ring tag.
  • Never tamper with any safety devices in valves or cylinders.
  • Never use cylinders as rollers for moving other items.
  • Shipment of a compressed gas cylinder that has been filled without the consent of the owner is a violation of federal law.

8.10.e  Storing Cylinders
(1)  Return all empty cylinders to the designated storage area by the SC loading dock doors.   Secure the empty cylinders to the wall with the chain. 
(2)  Cylinders are delivered to the storage cage inside the SC loading dock, and they are secured inside the locked cage door by the delivery personnel.  The cylinders are then moved by stockroom personnel to the cylinder storage cage in the room immediately next to the SC loading dock.  Cylinders must be stored in an upright position and securely fastened within the cylinder storage cage.  Remember to lock the cylinder storage cage door.

8.10.f  Using Cylinders
(1)  Cylinders must be securely fastened at all times, using a chain or clamp and belt, to a wall or anchored bench. 
(2)  Cylinders must not be used near sources of ignition, electricity, or heat.
(3)  Cylinders must be used in well-ventilated areas.
(4)  The cylinder valve should be accessible at all times (i.e., do not place items, even a towel, on a valve).
(5)  A cylinder cap or regulator must always be attached to the cylinder.  Never leave a cylinder with the valve exposed.
(6)  Always open the cylinder valve slowly. 
(7)  Use check valves or traps to prevent backflow of water or other contaminants if backflow can occur into the cylinder.  If backflow does occur, mark the cylinder “CONTAMINATED” and notify the supplier immediately.
(8)  Gas lines leading from a compressed gas supply must be clearly labeled with the identity of the gas, the laboratory being served, and relevant emergency telephone numbers.
(9)  When equipment is not operating or left unattended, the cylinder valve should never be left open.  Release the pressure from equipment connected to the cylinder at the end of a task.
(10) Cylinders should never be emptied to a pressure below 172 kPA (25 psi).
(11) Empty cylinders of gas should never be refilled, and the regulator should be removed and replaced with the valve cap.

8.10.g  Proper Use of Pressure Regulators
The following instructions are applicable to pressure regulators used when it is necessary to reduce the cylinder supply pressure to a lower pressure
(1)  Regulators must be compatible with the cylinders and the specific gas.  Do not use adapters.
(2)  Most regulators are similar in appearance; however, a principal difference occurs at the inlet connection. It is important that the inlet connection of the regulator is properly mated with the supply valve connection.  Checking proper mating will avoid putting the regulator into the wrong service.  Inlet connection standards are established by the Compressed Gas Association (CGA).

  • All pressure regulators should be equipped with spring-loaded pressure relief valves.
  • Selecting a Regulator

(a)   Select a regulator that is suited for the particular gas service.  CGA valve outlets are noted for each gas and gas mixture, and the CGA inlet for the regulator must correspond.
(b)  A single-stage regulator reduces the pressure from the main supply line pressure to the desired operating pressure.
(c)   A two-stage regulator is actually two regulators combined to automatically give uniform regulation over a wider supply range.

  • Attaching the Regulator

(a)   Identify the regulator; check the label and inlet and outlet gauges.  Ascertain that the high pressure gauge is suitable for the pressure of the cylinder or source system.
(b)  Inspect the regulator for evidence of damage or contamination.  If there is evidence of physical damage or foreign material inside the regulator, return it to the supplier.
(c)   Inspect the cylinder valve for evidence of damage.  Do not use if there is evidence of damage and inform the stockroom manager.
(d)   Attach the regulator to the cylinder and tighten securely.
(e)   Close the regulator by turning the adjusting knob to the full counterclockwise position.  The regulator must be closed completely before opening the cylinder valve.

  • Opening the Cylinder Valve and Safety Checking the System

(a)   Make sure that the regulator adjusting knob is turned fully counterclockwise.  Standing with the cylinder valve between yourself and the regulator, place both hands on the cylinder valve and open it slowly, allowing the pressure to rise gradually in the regulator.
(b)  When the high pressure gauge indicates maximum pressure, open the cylinder valve fully.
(c)   Always close the cylinder valve when it is no longer necessary to have it open.  Do not leave it open when the equipment is not in operation.

  • Adjusting the Pressure & Precautionary Measures

(a)   Turning the adjusting knob clockwise, establish the required use pressure by referring to the low pressure gauge.
(b)  Make sure that the cylinder valve is easily accessible.
(c)   Never exchange the discharge (low-pressure) gauge for one of lower pressure.  The gauge may rupture if the adjusting knob is unintentionally turned too far.
(d)   Check diaphragm regulators for creep (leakage of gas from the high-pressure side when the low pressure side is turned off).
(e)   Provide check valves if necessary.  Gas from a high-pressure system may back up, so backpressure protection is needed to prevent damage to a regulator.

  • Removing the Regulator from Service

(a)   Close the cylinder valve.
(b)  Vent the gases in the regulator and/or system by turning the adjusting knob clockwise to make certain that no pressure is trapped inside the regulator.
(c)   After relieving all the gas pressure, turn the adjusting knob counterclockwise as far as possible.
(d)   All low pressure equipment connected to sources of high pressure should be disconnected entirely or, if not, independently vented to the atmosphere as soon as the operation is completed or shut down for an extended period of time.
(e)   Disconnect the regulator.

  • If the regulator is to remain out of service, protect the inlet and outlet fittings from dirt, contamination, or mechanical damage.
  • Replace the cylinder valve cap

8.10.h  Basic Emergency Action Procedures Involving Gas Cylinders
The following guidelines, based on the four general compressed gas hazard categories, should be used in preparing your specific emergency response procedures.  These guidelines should be used to assist you in making decisions. They are not intended to serve as a substitute for your own knowledge or judgment. They provide only the most vital information and may not be necessarily adequate in all situations.
(1)  Fire Emergency Methods
(a)   Before working with any flammable material, first notify the CHO about the type of material being handled, and the best method to use in fighting that particular kind of fire.
(b)  In anticipation of an emergency, have self-contained, positive-pressure, breathing apparatus in the work area and in adjacent uncontaminated areas.
(c)   If an emergency should occur in which gas is burning, try to stop the flow of gas before extinguishing the fire. If the fire is extinguished before the gas is turned off, an explosive mixture with air may be formed, which could result in more extensive damage.
(d)   Consider the physical and chemical properties (specific gravity, solubility, reactivity, etc.) of the particular gas in relation to fire fighting measures to be employed. 
(e)   The possibility of oxidizing gases, nonflammable toxic gases, or nonflammable corrosive gases being present in the area or being involved in a fire is another important safety consideration. 
(i)   Develop procedures to eliminate or minimize the hazards associated with these products.
(ii)  If you attempt to fight such a fire, wear full protective clothing and a self-contained breathing apparatus.
(2)  Handling of Leaking Cylinders
(a)   Most leaks occur at the valve used in the top of the cylinder. Areas that may be involved are:
(i)   Valve stem, threads, or outlet
(ii)  Safety device
(b)  If a leak develops, effect emergency action procedures and notify the supplier.
(c)   Never attempt to repair a leak at the valve threads or safety device.
(d)   Consult the supplier for instructions if the leak is located at the valve stem or valve outlet.
(e)   The following general procedures are for leaks of minimum size where the indicated action can be taken without serious exposure to personnel.
(i)   If a leak develops in a cylinder containing flammables, inerts, or oxidants, ensure that there is adequate ventilation to dissipate the gas.
(ii)  Move the cylinder to an isolated area (away from combustible material if it is a flammable or oxidizing gas) and post signs that describe the hazards and state warnings.
(iii) Some corrosives are also oxidants or flammables, adding to the seriousness of the leak.  If the product is corrosive, the leak may increase in size as the gas is released.  Move the cylinder to an isolated, well-ventilated area and use suitable means to direct the gas into an appropriate chemical neutralizer.  Post signs that describe the hazards and state warnings.
(iv) Follow the same procedure for toxic gases as for corrosive gases.  Move the cylinder to an isolated, well-ventilated area and use suitable means to direct the gas into an appropriate chemical neutralizer. Post signs that describe the hazards and state warnings.
(v)  If it is necessary to move a leaking cylinder through populated portions of the building, place a plastic bag, rubber shroud, or similar protection over the top and tape it (preferably with duct tape) to the cylinder to confine the leaking gas.
(f)   When the nature of the leaking product or the size of the leak constitutes a hazard, wear self-contained breathing apparatus and protective clothing.
(g)  Basic action for large or uncontrollable leaks should include the following steps:
(i)   Evacuation of personnel
(ii)  Rescue of injured personnel by properly trained personnel equipped with adequate protective clothing and breathing apparatus
(iii) Fire-fighting action (by properly trained personnel)
(iv) Emergency repair (by properly trained personnel)
(v)  Decontamination(by properly trained personnel)

8.10.i  Dangers of Oxygen Deficient Atmospheres
Incidents have occurred where workers have lost their lives or been overcome by high concentrations of nitrogen gas or other “inert” gases.  Oxygen is normally at a concentration of 21% in the atmosphere.  The balance is nitrogen, with traces of other components.  The presence of any additional gas in the air (other than oxygen) dilutes the oxygen concentration, creating an oxygen deficient atmosphere.  As the oxygen concentration is progressively lowered, the physiological effects are giddiness, mental confusion, loss of judgment, uncoordinated movements, weakness, nausea, fainting, and death.
(1)  Immediate Effects of Breathing Oxygen Deficient Atmospheres
(a)   Blood that normally becomes enriched in oxygen in the lungs takes less than 10 seconds to reach the brain. Lung oxygen is washed out and replaced by gas (e.g., pure nitrogen) containing no oxygen.

  • Blood flowing through the lungs receives insufficient oxygen, as none has been inhaled.  In fact, the blood gives up whatever residual oxygen it may be carrying.
  • Blood severely depleted in oxygen then flows to the brain, where tissues rapidly become oxygen deficient.  The  result is swift unconsciousness because brain tissue is the body component most sensitive to the lack of oxygen.
  • Mental failure and coma follow a few seconds later.  Symptoms or warnings are generally absent, but even if present, the loss of mental competence and physical weakness, uncoordinated movements, or fainting prevents the victim from talking.  Death follows in two to four minutes.

(2)  Effects of Continued Breathing of Oxygen Deficient Atmospheres
The effects of continued exposure to oxygen deficient atmospheres depend on various factors: the degree of oxygen deficiency; the degree of physical exertion; and individual health factors (e.g., smoker/non-smoker).  Any exercise increases the body’s requirement for oxygen. Consequently, symptoms of oxygen deficiency will occur more rapidly among persons who are exerting themselves than would be the case among persons at rest.  Below are the signs and symptoms of breathing an oxygen deficient atmosphere while a person is at rest:
(a)   Oxygen Content of Air: 15%-19%
Decreased ability to work strenuously.  May impair coordination and may induce early symptoms in persons with coronary, pulmonary, or circulatory problems.
(b)  Oxygen Content of Air: 12%-14%
Respiration deeper, increased pulse rate, impaired coordination, perception, and judgment.
(c)   Oxygen Content of Air: 10%-12%
Further increase in rate and depth of respiration, further increase in pulse rate, performance failure, giddiness, poor judgment, blueness of lips.
(d)   Oxygen Content of Air: 8%-10%
Mental failure, nausea, vomiting, fainting, unconsciousness, ashen face, blueness of lips.
(e)   Oxygen Content of Air: 6%-8%
8 minutes, 100% fatal; 6 minutes, 50% fatal; 4-5 minutes, recovery with treatment for all exposures.
(f)   Oxygen Content of Air: 4%
Coma within 40 seconds, convulsions, respiration ceases, death.
(3)  Precautions
(a)   Do not work in areas without sufficient ventilation when using compressed gas cylinders.  Be aware that increases in gas consumption rate may require additional ventilation.
(b)  Do not rely on the absence of a visible plume as evidence of a normal air atmosphere.  A vapor cloud or plume, created by condensing water vapor in the air, can be evidence of the release of cold gas vapors.  As the gas warms to ambient temperature, the danger is still present, without the warning of the visible plume, unless adequate dilution of the inert gas has occurred.
(c)   Personnel must not work in or enter atmospheres containing less than 19.5% (as recommended by the CGA, NIOSH, and OSHA) unless equipped with a self-contained breathing apparatus.  This is also true for rescue personnel who may be overcome by the same oxygen deficient atmosphere as the initial victim.
(4)  First Aid
(a)   Persons suffering from lack of oxygen should quickly be moved to areas with normal atmosphere.
(b)  If the victim is not breathing, assisted ventilation should be the immediate step (and call 9-911).  Give supplemental oxygen with ventilation if oxygen is available.  Note: Coma due to lack of oxygen is not always fatal.  CPR certification is offered free-of-charge to all SC faculty and staff.


8.11  Cryogenic Substances and Liquefied Gases

8.11.a  Definitions and other Important Information
(1)  Cryogenic liquids have boiling points of less than –73 °C (-100 °F).
(2)  Because cryogenic liquids are at such low temperatures and because of their large ratio of volume expansion from liquid to gas, the main hazards associated with using cryogenic liquids are:
(a)   Fire or explosion.
(i)   Vaporization of liquid hydrogen in an enclosed work area can create a flammable mixture with air.  St. Olaf College does not use liquid hydrogen.
(b)  Pressure buildup.
(i)   All cryogenic liquids produce large volumes of gas when they vaporize.  If these liquids are vaporized in a sealed container, they can produce enormous pressures that could rupture the vessel. Any liquid or even cold vapor trapped between valves has the potential to cause an excessive pressure buildup to the point of violent rupture of a container or piping, hence use of reliable pressure relief devices is mandatory.
(c)   Frostbite; Embrittlement of structural materials.
(i)   Because they are all extremely cold, cryogenic liquids and their cold “boil-off” vapor can rapidly freeze human tissue, and can cause many common materials such as carbon steel, plastics, and rubber to become brittle or even fracture under stress.
(ii)  Exposure to these cold “boil-off” vapors that is too brief to affect the skin of the face or hands can affect delicate tissues, such as those of the eyes.
(d)   Asphyxiation.
(i)   The potential for asphyxiation must be recognized when handling inert cryogenic liquids. Because of the high expansion ratios, air can be quickly displaced.  Vaporization of all liquid cryogenics, except oxygen, in an enclosed work area can create an oxygen-poor atmosphere.
(3)  When spilled on a surface cryogenic liquids tend to cover it completely and therefore cool a large area. 

8.11.b  Examples
(1)  Liquid nitrogen, liquid helium, and dry ice are the only crygenic substances used in St. Olaf laboratories.

8.11.c  Standard Operating Procedures
(1)  Laboratory Supervisors must make sure that their laboratory workers are instructed and trained in the nature of cryogenic hazards and the proper steps to avoid them.  This should include emergency procedures, operation of equipment, safety devices, knowledge of the properties of materials used, and personal protective equipment required. 
(2)  Always handle cryogenic liquids carefully.  Skin contact with cryogenic liquids must be avoided.
(3)  Label all containers appropriately.
(4)  Work involving cryogens must be conducted in a well-ventilated area.
(5)  Use containers that are designed for the pressures and temperatures to which they are subjected.
(6)  Dewar flasks used for small amounts of material should have a dust cap over the outlet to prevent moisture from condensing and plugging the neck of the tube.
(7)  All equipment and cylinders containing flammable or toxic liquefied gases should have a spring-loaded pressure release device.
(8)  Liquid hydrogen must not be transferred in an air atmosphere.
(9)  Liquid oxygen must be kept away from organic materials.
(10) Liquid nitrogen must not be kept in any rooms that are not connected to the building ventilation system.
(11) Equipment and systems should be kept scrupulously clean and contaminating materials (oil, grease, etc.) avoided as these may create a hazardous condition upon contact with cryogenic fluids or gases used in the system.

8.11.d  Handling
(1)  Chemical splash goggles must always be worn when handling liquefied gases and cryogenic liquids.  If severe spraying or splashing may occur, a face shield should be worn for additional protection. 
(2)  Uninsulated objects containing cryogens must be handled with tongs, or fiberglass gloves. The gloves should be loose fitting to allow for rapid removal in case of a spill.
(3)  Use tongs to withdraw objects immersed in a cryogenic liquid.
(4)  Stand clear of boiling or splashing liquid and its issuing cold gas.  Boiling and splashing always occur when charging a warm container or when inserting objects into the liquid. Always perform these operations slowly to minimize boiling and splashing.
(5)  Never allow any unprotected part of your body to touch uninsulated pipes or vessels containing cryogenic liquids; the extremely cold material may stick fast and tear the flesh when you attempt to withdraw it.  Even nonmetallic materials are dangerous to touch at low temperatures.

8.11.e  Containers
The most common containers for laboratory use are the dewar or the liquid cylinder.  Since heat leak is always present, vaporization takes place continuously.  Rates of vaporization may be as low as 0.4% and as high as 3% of container content per day, depending upon the design of the container and the volume of the stored product. As there is always some gas present when using liquefied gases, container capacity should be designed to include an allowance for that portion which will be in the gaseous state.
(1)  Dewars
This type of container is considered a nonpressurized container.  Product may be removed by pouring from the smaller dewars.  Product should be removed from dewars with a capacity ≥ 50-liters by means of low pressurization and a transfer tube.  A dust cap over the outlet of the neck tube prevents atmospheric moisture from plugging the neck tube.
(2)  Cylinders
The cylinder is an insulated, vacuum-jacketed container.  Safety relief valves and rupture disks protect the cylinders from pressure buildup.  Since these cylinders operate at pressures up to 250 psig, their design must comply with Department of Transportation (DOT) specifications. 
Product may be withdrawn as a gas by passing liquid through a vaporizing coil, or as a liquid under its own vapor pressure.

8.11.f  First Aid for Cold Burns
Tissue contact with cryogenic liquids produces damage similar to that associated with thermal burns and causes severe deep-freezing with extensive destruction of tissue.  Seek medical attention promptly.
(1)  Flush affected areas with large volumes of tepid water (41-46°C [105-115°F]) to reduce freezing.  DO NOT APPLY HEAT.
(2)  If it is not in the area involved, loosen any clothing that may restrict circulation. 

  • Cover the affected area with a sterile protective dressing or with clean sheets if the area is large, and protect the area from further injury.
  • Note that frozen tissues are painless and appear waxy with a pallid yellow color.  Tissues become painful and edematous upon thawing and the pale color turns to pink or red as circulation of blood is restored.
  • Tissues that have been frozen show severe, widespread cellular injury and are highly susceptible to infections and additional trauma.  Therefore, rapid rewarming of tissues in the field is not recommended if transportation to a medical facility will be delayed.
  • If the body temperature is depressed, the patient must be warmed gradually.  Shock may occur during the correction of hypothermia.  Cardiac dysrhythmias may be associated with severe hypothermia.

8.12 – 8.17      Health Hazards

8.12  Corrosives

8.12.a Definitions and other Important Information
(1)  A Corrosive is a chemical that:
(a)   causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact  (OSHA, 29 CFR 1910.1200, App A)
(b)  has a pH<2.0, or > 12.5  (EPA, 40 CFR 261.22)
(2)  How Damage Occurs. Corrosives erode the skin, so such injuries may be very slow to heal.  Ingestion can cause immediate injury to the mouth, throat, and stomach and, in severe cases, can lead to death.  Eyes are particularly vulnerable to injury, and inhalation of vapors or mists can cause severe bronchial irritation or damage.
(3)  Classes of Corrosives. There are many classes of compounds that exhibit corrosive properties, and corrosive substances exist as solids, liquids and gases.  Strong acids and bases (also called caustics), strong dehydrating agents, strong oxidizing agents, halogens, and nonmetal chlorides tend to be the most common corrosive chemicals in science laboratories.
(4)  Corrosive liquids such as bromine, sulfuric acid, sodium hydroxide solutions and hydrogen peroxide solutions, tend to be especially dangerous since their action on skin occurs very rapidly.
(5)  Alkali metal hydroxides (especially potassium hydroxide and sodium hydroxide) are very dangerous when allowed to come into contact with tissue, especially the eyes.  They are less painful than the strong acids, but damage may extend to greater depths because the injured person may not be aware of the seriousness of the incident.
(6)  Corrosive gases or dusts from corrosive solids can seriously damage the respiratory tract.  Typical examples of corrosive gases include halogens (e.g., chlorine), ammonia and nitrogen dioxide.

  • Solids such as sodium hydroxide, phosphorous and phenol can be very dangerous when allowed to come in contact with the skin, and dusts from corrosive solids can also seriously damage the respiratory tract.
  • Dehydrating Agents such as sulfuric acid, sodium hydroxide, phosphorous pentoxide, calcium oxide, and glacial acetic acid can cause severe burns to the eyes or skin because of their strong affinity to water.
  • Hydrofluoric Acid is recognized as a “Particularly Hazardous Substance” – follow all rules and procedures found in 8.12.e(3).
  • Nonmetal Chlorides such as phosphorous trichloride and corresponding bromides react violently with water and are a common cause of laboratory accidents.
  • Halogens (in addition to being toxic) are corrosive on contact with skin, eyes, and the linings of the respiratory system.  Because they are gases they pose a greater danger, especially by inhalation, of coming in contact with tissue.

8.12.b Examples
(1)  Refer to Table 13 (Appendix A) for a list of common corrosive materials.

8.12.c Standard Operating Procedures
(1)  Minimize skin and eye contact by wearing chemical splash goggles, gloves that are resistant to the corrosive, and a lab coat.  If appropriate also use a face shield or other protective apparel.
(2)  Avoid inhalation of corrosives by working in a fume hood or other containment device when handling volatile corrosives (e.g., ammonia is a severe bronchial irritant).
(3)  Always add acids to water, never the reverse.  Add the agent to the water slowly, since splattering might occur when some types of corrosives are added to the water too quickly.
(4)  Types of Containers. Attempt to purchase corrosives in plastic-coated containers, so that if they are dropped, the most likely result should be only a leak through the plastic coating instead of a dangerous splashing.

  • Move corrosives in a hand-held bucket or (if numerous containers) on a chemically-resistant cart that has proper secondary containment.
  • Do not allow others to ride in the elevator when moving corrosives between floors.

(7)  In areas where corrosives are used and stored, an eyewash and safety shower must be readily available.
(8)  All containers and equipment used for storage and handling of corrosives must be corrosion resistant.

  • Containers of corrosives from incompatible classes must be segregated.
  • Incompatible classes of corrosives must not be mixed.
  • Hydrofluoric Acid.  Never handle or use Hydrofluoric Acid unless all following requirements have been met:
    • You have been given the proper training.
    • You have the proper knowledge and spill-response agents (Calcium glauconate cream & calcium carbonate).
    • All personnel with whom you are working have also received the proper spill-response training.  

8.12.d Storing Corrosives (See Table 9, Appendix A for an Incompatibility Guide of Chemicals)
Incompatible corrosives must be physically segregated (i.e., if two jars of incompatible chemicals break simultaneously, the chemicals must be stored in such a way so that the spilled chemicals cannot come in contact with each other).  The best method is to store incompatible chemicals in separate secondary containment trays and on separate shelves so that one chemical cannot spill on top of an incompatible chemical.
(1)  Store corrosives in secondary containment trays.
(2)  Always physically segregate acids from bases – use 2° containment trays if jars are on the same shelf.
(3)  Always physically segregate inorganic acids from organic acids (some inorganic acids, such as Nitric Acid, are oxidizers and will react with organic acids). 
(a)   Always store Nitric Acid separately.
(b)  Some examples of other inorganic acids are Hydrochloric Acid, Hydrofluoric Acid, Sulfuric Acid, and Phosphoric Acid
(c)   Some examples of Organic Acids are Acetic Acid, Butyric Acid, Formic Acid, Picric Acid, and Acrylic Acid
(4)  Perchloric Acid, Picric Acid and other strong oxidizing agents (e.g., chromic acid) require special handling and Prior Approval before even purchasing.  These substances must be stored in glass (unbreakable) or other inert containers.
(5)  Segregate oxidizing acids from flammable and combustible materials.
(6)  Segregate acids from chemicals that can generate toxic gases on contact, such as sodium cyanide and iron sulfide.
(7)  Segregate acids from active metals such as sodium, magnesium, and potassium.
(8)  Segregate acids from solvents such as toluene and xylene.
(9)  Large bottles (4L) must be stored in acid cabinets.
(10) Absorbents or neutralizers are readily available for acid spills.

8.12.e Emergency Procedures – Corrosives (see Chapter 11 for more details)
(1)  In areas where corrosives are used and stored, an eyewash and safety shower must be readily available.
(2)  Chemical Burns. In the event of skin or eye contact, immediately flush the area of contact with water for 15 minutes or longer to remove all traces of the chemical.
(a)   Remove all affected clothing & jewelry.  Do not hesitate to use a safety shower if you deem it necessary.
(a)   Do not apply ointments (except for HF – see below), baking soda, ice, or gauze covering to the wound.
(b)  Seek medical attention immediately.  If an eye is involved the person must be taken to an opthalmologist as soon as possible to determine if further treatment is needed.
(3)  Hydrofluoric Acid Exposure. Hydrofluoric acid is an extremely corrosive liquid that can cause severe injury via skin and eye contact, inhalation, and ingestion.  HF readily penetrates the skin and causes decalcification of the bones.  Laboratory workers must know the first-aid procedures for HF exposure before beginning work with HF.  In the event of contact with HF, first-aid must be started within seconds.  Do NOT allow affected area to touch your body!!
(a)   Calcium gluconate gel (2.5% w/w) must be readily accessible in work areas where any potential HF exposure exists.
(b)  Immediately flush the exposed area with tepid water, remove contaminated clothing, and call 9-911.
(c)   Apply the calcium gluconate gel after 5 minutes of flushing with water.  If the calcium gluconate gel is somehow unavailable, continue flushing the exposed areas with water until medical assistance arrives.
(d)   If ingested, immediately call 9-911 and the Poison Control Center (9-1-800-764-7661).
(e)   If the vapor is inhaled, move the victim to fresh air and call 9-911.


8.13  Irritants

8.13.a Definitions and other Important Information
(1)  Irritant.  A chemical which is not corrosive, but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact. (29 CFR 1910.1250)
(2)  There are a large number of chemicals, both organic and inorganic, that are irritants.

8.13.b Examples
(1)  Refer to Table 14 (Appendix A) for a list of irritants.

8.13.c Standard Operating Procedures
(1)  Minimize skin and eye contact by wearing chemical splash goggles and appropriate gloves.  If appropriate also use a face shield and other protective apparel.
(2)  Avoid inhalation of irritants by working in a fume hood or other containment device when handling volatile irritants.
(3)  An eyewash and safety shower must be readily available.


8.14  Sensitizers (Allergens)

8.14.a Definitions and other Important Information
(1)  Sensitizer.  A chemical that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure to the chemical (29 CFR 1910.1250)
(2)  An allergic reaction to a chemical results from previous sensitization to the chemical or to a structurally similar one.  The reaction can be immediate or delayed (e.g., contact with poison ivy) and, after sensitization occurs, can result from exposure to extremely small doses of the substance (e.g., formaldehyde).
(3)  The tendency to become sensitized to a chemical differs widely among individuals.  It is possible that an individual will exhibit an allergic response even if the recommended personal protective measures are taken.  Individuals working with sensitizers should be aware of the signs and symptoms associated with allergic responses to chemicals that include red, swollen and itchy skin and eyes.  Anaphylactic shock is an example of a severe immediate allergic reaction that can result in death if not treated quickly.  Consult the MSDS for the specific sensitizer.

8.14.b Examples
(1)  Refer to Table 15 (Appendix A) for a list of sensitizers.

8.14.c Standard Operating Procedures
(1)  Consult the MSDS or other references before working with the specific sensitizer.
(2)  Be aware of signs and symptoms associated with allergic responses to the sensitizer.
(3)  Be aware if emergency responses to allergic reactions to the sensitizer.
(4)  Avoid skin and eye contact by wearing chemical splash goggles and gloves.  If appropriate also wear other protective apparel.
(5)  Avoid inhalation by working in a fume hood or other containment device.


8.15  Asphyxiants

8.15.a Definitions and other Important Information
(1)  Asphyxiant.  A substance that interferes with the transport of an adequate supply of oxygen to the vital organs.
(2)  Simple asphyxiants are substances that literally displace oxygen from the air being breathed.  It is therefore important to recognize that chemically inert and biologically benign substances can be extremely dangerous under certain conditions (such as a leaking nitrogen cylinder in a closed room). 
(3)  Other chemicals have the ability to combine with hemoglobin, thus reducing the capacity of the blood to transport oxygen.  Carbon monoxide, hydrogen cyanide, and certain organic and inorganic cyanides are examples.

8.15.b Examples
(1)  Acetylene, carbon dioxide, argon, helium, ethane, nitrogen, and methane are common simple asphyxiants.

8.15.c Standard Operating Procedures
(1)  Consult the MSDS or other references for specific effects.
(2)  Be aware of signs and symptoms associated with exposure.
(3)  Be aware of emergency responses.
(4)  Use only in properly vented work areas.


8.16  Neurotoxins & Toxins Affecting Target Organs

8.16.a Definitions and other Important Information
(1)  Neurotoxins can induce an adverse effect on the structure or function of the central and/or peripheral nervous system, which can result in permanent damage.
(2)  Other toxic substances found in the laboratory may have adverse effects on many different target organs including the circulatory system, lungs, skin, eyes, the liver, and kidneys in  addition to the reproductive system.  Toxins affecting the reproductive system are treated in Section 8.17.

8.16.b Examples
(1)  Refer to Table 16 (Appendix A) for a list of neurotoxins and toxins affecting target organs.

8.16.c Standard Operating Procedures
(1)  Consult the MSDS for specific toxicological effects of the neurotoxin.
(2)  Be aware of signs and symptoms associated with exposure.
(3)  Be aware of emergency responses.
(4)  Avoid skin and eye contact by wearing eye protection, gloves and any other appropriate protective apparel.
(5)  Avoid inhalation by working in a fume hood or other containment device.
(6)  Mercury. Metallic mercury and mercury compounds are extremely toxic.  Store mercury in airtight, plastic containers away from direct sunlight or heat.  Trained personnel should clean up mercury spills. Whenever possible, use secondary containment devices to reduce the chance of a mercury spill.
(7)  Cyanides. Do not allow cyanide solutions to be mixed with acids.  Hydrogen cyanide, a lethal vapor, is produced when acids react with cyanides.
(8)  Sulfides. Do not allow sulfides to become mixed with acids.  Hydrogen sulfide is a lethal vapor.


8.17  Particularly Hazardous Substances
OSHA has noted that many laboratory workers use numerous chemicals that fall into this category.  While industrial workers might use only one of a limited few such chemicals, laboratory workers are likely to use many such chemicals, and exposures would at least have an additive if not synergistic impact on risk.

8.17.a Categories and Examples. According to the Laboratory Standard (29 CFR 1910.1450(e)(3)(viii)) certain classes of hazardous substances are considered to be particularly hazardous.  Provisions for additional protection for personnel working with these substances are required.  These three classes of substances are:
(1)  “Select Carcinogen” – Carcinogens are substances that are capable of causing cancer and are chronically toxic agents; e.g., they cause damage after repeated or long-duration exposure, and their effects may become evident only after a long latency period.  Therefore, carcinogens are extremely insidious toxins since they may have no immediate apparent harmful effects.  Those substances exhibiting the greatest carcinogenic hazard are referred to as “select carcinogens” and meet one of the following criteria (29 CFR 1910.1450(b)):
(a)   It is regulated by OSHA as a carcinogen  (    
(b)  It is listed under the category “Known to be Human Carcinogens” in the Annual Report on Carcinogens published by the National Toxicology Program (NTP) (
(c)   It is listed under Group 1 (“Carcinogenic to Humans”) by the International Agency for Research on Cancer Monographs (ARC) (
(d)   It is listed in either Group 2A ( or 2B ( by IARC, or under the category “Reasonably Anticipated to be Carcinogens” by NTP (, and causes statistically significant tumor incidence in experimental animals in accordance with any of the following criteria:
(i)   after inhalation exposure of 6-7 hours per day, 5 days per week, for a significant portion of a lifetime to dosages less than 10 mg/m3.
(ii)  after repeated skin application of less than 300 mg/kg of body weight per week.
(iii) after oral dosages of less than 50 mg/kg of body weight per day.
(2)  Reproductive/Embryo Toxins – chemicals that affect the reproductive capabilities, including chromosomal damage (mutagens) and effects on fetuses (teratogens).  Reproductive toxins can have adverse effects on both men and women.  Many reproductive toxins are chronic toxins and, therefore, the effects may only become evident after repeated or prolonged duration exposures.  Table 17 lists some examples of reproductive toxins. 
(3)  Substances that have a High Degree of Acute Toxicity.  Compounds with a high degree of acute toxicity are those that have a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight when administered orally to albino rates weighing between 200 and 300 grams each. 
(a)   OSHA List of Reproductive Toxins and Highly Acute Toxic Materials
(b)  OSHA List of Extremely Hazardous Chemicals
(c)   Table 18 (Appendix A) lists several examples of highly acute toxic materials.
(d)   Table 19 (Appendix A) lists the Category 1 Gaseous Inhalation Hazards as listed by the DOT.
(e)   Table 20 (Appendix A) contains a list of toxicity ratings/lethal doses based on ingestion amounts.
(f)   Exposure Limits.  For a relatively complete list of exposure limits to toxic and hazardous substances, including definitions of terms, refer to the following website at the University of Minnesota Department of Environmental Health & Safety: (  
(4)  Substances that have a High Degree of Chronic Toxicity.  Appendix A of the Laboratory Standard also recognizes that many substances can have high chronic toxicity.  Users of such chemicals must also follow the General Rules outlined in Section 8.17.b.  Examples of such substances include dimethylmercury, nickel carbonyl, other human carcinogens, or substances with carcinogenic potency in animals.

8.17.b General Rules
(1)  Designated Areas; Signs & Labels.  Establish “Designated Work Areas,” “Designated Storage Area,” and  “Restricted Access” areas.  These areas may include an entire laboratory, or an area of a laboratory, or a device such as a glove box or dedicated fume hood.
(a)   Appropriate signage (including “Authorized Personnel Only – Designated Area for use of [name of hazard]”) must be conspicuously posted at entrances to these work areas, and if necessary, the areas will be locked.  Only personnel with special instruction on the hazards and safe handling of these substances will be permitted access to the areas.
(b)  Equipment used for particularly hazardous substances should be isolated from general laboratory equipment.
(c)   Vacuum pumps should be protected by high-efficiency scrubbers or HEPA filters and must be vented into an exhaust hood.
(2)  Inventory.  All Laboratory Supervisors are required to maintain a list of particularly hazardous substances, and categorize each substance as a “Select Carcinogen,”  “Reproductive Toxin,” or “Compound with a High Degree of Acute Toxicity.”
(3)  SOPs.  Laboratory Supervisors are required to post written lab-specific Standard Operating Procedures and Precautions for work with Particularly Hazardous Substances.  All substance-specific SOP’s must be submitted to the Chemical Hygiene Office to be kept on file.
(4)  Records.  In all experiments involving particularly hazardous substances, the following information must be recorded:
(a)   The amounts of materials used.
(b)  Dates of use.
(c)   The names of workers involved.
(5)  PPE.  Proper gloves are mandatory.  In addition, consult the MSDS, LCSS or other appropriate sources of information for required protective equipment and apparel (beyond what is already required for handling “normal” hazardous chemicals).
(6)  Ventilation.  Use of ventilation equipment such as a fume hood or glove box is mandatory for any substance that can generate dust, vapors, aerosols, or mist.
(7)  Prior Approval.  
(a)   The laboratory worker must obtain permission from the laboratory supervisor prior to initiating any process involving Particularly Hazardous Substances.
(b)  The Laboratory Supervisor must obtain permission from the Campus Chemical Health & Safety Committee prior to ordering and using any substance that is recognized to have a high degree of acute toxicity.
(8)  Secondary Personnel.  Assure that at least two people are present at all times if the compound in use has a High Degree of Acute Toxicity.  Both persons must be properly trained in the use, hazards, and emergency response of the particular substance.
(9)  Amounts Used.  Work should be done with the smallest amounts possible.
(10) Action Levels.  For substances that have Action Levels, requirements for medical and exposure monitoring become effective.
(11) Procurement, Storage, and Moving.
(a)   Purchases of the chemicals will be restricted to minimal amounts necessary to prevent uninterrupted work.
(b)  Store chemicals in unbreakable, closed, chemically resistant secondary containers with a label such as WARNING! CANCER SUSPECT AGENT.
(c)   Store in a Designated Storage Area (that is labeled accordingly) in a cabinet or secondary containment tray.  Store volatile chemicals in a ventilated storage area (under a lightly negative pressure).
(d)   Movement of chemicals within and between lab spaces must be planned carefully.
(12) Contaminated Waste – Consult the MSDS, LCSS or other appropriate sources of information for toxicological properties, and special precautions.  Procedures for the safe removal of contaminated waste must be written and posted in the Designated Work Area. 
(13) Noncontamination/Decontamination Procedures must be written and posted in the Designated Work Area.  These Procedures must include:
(a)   Proper removal and disposal of PPE (this must occur before leaving the Designated Area).
(b)  Proper washing of hands, forearms, face, and neck (this must occur before leaving Designated Area).
(c)   Proper housekeeping, including decontamination of work surfaces (e.g., use of a wet mop or a vacuum cleaner equipped with a HEPA filter instead of dry sweeping if the toxic substance was a dry powder).
(d)   A written (and posted) requirement that all equipment (including PPE) must not be removed from the designated area without decontamination.
(14) First Aid. Ensure that the appropriate first-aid measures are readily available in the event of an exposure.
(15) OSHA 13 Carcinogens (29 CFR 1910.1003).  In regard to implementation of the OSHA Standard for the 13 Carcinogens you must provide particular information on how your laboratory-specific standard operating procedures deal with the following:
(a)   Set up and maintenance of the clean change rooms specified for use in conjunction with the regulated areas.
(b)  The medical surveillance program that must be instituted in conjunction with the use of any of the 13 Carcinogens.
(c)   29 CFR 1910.1003 can be found at
(d)   The OSHA 13 Carcinogens are:
4-Nitrobiphenyl, Chemical Abstracts Service Register Number (CAS No.) 92933;
alpha-Naphthylamine, CAS No. 134327;
methyl chloromethyl ether, CAS No. 107302;
3,3'-Dichlorobenzidine (and its salts) CAS No. 91941;
bis-Chloromethyl ether, CAS No. 542881;
beta-Naphthylamine, CAS No. 91598;
Benzidine, CAS No. 92875;
4-Aminodiphenyl, CAS No. 92671;
Ethyleneimine, CAS No. 151564;
beta-Propiolactone, CAS No. 57578;
2-Acetylaminofluorene, CAS No. 53963;
4-Dimethylaminoazo-benezene, CAS No. 60117; and
N-Nitrosodimethylamine, CAS No. 62759

8.17.c Medical Surveillance
(1)  If using toxicologically significant quantities of such a substance on a regular basis (e.g., 3 times per week), consult a qualified physician concerning desirability of regular medical surveillance.


    • Animal Work with Chemicals of High Chronic Toxicity

*** This Section is still under development


8.18.a Access. Facilities with restricted access are required.

8.18.b Administration of the Toxic Substance.
(1)  When possible, administer the substance by injection or gavage instead of in the diet.
(2)  If administration is in the diet, use a caging system under negative pressure or under laminar airflow directed toward HEPA filters.

8.18.c Aerosol Suppression.
(1)  Devise procedures which minimize formation and dispersal of contaminated aerosols, including those from food, urine, and feces (e.g., use HEPA filtered vacuum equipment for cleaning, moisten contaminated bedding before removal from the cage, mix diets in closed containers in a hood).

8.18.d Personal Protection.
(1)  When working in the animal room, wear plastic or rubber gloves, fully buttoned laboratory coat or jumpsuit and, if needed because of incomplete suppression of aerosols, other apparel and equipment (shoe and head coverings, respirator).

8.18.e Waste Disposal.
(1)  Dispose of contaminated animal tissues and excreta by incineration if the available incinerator can convert the contaminant to non-toxic products); otherwise, package the waste appropriately for burial in an EPA-approved site.