The following sections provide chemical safety guidelines and procedures. This chapter covers the following topics:
10.2 General Safety Guidelines
Almost everyone works with or around chemicals and chemical products every day. Many of these materials have properties that make them hazardous: they can create physical (fire, explosion) and/or health hazards (toxicity, chemical burns.) However, there are many ways to work with chemicals which can both reduce the probability of an accident to a negligible level and reduce the consequences to minimum levels should an accident occur. Chemical safety is inherently linked to other safety issues including laboratory procedures, personal protective equipment, electrical safety, fire safety, and hazardous waste disposal. Refer to other chapters in this manual for more information on these topics. The hazardous properties of the material and intended use will dictate the precautions to be taken.
Another important distinction is the difference between hazard and risk. The two terms are sometimes used as synonyms. The chemical's hazard is defined as its inherent capacity to do harm by virtue of its toxicity, flammability, explosiveness, corrosiveness, etc. Risk is a function of both the chemical hazard and the exposure potential (the likelihood or probability that a chemical will cause harm.) Thus, an extremely toxic chemical such as strychnine cannot cause poisoning if it is in a sealed container and does not contact the handler. In contrast, a chemical that is not highly toxic can be lethal if a large amount is ingested.
Not all chemicals are considered hazardous. Examples of nonhazardous chemicals include buffers, sugars, starches, agar, and naturally occurring amino acids.
The following sections provide general guidelines for chemical safety.
10.3 Chemical Safety Guidelines
Always follow these guidelines when working with chemicals:
Assume that any unfamiliar chemical is hazardous.
- Know all the hazards of the chemicals with which you work. For example, perchloric acid is a corrosive, an oxidizer, and a reactive. Benzene is an irritant that is also flammable, toxic, and carcinogenic.
- Consider any mixture to be at least as hazardous as its most hazardous component.
- Never use any substance that is not properly labeled.
- Follow all chemical safety instructions precisely.
- Minimize your exposure to any chemical, regardless of its hazard rating.
- Use appropriate personal protective equipment.
- Use common sense at all times.
10.4 Material Safety Data Sheets
Before using any chemical, read the container label and the appropriate Material Safety Data Sheets (MSDSs.) Container labels and MSDSs are good sources of information for chemical safety. They provide the following information:
- Hazardous ingredients
- Exposure limits
- Physical and chemical characteristics, including the boiling point, vapor pressure, color and odor
- Physical hazards, including the flammability, explosiveness, and reactivity
- Health hazards, including toxicity and carcinogenicity
- First-aid procedures
- Proper leak, spill, and disposal techniques
- Proper storage and handling procedures
- Other special provisions
10.5 Safe Handling Guidelines
Employees should treat all chemicals and equipment with caution and respect. When working with chemicals, remember to do the following:
10.6 Hygiene and Chemical Safety
- Remove and use only the amount of chemicals needed for the immediate
job at hand.
- Properly seal, label, and store chemicals in appropriate containers. Keep the containers clearly marked and in a well-ventilated area.
- Check stored chemicals for deterioration and broken containers.
- Learn how to dispose of chemicals safely and legally. Follow UT waste
- Clean up spills and leaks immediately.
- Know what to do in an emergency.
- Do not store chemicals near heat or sunlight or near substances which might initiate a dangerous reaction.
- Do not store flammable materials near electrical sources.
- Do not transport unprotected chemicals between the work area and other areas. Use a tray, rack, cart, or rubber carrier. Always use a secondary container when transporting hazardous or highly odorous chemicals on an elevator.
- Do not pour hazardous chemicals down the drain.
- Do not put fellow workers or yourself in danger.
10.6.1 Exposure Hazards
Health hazards associated with chemicals include exposure by the following routes:
Inhalation. Inhalation of a solvent may cause bronchial irritation, dizziness, central nervous system depression, nausea, headache, coma, or death. Prolonged exposure to excessive concentrations of solvent vapors may cause liver or kidney damage. The consumption of alcoholic beverages can enhance these effects.
Skin Contact. Skin contact with solvents may lead to defatting, drying, and skin irritation.
Ingestion. Ingestion of a solvent may cause severe toxicological effects. Seek medical attention immediately.
The odor threshold for the following chemicals exceeds acceptable exposure limits. Therefore, if you can smell it, you may be overexposed---increase ventilation immediately.
- Carbon Tetrachloride
- Methylene Chloride
NOTE: Do not depend on your sense of smell alone to know when hazardous vapors are present. The odor of some chemicals is so strong that they can be detected at levels far below hazardous concentrations (e.g., xylene.) In addition, some solvents (e.g., benzene) are known or suspected carcinogens.
Good personal hygiene will help minimize exposure to hazardous chemicals. When working with chemicals, follow these guidelines:
- Wash hands frequently and before leaving the laboratory. Also, wash hands before eating, drinking, smoking, or applying cosmetics.
- Remove contaminated clothing immediately. Do not use the clothing again until it has been properly decontaminated.
- Follow any special precautions for the chemicals in use.
- Do not eat, drink, smoke, or apply cosmetics in the laboratory.
- Do not keep food or food containers anywhere near chemicals.
- Do not use laboratory equipment to serve or store food or drinks.
- Do not sniff or taste chemicals.
10.7 Hazard Communication Program
UTIA has a written program (UTIA Hazard Communication Program) that complies with OSHA standards and the Tennessee Hazard Communication Act for hazardous chemicals. This program can be found in Section 5 of this plan. It requires the following:
- Employee training (including recognition of signs of exposure)
- Labeling procedures
- Material Safety Data Sheet(s) (MSDSs) for chemicals at each work place
- Instructions on how to read and interpret MSDSs
- Chemical inventory reporting procedures
- Record keeping requirements
- Emergency response procedures
Refer to the UTIA Hazard Communication Program and other sections in this manual for detailed information on these topics.
An integral part of hazard communication is hazard identification. Everyone who works with hazardous chemicals should know how to read and interpret hazard information. Signs, like the NFPA (National Fire Protection Association) Diamond alert employees to the known hazards in a particular location.
A corrosive chemical destroys or damages living tissue by direct contact. Some acids, bases, dehydrating agents, oxidizing agents, and organics are corrosives. See Examples of Corrosives.
10.8.1 Safe Handling Guidelines for Corrosives
To ensure safe handling of corrosives, the following special handling procedures should be used:
- Always store corrosives properly. Handle these chemicals with care and clean any spills, leaks, or dribbles immediately. Refer to the MSDSs and the Chemical Storage section for more information.
- Always wear non-latex gloves, face, and eye protection when working with corrosives. Wear other personal protective equipment, as appropriate.
- To dilute acids, always add the acid to the water.
- Use a chemical fume hood when handling fuming acids or volatile irritants (e.g., ammonium hydroxide.)
- A continuous flow eye wash station must be in every work area where corrosives are present. An emergency shower should also be within 100 feet of the area.
10.8.2 Corrosive Example: Perchloric Acid
10.9 FLAMMABLE CHEMICALS
A flammable chemical is any solid, liquid, vapor, or gas that ignites easily and burns rapidly in air. Consult the appropriate MSDSs before beginning work with flammable chemicals.
10.9.1 Flashpoint, Boiling Point, and Ignition Temperature
Flammable chemicals are classified according to flashpoint, boiling point, and ignition temperature. Flashpoint (FP) is the lowest temperature at which a flammable liquid gives off sufficient vapor to ignite. Boiling point (BP) is the temperature at which the vapor pressure of a liquid is equal to the atmospheric pressure under which the liquid vaporizes. Flammable liquids with low BPs generally present special fire hazards. The ignition temperature is the lowest temperature at which a chemical will ignite and burn independently of its heat source.
The linked table provides examples of common chemicals and their flashpoint and boiling point.
10.9.2 Conditions for a Fire
When working with flammable materials, always take care to minimize vapors which act as fuel. Improper use of flammable liquids can cause a fire. The following conditions must exist for a fire to occur:
- Flammable material must be present in sufficient concentration to support a fire (i.e., fuel.)
- Oxygen or another oxidizer must be present.
- An ignition source must be present (i.e., heat, spark, etc.)
10.9.3 Safe Handling Guidelines for Flammable Materials:
- Handle flammable chemicals in areas free from ignition sources.
- Never heat flammable chemicals with an open flame. Use a water bath, oil bath, heating mantle, hot air bath, etc.
- Use grounding straps when transferring flammable chemicals between metal containers to avoid generating static sparks.
- Use a fume hood when there is a possibility of dangerous vapors. (Ventilation will help reduce dangerous vapor concentrations.)
- Restrict the amount of stored flammable materials, and minimize the amount present in a work area.
- Remove from storage only the amount of chemical needed for a particular experiment or task.
Organic solvents are often the most hazardous chemicals in the work place. Solvents such as ether, alcohols, and toluene, for example, are highly volatile or flammable. Chlorinated solvents such as chloroform are nonflammable, but when exposed to heat or flame, may produce carbon monoxide, chlorine, phosgene, or other highly toxic gases.
When working with volatile and flammable solvents, use a fume hood. Never use ether or other highly flammable solvents in a room with open flames or other ignition sources present.
10.10.1 Reducing Solvent Exposure
To decrease the effects of solvent exposure, substitute hazardous solvents with less toxic or hazardous solvents whenever possible. For example, use Hexane instead of Diethyl Ether, Benzene, or a chlorinated solvent.
NOTE: The best all-around solvent is water; use it whenever possible.
See Solvent Substitution Table for examples.
10.11 Toxic Chemicals
The toxicity of a chemical refers to its ability to damage an organ system (kidneys, liver) disrupt a biochemical process (e.g., the blood-forming process,) or disturb an enzyme system at some site remote from the site of contact. Toxicity is a property of each chemical that is determined by molecular structure. Any substance can be harmful to living things. But, just as there are degrees of being harmful, there are also degrees of being safe. The biological effects (beneficial, indifferent, or toxic) of all chemicals are dependent on a number of factors.
For every chemical, there are conditions in which it can cause harm and, conversely, there are conditions in which it does not cause harm. A complex relationship exists between a biologically active chemical and the effect it produces involving: dose (the amount of a substance to which one is exposed), time (how often, and for how long during a specific time, the exposure occurs), the route of exposure (inhalation, ingestion, absorption through skin or eyes), and many other factors such as gender, reproductive status, age, general health and nutrition, lifestyle factors, previous sensitization, genetic disposition, and exposure to other chemicals.
The most important factor is the dose-time relationship. The dose-time relationship forms the basis for distinguishing between two types of toxicity: acute toxicity and chronic toxicity. The acute toxicity of a chemical refers to its ability to inflict systemic damage as a result (in most cases) of a short-term exposure (less than 24 hours) to relatively high dose of the chemical. In most cases, the exposure is sudden and results in an emergency situation. Do not work alone when handling acute toxins. Use a fume hood to ensure proper ventilation. Chronic toxicity refers to a chemical's ability to inflict systemic damage as a result of repeated exposures, over a prolonged time period (up to 6 months), to relatively low levels of the chemical. Some chemicals are extremely toxic and are known primarily as acute toxins (ie, hydrogen cyanide); some are known primarily as chronic toxins (ie, lead.) Other chemicals, such as some of the chlorinated solvents, can cause either acute or chronic effects.
The toxic effects of chemicals can range from mild and reversible (e.g., a headache from a single episode of inhaling the vapors of petroleum naphtha that disappears when the victim gets fresh air) to serious and irreversible (liver or kidney damage from excessive exposures to chlorinated solvents.) The toxic effects from chemical exposure depend on the severity of the exposures. Greater exposure and repeated exposure generally lead to more severe effects.
The following sections provide examples and safe handling guidelines for the following types of toxic chemicals:
- Reproductive toxins
IMPORTANT: Minimize your exposure to any toxic chemical.
Carcinogens are materials that can cause cancer in humans or animals. Several agencies including OSHA, NIOSH, and IARC (International Agency for Research on Cancer) are responsible for identifying carcinogens. There are very few chemicals known to cause cancer in humans, but there are many suspected carcinogens and many substances with properties similar to known carcinogens.
Examples of known carcinogens include the following:
- Tobacco smoke
- Chromium, hexavalent
Zero exposure should be the goal when working with known or suspected carcinogens. Workers who are routinely exposed to carcinogens should undergo periodic medical examinations.
A sensitizer may cause little or no reaction upon first exposure. Repeated exposures may result in severe allergic reactions. Examples of sensitizers include the following:
- Nickel salts
- Beryllium compounds
Irritants cause reversible inflammation or irritation to the eyes, respiratory tract, skin, and mucous membranes. Irritants cause inflammation through long-term exposure or high concentration exposure. For the purpose of this section, irritants do not include corrosives. Examples of irritants include the following:
- Sulfur dioxide
10.11.4 Reproductive Toxins
Reproductive toxins are chemicals that can produce adverse effects in parents and developing embryos. Chemicals including heavy metals, some aromatic solvents (benzene, toluene, xylene, etc.) and some therapeutic drugs are capable of causing these effects. In addition, the adverse reproductive potential of ionizing radiation and certain lifestyle factors, including excessive alcohol consumption, cigarette smoking, and the use of illicit drugs, are recognized. While some factors are known to affect human reproduction, knowledge in this field (especially related to the male) is not as broadly developed as other areas of toxicology. In addition, the developing embryo is most vulnerable during the time before the mother knows she is pregnant. Therefore, it is prudent for all persons with reproductive potential to minimize chemical exposure.
10.12 Reactives and Explosives
Reactive chemicals are sensitive to either friction or shock, or they react in the presence of air, water, light, or heat. Explosive chemicals decompose or burn very rapidly when subjected to shock or ignition. Reactive and explosive chemicals produce large amounts of heat and gas; they are extremely dangerous. See Linked Table for examples.
10.13 Cleaning Agents
Many of the chemicals contained in cleaning agents are corrosive. Follow these guidelines when working with any cleaning agent.
- Always read and understand the label instructions or the Material Safety Data Sheet(s) (MSDSs) before using any cleaning agent.
- Mix solutions to the recommended strength.
- When diluting acid with water, always add the acid to the water.
- Wear appropriate eye protection and non-latex gloves for the job (e.g., neoprene, nitrile, or rubber.)
- Do not leave aerosol cans in direct sunlight or areas where the temperature may exceed 120F. Heated aerosol cans may explode.
The linked table outlines common cleaning agents, their hazards, and safety precautions
10.14 Spill Response
Spills are likely whenever chemicals are used. Personnel should be trained and equipped to handle most of the spills in their work area. Contact the Safety Officer for assistance or advice about a chemical spill.
10.14.1 Spill Prevention and Planning
Prevention is the best safety strategy for any environment. Use safe handling procedures and be aware of the potential hazards associated with chemicals. For example, before working with any chemicals, review the appropriate Material Safety Data Sheet(s) (MSDSs.)
Be prepared to respond to any chemical spill under 1 gallon. To prepare for a potential spill, follow these guidelines:
- Develop and periodically review written procedures for emergency response
- Keep a fully stocked chemical spill response kit available
- Know the location and proper use of cleanup materials
- Know how to turn off equipment, heat sources, electrical panels, etc
- Review appropriate Material Safety Data Sheet(s).
10.14.2 Spill Response Kit
Work areas that contain potentially hazardous chemicals should have a chemical spill response kit. This kit should include the following items:
- disposable laboratory/surgical gloves
- disposable vinyl gloves
- safety goggles
- absorbent (e.g., spill pillows, vermiculite, litter box filler, etc.)
- plastic scoop
- plastic trash bags
- mercury spill kit (if mercury is present)
10.14.3 Responding to Chemical Spills
The following sequence provides a brief overview of proper chemical spill response procedures:
- Notify others in the immediate area that a spill has occurred. Evacuate the area if necessary.
- Attend to injured and exposed people.
- Identify the spilled chemical(s), and read the MSDS to determine the proper procedure for cleaning up the spill.
- Based on the hazards and the personal protective equipment needed (e.g., respiratory protection), determine if you can safely clean the spill or if assistance is necessary. (Most spills can be cleaned safely by the people who were using the chemical.)
If you determine that you can safely clean the spill without emergency assistance, follow these guidelines:
- Wear appropriate protective clothing and equipment.
- Have another person stand by during the cleanup.
- Clean up the spill and collect all wastes for proper disposal.
- Ventilate the area, as necessary, before it is re-occupied.
- Decontaminate reusable cleanup supplies such as scoops, rubber boots, etc.
- Restock the chemical spill kit and return it to the normal storage location before using any more chemicals.
Do not take unnecessary risks with chemical spills. Call the Safety Officer whenever a spill involves the following:
- large volume of spilled material
- very hazardous material
- very hazardous conditions (e.g., fire, explosion, toxicity, etc.)
- strong odor
- personnel injury or exposure
10.15 Chemical Storage
Proper chemical storage is as important to safety as proper chemical handling. Often, seemingly logical storage ideas, such as placing chemicals in alphabetical order, may cause incompatible chemicals to be stored together.
10.15.1 General Guidelines
Follow these guidelines for safe chemical storage:
- Read chemical labels and Material Safety Data Sheet(s) (MSDSs) for specific storage instructions.
- Store chemicals in a well-ventilated area; however, do not store chemicals in a fume hood.
- Maintain an inventory of all chemicals in storage.
- Return chemical containers to their proper storage location after use.
- Store glass chemical containers so that they are unlikely to be broken.
- Store all hazardous chemicals below eye level.
- Never store hazardous chemicals in a public area or corridor.
10.15.2 Storage Guidelines by Specific Chemical Group
10.15.2.1 Separating Hazardous Chemicals
The following information provides examples of incompatible chemicals (meaning these chemicals should never be stored together.) This list should not be considered complete and persons unsure as to the status of a particular chemical are advised to refer to more recent literature, the manufacturer, as well as MSD Sheets. This information was extracted from the University of Kentucky's Model Chemical Hygiene Plan and "Safety in Academic Chemistry Laboratories," from the American Chemical Society.
10.15.2.2 Incompatible Chemicals
The linked table provides examples of Incompatible Chemicals.
10.15.3 Common Compounds That Form Peroxides During Storage
The linked table provides examples of Peroxide Forming Chemicals.
10.16 Shipping/Receiving Chemicals
The U.S. Department of Transportation regulates the shipment of hazardous materials. Anyone who packages, receives, unpacks, signs for, or transports hazardous chemicals must be trained and certified in Hazardous Materials Transportation. The Institute of Agriculture will receive, but does not ship hazardous materials. Contact the Safety Office for more information.