MSDSs

6.0 CHEMICAL HAZARDS

"What is it that is not poison? All things are poison, and nothing is without poison. It is the dose only that makes a thing not a poison."
- Paracelsus (1493 - 1541)

6.1.1 Exposure Routes. Chemicals enter the body through the following routes:

• Inhalation - absorption through the respiratory tract by inhalation. This is probably the easiest way for chemicals to enter the body.
• Ingestion - absorption through the digestive tract by eating or smoking with contaminated hands or in contaminated work areas. Depending on particle or droplet size, aerosols may also be ingested.
• Skin or eye contact - absorption through the skin or eyes. Skin contact is the most common cause of the widespread occupational disease dermatitis. The eyes are very porous and can easily absorb toxic vapors that cause permanent eye damage.
• Injection - percutaneous injection through the skin. This can occur through misuse of sharp items, especially hypodermic needles.
• Toxic effects can be immediate or delayed, reversible or irreversible, local or systemic.

6.1.2 Acute and Chronic Toxicity. Toxicity is the measure of a poisonous material's adverse effect on the human body or its ability to damage or interfere with the metabolism of living tissue. Generally, toxicity is divided into two types, acute and chronic. Many chemicals may cause both types of toxicity, depending on the pattern of use.

Acute toxicity is an adverse effect with symptoms of high severity coming quickly to a crisis. Acute effects are normally the result of short-term exposures and are of short duration. Examples of acutely toxic chemicals are hydrogen cyanide and ammonia.

Chronic toxicity is an adverse effect with symptoms that develop slowly over a long period of time as a result of frequent exposure. The dose during each exposure period may frequently be small enough that no effects are noticed at the time of exposure. Chronic effects are the result of long-term exposure and are of long duration. Carcinogens as well as many metals and their derivatives exhibit chronic toxicity.

Cumulative poisons are chemicals that tend to build up in the body as a result of numerous chronic exposures, leading to chronic toxicity. The effects are not seen until a critical body burden is reached. Examples of cumulative poisons are lead and mercury.

With substances in combination, such as exposure to two or more hazardous materials at the same time, the resulting effect can be greater than the combined effect of the individual substances. This is called a synergistic or potentiating effect. One example is concurrent exposure to alcohol and chlorinated solvents.

The published toxicity information for a given substance is general-human data may not be available-and the actual effects can vary greatly from one person to another. Do not underestimate the risk of toxicity. All substances of unknown toxicity should be handled as if they are toxic, with the understanding that any mixture may be more toxic than its most toxic component.

6.1.3 Carcinogenicity. A carcinogen is a chemical that causes malignant (cancerous) tumors. Individual carcinogens currently regulated by OSHA are listed in Appendix A along with recognized and suspected carcinogens identified by other agencies. The use of carcinogens is regulated by the University and requires submission of a Laboratory Safety Profile. Any chemical identified in Appendix A shall be handled as a known carcinogen.

6.1.4 Reproductive Toxins. Chemicals can affect both adult male and female reproductive systems. Chemicals may also affect a developing fertilized ovum, embryo, or fetus through exposure to the mother (teratogenic effects). Reproductive hazards affect people in a number of ways, including mental disorders, loss of sexual drive, impotence, infertility, sterility, mutagenic effects on cells, teratogenic effects on the fetus, and transplacental carcinogenesis. Consult the MSDS for information on possible reproductive hazards. The use of reproductive toxins is regulated by the University and requires submission of a Laboratory Safety Profile.

6.1.5 Designated Area. Work involving selected carcinogens, reproductive toxins, and substances of high acute toxicity shall be conducted in a "designated area." This is a requirement of the OSHA Laboratory Standard. This area shall be so posted, and all employees working within the area shall be informed of the hazardous substances used there. The designated area may be a chemical fume hood, a part of a laboratory, or the entire laboratory.

6.1.6 Material Safety Data Sheets (MSDSs). MSDSs are the most basic source of chemical hazard information. The MSDS summarizes the chemical's properties, the health and physical hazards, including the type of toxicity information discussed in the sections above, and related safety information required by emergency responders.Principal investigators or supervisors shall provide staff with easy access to MSDSs for each of the chemicals in use or storage in their labs. Contact ORS for help in obtaining MSDSs.

6.1.7 Monitoring Airborne Concentrations of Contaminants. OSHA has established permissible exposure limits (PELs) for airborne concentrations of selected materials. The PEL is defined as a time-weighted average (TWA) concentration of a particular substance for a normal eight-hour workday and a 40-hour workweek, a concentration to which nearly all workers may be exposed, day after day, without adverse effect.

Corollaries to the eight-hour PEL are the short-term exposure limit (STEL) and the ceiling exposure limit. The STEL is the time-weighted average concentration of a compound to which a worker may be exposed over a period of fifteen minutes without expecting symptoms of irritation, chronic or irreversible tissue damage, or narcosis. The ceiling is the concentration of a substance that should not be exceeded during any part of the working exposure. When instantaneous monitoring is not feasible, the ceiling limit is measured over a period of ten to fifteen minutes.

As the PELs were designed to protect workers in industrial settings, it is unlikely that these limits will be exceeded during the performance of laboratory procedures. Laboratory workers generally do not handle the same quantities of hazardous materials as do manufacturing and production employees

Nonetheless, exposure to airborne chemicals in laboratories shall not exceed PELs. If there is reason to believe that airborne concentrations may exceed PELs, contact ORS for consultation on the need for air monitoring. PELs are listed on Material Safety Data Sheets, are available from ORS, or may be found on the OSHA Web page (http://www.osha.gov/SLTC/pel/index.html). Please note that PELs have not been developed for all the compounds to which laboratory workers may be exposed. In all circumstances, caution shall be used in handling hazardous chemicals.

In addition to PELs, OSHA has set action levels for specific compounds, such as formaldehyde, cadmium, and lead, for which individual standards have been promulgated. OSHA has classified these compounds as potential carcinogens. The Laboratory Safety Profile discusses the specific requirements which apply to OSHA-classified carcinogens. Action levels are concentrations of a chemical in air at which OSHA regulations to protect workers take effect.

If monitoring of airborne concentrations reveals that levels are above the OSHA action level, then levels shall either be immediately reduced by a procedural change or equipment modification or the department head and principal investigator shall comply with the requirements of the OSHA standard for the chemical. OSHA regulations govern periodic monitoring and termination of monitoring, as well as employee notification. Medical surveillance may be a requirement.

For chemicals without regulated action levels, the general rule is that half the PEL may be considered a de facto action level. Engineering controls shall be instituted to reduce exposure to the hazardous substance in question.

6.2 Guidelines for Handling Chemicals The chemical handling guidelines described in this document are founded on several basic principles:

• Substitute less hazardous chemicals whenever possible
• Minimize chemical exposures
• Avoid underestimating risk
• Provide adequate ventilation

Since most chemicals are hazardous to some degree, it is prudent to minimize exposure to chemicals as a general rule, rather than implementing safety protocols only for specific compounds. Avoid skin contact with chemicals as much as possible. Assume that mixtures are more toxic than their components and that all substances of unknown toxicity are toxic. Do not work with a volatile or aerosolizing material without adequate ventilation from chemical fume hoods or other protective devices. Remember: Prepare yourself, then protect yourself.

6.2.1 General Guidelines. The following guidelines are applicable to nearly all uses of chemicals in laboratories. They apply to most hazardous chemicals, such as acids, bases, and flammable liquids. They are also applicable to chemicals that display low carcinogenic potency in animals and are not considered carcinogens.

The general guidelines are not, by themselves, adequate for chemicals with high acute toxicity or high chronic toxicity such as heavy metals, chemical carcinogens, or reproductive toxins.

1. Wear eye protection at all times where chemicals are used or stored.
2. Wear a lab coat or other protective clothing (e.g., aprons).
3. Wear gloves selected on the basis of the hazard. Inspect them before use. Wash reusable gloves before removal. Turn disposable gloves inside out carefully when removing to avoid contaminating hands.
4. Wash hands immediately after removing gloves, after handling chemical agents, and before leaving the lab, even though you wore gloves.
5. Lab coats and gloves are worn only in the lab. They are not taken outside the lab to lunch rooms or offices nor are they worn outdoors. Lab coats shall be cleaned frequently.
6. Confine long hair and loose clothing.
7. Wear sturdy shoes that cover feet completely.
8. Do not store or prepare food, eat, drink, chew gum, apply lip balm or cosmetics, or handle contact lenses in areas where hazardous chemicals are present.
9. Check with your supervisor regarding contact lens policy in your lab. If wearing them is acceptable, take appropriate precautions such as informing other lab occupants and having a suction-type removal device in your first aid kit.
10. Food is stored in cabinets or refrigerators designated for such use only.
11. Never pipette or start a siphon by mouth.
12. Label all chemical containers (see Section 6.5.1).
13. Chemical storage is by hazard class (see Section 6.7). Chemicals are not stored merely by alphabetical order (see Section 6.5).
14. Never smell or taste chemicals. Again, label containers properly to avoid confusion about contents.
15. Keep work areas clean and uncluttered.
16. Keep personal belongings away from chemicals.
17. Obtain an MSDS for each chemical, and consult the MSDS before you use a chemical.
18. Know the emergency procedures for the building, the department, and the chemicals being used.
19. Vent into local exhaust devices any apparatus that may discharge toxic vapors, fumes, mists, dusts, or gases. Never release toxic chemicals into cold rooms or warm rooms that have recirculating atmospheres.
20. Use chemical fume hoods or other engineering controls to minimize exposure to airborne contaminants.
21. Properly handle, collect, and dispose of surplus and waste chemicals (see Section 6.8).

6.2.2 Guidelines for Working with Chemicals of Acute Toxicity. Chemicals of acute toxicity are defined by OSHA as those that cause rapid effects as a result of a short-term exposure-generally sudden and severe, as in the case of a leak from equipment. Acute toxic effects include irritation, corrosion, sensitization, and narcosis.

To illustrate, hydrofluoric acid (HF) is a chemical of high acute toxicity because of its destructive effect on skin and bone tissue. Arsine and other hydrides may be lethal at low concentrations because of red blood cell hemolysis. Inhalation of high concentrations of carbon monoxide can cause immediate poisoning and death, as the gas directly interferes with oxygen transport in the body by preferentially binding to hemoglobin. Hydrogen cyanide inhalation inhibits enzyme systems vital to cellular uptake of oxygen.

When working with significant quantities of such chemicals, the aim is to minimize exposure to the material. Special care should be taken in the selection of protective clothing to ensure it is appropriate for the hazard. Personal hygiene and work practices should also be carefully evaluated to minimize exposure. The following guidelines should be practiced in addition to the general guidelines for handling chemicals.

1. When performing procedures that may result in the release of airborne contaminants, use a chemical fume hood.
2. Trap or treat effluents to remove gases, fumes, vapors, and particulates before discharging them to facility exhaust.
3. Restrict access to the laboratory or work area.
4. Establish and label a "designated area" for work with acutely toxic chemicals. Keep materials within the designated area.
5. Use plastic-backed paper or trays under work areas. Replace the paper when contaminated.
6. Develop and know special emergency procedures. Keep emergency supplies at hand for immediate use. When hydrofluoric acid is in use, the first aid kit should contain HF antidote gel. See the First Aid Kit Policy and Guidelines for Laboratories for purchasing and application information.

6.2.3 Guidelines for Chemicals with High Chronic Toxicity, Carcinogens, and Reproductive Toxins. In addition to the general guidelines for handling chemicals, use the following guidelines for handling chemicals with high chronic toxicity, which include most heavy metals, chemicals displaying moderate to high carcinogenic potency in animals, and reproductive toxins.

1. For carcinogens, determine if the chemical is regulated by OSHA in a substance-specific standard. If so, the principal investigator or lab supervisor shall document a hazard evaluation. See your Laboratory Safety Profile.
2. Designated work and storage areas shall be established for carcinogens, chemicals with high chronic toxicity, and reproductive toxins. Materials shall be kept within the designated area to the extent possible.
3. Designated work and storage areas for chemical carcinogens, including chemical fume hoods and refrigerators, shall be labeled "Chemical Carcinogen." The outer door to the laboratory shall also be labeled "Chemical Carcinogen."
4. Designated work and storage areas used for chemicals with high chronic toxicity or reproductive toxins shall be labeled "Toxic Chemical" or "Toxic Substance."
5. Access procedures shall be used if work involves moderate or greater amounts of carcinogens or moderate to lengthy procedures. These procedures may include:
   • closed doors
   • restricted access-only authorized personnel permitted
   • written access procedures posted on the outer door.
6. Cover laboratory surfaces, including chemical fume hood surfaces, with plastic-backed paper or protective trays. Inspect work surfaces following procedures, and remove the paper if contamination is present. Dispose of the used paper as hazardous waste.
7. Disposable gloves shall be disposed of as hazardous waste. Wash reusable gloves before removing them. Contact ORS prior to washing to determine if the wash water must be collected for disposal as a hazardous waste.
8. Transport highly toxic or carcinogenic materials through public areas, such as hallways, in closed containers within unbreakable outer containers. Sealed plastic bags may be used as secondary containment in many cases.
9. To avoid potential inhalation hazards, handle powdered carcinogens and toxins in a chemical fume hood, even during weighing procedures. Inside the chemical fume hood, measure the powder with a spatula into a preweighed vessel then seal or cover the vessel, remove it from the chemical fume hood, and take it to the balance to be weighed. If more or less material is needed, return the container to the chemical fume hood for addition or subtraction of material. Close the container again and reweigh it. Repeat these steps until the desired amount is obtained. This procedure eliminates contamination of the air, the work bench, and the scale. Procedures generating either solid or liquid airborne contaminants or involving volatile chemicals are always to be performed in a chemical fume hood.
10. Vacuum pumps shall be protected against contamination (e.g., traps and filters in lines) and vented into direct exhaust ventilation. Pumps and other equipment and glassware shall be decontaminated before they are removed from the designated area. The designated area shall be decontaminated before other normal work is conducted. Vacuum pump oil shall be collected as a contaminated waste and disposed of through ORS.
11. Water vacuum lines shall be equipped with traps to prevent vapors from entering the wastewater stream.
12. Floors shall be wet-mopped or cleaned with a high-efficiency particulate air filter (HEPA) vacuum cleaner if powdered materials are used.

6.3 Chemical Emergency Procedures

6.3.1 Procedures for Spills of Volatile, Toxic, or Flammable Materials.

1. Warn all persons nearby.
2. Turn off any ignition sources such as burners, motors, and other spark-producing equipment.
3. Leave the room and close the door if possible.
4. Call 911 to report a life-threatening hazardous material spill (dial 456 for non-emergencies).
5. Small spills can be absorbed with paper towels or other absorbents. However, these materials can increase the surface area and evaporation rate, increasing the potential fire hazard if the material is flammable and airborne concentration reaches the flammability level.

6.3.2 Procedures for Chemical Spill on a Person.

1. Know where the nearest eyewash and safety shower are located.
2. For small spills on the skin, flush immediately under running water for at least fifteen minutes, removing any jewelry that might contain residue. If there is no sign of a burn, wash the area with soap under warm running water. Exception: only five minutes of flushing for HF burns. Proceed to aggressive antidote gel application as soon as possible. The antidote is the best hope of preventing permanent bone or tissue damage.
3. If pain returns after the fifteen-minute flooding, resume flooding the area (but not for HF spills). When providing assistance to a victim of chemical contamination, use appropriate personal protective equipment.
4. For a chemical splash in the eyes, immediately flush the eyes under running potable water for fifteen minutes, holding the eyes open and rotating the eyeballs. This is preferably done at an eyewash fountain with tepid water and properly controlled flow. Hold the eyelids open and move the eye up, down, and sideways to ensure complete coverage. Use an irrigator loop to thoroughly flush the conjunctiva under the upper eyelid, if available in your first aid kit. If no eyewash fountain is available, put the victim on his or her back and gently pour water into the eyes for fifteen minutes or until medical personnel arrive. If HF is splashed in the eye, flush for five minutes and then irrigate the eye with a 1% solution prepared from the calcium gluconate antidote gel.
5. For spills on clothing, immediately remove contaminated clothing, including shoes and jewelry, while standing under running water or the safety shower. When removing shirts or pullover sweaters, be careful not to contaminate the eyes. Cutting off such clothing will help prevent spreading the contamination. To prepare for emergencies, shears (rounded-tip scissors) should be available in the first aid kit to allow safe cutting of contaminated clothing.
6. Consult the MSDS to see if any delayed effects should be expected, and keep the MSDS with the victim. Call UP to have the victim taken to the emergency room for medical attention. Be sure to inform emergency personnel of the decontamination procedures used prior to their arrival (for example, flushing for fifteen minutes with water). Be certain that emergency room personnel are told exactly what the victim was contaminated with so they can treat the victim accordingly.

6.3.3 Procedure for Cryogenic Liquid Spill on a Person. Contact with cryogenic liquids may cause crystals to form in tissues under the spill area, either superficially or more deeply in the fluids and underlying soft tissues. The first aid procedure for contact with cryogenic liquids is identical to that for frostbite. Rewarm the affected area as quickly as possible by immersing it in warm, but not hot, water (between 102° and 105° F). Do not rub the affected tissues. Do not apply heat lamps or hot water and do not break blisters. Cover the affected area with a sterile covering and seek assistance as you would for burns.

6.3.4 Incidental Spills—Procedure for Small, Low-Toxicity Chemical Spills. Be prepared. Keep appropriate spill-containment material on hand for emergencies. Consult with ORS to determine which materials are suitable in a particular lab.

Laboratory workers must receive training to distinguish between the types of spills they can handle on their own and those spills that are classified as "MAJOR." Major spills dictate the need for outside help.

Laboratory workers are qualified to clean-up spills that are "incidental." OSHA defines an incidental spill as a spill that does not pose a significant safety or health hazard to employees in the immediate vicinity nor does it have the potential to become an emergency within a short time frame. The period that constitutes a short time is not defined. Laboratory workers can handle incidental spills because they are expected to be familiar with the hazards of the chemicals they routinely handle during an "average" workday. If the spill exceeds the scope of the laboratory workers' experience, training or willingness to respond, the workers must be able to determine that the spill cannot be dealt with internally.

Emergency assistance is provided by ORS or an outside agency. Spills requiring the involvement of individuals outside the lab are those exceeding the exposure one would expect during the normal course of work. Spills in this category are those which have truly become emergency situations in that laboratory workers are overwhelmed beyond their level of training. Their response capability is compromised by the magnitude of the incident.

Factors that clearly indicate a major spill are:

• the need to evacuate employees in the area
• the need for response from outside the immediate release area
• the release poses, or has potential to pose, conditions that are immediately dangerous to life and health
• the release poses a serious threat of fire and explosion
• the release requires immediate attention due to imminent danger
• the release may cause high levels of exposure to toxic substances
• there is uncertainty that the worker can handle the severity of the hazard with the PPE and equipment that has been provided and the exposure limit could be easily exceeded
• the situation is unclear or data is lacking regarding important factors.

The following steps shall be followed for incidental spills:

1. Alert persons in the area that a spill has occurred.
2. Evaluate the toxicity, flammability, and other hazardous properties of the chemical as well as the size and location of the spill (for example, chemical fume hood or elevator) to determine whether evacuation or additional assistance is necessary. Large or toxic spills are beyond the scope of this procedure.
3. Contain any volatile material within a room by keeping doors closed. Increase exhaust efficiency by minimizing sash height of the chemical fume hood or activating the emergency purge, if available.
4. Consult your MSDS, the laboratory emergency plan, or procedures in this document, or call ORS for correct cleaning procedures.
5. Obtain cleaning equipment and protective gear from ORS, if needed.
6. Wear protective equipment such as goggles, apron, laboratory coat, gloves, shoe covers, or respirator. Base the selection of the equipment on the hazard.
7. First, cordon off the spill area to prevent inadvertently spreading the contamination over a much larger area.
8. Absorb liquid spills using paper towels, spill pillows, vermiculite, or sand. Place the spill pillow over the spill and draw the free liquid into the pillow. Sprinkle vermiculite or sand over the surface of the free liquid.
9. Place the used pillows or absorbent materials in plastic bags for disposal along with contaminated disposable gear, such as gloves.
10. Neutralize spills of corrosives and absorb, if appropriate. Sweep up waste and place in plastic bags for disposal.
11. Complete a Surplus Chemical Collection Form. ORS will pick up the wastes.
12. Complete an Incident Report describing the spill and send a copy to ORS. A copy may be kept by the department head, if required.

Note: Information for specific chemicals may be found in Table 6.1, "Quick Reference for Spill Cleanups," and Section 6.3.5, "Mercury Spill Procedure." Consult the MSDS and your laboratory's Laboratory Safety Profile, which has specific information on spill procedures for your workplace.

6.3.5 Mercury Spill Procedure. Mercury is a high-density, low-viscosity liquid at room temperature. During a spill, it can form tiny droplets that adhere to surfaces and enter cracks and crevices. ORS has a mercury vacuum and mercury vapor analyzer available to assist with large or difficult-to-clean mercury spills. In the case of small mercury spills (e.g., mercury-containing thermometers), laboratory personnel should be able to handle the cleanup. Cleanup kits are available from ORS.

To minimize the spill hazard, place a splash plate beneath all mercury-containing equipment.

Procedures for small mercury spills:
Equipment needed – Mercury Spill Kit from ORS

Mercury vacuum pump, eyedropper, water or vacuum drive aspirator (optional)

Chemical amalgam

Laboratory coat

Gloves

Shoe protectors

Glass or plastic collection container

Plastic bags

Wipes or paper towels

Barricade tape

1. Before entering the contaminated area, put on protective clothing.
2. Establish a cleanup area and section it off to avoid spreading mercury.
3. Draw all visible mercury into a glass or plastic collection container.
4. Sprinkle the contaminated area with chemical amalgam. Wet with a little water.
5. Wipe up the powder from the contaminated area with a wet towel or a damp sponge impregnated with chemical amalgam. Repeat steps 4 and 5.
6. Sprinkle a very light coating of chemical amalgam into the cracks and crevices.
7. Dispose of the contaminated solid waste material (such as boots, gloves, wipes, or thermometer glass) in a plastic bag and seal tightly.
8. Dispose of the collected mercury and the bags of waste through ORS. Do not bring the waste bag to ORS; it will be picked up from your laboratory. Store the bag in a chemical fume hood until it is collected by ORS.
9. The principal investigator shall ensure that an Incident Report is completed and sent to ORS.

6.4 Medical Surveillance

6.4.1 When is Medical Surveillance Required?

Signs and Symptoms. Whenever an employee or student develops signs or symptoms associated with a hazardous chemical exposure, that person shall be provided an opportunity to receive an appropriate medical examination.

Exposure Monitoring. If exposure monitoring reveals that the airborne concentration of a chemical is above the action level or the permissible exposure limit (if no action level is set) for a chemical regulated by OSHA, medical surveillance shall be implemented for affected persons as prescribed in the OSHA standard for the material.

Spills, Leaks, and Other Releases. If a spill, leak, explosion, or other occurrence results in the likelihood of a hazardous chemical exposure, affected employees shall be provided an opportunity for a medical consultation. The consultation will determine whether there is a need for a medical examination.

6.4.2 Medical Consultation and Evaluation. Medical consultation and evaluation shall be performed under the direct supervision of a licensed physician without cost to the employee or student, without loss of pay, and at a reasonable time and place. For employees, medical examinations or surveillance shall be provided through the Workers' Compensation Program administered by the claims manager in the Office of Risk Management. For students, the medical program shall be administered through the University Health Service facilities.

The principal investigator or laboratory supervisor shall ensure that the following information is provided to the physician: the identity of the chemical involved in the exposure, a description of conditions relating to the exposure, any quantitative data available regarding the exposure, and a description of signs and symptoms experienced by the affected person.

The principal investigator or laboratory supervisor shall ensure that the following information is obtained from the physician in writing:

• Recommendation for medical follow-up.
• Results of the medical examination and associated tests.
• Any medical condition revealed in the course of the examination that may place the affected person at increased risk as a result of the exposure.
• A statement that the physician has informed the affected person of the results of the consultation or examination and any medical condition that may require further treatment.
• The physician shall not reveal specific findings or diagnoses unrelated to the chemical exposure. All medical records shall be kept as part of an employee's or student's permanent file.

6.4.3 Medical Surveillance for Chemicals of High Chronic Toxicity. Routine medical surveillance may be warranted for individuals working with chemicals of high chronic toxicity, including carcinogens.

Although no restriction of hiring can be made, candidates for work with carcinogens shall be informed of the possibility of increased risk associated with these conditions:

• Strong family history of cancer, comprising at least two first-generation relatives from maternal and paternal ancestry or a specific pattern of cancer incidence that can be recognized as a genetic trait.
• A precancerous condition or past history of cancer.
• A history of exposure to therapeutic doses of radiation.
• A history of treatment with cytotoxic drugs.
• A history of impaired immunity or current use of therapeutic doses of steroids or other immunosuppressive drugs.
• Concurrent pregnancy or likelihood of pregnancy during employment.

Job tasks for certain workers using chemicals of high chronic toxicity should be evaluated to determine whether these workers should be temporarily excluded from work or reassigned to less hazardous activities. This is particularly appropriate for pregnant women or persons receiving immunosuppressive drugs or therapy.

6.5.1 Chemical Labels. Label all containers of hazardous chemicals in accordance with the OSHA Hazard Communication Standard. Each container of and/or apparatus with hazardous chemical contents in the lab shall be labeled with the following information:

• identity of the hazardous chemical(s)
• hazard warnings in words, pictures, symbols, or a combination thereof, which provide at least general information regarding the hazards of the chemical(s)

See the Hazard Communication Program for further labeling guidance.

6.5.1.1 NFPA 704 System
National Fire Protection Association 704, "Standard for the Identification of Fire Hazards of Materials," is one of the most widely used marking systems. Although there is no University requirement that labeling must comply with this system, it is helpful to be familiar with these labels as they are so pervasive. Be prepared to recognize these markings on containers received from vendors. Be aware that this labeling system does not in itself meet the requirements of the Hazard Communication Standard.

The system was originally devised for industry to use on such facilities as storage tanks or buildings so that firefighters could assess the hazard from a safe distance and better evaluate what fire-fighting techniques to employ. The system can also be useful in situations other than fires when used on container labels or room doors so that a person working in the room or area can quickly determine the degree of hazard of a particular chemical. Several kinds of kits with pressure-sensitive diamonds and separate numbers in several sizes can be purchased from safety supply distributors.

The system does not provide any detailed hazard information and does not supersede the need for posting the other required information (such as the name of the chemical and the name of the manufacturer) on a portable container label. The diamond-shaped label shown identifies three categories of hazards in three squares of different colors. The blue square at the left indicates health hazard, the red square at the top indicates flammability, and the yellow square at the right indicates reactivity.

The degree of severity under fire conditions is indicated numerically by five divisions ranging from 0 to 4, with 0 indicating no hazard and 4 indicating severe hazard. Any special hazard, such as unusual reactivity with water, is indicated in a white square at the bottom of the diamond.

HMIS was developed by the National Paint and Coatings Association. It uses the same numbering system as NFPA 704 for health, flammability, and reactivity hazards, but the label includes some additional information.

The identity of the chemical (chemical or trade name) is shown at the top of the label. Instead of the three colored diamonds used by NFPA 704, the HMIS uses colored bars (blue for health, red for flammability, yellow for reactivity), each with its separate numerical coding. As in NFPA 704, the degree of hazard is expressed in a numerical rating on a scale of 0 to 4, with 0 denoting a minimal hazard and 4 a severe hazard.

A white bar at the bottom of the label contains a letter representing one or more personal protective devices that must be used when handling that substance. The label also specifies chronic health hazards.

6.5.1.3 Chemical Dating
Chemicals shall be dated on receipt in the laboratory and on opening. This information provides a history of the chemicals in each container and guides future researchers as to potential quality of the chemicals stored in the laboratory. Providing container-opening dates is especially important for peroxide-forming chemicals such as ethers, dioxane, isopropanol, and tetrahydrofuran that could pose an explosion hazard. Solutions shall be labeled and dated when prepared. Chemicals shall be removed from the laboratory if they are past their expiration date.

6.5.2 Chemical Compatibility. Chemicals shall be stored only with other compatible chemicals (see Table 6.2 for classes of incompatible chemicals). Do not store them alphabetically, except within a grouping of compatible chemicals. Chemical groupings are listed below, and their storage arrangement is shown in a picture of a laboratory below.

• Highly toxic (poisons) and habit-forming organic chemicals.
• Flammable organic chemicals and organic acids.
• Organic bases and other organic compounds.
• Inorganic (mineral) acids and inorganic oxidizers (some additional separation may be required because of the reactivity of these materials).
• Inorganic bases, reducers, and salts.

Take into account specific chemical incompatibilities in all storage of chemicals (see Table 6.3). For example, nitric and chromic acids are incompatible and shall not be stored together. Nitric acid and organic compounds together present a dangerous fire risk. Carcinogenic chemicals are to be stored with others of a similar grouping based on their properties.

6.5.3 Storage Facilities. Highly toxic chemicals (such as cyanide, cacodylic acid), shock-sensitive chemicals (such as solid sodium azide or picric acid), and habit-forming chemicals (amyl nitrite) shall be stored in locked cabinets to prevent theft.

Peroxide-forming chemicals and those that may become shock-sensitive with long-term storage shall be stored separately and shall be labeled and dated. Peroxide-forming chemicals shall be stored in a cool, dark, dry place.

Flammable liquids shall be stored in flammable-liquid cabinets if the laboratory contains a total of 10 gallons or more, including flammable liquid wastes.

Volatile or highly odorous chemicals shall be stored in a well-ventilated area; a ventilated cabinet is preferable. Chemical fume hoods shall not be used for storage, as containers block proper air flow in the hood and take up work space.

Storage areas for carcinogens shall be labeled "Chemical Carcinogen." This requirement for cancer-warning labels applies even to chemicals that exhibit more than one hazard (e.g., carcinogenic and flammable).

6.5.4 Inspection of Stored Chemicals.

6.5.4.1 Storage Area
Chemical storage areas shall be inspected at least annually and any unwanted or expired chemicals shall be removed. During this inspection, the list of chemicals present in the laboratory shall be updated or verified and the date and name of the inspector recorded.

6.5.4.2 Inspections
Although the deterioration in storage of a specific compound cannot be predicted in detail, generalizations can often be made about the reaction characteristics of groups of compounds. Some general conclusions about the stability of classes of chemicals can be reached, and corresponding storage time spans can be identified. Visual inspection of stored chemicals is important in the disposal decision.

Chemicals showing any of the indications listed below shall be turned over to ORS for safe disposal:

• Slightly cloudy liquids.
• Darkening or change in color.
• Spotting on solids.
• Caking of anhydrous materials.
• Existence of solids in liquids or liquids in solids.
• Pressure buildup in containers.
• Evidence of reaction with water.
• Corrosion or damage to the container.
• Missing or damaged (i.e., illegible) labels

6.5.5 Refrigerator Storage. Flammable liquids shall not be stored in ordinary domestic refrigerators. Refrigerator temperatures are almost universally higher than the flash points of flammable liquids, and ignition sources are readily available inside the storage compartment. Furthermore, the compressor and its circuits are typically located at the bottom of the units, where vapors (from flammable liquid spills or leaks, for example) may easily accumulate.

Some domestic refrigerators can be modified to become "explosion-safe," permitting storage of flammable liquids. The modifications to the units include relocation of manual temperature controls to the exterior of the storage compartment, removal of light switches and assemblies, and replacement of positive mechanical door latches with magnetic door gaskets. The primary intent of these modifications is to eliminate ignition of vapors inside the storage compartment by removing ignition sources within the compartment. To inquire whether a particular domestic refrigerator can be modified, contact the manufacturer for possible conversion.

Ideally, labs requiring refrigerator storage for flammable liquids shall purchase explosion-safe models that require no modification. Under no circumstances should lab workers attempt to perform modification themselves. Modification may only be conducted by manufacturer representatives who will certify the safety of the work.

Please note that "explosion-safe" refrigerators are not "explosion-proof." "Explosion-proof" refers to refrigeration equipment that has been designed to protect against ignition of flammable vapors both inside and outside the storage compartment.

If refrigerators are not "explosion-safe" or "explosion-proof," they shall be labeled "Caution. Not approved for flammable liquid storage." Self-adhering stickers are available from the Safety and Loss Prevention Division and ORS. Flammable liquids shall not be stored in cold rooms that do not have explosion-proof wiring and fixtures. Such storage facilities pose explosion hazards because the various control switches and defroster heaters can spark and ignite flammable vapors.

Chemicals stored in refrigerators or cold rooms shall be sealed and labeled with the name of the person who stored the material, in addition to the labeling requirements under Section 6.0. Old chemicals shall be disposed of after a specified storage period.

Food shall not be stored in a refrigerator used for chemical storage. The refrigerator shall be labeled "Food Must Not Be Stored in This Refrigerator" or equivalent. Refrigerators used for food shall be marked "Food Only" or equivalent and shall not be in the work area.

6.6 Safety for Specific Chemical Operations

6.6.1 Unattended/Overnight Operations. If experiments run while a researcher is not present, an Overnight Experiment Notice containing information about the experiment and the name of a contact person for emergencies shall be posted on the laboratory door. Forms are available from ORS.

The "Emergency Information for Laboratories" posting on the outside of the laboratory shall have current emergency contact information.

Reactions that are left unattended for long periods of time or overnight are prime sources of fires, floods, and explosions. Do not let equipment such as power stirrers, hot plates, heating mantles, and water condensers run overnight without fail-safe provisions such as flow monitors that will shut down equipment in case of water supply failure, temperature monitors interlocked into the system, or fail-safe hose connectors.

At its discretion, the Chemical and Biological Safety Committee may specify and require labels or signs for operations involving chemical agents. Signs and warning labels are specified in Section 5.0. Remember that at night, emergency personnel are entirely dependent on accurate instructions and information available at the laboratory.

6.6.2 Extractions and Distillations.

6.6.2.1 Extractions Extractions can present a hazard because of the potential buildup of pressure from a volatile solvent and an immiscible aqueous phase. Glass separatory funnels used in laboratory operations are particularly susceptible to problems because their stoppers or stopcocks can be forced out, resulting in a spill of the contained liquid. It is even possible for pressure to burst the vessel.

To use a separatory funnel correctly, do not attempt to extract a solution until it is cooler than the boiling point of the extractant. When a volatile solvent is used, the unstoppered separatory funnel should first be swirled to allow some solvent to vaporize and expel some air. Close the funnel and invert it with the stopper held in place and immediately open the stopcock to release more air plus vapor. Do this with the hand extended around the barrel to keep the stopcock plug securely seated.

Point the barrel of the separatory funnel away from yourself and others and vent it to the hood. Do not vent the funnel near a flame or other ignition source. Close the stopcock, shake with a swirl, and immediately open the stopcock with the funnel in the inverted position to vent the vapors again. If it is necessary to use a separatory funnel larger than one liter for an extraction with a volatile solvent, the force on the stopper may be too great, causing the stopper to be expelled. Consider performing the extraction in several smaller batches.

6.6.2.2 Distallations Potential dangers arise from pressure buildup, commonly used flammable materials, and the use of heat to vaporize the chemicals involved. Careful design and construction of the distillation system is required to accomplish effective separation and avoid leaks that can lead to fires or contamination of the work area. For example, wrap distillation collection flasks with cloth tape or wire for support and reinforcement.

It is necessary to ensure smooth boiling during the separation process and avoid bumping, which can blow apart the distillation apparatus. Stirring the distillation mixture is the best method to avoid bumping. Boiling stones are only effective for distillations at atmospheric pressure. Use fresh boiling stones when a liquid is boiled without stirring. Do not add boiling stones or any other solid material to a liquid that is near its boiling point, because this may cause it to boil over spontaneously.

An electric mantle heater, a ceramic cavity heater, steam coils, or a nonflammable liquid bath are best to provide even heating. Silicone oil or another suitable high-boiling-temperature oil can be used on a hot plate. Hot water or steam may also be used in some cases. An extra thermometer inserted at the center bottom of the distilling flask will warn of dangerously high temperatures that could indicate exothermic decomposition. Do not distill or evaporate organic compounds to dryness unless they are known to be free of peroxides.

Because superheating and bumping occur frequently during distillation using reduced pressure, it is important that the distillation assembly is secure and the heat distributed more evenly than is possible with a flame. Evacuate the assembly gradually to minimize the possibility of bumping. Stirring, or using an air or nitrogen bleed tube, provides good vaporization without overheating and decomposition.

Put a standing shield in place for protection in the event of an implosion. After finishing a reduced-pressure distillation, cool the system, then slowly bleed in air so as not to induce an explosion in a hot system. Pure nitrogen is preferred to air and can be used even before cooling the system.

In a steam distillation, minimize the accumulation of condensate in the distillation flask. The heat of steam condensation is very high, and overfilling the flask is less likely if condensation from the entering steam line is trapped and the flask heated or insulated to prevent excessive condensation.

Alternative. There are commercially available distillation units that can replace traditional solvent stills which require sodium metal as a drying agent, a very hazardous process prone to fires. The National Safety Foundation (NSF) will provide supplements to grants for specific types of safety equipment, including the new still technology that does not rely on reactive metals. Consider purchasing this alternative system to reduce the risk associated with the older method.

6.6.3 Temperature Control. Since the rates of most reactions accelerate as the temperature increases, highly exothermic reactions can become violent without adequate cooling. Viscous liquids transfer heat poorly and require special precautions. Apparatus shall be assembled so that either heating or cooling can be applied or withdrawn readily.

6.6.3.1 Oil and Sand Baths Improper use of a hot oil or sand bath may create serious hazards such as an overturned bath, spatter from water falling into the bath, smoke caused by decomposition of the oil or organic materials in the oil, and fire from overheating the oil. Baths shall not be left unattended without a high-temperature shutoff. The oil shall be properly labeled, including information on its safe working temperature.

6.6.3.2 Cooling Baths Ice with salt may be used when ice water is not cool enough for use as a bath. Dry ice may be used with an organic liquid. A cooling liquid ideal for use with dry ice should have nontoxic vapors, low viscosity, no flammability, and low volatility. Although no substance is likely to meet all these criteria, some of the better liquids are:

• Ethylene glycol or propylene glycol in a 3:2 ratio with water and thinned with isopropyl alcohol.
• Isopropyl alcohol (less flammable than other common solvents such as acetone or butanone).
• Some glycol ethers.

Either add the dry ice to the liquid or the liquid to the dry ice in small increments. Wait for the foaming to stop before proceeding with the addition. The rate of addition can be increased gradually as the liquid cools. Do not handle dry ice with bare hands; if the skin is even slightly moist, severe burns can result. Use dry leather gloves or suitable cryo-gloves. Wear goggles when chipping ice.

Cryogenic coolants shall be handled in properly vented containers. Very-low-temperature coolants may condense oxygen and cause an explosion with combustible materials. Use gloves and a face shield; immerse the cooling object slowly to avoid too-vigorous boiling and overflowing the coolant. Dewar flasks should be made of borosilicate glass and wrapped with cloth-backed friction or duct tape or put in a metal enclosure to contain flying pieces in the event of implosion.

Dewar flasks should be equipped with safety necks. The flasks should be inspected periodically (at least once a day) to ensure that no air or ice plugs have collected in the neck opening.

Avoid pouring cold liquid onto the edge of a glass Dewar flask when filling because the flask may break and implode. For the same reason, do not pour liquid nitrogen out of a glass Dewar flask. Instead, use mild air pressure or a siphon. Metal or plastic Dewar-type flasks are preferable and eliminate this problem. Never use a household Thermos bottle in place of a Dewar flask.

6.6.4 Reduced Pressure Operations. Protect vacuum dessicators by covering them with cloth-backed friction or duct tape or shielding them for protection in case of implosion. Vacuum lines shall be trapped and shielding used whenever apparatus is under reduced pressure. Only chemicals being dehydrated should be stored in a dessicator. Before opening a dessicator that is under reduced pressure, make sure that atmospheric pressure has been restored.

Water aspirators for reduced pressure are used mainly for filtration purposes, and only equipment that is approved for this purpose should be used. Never apply reduced pressure to a flat-bottomed flask unless it is a heavy-walled filter flask designed for that purpose. Place a trap and a check valve between the aspirator and the apparatus so that water cannot be sucked back into the system if the water pressure falls unexpectedly during filtering. This also applies to rotary evaporation equipment that use water aspirators for reduced pressure.

If vacuum pumps are used, place a cold trap between the apparatus and the vacuum pump so that volatiles from a reaction or distillation do not get into the pump oil or out into the atmosphere. Exhausts from pumps shall be vented to a hood or ventilation system. Pumps with belt drives must be equipped with belt guards to prevent hands, hair, or loose clothing from being caught in the belt pulley.

6.6.4.1 Dessicators If a glass vacuum dessicator is used, it should be made of Pyrex or similar glass, completely enclosed in a shield or wrapped with friction tape in a grid pattern that leaves the contents visible and at the same time guards against flying glass should the vessel implode. Plastic (e.g., polycarbonate) dessicators reduce the risk of implosion and may be preferable, but should also be shielded while evacuated. Solid desiccants are preferred. An evacuated dessicator should never be carried or moved. Care should be taken in opening the valve to avoid a shock wave into the dessicator.

6.6.4.2 Rotary Evaporators Glass components of the rotary evaporator should be made of Pyrex or similar glass, completely enclosed in a shield or wrapped in cloth tape or mesh to guard against flying glass should the components implode. Increases in rotation speed and application of a vacuum to the flask whose solvent is to be evaporated should be gradual.

6.6.5 Cold Traps. Cold traps used in reduced-pressure systems should be placed in vermiculite-filled metal cans. If this option is not possible, the cold traps should be wrapped with cloth-backed friction or duct tape. In the event of an implosion, the tape will reduce the amount of flying glass.

Users of cold traps should be aware of the boiling points of the components and the possible products of materials in the reduced-pressure system. For instance, argon, a common inert gas, may condense into traps cooled with liquid nitrogen. When the cooling bath is removed, the argon rapidly vaporizes, and the rate of pressure buildup may be too great for the gas to be vented or pumped down. A serious explosion could occur.

6.6.6 Transporting Chemicals In-House. The precautions that should be followed to protect colleagues, nonlaboratory personnel, and facilities when you transport chemicals in University buildings are listed below.

Use secondary containers. The container-within-a-container concept will protect the primary containers from shock during any sudden change of movement. Secondary containment is especially important when chemicals are moved in public areas, such as hallways or elevators, where the effects of a spill would be more severe.

Always use a sturdy cart, and make sure the cart has a low center of gravity. Carts with large wheels are best for negotiating irregularities in floors and at elevator doors.

Freight elevators shall be used for moving chemicals and biological materials. Passenger elevators shall not be used for this purpose.

Do not transport incompatible chemicals together on the same cart.

All chemical containers being transported shall have labels identifying the contents. See labeling requirements in Section 6.5.1.

Transport large containers of corrosives in a chemically-resistant bucket or other container designed for this purpose.

Anticipate sudden backing up or changes in direction from others. If you stumble or fall while carrying glassware or chemicals, try to project them away from yourself and others.

6.7 Hazards of Chemical Groups

6.7.1 Corrosives: Acids and Bases. See Table 6.4 for inorganic acid neutralization procedures. Corrosive acids and bases attack the skin and can cause permanent damage to the eyes. Therefore, exercise great care in attempting neutralization.

All the hydrogen halide acids are serious respiratory irritants. Hydrofluoric (HF) acid poses a special danger; both its gas and solutions are toxic, and it is rapidly absorbed through the skin, penetrating deeply into the body tissues. Contact with dilute solutions of hydrofluoric acid may cause no pain for several hours but result in serious burns. In all cases, immediate and thorough flushing with water for 5 minutes, followed by calcium gluconate antidote gel application and prompt attention by a physician are necessary.

Oxyacids such as sulfuric and nitric acid have widely differing properties. Sulfuric acid is a very strong dehydrating agent. When preparing solutions, always add the acid to water and remember that the heat of solution may produce a large increase in temperature. Nitric acid is a strong oxidizing agent that acts rapidly and turns exposed skin yellow to brown as a denaturing reaction occurs. Paper that has been used to wipe up nitric acid spills can ignite spontaneously when dry and should not be thrown into a wastebasket until first rinsed with water and neutralized.

Chromic acid is generally prepared as a cleaning solution; ORS recommends the use of replacement cleaners without chromium, which is carcinogenic. All chromic acid waste shall be collected and disposed of through ORS. For information regarding chromic acid substitutes, contact ORS.

Perchloric acid is a powerful oxidizing agent that may react explosively with organic compounds and other reducing agents. If heated, it shall be used only in a perchloric-acid, water-wash-down fume hood of noncombustible construction. Perchloric acid should be handled with extreme care and kept from organic matter to prevent a serious explosion. Beakers of fuming perchloric acid shall be handled with tongs rather than rubber gloves. Perchloric acid hoods shall be washed down after every perchloric acid digestion.

Perchloric acid containers shall be stored in glass outer containers and shall not be stored on wood shelving, as drips or leaks may render the wood shock-sensitive. Keep perchloric acid bottles on glass or ceramic trays that are large enough to hold all the acid if the bottle breaks. Storage of perchloric acid containers should not exceed one year. Digest organic matter with nitric acid before addition of perchloric acid. Never heat perchloric acid with sulfuric acid because dehydration may produce anhydrous perchloric acid, which is explosive.

Perchlorate esters have the same shattering effect as nitroglycerine. Transition metal perchlorates are capable of exploding. Perchlorates shall not be used without prior consultation with ORS.

The most common bases found in laboratories include the alkali metal hydroxides and aqueous solutions of ammonia. Sodium and potassium hydroxides are extremely destructive to both skin and eye tissues. When concentrated solutions are prepared, the heat of solution can raise the temperature to dangerous levels. Because ammonia solution vapors are such strong irritants, they should be used only in a chemical fume hood.

6.7.2 Flammable and Combustible Liquids. Definitions. According to most fire codes and regulations, including those for laboratories, a flammable liquid is a liquid with a flash point below 100°F and a vapor pressure not exceeding 40 psi (absolute) at 100° F; it is called a Class I liquid. A liquid with a flash point at or above 100° F is classified as a combustible liquid and may be referred to as a Class II or Class III liquid (see Table 6.5).

The U.S. Department of Transportation (DOT) and the U.S. Environmental Protection Agency (EPA) use a different definition. These agencies define flammable liquids as those with a flash point of 140° F or lower and combustible liquids as those with a flash point greater than 140° F but less than 200° F. DOT and EPA definitions apply primarily to chemicals in transit and hazardous waste.

Flash point is the minimum temperature at which the liquid gives off vapors in sufficient concentration to form an ignitable mixture with air. The classes of liquids are further divided into subclasses, depending on the flash points and boiling points of the liquids. The classifications are important because regulations governing storage and use of a liquid are largely based on the liquid's flash point.

Flammable liquids shall be handled only in areas with no ignition sources and shall not be heated with open flames. If flammable liquids in metal containers or equipment are transferred, the equipment and containers shall be bonded to avoid static-generated sparks.

Storage. Flammable liquids shall not be stored in ordinary refrigerators or cold rooms. If it is necessary to refrigerate flammable materials, "explosion-proof," "explosion-safe" or flammable-storage refrigerators shall be used. Combustible liquids are less of a fire hazard, although a rise in temperature increases their evaporation rate and the potential for ignition. If the quantity of flammable liquids in storage exceeds 10 gallons (including liquid waste), flammable-liquid storage cabinets shall be used.

Allowable Quantities. The maximum allowable size of containers and portable tanks for flammable and combustible liquids is shown in Table 6.6. Although the table indicates that the maximum allowable size of glass containers for Class IA and Class IB are one pint and one quart respectively, the liquids may be stored in glass containers of not more than one-gallon capacity if the required liquid purity (such as ACS analytical reagent grade or higher) would be affected by storage in metal containers or if the liquid would cause excessive corrosion of the metal container.

Bonding and Grounding. When a flammable liquid is poured into or withdrawn from a metal drum, the drum and the secondary container shall be electrically bonded to each other and to the ground to avoid the possible buildup of a static charge. Only small quantities should be transferred to a glass container. If the liquid is transferred from a metal container to glass, the metal container should be grounded. Drums of flammable liquids are not permitted in laboratories unless the quantity is necessary for daily use and is approved by ORS. In Evanston, transfer of a flammable liquid by gravity from a drum or carboy is permitted only through a self-closing valve or faucet. Chicago Fire Code for Flammable Liquids prohibits gravity transfer and requires that the liquid be transferred by pumping from an opening in the top of the container.

6.7.3 Compressed Gases.
Securing Cylinders. An added hazard of toxic, oxidizing, and other hazardous gases as well as inert gases in cylinders is the potential for accidental pressure release; a cylinder with the valve broken off can turn into a rocket. It is important to keep cylinders secured to the bench or wall and to keep the caps on when they are not in use. Chicago code requires that cylinders be chained to the wall. In Evanston, cylinders may be secured by bench straps, floor stands, or chains. See Table 6.7 for maximum size and quantity limitations for compressed-gas or liquified-gas cylinders in laboratories.

Storage. Only cylinders that are in use shall be kept in the laboratory. All others, including empties, shall be sent to the compressed-gas cylinder storage area for the particular facility. When the cylinder is not in use, close the main cylinder valve tightly. Promptly remove the regulator from an empty cylinder, replace the protective cap