There are generally 9 or 10 sections in a MSDS. A detailed description of the information given in each section, along with definitions of many terms, is presented below.

1. MANUFACTURERS INFORMATION

• The manufacturer's name and address is given. If information in the MSDS is taken from another source, that source is also listed.
• In the event of an emergency involving the material, emergency phone numbers are given by which additional information can be obtained.

2. IDENTIFICATION

• The chemical name is given, referring only to products that are single substances or compounds, such as oxygen or methyl ethyl ketone.
• Synonyms of the chemical name are given, including trade names.
• The chemical formula is given, referring only to the chemical formula for single elements or compounds, not to the formulation of a mixture. For example, O2 is used for oxygen and C2H5COCH3 for methyl ethyl ketone.
• The hazardous ingredients of the material are listed. The percentage by weight or volume of component(s) should be specified. In mixtures, hazardous chemicals in amounts greater than 5 percent must be specified; frequently, lower percentages must also be specified. For all specified ingredients, the threshold limit value (TLV) should be provided.

3. TOXICITY HAZARDS

• Irritation data are presented in terms of exposure levels which have been demonstrated to produce irritation in human or animal studies. The data present the type of tissue tested for the irritation (for example, eye or skin), the type of animal model used (for example, rabbit, human, or mouse), and the dosage required to produce the irritation in each tissue type (for example, 350 ppm, 80 mg, or 500 mg/24 hr).
• Toxicity data are presented in terms of the experimentally derived dose, administered by ingestion or injection, which would kill 50% of the animals tested (LD50), or the concentration in air of gas, vapor, mist, fumes, or dust which would kill 50% of the animals exposed to it for a given period of time (LC50). The animal model used is also identified for each value.
• The toxicity reviews, standards, and regulations section lists the maximum permissible employee exposure to the material. The findings of several agencies will be reported. They may include:
  • RTECS: Registry of Toxic Effects of Chemical Substances
  • IARC: International Agency for Research on Cancer
  • OSHA: Occupational Safety and Health Act
  • NIOSH: National Institute of Occupational Safety and Health
  • EPA: Environmental Protection Agency

The Threshold Limit Value (TLV) is a safe exposure level set by the American Conference of Governmental Industrial Hygienists (ACGIH). A Permissible Exposure Limit (PEL) is a similar standard set by OSHA. Both refer to airborne concentrations of substances and represent an exposure level under which most people can work constantly for eight hours a day, day after day, with no harmful effects.

Three categories of TLV's are specified as follows:

1. Time Weighted Average (TLV-TWA) - The time-weighted average concentration is the concentration to which personnel can be exposed for a normal 8 hour day or 40 hour work week without adverse effect.
2. Short-term Exposure Limit (TLV-STEL) - The maximum concentration to which personnel can be exposed continuously for a period of up to 15 minutes without suffering from irritation, chronic or irreversible tissue change, or narcosis of sufficient degree to impair self-rescue or reduce work efficiency. No more than four 15 minute exposure periods per day are permitted with at least 60 minutes between those exposure periods.
3. Ceiling (TLV-C) - The maximum concentration that should not be exceeded even instantaneously.

• The section on target organ data lists the specific organs affected by the material (for example, liver, lungs, or sense organs).

4. HEALTH HAZARDS

This section deals mainly with acute health hazards - the possibility that exposure will result in effects which may appear almost immediately, or may produce effects after only a brief exposure to the material. Chronic health effects (those which may not appear until after days, months, or years of exposure) may be listed separately, or they may be found in the toxicity hazards section.

• Route of entry and effects of exposure indicate the avenue and effects of routine exposure. Examples include: Causes eye irritation. Harmful if absorbed through skin. Causes severe burns.
• A listing of the effects of overexposure provides a physical description of an individual suffering from overexposure to the material and the most common sensations or reactions which will likely result from such overexposure (for example: nausea, vomiting, flushing, mental excitement or depression). In many cases, the effects of overexposure are not specific: A headache, dizziness, or nausea can result from many causes other than toxic overexposure. Nonetheless, this information will alert you to the possible toxic effects of overexposure to the material.
• Pre-existing medical conditions are existing medical conditions which may be aggravated by exposure to the material.
• The emergency and first aid procedures covered in this section deal only with problems resulting from inhalation, or from skin or eye contact. These are first attempt emergency procedures only. The victim should be examined by a doctor as soon as possible after exposure. This section should help in determining whether provisions such as eye-wash stations, emergency showers, first-aid kits, or respiratory support are needed.

5. PHYSICAL DATA

• The boiling point is the temperature at which a liquid boils, measured in degrees F, at an atmospheric pressure of 760 mm Hg. For mixtures, a boiling range is given.
• The vapor pressure is the pressure of a saturated vapor present above a liquid, measured in mm Hg, at 20 degrees C (68 degrees F). Vapor pressure is a measure of the tendency of a liquid to evaporate, and provides an indication of the volatility of a liquid. The higher the vapor pressure, the more likely it is to evaporate.
• Vapor Density refers to the density or weight of a vapor or gas (with no air present) relative to an equal volume of air. Values should be given in the ambient temperature range of 60-90 degrees F. Although vapor density indicates whether the vapor is heavier or lighter than air, one must remember that this value is for a pure vapor (no air). Realistically, a vapor is usually mixed with air and the effective density will be closer to one. It will not be equal to one unless stated as such.
  When the vapor density is greater than one, released vapors will tend to travel and collect in the lowest spot. Ignition source control in these low areas is critical if the vapor is flammable. One must be alert to vapors traveling to an ignition source and then flashing back to the vapor source.
• The solubility of the material in water may be listed. Solubility in other solvents may also be given.
• Specific gravity is the ratio of the weight of a volume of material relative to the weight of an equal volume of water at 39.2 degrees F. The specific gravity is an indication of whether the material will float or sink in water. Specific gravity less than or equal to one indicates that water should not be used as an extinguishing media (unless applied from automatic sprinklers) since the water will not cover over and extinguish the flaming material.
• Percentage volatile by volume is the percentage of the liquid or solid by volume that evaporates at the ambient temperature of 70 degrees F. This also applies to some solids such as naphthalene.
• The evaporation rate is the rate of evaporation relative to that of either butyl acetate or ethyl ether (the source for comparison should be listed). The process by which liquid changes to vapor depends on a number of parameters other than the properties of the liquid itself. Size of container, surface area of liquid, rate of air flow over the surface, and the temperature of the liquid represent some of those parameters.
• Appearance and odor provide a brief description of the physical appearance of the substance. Examples include: Clear, colorless, fragrant liquid, burning taste.

6. FIRE and EXPLOSION HAZARD DATA

• The flash point is the temperature, in degrees F, at which a liquid will give off enough flammable vapor to allow ignition (the test method used will be indicated). Thus, the flash point is the minimum temperature at which an ignitable mixture is formed. Sufficient combustion is not necessary to produce sustained burning. Sustained burning will occur at the fire point which is generally within 3 to 5 degrees of the flash point.

  OSHA classifies flammable and combustible liquids as follows:

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  Description Class	Flash Point in Degrees F	Flash Point in Degrees C
  Flammable IA	less than 73 (a)	less than 22.8
  Flammable IB	less than 73 (b)	less than 22.8
  Flammable IC	73-99.9	22.8-37.7
  Combustible II	100-139.9	37.8-59.9
  Combustible IIIA	140-199.9	60.0-92.8
  Combustible IIIB	200 or more	93.3 or more

  (a) Boiling point less than 100 degrees F (37.8 degrees C)
  (b) Boiling point of 100 degrees F (37.8 degrees C) or more

  ---

  In dealing with flammable liquids, control of ignition sources is critical. Ignition sources include smoking, electrical equipment and wiring, cutting and welding, static electricity, etc. When the flash point is below 110 degrees F, extra care must be taken since, on a hot summer day, the temperature of the liquid could be high enough to have an ignitible mixture exist and introduction of any ignition source could cause a fire. The red diamond used by the Department of Transportation (DOT) is required on all liquids classified by OSHA as flammable.

• Flammable or Explosive limit is the range of gas or vapor concentrations (percent by volume in air) which will burn or explode if an ignition source is present. The two explosive limits listed are defined as follows:
  • The Lower Explosive Limit (L.E.L.) is the minimum amount of vapor in air which can be ignited.
  • The Upper Explosive Limit (U.E.L.) is the maximum amount of vapor in air that can be ignited or exploded.
• The extinguishing media lists the fire fighting media suitable for use on the burning material. For certain specific chemicals, special formulations, in addition to the standard agents, are available for extinguishing fires. These fire fighting agents are water, fog, foam, alcohol foam, CO2, and dry chemical.

  The four classes of fires are:

  1. Class A Paper, wood, straw, cloth, etc.
  2. Class B Flammable and combustible liquids
  3. Class C Involving energized electrical equipment
  4. Class D Combustible metals
  
  The letter rating given on a fire extinguisher by testing laboratories refers to the class of fire on which the extinguisher can be properly used. Generally, Class A fires are fought with water, Class B fires with carbon dioxide, foam or dry chemical, Class C fires with carbon dioxide or dry chemicals, and Class D with special extinguishing compounds.
• Special Fire Fighting Procedures are listed if water is an unsuitable extinguishing agent. In addition to specifying the agent to be used any necessary personal protective equipment will be listed. This would include an evaluation of the toxicity of combustion products, and evaluation of the toxicity of the material on personnel fighting the fire.
• Unusual fire and explosion hazards are special fire hazards which apply to the material. Examples include: Vapor flashback. Emits toxic fumes under fire conditions. Container explosion may occur under fire conditions.

7. REACTIVITY DATA

• Stability indicates whether a chemical is stable or unstable under reasonable foreseeable conditions of storage, use, and/or misuse. If unstable, those conditions which may cause a dangerous reaction are listed (for example, avoid shocks, avoid temperature above 150 degrees F, reacts violently with water, etc.). This section will indicate any specific conditions to be avoided.
• Incompatibility indicates any common materials and/or contaminants which should be avoided since contact between these materials and the chemical would produce a reaction releasing large amounts of energy. This section will specifically indicate any materials which must be kept segregated from the MSDS material to avoid fires, explosions or other problems resulting from contact between substances.
• Hazardous decomposition products are any hazardous materials that would be produced in dangerous amounts as a result of burning, oxidizing, or heating from welding, and these products should be listed. For example, thermal decomposition of vinyl chloride plastics produces such hazardous materials as CO, CO2, and HCl. This section will indicate to which products personnel could be exposed if the material is burned or heated.
• Hazardous polymerization is a chemical reaction in which molecules of a material unite to form a larger, different material and which is accompanied by the release of large amounts of energy. Frequently, the energy that is produced is sufficient to cause ignition, over pressurization of storage containers, or other hazardous situations. Reasonable foreseeable storage conditions which could result in polymerization are generally specified. Any known inhibitors (a chemical which can be added to prevent or retard polymerization) are indicated along with their expected duration. Also included is the expected time period in which the inhibitors may be used up.

8. SPILL and LEAK PROCEDURES

This section indicates the proper procedures to follow and the protective equipment to be used in dealing with a spill or leak. Proper waste disposal methods will also be given.

• Precautionary measures are steps to be taken in the event of a spill or leak. Examples include: Avoid breathing gases or vapors, Avoid contact with liquids and solids, Remove sources of ignition. Recommended special equipment to be used in clean-up will be indicated; for example, Use glass or plastic scoops; Use only non-sparking tools.
• The waste disposal method indicates proper methods of disposal of spoiled solids or liquids. Examples include: Flush with water; Return material to container for burning. Once the spill or leak has been cleaned up, you must properly dispose of the material. Frequently, this section will include a statement that Federal, State and Local regulations should be followed. This section is very important to ensure that proper disposal procedures are followed.

9. GENERAL PRECAUTIONS IN HANDLING AND STORAGE

• The Personal Protective Equipment list indicates the appropriate protective equipment to be worn when handling the chemical.
  1. Appropriate eye protection (as listed) is to be worn. Examples include safety glasses, chemical splash goggles, and/or a faceshield.
  2. Skin protection indicates under what conditions gloves are required, and specifies the required type of glove material. Other protective clothing, such as a lab apron may also be required.
  3. The ventilation specifications indicate the type of ventilation needed to safely work with the chemical.
     • Mechanical ventilation indicates the normal ventilation used to distribute heated or cooled air in a building.
     • Local exhaust ventilation specifies a ventilation system with high velocity and low volume that captures a material very soon after its release and before it reaches an employee's normal breathing zone.
     • Chemical fume hood - Self-explanatory.
• Special precautions highlights any precautions which should be taken during handling and storage to avoid the occurrence of problems such as incompatibility, hazardous polymerization, etc. Examples include: Store under nitrogen; Keep in a cool dry place; Protect from moisture.

10. ADDITIONAL PRECAUTIONS and COMMENTS

• The footnotes section will list any special incompatibilities, for example, reacts violently with bromine trifluoride and lithium. If the reactivity rating on the HMIS label has the .1 designation, this section is where the specific incompatibilities will be indicated.
• Legal reporting requirements indicate any federal reporting requirements pertaining to the chemical. An example is: SARA III.
• DOT labeling indicates the labeling required by the Dept. of Transportation
• Manufacturers disclaimer is self-explanatory.

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