Chemical Safety / Assessing Chemical Hazards

Assessing Chemical Hazards

MSDSs and SDSs are an invaluable source of information when assessing the hazards associated with particular chemicals. They can, however, require a great deal of subjective interpretation because of the extent of the information provided.  The National Fire Protection Agency (NFPA Diamond) and the National Paint and Coatings Association (Hazard Management Information System – HMIS® III) provide independent assessment of chemicals that make an evaluation of their hazards much more convenient.  In both systems chemicals are rated between 0 and 4 for each potential hazard; health, flammability and reactivity (physical).  The NFPA and HMIS® ratings can be found on most MSDSs.  While both systems are effective, the HMIS® III has two important advantages, both related to health ratings, for academic laboratories:

1)     HMIS® III rates the hazards of chemicals at the bench. The NFPA ratings are intended for first responders and rate chemicals under emergency conditions such as fire.

2)     HMIS® III provides a Chronic Hazard Indicator which identifies chemicals for which there is health effects associated with long term, or repetitive exposures.


Ratings for Flammable and Physical (Reactivity) hazards of chemicals are similar for the two rating systems. A more detailed description of the criteria used for Physical hazard ratings for individual classes of chemicals (water reactive, organic peroxides, explosive, compressed gases, pyrophorics, oxidizers, and unstable reactives) can be found in HMIS® Implementation Manual (third edition).  The HMIS® Health, Flammability, and Physical hazard ratings are presented below.

The HMIS® and NFPA ratings are useful indicators of the risk of working with a particular chemical. However, a consideration of the amount of the chemical that a worker could be exposed to (the potential dose) is necessary to assess the potential hazard of working with that chemical. As indicated by dose-response curves, the size of a chemical exposure determines the extent of harm; from benign, to therapeutic, to harmful, to deadly.  Similarly, small amounts of an explosive chemical may result in little more than a ‘POP” when detonated, while the detonation of large quantities could result in considerable damage and injury. In general, the greater the amount of a chemical present, the more likely a health, flammable or reactive event will occur and the more severe the effects will be.  Thus the potential hazard of working with a highly hazardous chemical is reduced by drawing from smaller stock quantities (1g stock rather than a 100g stock). The potential hazard of working with less hazardous chemicals can be increased by the presence of large quantities (e.g. 4L bottle rather a 500 mL bottle).  An example of a rating for exposure based on chemical amount/volume is provided below. An example of a hazard assessment for chemicals is provided in Appendix 2.

HMIS: Health Hazard Rating Chart

* Chronic Hazard – Chronic (long-term) health effects may result repeated or long-term overexposure.

0 = Minimal Hazard - no significant health risk; no effect anticipated; practically nontoxic; irritation of skin or eyes not anticipated

1 = Slight Hazard - irritation or minor reversible injury may occur; may irritate the stomach if swallowed; may defat the skin and exacerbate existing dermatitis

2 = Moderate Hazard - temporary or transient injury may occur; prolonged exposure may affect the CNS and lead to apparent intoxication, nausea, headache, dizziness, weakness or fatigue.

3 = Serious Hazard - major injury likely unless prompt action is taken and medical treatment given; high level of toxicity; corrosive.

4 = Severe Hazard - life-threatening; major or permanent damage may result from single or repeated overexposures; extremely toxic; irreversible injury may result from brief contact.

HMIS: Flammability Hazard Rating Chart

0 = Minimal Hazard - Materials that will not burn.

1 = Slight Hazard - Materials that must be preheated before ignition will occur, including liquid, solid and semi-solid chemicals with a flash point above 200° F (Class IIIB).

2 = Moderate Hazard – Materials that must be heated moderately or exposed to high ambient temperatures before ignition will occur, including liquid chemicals with a flashpoint at or above 100° F but below 200° F (Classes II & IIIA).

3 = Serious Hazard - Materials capable of ignition under almost all normal temperature conditions.  Includes flammable liquids with flash points below 73° F and boiling points above 100° F as well as liquids with flash points between 73° F and 100° F (Class IB & IC).

4 = Severe Hazard - Materials may ignite spontaneously with air. Flammable gases, or very volatile flammable liquids with flash points below 73° F, and boiling points below 100° F (Class IA).

HMIS: Physical Hazard Rating Chart

0 = Minimal Hazard - Materials that are normally stable, under fire conditions and will not react to water, polymerize, decompose, condense or self react.

1 = Slight Hazard - Materials that are normally stable but can become unstable at high
temperature and pressures. Materials may react non-violently with water or undergo hazardous polymerization in the absence of inhibitors.

2 = Moderate Hazard - Materials that are unstable and may undergo violent chemical change at normal temperature and pressure with low risk for explosion. Materials may react violently with water or form peroxides upon exposure to air.

3 = Serious Hazard - Materials that may form explosive mixtures with water are capable of
detonation or explosive reaction in the presence of a strong initiating source or undergo chemical change at normal temperature and pressure with moderate risk of explosion.

4 = Severe Hazard - Materials that are readily, capable of water reaction, detonation or explosive decomposition at normal temperatures and pressures.

Potential Dose Rating

Exposure (Dose) based on the amount of chemical in the workers presence, not simply the amount used in a reaction or procedure (based on U of A EHS Spill Response Guidelines).

High = High Exposure – For Stock Chemicals/Solutions: Flammable liquids more than 500ml; all other Chemicals more than 1 litre liquid or 500 grams solid (Spill is considered by U of A EHS to be an Emergency).

Med =Moderate Exposure - Stock Chemicals/Solutions: Flammable liquids between 100 ml and 500 ml; all other chemicals between 100 mL and 1 L liquid or between 50 and 500 g solid

Low = Low Exposure - Stock Chemicals/Solutions: Flammable liquids less than 100ml; all other chemicals less than 100 mL liquid or 50 g solid.

Chemical Spill Protocol

When a Chemical spill occurs, contact Kelvin Lien (, 780-492-0649) or Urmila Basu (, 780-492-8712) for assistance. Follow The University of Alberta Biological Spill Remediation Protocol

Spill Clean Up Equipment

·       Chemical absorbent (20 litres)

·       Plastic pail (20 litre) with lid (2)

·       Felt marking pen (2)

·       Heavy Plastic Bags; at least 3 mil thickness (12)

·       Plastic bucket with handle (1)

·       Long handle sponge mop (1)

·       Extra sponges (4)

·       Plastic dust pan (1)

·       Broom (1)

·       Duct tape (roll)

·       Detergent (box)

·       Citric Acid (500g)

·       Sodium Bicarbonate (500g)

·       Sodium Thiosulfate (500g)

·        Spill Response Guideline