Recognize the Hazards (Advanced)

Graduate students should be able not only to recognize common laboratory hazards, but also to explain why they are hazards.

This involves using hazard rating systems, including (but not limited to):

Familiarity with hazard rating systems will help students characterize the relative severity of a hazard, which is required to assess the risk.

Common Laboratory Hazards

Chemical Hazards

  • Corrosive chemicals
    • Typically, strong acids and bases, solutions with a pH < 2 or a pH > 12, and some solvents, such as formic acid, glacial acetic acid, and trifluoroacetic acid, which are particularly aggressive against tissue.
  • Flammable chemicals
    • Chemicals that are easily ignited or explode under usual laboratory working conditions, such as low-molecular-weight alcohols, aldehydes, ketones, and hydrocarbons.

Physical Hazards

  • Incompatible chemicals for storage or handling
    • Storing strong oxidizers, such as nitric acid, with reduced compounds, such as hydrocarbons  Reactants that react with air or water, such as alkyl metals or acid halides.
  • Compressed gases and high-pressure systems
    • This includes both the chemical hazard of the gases and the physical hazard of all parts of the system subjected to greater than 1 bar (>100 kPa).
  • Low-pressure and vacuum systems
    • This includes any system that operates at less than 1 bar (<100 kPa), including rotary evaporators.
  • Electrical hazards
    • All electrical equipment and energy sources.
  • Radiation hazards
    • Both ionizing and non-ionizing radiation, including lasers and ultraviolet lamps.
  • Cryogenic hazards
    • Any system operating below 0 °C  Examples are dry ice (solid CO2), liquid nitrogen (LN2), liquid oxygen LOx), liquid hydrogen (LH2), and liquid helium (LHe)  Any system operating at greater than 90 1 K (the boiling point of O2) will condense oxygen and create a potentially highly flammable environment.

Health Hazards

  • Toxic substance classifications
    • Students should be able to explain terms such as “highly toxic”, “acutely toxic”, “chronically toxic”, carcinogens, allergens, mutagens, and teratogens.
  • Acute chemical exposures
    • Students should recognize that brief exposures to highly toxic or allergenic chemicals can have a significant impact on health, and should be able to identify chemicals with these properties. Biological chemicals can also have significant effects, such as biological enzymes that can produce allergic reactions.
  • Chronic chemical exposures
    • Students should recognize that extended exposure to chronically toxic chemicals can result in cancer or other organ-specific damage, and should be able to identify such compounds.
  • Nanomaterials
    • The small size of nanomaterials allows these materials to enter deeply into the respiratory tract or to penetrate unprotected skin. Currently, there is very limited information about the health impact of nanomaterials, so strict handling precautions are required.

Reaction Hazards

  • Scale-up and potential runaway reactions
    • During a research career, the need to synthesize larger quantities of a specific chemical is likely. This scale-up may alter reaction kinetics unpredictably and may create conditions under which a reaction vessel can self-heat more than passive cooling can dissipate away, creating a thermal runaway reaction.
  • Catalyst effects on reactions
    • Whenever a catalyst is added to a reaction, the reaction rate changes, as does the rate of generation of heat and byproducts. Separating some catalysts from reaction mixtures may cause fires.
  • Reactive and unstable chemicals
    • Students should be able to explain what makes chemicals reactive or unstable, including both explosive chemicals and reactions that could lead to explosions. Pyrophoric chemicals require special techniques for handling, and students must be trained specifically in these techniques if they are to use these chemicals. Chemicals that react with air or water, such as phosphorus oxychloride (POCl3), sodium metal (Na), or acetic anhydride (Ac2O), require special handling to address their reactive hazards. Also included are chemicals that become unstable over time, such as cyclic polyenes or some alkyne structures.
  • Peroxides and peroxide-forming chemicals
    • Students should be able to explain peroxide reactivity and the types of chemicals that form peroxides spontaneously at varying rates. Most –C–O–C– compounds that contain an activated α-hydrogen will slowly react to form the corresponding peroxide –C–O–O–C–, which may be violently unstable.

Example of Hazards Commonly Identified for Research Activities

  • Agent Hazards
    • Examples: Carcinogenic, teratogenic, corrosive, pyrophoric, toxic, mutagenic, reproductive hazard, explosive, non-ionizing radiation, biological hazard/pathogenic, flammable, oxidizing, self-reactive or unstable, potentially explosive, reducing, water-reactive, sensitizing, peroxide-forming, catalytic, or chemical asphyxiant
  • Condition Hazards
    • Examples: High pressure, low pressure, electrical, uneven surfaces, pinch points, suspended weight, hot surfaces, extreme cold, steam, noise, clutter, magnetic fields, simple asphyxiant, oxygen-deficient spaces, ultraviolet radiation, or laser light
  • Activity Hazards
    • Examples: Creation of secondary products, lifting, chemical mixing, long-term use of dry boxes, repetitive pipetting, scale-up, handling waste, transportation of hazardous materials, handling glassware and other sharp objects, heating chemicals, recrystallizations, extractions, or centrifuging

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