Hazard signs

Hazard signs, black images enclosed in orange squares. Corrosive sign, two test tubes drip liquid onto a hand and a surface. The liquid is eroding the hand and the surface. Explosive sign, an explosion radiates out from a sphere and carries fragments of the sphere. Flammable sign, a flame in the centre of the square. Environmental hazard sign, a dead tree and a dead fish sit on a surface. Oxidizing sign, a flame sits on top of an empty circle. Toxic sign, a skull on top pf a pair of crossed bones. Harmful irritant sign, a large black X fills the square. Biohazard symbol, three partially closed circles radiate out from a central point. Radioactive symbol, three broad  black blades radiate out from a circle in the centre.

Dangerous goods (or hazardous materials) are solids, liquids or gases that can damage people, other living organisms or the environment and they need to be controlled with chemical regulations. These hazards include materials that are radioactive, flammable, explosive, corrosive, oxidizing, asphyxiating, biohazardous, toxic, pathogenic or allergenic. Here is a list of the categories in which these hazardous materials are grouped:

  • Class 1: Explosives -> dynamite, nitroglycerine…
  • Class 2: Gases -> inflammable gases (acetylene, hydrogen…), non inflammable one (nitrogen, neon…) or poisonous ones (fluorine, hydrogen cyanide…)
  • Class 3: Flammable liquids -> diethyl ether, carbon disulfide, gasoline, acetone…
  • Class 4: Flammable solids -> nitrocellulose, magnesium, white phosphorus, sodium…
  • Class 5: Oxidizing agents and organic peroxides -> calcium hypochlorite, ammonium nitrate, hydrogen peroxide, cumene hydroperoxide…
  • Class 6: Toxic and infectious substances -> biohazards (human material, virus cultures…), potassium cyanide, mercuric chloride, pesticides)…
  • Class 7: Radioactive substances -> uranium, plutonium…
  • Class 8: Corrosive substances -> acids (sulfuric acid, hydrochloric acid…) and bases (potassium hydroxide, sodium hydroxide…).
  • Class 9: Miscellaneous -> asbestos, air-bag inflators, self inflating life rafts, dry ice…

Each hazard can be denoted with a specific sign, which is used to know the risks of using each chemical substance.

Protection gear

Personal protective equipment in the laboratory includes gloves, respiratory protection, eye protection and protective clothing. The need for each type of protection depends on each specific case, type of operations, nature of the chemicals and the amounts used.

  • Protective gloves should be worn when handling irritant, harmful and corrosive materials, chemicals of unknown toxicity and very hot or very cold materials. Gloves used in the laboratory are normally made of latex, vinyl or nitrile.
  • A respirator may only be used when ventilation is necessary and the fume hood does not reduce the harm of the chemical under acceptable levels.
  • Safety glasses are used to protect your eyes from flying particles, glass or powders among others.
  • Protective clothing such as lab coats, which resist physical and chemical hazards, should be worn. Shorts, open shoes, ties and unrestrained hair should be avoided.

In the case of biohazards, four categories are found: the lowest one (Level 1) corresponds to the minimum risk and the highest one (Level 4) corresponds to the maximum risk. In the minimum risk, it is enough to work with gloves and some facial protection. In contrast, Level 4 requires specific precautions such as wearing a positive pressure personnel suit with a segregated air supply, taking several showers, utilization of a vacuum room, an ultraviolet light room or an autonomous detection system.

Acid and base

Theory overview