Chemical Safety

It is necessary to make an Assessment of the health risks to you in handling chemicals before the materials are used.

The following points are worth emphasising:

Common Solvents

Many common solvents, e.g., CH2Cl2, are toxic and in handling (or spilling them) in the open laboratory you may exceed danger limits for the vapour concentration. Use an effective fume-hood whenever possible. Dusty substances can be as dangerous as highly volatile substances both in toxicity and in explosion risks.


Absorbent granules to mop up spilled solvent are available at Lab Supplies or in the teaching laboratories. If you are using large amounts of acid or base or any amount of strongly smelling material you must keep a neutralising agent at hand.

Carcinogenic Materials

The handling and storage of carcinogenic materials are classified into the following categories:

Category 1 - substances known to be carcinogenic to humans. There is sufficient evidence to establish a causal association between human exposure to the substance and the development of cancer. Category 2 - substances that should be regarded as if they are carcinogenic to humans, for which there is sufficient evidence, based on long-term animal studies and other relevant information, to provide a strong presumption that human exposure may result in the development of cancer. Category 3 - substances that cause concern owing to possible carcinogenic effects but for which available information is not adequate to make satisfactory assessments.

Categories 1 and 2, if purchased from a supplier will carry the "toxic" (T) symbol and the Risk Phrase R45 (May cause cancer) or R49 (May cause cancer by inhalation). Category 3, if purchased from a supplier carries the "harmful" (Xn) symbol and the Risk Phrase R40 (Limited evidence of a carcinogenic effect).

In the Department of Chemistry, the following rules apply for Category 1 and 2 carcinogens:

  • •The worker should be fully informed of the carcinogenic nature of the chemicals and the procedures for proper handling and disposal.
  • A record must be kept by the PI of all user exposure to such material (a suitable form is provided).
  • Carcinogenic materials must be disposed of carefully and not via the waste solvents. Arrangements must be made by the PI with the chemical waste disposal company.
Mercury Mercury is very toxic. All glass apparatus containing mercury must have secondary containment to catch mercury in the event of a breakage. Spilt mercury should be collected up immediately. Details on how to clean up a mercury spill are given at:/PSSO/Safety/SafetyPrac.htm#Mercury.
Cyanides Great care must be taken when working with cyanides. The use of cyanides outside of normal working hours is forbidden.
Hydrofluoric acid

Great care must be taken when working with HF. The use of HF outside of normal working hours is forbidden. At concentrations above 1M (2%) in water, HF can cause very painful burns that may not be apparent for some hours. Always wear gloves, a lab-coat and safety glasses when using this acid. Have available a tube of "HF Antidote Gel" which should be applied if concentrated acid contacts the skin.

In the event of HF accidents, contact Lab Supplies (2691) or A/P G. K. Chuah (2839).