ABC of Safety in the Biological Sciences
Leakage of radiation from microwave ovens is extremely rare. The door, being the most vulnerable part, operates an automatic switch which instantly halts the operation once the door is opened. If the switch fails an operator can be exposed to microwaves which can cause severe skin burns.108 Microwave leak detectors are available from commercial sources and are a useful adjunct where a microwave oven is used.
Microwave ovens are finding more frequent use in laboratories for rapid fixation and staining. The procedure generally requires the heating of solvents and toxic substances which may generate potentially toxic fumes. These fumes can be inhaled by an operator and/or can find their way into the sensitive electrical control system, where high voltage switching occurs with the risk of fire.109 It is advisable therefore, when microwave ovens are used for laboratory procedures, to purchase units to which can be fitted fume extraction systems.
Metal containers or metal objects placed into a microwave radically alter the electromagnetic fields causing arcing which in the presence of a solvent or combustible liquid can cause an explosion.
Because heating causes vaporisation it is advisable to microwave containers with loosely fitting and not tightly fitting caps to allow pressure build up in containers to escape, thus avoiding the possibility of a container exploding.
Damage to the magnetron will result if the microwave oven is operated without a load in the chamber.