Radiation Leakage of Before-Sale and Used Microwave Ovens

Conclusions and Recommendation

There is a continuing public concern about possible health hazards that may be caused by exposure to radiation emitted from microwave ovens. In order to protect people who are using these appliances, Health Canada promulgated regulations, under the Radiation Emitting Devices Act, to deal with microwave ovens. The regulatory leakage limits are based on the scientific knowledge about health-related effects of microwaves, and considerable safety margins were incorporated to derive the safety limits.

Based on our recent surveys, all before-sale domestic microwave ovens were found to be in compliance with the regulations. Therefore, exposures to microwave radiation during cooking with these ovens would, in general, be very low, and no detrimental health effects should occur. Of the 60 microwave ovens surveyed, there were six models which were incorrectly labelled. The manufacturers were notified of the deficiencies; rapid response was made to bring the product labels into compliance.

The microwave leakage levels from all but one of the 103 used ovens were found to be within the limits specified in the regulations. Only one unit was found to emit microwave radiation in excess of the limit when tested with a water load. This unit was 23 years old at the time of the survey. However, excessive leakage was not observed on another oven of a similar age, and as such age cannot be taken as the definitive consideration for excessive leakage.

Low radiation leakage levels can be maintained by keeping the microwave ovens in good working order, and this responsibility rests with the microwave oven owner. The most frequent causes of leakage from microwave ovens are mechanical abuse of doors and door seals, build-up of dirt around door seals, improper servicing, and, with older ovens, failure to replace or repair worn-out door hinges and latches. If excessive leakage is suspected, microwave oven owners should contact the product manufacturer, distributor or service person to have the oven professionally inspected.