Two small children in Fort McMurray died this week after their mother used the pesticide to try to kill bedbugs in the family apartment.
The family brought the pesticide, which is highly toxic to humans and animals, back from Pakistan after a recent trip there.
Health Canada said phosphine pesticides can only be sold in Canada to people holding an appropriate pesticide applicator certificate or licence, and are not approved for use on bedbugs.
The agency said it is also aware of other incidents involving the use of ozone generators (machines that produce ozone gas) for the control of bedbugs. The warning said such devices are not safe to use and can cause respiratory problems including coughing, chest pain, shortness of breath, and irritation of eyes, nose and throat.
Pesticides should only be used according to the directions outlined on product labels. The agency recommends hiring a licensed professional pest control operator to deal with a bedbug infestation.
Tenants who have bedbugs should notify their landlord and speak with a public health officer about dealing with the infestation.