Health Canada is advising Canadians not to use disposable face masks that contain graphene.
Health Canada issued the notice on Friday and said wearers could inhale graphene, a single layer of carbon atoms.
Masks containing the toxic particles may have been distributed in some health-care facilities.
The recall comes after the Quebec government warned against wearing those masks last week. They had previously been distributed in schools and daycares in that province.
CBC News has asked the New Brunswick government if the masks have been used in schools and is waiting to hear back.
Preliminary research with animals shows graphene has potential to cause lung toxicity, according to Health Canada. The potential risk with masks is unknown. The department has requested data from mask manufacturers and is investigating.
Manufacturers, distributors and sellers have been directed to stop selling the recalled masks.
People who have masks containing graphene should not wear them. Those who have used one should consult with a health care professional if issues develop, such as shortness of breath.