The FDA is asking the manufacturers of denture cleansers to revise labeling and to consider appropriate alternatives to an ingredient in their products. This action is in response to reports of 73 severe reactions linked to these cleansers, including at least one death.
The ingredient, persulfate, which is known to cause allergic reactions, is the most likely cause of the problem according to literature and research. Persulfates are used in these products as part of the cleaning and bleaching process.
The full FDA release, with links to additional information, may be read here.