Potassium pyrosulfite and dipotassium disulfite are other names for this sodium salt of sulfurous acid. Chemical formula is : K2SO3

Campden tablets are  made from potassium or sodium metaisulfite and are used in wine, beer and cider making to kill bacteria and to inhibit the growth of most wild yeast. 

These campden tablets are also used to eliminate free chlorine and chloramine from water sources like municipal water sources.

In textile industry potassium metabisulfite is used for dyeing and cotton printing.

Potassium metabisulfite can be used also in certain photographic developers and solutions instead of sodium bi- and metabisulfites.

It is also used in gold processing as  ‘aqua regia’.

Symptoms what you can get from potassium metabisulfites are similar like from the other sulfites. You don’t need to have asthma to be prone to get reactions from sulfites, even though asthma related symptoms are often observed and what doesn’t make any sense is that often asthma puffers contain some forms of sulfites. Sodium metabisulfites are common preservative in asthma puffers and many other medicines.

Potassium metabisulfite can be found in following foods and drinks:

• Wine
• Beer
• Cider
• Quick frozen shrimps, lobsters and other shellfish
• Lemon juice concentrate
• Fruit juice concentrates
• Dried fruits
• Smoked meats
• Processed meats
• Bleaching of coconut cream
• Pickles
• Canned fruits

Non food uses of potassium metabisulfite:

• Textile  Industry
• Photography industry
• Oil field companies
• Leather Industry

Miscellaneous uses:

• Campden tablets
• Gold processing
• Liquid fertilizers
• Fresh flowers during storage and transport