What Is Sodium Metabisulfite?

FDA regulations at 21 CFR 182.3766 list sodium metabisulfite as generally recognized as safe when used in accordance with good manufacturing practice, except that it is not used in meats, in foods recognized as a source of vitamin B1, or on fruits or vegetables intended to be served or sold raw to consumers or presented to consumers as fresh. The FDA says sulfites may also be added to certain drug products as preservatives, to help prevent the active drug ingredient from breaking down and becoming less effective.

FDA labeling rules at 21 CFR 101.100 name sodium metabisulfite among sulfiting agents and define a detectable amount as 10 parts per million or more of sulfite in the finished food, and the FDA says sulfiting agents must be declared on food labels at or above 10 ppm total sulfites, due in part to adverse reactions such as asthma in sensitive individuals. The FDA says studies have demonstrated that sulfites may cause allergic-type reactions in susceptible people, especially patients with asthma, including anaphylactic symptoms and life-threatening or less severe asthmatic episodes. The NIOSH Pocket Guide lists a recommended exposure limit for sodium metabisulfite of 5 mg/m3 as a time-weighted average, with no OSHA permissible exposure limit.