Colorado State University Extension
SafeFood Rapid Response Network


SAFEFOOD NEWS - Spring 1997 - Vol. 1, No. 3

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Sulfites Dangerous For Some

Sulfur-based preservatives, or sulfites, have been used around the world for hundreds of years to inhibit oxidation of fruits and vegetables; prevent melanosis ("black spot") on shrimp and lobster; discourage bacterial growth as wine ferments; "condition" dough; bleach food starches; and maintain the stability and potency of some medications.

The FDA estimates that one of a hundred people is sulfite- sensitive, and that 5 percent of those with asthma are also at risk of suffering an adverse reaction to sulfites. A person can develop sulfite sensitivity at any point in life, and no one knows what triggers onset or the mechanism by which reactions occur.

"Doctors believe that asthmatics develop difficulty breathing by inhaling sulfite fumes from treated foods," notes Dan Atkins, M.D., pediatrician at the National Jewish Center for Immunology and Respiratory Medicine in Denver. In a severe reaction an overwhelming degree of bronchial constriction occurs, causing breathing to stop. Atkins says that more severe asthmatics and those dependent on corticosteroids are especially prone to sulfite sensitivity and most at risk of having a severe reaction. It is not known which comes first, asthma or sulfite sensitivity.

Sulfite sensitivity can be tricky to diagnose. People reacting to sulfites know it's something they ate, but may not know exactly what the something is. If a person develops hives after ingesting sulfites, the doctor will do a prick test. "People who have positive skin tests to sulfites are likely to be allergic to the additive, rather than have a sensitivity. These people, who are usually not asthmatic, are most at risk of anaphylactic shock," says Ron Simon, M.D., head of Allergy, Asthma and Immunology at Scripps Clinic and Research Foundation in La Jolla' California.

Simon says "the most rapid reactions occur when sulfites are sprayed onto foods or are present in a beverage, but the most severe reactions occur when sulfites are constituents of the food itself."

Scientists have not determined the smallest concentration of sulfites needed to cause a reaction in a sensitive or allergic person. FDA requires food manufacturers and processors to disclose the presence of sulfiting agents in concentrations of at least 10 parts per million (ppm), but the threshold may be even lower. The assay used to detect sulfite levels in food is not sensitive enough to detect amounts less than 10 ppm in all foods, so that's what regulation has to be based on.

Currently, the following regulations are in place to protect sulfite-sensitive individuals:

• It is prohibited to use sulfites to maintain color and crispness on fruits and vegetables meant to be eaten raw (for instance, restaurant salad bars or fresh produce in the supermarket).
• Companies are required to list on product labels sulfiting agents that occur at concentrations of 10 ppm or higher, and any sulfiting agents that had a technical or functional effect in the food (for instance, as a preservative) regardless of the amount present. (This labeling requirement was extended to standardized foods, such as pickles and bottled lemon juice, in 1993.)
• FDA requires that the presence of sulfites be disclosed on labels of packaged foods (although manufacturers need not specify the particular agent). This information will be included in the ingredient portion of the label, along with the function of the sulfiting agents (for instance, a preservative).
• When food is sold unpackaged in bulk form, store managers must post a sign or some other type of labeling that lists the food's ingredients on the container or at the counter so that consumers can determine whether the product was treated with a sulfiting agent.

FDA consumer safety officer JoAnn Ziyad, Ph.D., says that "the [FDA] continues to have concerns about the safety of sulfiting agents, and plans further action to protect the consumer." Steps being considered include establishing maximum residual levels for specific foods and additional labeling rules.

Since 1985 FDA's Adverse Reaction Monitoring System has been tracking reactions to sulfites. Over a 10-year period 1,097 cases have been reported. However, due to regulatory action taken by FDA over the years, as well as increased consumer savvy, the number of reported sulfite-related health incidents has been dropping steadily. In 1995 just six cases were reported.

Ziyad notes that sulfite-sensitive consumers, despite regulations, "shouldn't take anything for granted." Atkins recommends the following measure to avoid sulfites when buying unlabeled foods at the deli or supermarket and ordering at a restaurant:

• If the food is packaged, read the label. If it is being sold loose or by the portion, ask the store manager or waiter to check the ingredient list on the product's original bulk-size packaging.
• Avoid processed foods that contain sulfites, such as dried fruits, canned vegetables, maraschino cherries, and guacamole. If you want to eat a potato, order a baked potato rather than hash browns, fries, or any dish that involved peeling the potato first.
• If you have asthma, have your inhaler with you when you go out to eat. Similarly, if you've experienced a severe reaction to sulfites in the past (such as breaking out in hives), carry an antihistamine and make sure you have handy a self-administering injectable epinephrine, such as EpiPen, so that if you have a reaction, you can stabilize your condition until you get to an emergency room.

"It takes some doing, but you can take steps to minimize your contact with sulfites if you are diagnosed with asthma or sulfite sensitivity," says Ziyad. "But you may not even know you have a problem with sulfites until a reaction occurs. Undiagnosed people are at risk because even if they know that sulfites can cause adverse reactions, they often don't associate sulfites with their own health problems," says Ziyad.

"Regulations can go a long way towards protecting people, but there's no substitute for knowledge."

For more information on sulfites, call 1-800-FDA-4010.

Source: FDA Consumer, December 1996.

Updated Monday, August 29, 2011