A review of sulphites in foods: analytical methodology and reported findings

Sulphites in various forms have been added to foods for centuries. Their use became an issue of concern when certain sensitive individuals exhibited adverse reactions to sulphite residues in foods. Analytical methods were developed to monitor these compounds at the regulatory limit of 10 ppm. In this report, analytical methods for determining sulphites in foods are reviewed, along with a critique of their chemistry and procedural schemes. An assessment of the key features of each method category is presented together with some comparative data. The classification scheme used is based upon the fact that determination of the sulphite content of a food is influenced more by the treatment and cleanup of the test solution than by the final determinative step. Based on a 60-year database, the Monier-Williams procedure still remains the method of choice.

Sulfite hypersensitivity. A critical review

Sulfiting agents (sulfur dioxide and the sodium and potassium salts of bisulfite, sulfite, and metabisulfite) are widely used as preservatives in foods, beverages, and pharmaceuticals. Within the past 5 years, there have been numerous reports of adverse reactions to sulfiting agents. This review presents a comprehensive compilation and discussion of reports describing reactions to ingested, inhaled, and parenterally administered sulfite. Sulfite hypersensitivity is usually, but not exclusively, found within the chronic asthmatic population. Although there is some disagreement on its prevalence, a number of studies have indicated that 5 to 10% of all chronic asthmatics are sulfite hypersensitive. This review also describes respiratory sulfur dioxide sensitivity which essentially all asthmatics experience. Possible mechanisms of sulfite hypersensitivity and sulfur dioxide sensitivity are discussed in detail. Sulfite metabolism and the role of sulfite oxidase in the detoxification of exogenous sulfite are reviewed in relationship to the etiology of sulfite hypersensitivity.

Sulfite sensitivity: significance in human health

Endogenous sulfite is generated as a consequence of the body's normal processing of sulfur-containing amino acids. Sulfites occur as a consequence of fermentation and also occur naturally in a number of foods and beverages. As food additives, sulfiting agents were first used in 1664 and approved in the United States as long ago as the 1800s. With such long experience with their use, it is easy to understand why these substances have been regarded as safe. They are currently used for a variety of preservative properties, including controlling microbial growth, preventing browning and spoilage, and bleaching some foods. It is estimated that up to 500,000 (< .05% of the population) sulfite-sensitive individuals live in the United States. Sulfite sensitivity occurs most often in asthmatic adults--predominantly women; it is uncommonly reported in preschool children. Adverse reactions to sulfites in nonasthmatics are extremely rare. Asthmatics who are steroid-dependent or who have a higher degree of airway hyperreactivity may be at greater risk of experiencing a reaction to sulfite-containing foods. Even within this limited population, sulfite sensitivity reactions vary widely, ranging from no reaction to severe. The majority of reactions are mild. These manifestations may include dermatologic, respiratory, or gastrointestinal signs and symptoms. Severe nonspecific signs and symptoms occur less commonly. Broncho-constriction is the most common sensitivity response in asthmatics. The precise mechanisms of the sensitivity responses have not been completely elucidated. Inhalation of sulfur dioxide (SO2) generated in the stomach following ingestion of sulfite-containing foods or beverages, a deficiency in a mitochondrial enzyme, and an IgE-mediated immune response have all been implicated.(ABSTRACT TRUNCATED AT 250 WORDS)

"Inactive" ingredients in pharmaceutical products: update (subject review). American Academy of Pediatrics Committee on Drugs

Because of an increasing number of reports of adverse reactions associated with pharmaceutical excipients, in 1985 the Committee on Drugs issued a position statement recommending that the Food and Drug Administration mandate labeling of over-the-counter and prescription formulations to include a qualitative list of inactive ingredients. However, labeling of inactive ingredients remains voluntary. Adverse reactions continue to be reported, although some are no longer considered clinically significant, and other new reactions have emerged. The original statement, therefore, has been updated and its information expanded.

Role of sulfite additives in wine induced asthma: single dose and cumulative dose studies

BACKGROUND

Wine appears to be a significant trigger for asthma. Although sulfite additives have been implicated as a major cause of wine induced asthma, direct evidence is limited. Two studies were undertaken to assess sulfite reactivity in wine sensitive asthmatics. The first study assessed sensitivity to sulfites in wine using a single dose sulfited wine challenge protocol followed by a double blind, placebo controlled challenge. In the second study a cumulative dose sulfited wine challenge protocol was employed to establish if wine sensitive asthmatics as a group have an increased sensitivity to sulfites.

METHODS

In study 1, 24 asthmatic patients with a strong history of wine induced asthma were screened. Subjects showing positive responses to single blind high sulfite (300 ppm) wine challenge were rechallenged on separate days in a double blind, placebo controlled fashion with wines of varying sulfite levels to characterise their responses to these drinks. In study 2, wine sensitive asthmatic patients (n=12) and control asthmatics (n=6) were challenged cumulatively with wine containing increasing concentrations of sulfite in order to characterise further their sensitivity to sulfites in wine.

RESULTS

Four of the 24 self-reporting wine sensitive asthmatic patients were found to respond to sulfite additives in wine when challenged in a single dose fashion (study 1). In the double blind dose-response study all four had a significant fall in forced expiratory volume in one second (FEV(1)) (>15% from baseline) following exposure to wine containing 300 ppm sulfite, but did not respond to wines containing 20, 75 or 150 ppm sulfite. Responses were maximal at 5 minutes (mean (SD) maximal decline in FEV(1) 28.7 (13)%) and took 15-60 minutes to return to baseline levels. In the cumulative dose-response study (study 2) no significant difference was observed in any of the lung function parameters measured (FEV(1), peak expiratory flow (PEF), mid phase forced expiratory flow (FEF(25-75))) between wine sensitive and normal asthmatic subjects.

CONCLUSIONS

Only a small number of wine sensitive asthmatic patients responded to a single dose challenge with sulfited wine under laboratory conditions. This may suggest that the role of sulfites and/or wine in triggering asthmatic responses has been overestimated. Alternatively, cofactors or other components in wine may play an important role in wine induced asthma. Cumulative sulfite dose challenges did not detect an increased sensitivity to sulfite in wine sensitive asthmatics and an alternative approach to identifying sulfite/wine sensitive asthma may be required.

Allergic and asthmatic reactions to alcoholic drinks

Alcoholic drinks are capable of triggering a wide range of allergic and allergic-like responses, including rhinitis, itching, facial swelling, headache, cough and asthma. Limited epidemiological data suggests that many individuals are affected and that sensitivities occur to a variety of drinks, including wine, beer and spirits. In surveys of asthmatics, over 40% reported the triggering of allergic or allergic-like symptoms following alcoholic drink consumption and 30 - 35% reported worsening of their asthma. Sensitivity to ethanol itself can play a role in triggering adverse responses, particularly in Asians, which is due mainly to a reduced capacity to metabolize acetaldehyde. In Caucasians, specific non-alcohol components are the main cause of sensitivities to alcoholic drinks. Allergic sensitivities to specific components of beer, spirits and distilled liquors have been described. Wine is clearly the most commonly reported trigger for adverse responses. Sensitivities to wine appear to be due mainly to pharmacological intolerances to specific components, such as biogenic amines and the sulphite additives. Histamine in wine has been associated with the triggering of a wide spectrum of adverse symptoms, including sneezing, rhinitis, itching, flushing, headache and asthma. The sulphite additives in wine have been associated with triggering asthmatic responses. Clinical studies have confirmed sensitivities to the sulphites in wine in limited numbers of individuals, but the extent to which the sulphites contribute to wine sensitivity overall is not clear. The aetiology of wine-induced asthmatic responses may be complex and may involve several co-factors.

Prevalence of sensitivity to sulfiting agents in asthmatic patients

Ingestion of sulfiting agents can induce wheezing in some asthmatic patients. However, neither the prevalence of sulfite sensitivity nor the clinical characteristics of the affected asthmatic population are known. In a prospective single-blind screening study, 120 non-steroid-dependent and 83 steroid-dependent asthmatic patients underwent challenge with oral capsules of potassium metabisulfite. Five non-steroid-dependent and 16 steroid-dependent asthmatic patients experienced a greater than 20 percent reduction in their one-second forced expiratory volume within 30 minutes following the oral challenge. Twelve of these sulfite reactors were rechallenged with metabisulfite capsules in a double-blind protocol. Under these conditions, only three of seven steroid-dependent patients had a positive response. Moreover, only one of five non-steroid-dependent patients had a response to double-blind challenge. On the basis of this challenge study, the best estimate of the prevalence of sulfite sensitivity in the asthmatic patients studied is 3.9 percent. This population, however, contained a larger number of steroid-dependent asthmatic patients than would be found in the general asthmatic population. It is concluded, therefore, that the prevalence of sulfite sensitivity in the asthmatic population as a whole would be less than 3.9 percent and that steroid-dependent asthmatic patients are most at risk.

Adverse reactions to drug additives

There is a long list of additives used by the pharmaceutical industry. Most of the agents used have not been implicated in hypersensitivity reactions. Among those that have, only reactions to parabens and sulfites have been well established. Parabens have been shown to be responsible for rare immunoglobulin E-mediated reactions that occur after the use of local anesthetics. Sulfites, which are present in many drugs, including agents commonly used to treat asthma, have been shown to provoke severe asthmatic attacks in sensitive individuals. Recent studies indicate that additives do not play a significant role in "hyperactivity." The role of additives in urticaria is not well established and therefore the incidence of adverse reactions in this patient population is simply not known. In double-blind, placebo-controlled studies, reactions to tartrazine or additives other than sulfites, if they occur at all, are indeed quite rare for the asthmatic population, even for the aspirin-sensitive subpopulation.

Sensitivity to ingested metabisulfite: variations in clinical presentation

Two patients presented with histories compatible with an anaphylactic reaction temporally related to meals. Detailed allergy and immunologic studies indicated that the episodes were caused by sensitivity to metabisulfites. Some of the clinical implications are briefly discussed.

Sulphiting agents in foods: some risk/benefit considerations

The current toxicological status of sulphiting agents is reviewed, including evidence of adverse reactions to sulphited foods by a sub-population of asthmatics. Against this background are assessed the applications and benefits of sulphiting agents in foods. It is concluded that further information is required to determine the magnitude of risk and that, in the interim, the controlled use of sulphiting agents is justifiable.

Local anesthetic intolerance due to metabisulfite

The case of a 40-year-old woman with severe edema of the face and neck after the injection of a local dental anesthetic is presented. The reaction is attributed to the presence of sodium metabisulfite, and antioxidant, in the local anesthetic. Both the anesthetic and the sodium metabisulfite gave a delayed positive patch-test response.

Positive skin tests and Prausnitz-Küstner reactions in metabisulfite-sensitive subjects

Sulfiting agents have been reported to cause anaphylaxis, asthma, urticaria/angioedema, seizure, nausea, abdominal pain and diarrhea, and death. There is no consensus regarding the pathogenesis of these reactions. The possible role of IgE-mediated mechanism has been debated. To clarify the pathogenesis of these reactions, we studied 53 patients with a variety of symptoms related to either restaurant meals or alcoholic beverages. Food allergy was excluded as a cause of their symptoms by means of skin testing and elimination diet. Symptoms included urticaria/angioedema (32), asthma (nine), headache (eight), rhinoconjunctivitis (two), and abdominal pain (one), and one patient with anaphylaxis. Twenty normal control subjects were studied as well. Prick and intradermal skin testing with potassium metabisulfite (K2S2O5, 1 mg/ml) were carried out on all subjects. Single-blind oral provocative challenge tests were conducted with placebo (lactose) and with 1, 5, 10, 25, and 50 mg of K2S2O5 in all nine subjects with asthma, nine patients with urticaria/angioedema (excluding one subject with severe coronary insufficiency and positive skin testing to 1 mg of K2S2O5), four subjects with headache, one subject with rhinoconjunctivitis, and one patient with anaphylaxis. Pulmonary function tests (FEV1 and FVC) were measured in all subjects with asthma. Five patients had positive skin tests. One subject with asthma had a positive prick test. Four positive intradermal tests occurred (two subjects with asthma, one subject with urticaria/angioedema, and one subject with anaphylaxis). Single-blind oral provocative challenge testing was positive in the subject with anaphylaxis, as was intradermal skin testing, and also in three subjects with asthma, two of whom had positive skin testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Bisulfite sensitivity manifesting as allergy to local dental anesthesia

A case of sulfite sensitivity first manifested as possible allergy to local anesthetics is described. Implications for the broad problem of local anesthetic reactivity are discussed and a possible approach by sulfite challenge of suspect patients is outlined.

Sulfites--a food and drug administration review of recalls and reported adverse events

Sulfite-sensitive individuals can experience adverse reactions after consuming foods containing sulfiting agents (sulfites), and some of these reactions may be severe. In the 1980s and 1990s, the U.S. Food and Drug Administration (FDA) acted to reduce the likelihood that sulfite-sensitive individuals would unknowingly consume foods containing sulfites. The FDA prohibited the use of sulfites on fruits and vegetables (except potatoes) to be served or presented fresh to the public and required that the presence of detectable levels of sulfites be declared on food labels, even when these sulfites are used as a processing aid or are a component of another ingredient in the food. In the present study, data from FDA recall records and adverse event reports were used to examine the current status of problems of sensitivity to sulfites in foods. From 1996 through 1999, the FDA processed a total of 59 recalls of foods containing undeclared sulfites; these 59 recalls involved 93 different food products. Fifty (55%) of the recalled products were classified as class I, a designation indicating that a consumer reasonably could have ingested > or = 10 mg of undeclared sulfites on a single occasion, a level that could potentially cause a serious adverse reaction in a susceptible person. From 1996 through mid-1999, the FDA received a total of 34 reports of adverse reactions allegedly due to eating foods containing undeclared sulfites. The average of 10 reports per year, although derived from a passive surveillance system, was lower than the average of 111 reports per year that the FDA received from 1980 to 1987, a decrease that may have resulted in part from FDA regulatory action.

Sodium metabisulfite allergy is common but is it relevant?

Positive patch tests to sodium metabisulfite (SMB) are frequent. Standard series patch testing to SMB in 1751 patients showed 71 reactions interpreted as positive and allergic. 33 (46.5%) reactions were originally reported as relevant and 38 (53.5%) were of unexplained relevance depending on the presence or absence of identifiable sources responsible for the presenting dermatitis. A breakdown of these findings is presented. An additional detailed study of the sources of SMB in the environment and a retrospective analysis of these results have been undertaken to identify further, possibly overlooked sources of SMB exposure based on the occupational and recreational history. Most of the positive reactions in the relevant group were attributed to the use of Trimovate cream (63%). 5 patients (13%) with positive reactions in the unexplained relevance group were potentially exposed to SMB in local anaesthetic solutions while at work. 3 patients in the unexplained relevance group (7.8%) and 4 (12.1%) in the relevant group had potential for occupational exposure to SMB as bakers or caterers. Overall, occupational exposure was considered as a possible source of sensitization in 10 (26.3%) patients in the unexplained relevance group. We propose that sensitization to SMB from parenteral solutions and occupational exposure from food handling may account for some of the otherwise unexplained positive patch test reactions. A detailed occupational history should be therefore be sought in otherwise unexplained positive reactions to SMB. We also propose that it is worthwhile including SMB in our standard series in the UK.

Wine-induced asthma: a placebo-controlled assessment of its pathogenesis

BACKGROUND

The sulfite family of food additives has been implicated in the pathogenesis of wine-induced asthma. However, the evidence supporting this is weak, and because wines have many hundreds of components, nonsulfite-associated mechanisms may also play a role.

OBJECTIVES

The aim of the study was to assess the potential sensitivity of persons with asthma to nonsulfite components in wine by using low-sulfite wine challenges.

METHODS

Sixteen adults with a strong history of wine-induced asthma were challenged with both low-sulfite red and white wines and wine-placebo drinks. Challenges were performed double blind, using a Latin square design, with lung function being assessed before the challenge and at 5, 10, 15, 30, and 60 minutes after the challenge. Subsequently, single-blind challenges with high-sulfite white wine were also completed in 10 individuals whose lack of reactivity to low-sulfite white wine suggested possible reactivity to sulfite additives.

RESULTS

The mean FEV1; forced expiratory flow, mid-expiratory phase; and peak expiratory flow of subjects to low-sulfite red and white wines and red and white placebo wines were not significantly different. Furthermore, with a predetermined criterion of a fall in FEV1 of more than 15% representing a positive challenge, only one individual exhibited a positive reaction in the presence of a negative response to placebo. Only 2 of the 10 test individuals who were challenged with a high-sulfite wine demonstrated a marked and rapid fall in FEV1. Reactivity to low-sulfite wines appears to occur only in a small number of individuals who report sensitivity to wines, suggesting that the sulfite additives may be the major cause of wine-induced asthmatic reactions. However, direct challenge with high-sulfite wine revealed only 2 clear reactions in this asthma cohort.

CONCLUSION

Wine-induced asthma appears to be a complex phenomenon and may involve several mechanisms that are codependent.

Sulfite contact allergy

In the last 2 years, 2,894 consecutive eczematous patients were patch tested with sodium metabisulfite 1% pet. Positive reactions were elicited in 50 subjects (1.7%). All 50 patients were also positive to potassium metabisulfite 1% pet. and sodium bisulfite 1% and 5% pet., while only 2 of them were positive to sodium sulfite 1% pet. Prick tests and intradermal tests with a sodium metabisulfite solution (10 mg/ml) were negative. No flare-ups of dermatitis or patch test were provoked by oral challenge with 30 mg and 50 mg of sodium metabisulfite. The dermatitis was taken to be occupational in 7 cases. In only 5 out of 43 non-occupational cases was the positive reaction considered relevant.

Characterisation of bronchoconstrictor responses to sodium metabisulphite aerosol in atopic subjects with and without asthma

Inhalation of sodium metabisulphite is thought to induce bronchoconstriction by release of sulphur dioxide. We sought to establish the reproducibility of the airway response to inhaled sodium metabisulphite given in increasing doubling concentrations (0.3 to 160 mg/ml) to 13 asthmatic and five atopic non-asthmatic subjects and the contribution of cholinergic mechanisms to this response. In 15 of the 18 subjects bronchoconstriction was sufficient to allow calculation of the dose of metabisulphite causing a 20% reduction in the forced expiratory volume in one second (FEV1) from baseline values (PD20 metabisulphite). The 95% confidence limit for the difference between this and a second PD20 metabisulphite determined 2-14 days later was 2.5 doubling doses. The difference between repeat PD20 metabisulphite measurements was unrelated to the number of days between challenges or change in baseline FEV1. Ten subjects returned for a third study 3-120 days after the second challenge; variability in PD20 metabisulphite did not differ from that seen between the first and second challenges. PD20 methacholine was determined between the two metabisulphite challenges and found to correlate with PD20 metabisulphite (r = 0.71). Inhaled ipratropium bromide 200 micrograms given in a randomised, placebo controlled, crossover study to 10 subjects increased PD20 methacholine 42 fold but had no significant effect on the response to metabisulphite. A single inhalation of the PD20 metabisulphite in five subjects induced maximal bronchoconstriction 2-3 minutes after inhalation, with a plateau in FEV1 lasting a further four minutes before recovery. A further single inhalation of the same PD20 dose 43 minutes later produced a 27% (SEM 4%) smaller fall in FEV1 than the first inhalation. These results show that metabisulphite PD20 values measured over days and weeks show similar reproducibility to those reported for histamine inhalation and that PD20 metabisulphite correlates with methacholine responsiveness. Most of the bronchoconstriction is not inhibited by antimuscarinic agents; the underlying mechanisms require further investigation.

Changes in bronchial hyperresponsiveness following high- and low-sulphite wine challenges in wine-sensitive asthmatic patients

BACKGROUND

Previous studies suggest that challenge of most wine-sensitive asthmatic patients may not result in a reduction in forced expiratory volume in 1 s (FEV(1)).

OBJECTIVE

The aim of this study was to assess whether changes in bronchial hyperresponsiveness (BHR) occur following wine challenge of asthmatic patients who report sensitivity to wine, and whether such changes could help clarify the role of sulphite additives in wine-induced asthmatic responses.

METHODS

Eight self-reporting wine-sensitive asthmatic patients completed double-blind challenges with high- and low-sulphite wines on separate days. FEV(1) and histamine PC(20) were measured before and after consumption of 150 mL of wine.

RESULTS

None of the eight subjects demonstrated a clinically significant >or=15%) reduction in FEV(1) following challenge with either high- or low-sulphite wine. In contrast, one patient demonstrated clinically significant increase in BHR following challenge with both high- and low-sulphite wines, and a smaller increase in BHR following placebo challenge. A second patient showed a significant increase, while another showed a significant decrease in BHR following challenge with low-sulphite wine. A fourth patient showed borderline increases in BHR following challenge with both high- and low-sulphite wines.

CONCLUSIONS

Although changes in BHR, in the absence of reductions in FEV(1), were observed in some asthmatic patients following wine challenge, these changes were not consistent with a single aetiology. Consequently, this study did not support a major role for the sulphite additives in wine-induced asthmatic responses in the patients studied. The aetiology of wine-induced asthma is likely to be complex and appears to vary among individuals who are sensitive to these drinks.

Contraindications to vasoconstrictors in dentistry: Part II. Hyperthyroidism, diabetes, sulfite sensitivity, cortico-dependent asthma, and pheochromocytoma

Dentists are aware of contraindications to the use of vasoconstrictors in patients with cardiovascular diseases. However, there are some other noncardiac conditions we should know. This article discusses the absolute contraindications to the use of vasoconstrictors in patients with a history of hyperthyroidism, diabetes, allergy to sulfites, asthma, and pheochromocytoma.

Bronchoconstrictor additives in bronchodilator solutions

Nebulized bronchodilator solutions are available in the United States as both nonsterile and sterile-filled products. Sulfites, benzalkonium chloride (BAC), or chlorobutanol are added to nonsterile products to prevent bacterial growth, but there have been reports of contaminated solutions containing preservatives. Ethylenediamine tetraacetic acid (EDTA) is added to some products to prevent discoloration of the solution. With the exception of chlorobutanol, all of these additives are capable of inducing bronchospasm in a concentration-dependent manner. However, it is rarely apparent to the patient or health care provider that the additive diminishes the bronchodilator effects. Older products (eg, isoproterenol and isoetharine) contain enough sulfites to produce bronchospasm in most patients with asthma, even in those without a prior history of sulfite sensitivity. Bronchoconstriction from inhaled BAC is cumulative, prolonged, and correlates directly with basal airway responsiveness. The multidose dropper bottle of albuterol contains 50 microg BAC/dose, which is below the threshold for bronchoconstriction whereas the screwcap unit-dose vial contains 300 microg/dose, which is above the threshold for many patients. If the screwcap product is used in the emergency department, a patient could receive as much as 1800 microg of BAC in the first hour. Three sterile-filled unit dose albuterol products contain no additives, whereas a fourth, (manufactured by Dey Laboratories) contains 300 microg of EDTA, which is also below the threshold dose for bronchoconstriction. Only additive-free sterile solutions should be used for hourly or continuous nebulization of albuterol. The multidose dropper bottle or the Dey product can be used when the interval between doses is longer, whereas the screwcap product should not be used for acute therapy. Ipratropium is available only as a sterile, additive-free unit-dose vial, as is levalbuterol.

Approach to patients with suspected hypersensitivity to local anesthetics

Adverse reactions to local anesthetics are relatively common, but true IgE-mediated hypersensitivity is extremely rare. Fortunately, the vast majority of adverse reactions occur via nonimmunologic means, but considerable confusion still exists among providers. We conducted a review of the literature to determine if earlier estimates of IgE-mediated allergy are consistent with current reports and whether current management strategies are consistent with these findings. We identified several confounding variables involved in the evaluation, including the roles of preservatives/additives, epinephrine, latex, and inadequate testing procedures. These problems may cause significant diagnostic challenges for clinicians. It is in fact much more likely that there is an alternate diagnosis, and in many cases clinicians can begin the evaluation in the office. When local anesthetic allergy is still suspected, the patient should be referred to an allergist for testing to determine if the suspected culprit drug can be safely used, or, if necessary, identify a suitable alternative.