Sulfur dioxide is a chemical compound, sulfur oxide or sulfur dioxide.

It comes in the form of a colorless gas with an irritating smell.

The sulphite group includes:

What it is used for and where

Food

Ingredient on the European food additives list as E220, preservative and antioxidant in food. 

Sulfur dioxide is used as a preservative and antioxidant especially in the oenological field with the name of Sulfites.

Safety

The maximum levels of sulfur dioxide that a wine can contain are 160 ppm for red wine, 210 ppm for white wine and 400 ppm for sweet wines. These are the rules in force in the European Union. Fairly similar levels apply in the United States, Australia and around the world.

Sulphites are responsible for adverse reactions to sulfite sensitive individuals, such as headaches.

The critical points are the local effects, e.g. gastrointestinal irritation or corrosiveness (1). 

The most relevant studies on this chemical compound have been selected with a summary of their contents:

Sulfur dioxide studies

• Molecular Formula: SO₂  O₂S
• Molecular Weight: 64.058 g/mol
• UNII: 0UZA3422Q4
• CAS: 7446-09-5    12624-32-7  12396-99-5  8014-94-6  83008-56-4  89125-89-3  1239882-82-6
• EC Number: 231-195-2
• FEMA Number: 3039
• PubChem Substance ID 329769309
• MDL number MFCD00011450
• Beilstein Registry Number 3535237

Synonyms:

• Sulfur dioxide
• Sulphur dioxide
• Sulfurous anhydride
• Surfur dioxide (anhydrous)
• Sulfur dioxide (NF)
• Sulfurdioxide
• sulfer dioxide
• Dioxide, Sulfur
• Sulfon
• E220
• Oxosulfane oxide 

References_____________________________________________________________________

(1) Kramer NI, Hoffmans Y, Wu S, Thiel A, Thatcher N, Allen TEH, Levorato S, Traussnig H, Schulte S, Boobis A, Rietjens IMCM, Vinken M. Characterizing the coverage of critical effects relevant in the safety evaluation of food additives by AOPs. Arch Toxicol. 2019 Aug;93(8):2115-2125. doi: 10.1007/s00204-019-02501-x. 

Abstract. There is considerable interest in adverse outcome pathways (AOPs) as a means of organizing biological and toxicological information to assist in data interpretation and method development. While several chemical sectors have shown considerable progress in applying this approach, this has not been the case in the food sector. In the present study, safety evaluation reports of food additives listed in Annex II of Regulation (EC) No 1333/2008 of the European Union were screened to qualitatively and quantitatively characterize toxicity induced in laboratory animals. The resulting database was used to identify the critical adverse effects used for risk assessment and to investigate whether food additives share common AOPs. Analysis of the database revealed that often such scrutiny of AOPs was not possible or necessary. For 69% of the food additives, the report did not document any adverse effects in studies based on which the safety evaluation was performed. For the remaining 31% of the 326 investigated food additives, critical adverse effects and related points of departure for establishing health-based guidance values could be identified. These mainly involved effects on the liver, kidney, cardiovascular system, lymphatic system, central nervous system and reproductive system. AOPs are available for many of these apical endpoints, albeit to different degrees of maturity. For other adverse outcomes pertinent to food additives, including gastrointestinal irritation and corrosion, AOPs are lacking. Efforts should focus on developing AOPs for these particular endpoints.