Sulfur dioxide-hypersensitivity

Dissolved in water, sulfur dioxide produces sulfurous acid (H2S03), hydrogen sulfite ion (HSOj), and sulfite ion (SOf ). Sodium sulfite (Na2S03) has been used as a chemical food preservative, although some individuals are hypersensitive to it. 

Sulfur dioxide, SO2, dissolves in water and accordingly, largely removed in the upper respiratory tract. It is an irritant to the eyes, skin, mucous membranes and respiratory tract. Some individuals are hypersensitive to sodium sulfite,Na2S03, which is used as a chemical food preservative. Sulfur dioxide is especially hazardous for ecosystems due to acid rains (see Chapter 4). 

Sodium bisulfite (sodium hydrogen sulfite, NaHSOj [CAS 7631-90-5]) Irritating to eyes, skin, and respiratory tract. Hypersensitivity reactions (angioedema, bronchospasm, or anaphylaxis) may occur. 5 mg/m White crystalline solid with a slight sulfur dioxide odor and disagreeable taste. Widely used as a food and chemical presenrahve. 

Sodium melabisutfile (sodium pyrosutfile [CAS 7681-57-4]) Very irritating to eyes and skin upon direct contact. Dusts irritating to eyes and respiratory tract pulmonary edema may result. Hypersensitivity reactions may occur. 5 mg/m White powder or crystalline material with a slight odor of sulfur dioxide. Reacts to form sulfur dioxide in the presence of moisture. 

Hypersensitivity to the irritant effects of inhaled sulfur dioxide is well recognized and is a usual feature of asthma. As little as 1.0 ppm of the inhaled gas can produce significant broncho-constriction in groups of asthmatics (Koenig et ai, 1980 Koenig et ai, 1982), and the symptomatic severity of asthma can be correlated with atmospheric SO2 pollution (Boushey, 1982). Hypersensitivity appears to be due to an exaggerated reflex response to chemical irritation on the background of the bronchial hyper-reactivity which characterizes the asthmatic state (Boushey, 1982). 

Sulfur dioxide is an irritant that affects eyes, the respiratory system, mucous membranes, and skin. Because of its water solubility, it is largely removed in the upper respiratory tract, which may be irritated by exposure to the sulfur dioxide, causing bronchioconstriction and increased airflow resistance. Some people are hypersensitive to sulfur dioxide and suffer allergic reactions to it. Included among such people are some asthmatics who are especially sensitive to exposure to the sulfur dioxide. 

---