Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

Short description of key information on bioaccumulation potential result: 
Sulfur dioxide rapidly dissolves extra- or intracellularly in contact with the moist surfaces of the mucous membranes of the respiratory tract forming sulfite and bisulfite as hydration products. Reaction with disulfide structures resulting in formation of S-sulfonates as well as radical intermediates can be involved in the biochemistry of such subsequently formed sulfites. In addition sulfite is further metabolized by oxidation to sulfate by sulfite oxidase. Most of the sulfur dioxide and its metabolites are distributed widely in the body and stay there for long time. Elimination occurs as unchanged sulfur dioxide from the lung and as sulfate in the urine. The available studies do not provide information on the relative amount of sulfur dioxide excreted via the different routes.

Key value for chemical safety assessment

Additional information

During nose breathing sulfur dioxide is nearly completely retained in the nose as the air stream is inhaled, both in humans and in animals. With increasing sulfur dioxide concentration also the deeper airways are reached. The absorptive capacity of the mouth and pharynx tissue is lower than that of the nose, especially if the airflow is increased. Consequently it can be assumed, that sulfur dioxide reaches also the deeper airways of humans during mouth breathing and exercise.

Sulfur dioxide rapidly dissolves extra- or intracellularly in contact with the moist surfaces of the mucous membranes of the respiratory tract forming sulfite and bisulfite as hydration products. It further reacts with disulfide structures resulting in formation of S-sulfonates. Radical intermediates of sulfites can also be involved in the biochemical reactivity. In addition sulfite is further metabolized by oxidation to sulfate by sulfite oxidase. Most of the sulfur dioxide and its metabolites are distributed widely in the body and stay there for long time. Elimination occurs as unchanged sulfur dioxide from the lung and as sulfate in the urine. The available studies do not provide information on the relative amount of sulfur dioxide excreted via the different routes.

Entry adopted from the OECD SIAR on sulfur dioxide without modification