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Description of key information

Key value for chemical safety assessment

Additional information

No experimental data on toxicokinetics, dynamics or metabolism of the test item are available. Thus, information on toxicokinetics and distribution are derived from longterm studies, physico-chemical data and structur-activity-relationhsips.

Test item

The test item is solid with a melting point of app. 180°C and a very low vapour pressure of 10^-9 Pa. In water the substance is expected to be instable and to dissolve slowly into di-tert-butylphenol and phosphate. Low pH conditions may enhance this reaction. Thus, data on metabolism and kinetics base upon these hydrolysis products, too. Subchronic and chronic administration of the material to rats and dogs did not induce toxicity. At 1000 ppm, slight extramedullary hematopoisis and a slight decrease in body weight were observed. Concerns about possible neurotoxicity were not confirmed, a test on delayed neurotoxicity gave no hint on behavioural changes or pathologic findings at the nervous system.

Uptake and Distribution

After ingestion, the material dissolves presumbly into di-tert-butyl-phenol and phosphate. Phosphate is taken up via passive diffusion or, to a minor extend, by active transport to be incorporated into bones and teeth or it is right after excreted via the kidneys. Repeated dose studies on di-tert-buty-phenol indicate that the substance is absorbed after oral application to be transported to the liver. Increased liver weights, hepatocellular hypertrophy and changes in hematology and clinical chemistry give reason to belive that the substance is bioavailable.

Metabolism and Kinetics

Following systemic exposure to di-tert-butyl-phenol in the circulation, a rapid metabolism by conjugation with glucuronic acid at the OH-group may be predicted from the chemical structure with excretion via the kidneys or via bile. Furthermore, hydroxylation of the di-tert-butyl residues is possible.

Excretion

Conjugation with activated glucuronic acid increases the molecular weight of the compound for 200 g/mol. Conjugated di-tert-butyl-phenol then has a MW of app. 400 g/mol which supports renal excretion. Bioaccumulation of the test item or the hydrolysis product di-tert-butyl-phenol is not expected.