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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Considering the overall information available for thioglycolic acid and its main oxidation product, the diammonium dithiodiglycolate, it can be 
considered that thioglycolic acid and its salts are ready biodegradable and do not raise concern in terms of persistency.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Ready biodegradation tests:

A study was performed to assess the ready biodegradability of diammonium dithiodiglycolate (DADTDG ) in an aerobic aqueous medium (Clarke, 2005; reliability 2) following OECD 301B, "Ready Biodegradability; CO2Evolution Test.

An initial experiment was conducted at a concentration of 10 mg C/L, however, inhibition of CO2evolution in the test vessels was observed after 8 days. Therefore, following the recommendations of the Test Guidelines, DADTDG was exposed to activated sewage sludge micro-organisms, at a concentration of 5 mg C/L with culture medium in sealed culture vessels in the dark at 21°C for 28 days. The degradation of DADTDG was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the standard material, sodium benzoate, together with a toxicity control were used for validation purposes.

The test material attained 80% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No 301B the test material cannot be considered to be readily biodegradable as the test material failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation rate exceeding 10%.

However, the test material has exhibited the potential for rapid degradation. All the validation criteria for this test were satisfied