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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

OECD 301E (Experimental investigation): 86 % degradation after 28 days - readily biodegradable, but not fulfilling the 10-d window 
BIOWIN v4.10 (QSAR prediction): Not readily biodegradable, not persistent in the environment

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

Regarding biodegradation in water (screening tests) an experimental (key study, Klimisch score 2) as well as a QSAR result (supporting study, Klimisch score 2) is available for the test substance. The study was conducted according to OECD Guideline 301E (Kuhlmann, 1990). The degradation parameter was the DOC removal in the samples, measured by a total organic carbon analyser (DC 90 Dohrmann) according to DIN 38409 T3. After 2 weeks incubation 2 % of the test substance was degraded, after 19 days 42 %, after 27 days 85 % and at the end of the experiment (28 days) 86 % degradation had occurred. Tetrapropylbenzolsulfonat (TPBS) and Marlon A were used as reference substances. After 28 days incubation with activated sludge (adaption not further specified) these substances were degraded for 24 % and 58 %, respectively. Based on the results of the key study the substance is readily biodegradable, but fails the so-called 10 -day window defined in the guideline.

For completeness, a prediction for biodegradability of PPS was performed with the computer program BIOWIN v4.10 (EPIWIN software) by US-EPA (Chemservice S.A., 2011). This program predicts biodegradation by using seven different models: Linear Model (Biowin 1), Non-linear Model (Biowin 2), Ultimate Biodegradation Timeframe (Biowin 3), Primary Biodegradation Timeframe (Biowin 4), MITI Linear Model (Biowin 5), MITI Non-linear Model (Biowin 6) and Anaerobic Model (Biowin 7). The overall result gives the ready biodegradability prediction of the compound.

If the Biowin 3 result is given in weeks or even faster and the Biowin 5 probability is ≥ 0.5, then the overall prediction is “yes”, thus the substance will be considered as readily biodegradable. This procedure is based on application of Bayesian analysis to ready biodegradation data.

Biowin 5 and 6 predict the ready biodegradability for degradation in the OECD Guideline 301C only and thereby using the database from the Chemicals Evaluation and Research Institute Japan (CERIJ).

According to Biowin 1 and 2 PPS is biodegrading fast. The Ultimate Biodegradation Timeframe is given in weeks, whereas the Primary Biodegradation Timeframe gives days-weeks as result. Both MITI Models predict that the substance is not readily biodegradable, which is also the overall prediction result. Also under anaerobic conditions the substance is expected to be not degraded fast. However, the given Primary and Ultimate Timeframe (weeks / days-weeks) confirm that the substance will not be persistent in the environment.

In conclusion, 1-(3-sulphonatopropyl)pyridinium is assessed as readily biodegradable based on a valid experimental test and supporting QSAR estimations.