Registration Dossier
Registration Dossier
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EC number: 247-094-1 | CAS number: 25550-51-0
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
- Endpoint:
- biodegradation in water: ready biodegradability
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- weight of evidence
- Justification for type of information:
- REPORTING FORMAT FOR THE ANALOGUE APPROACH
Please refer to IUCLID Section 13. - Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Key result
- Parameter:
- other: degradation to acid
- Value:
- ca. 100
- Sampling time:
- 4 min
- Key result
- Parameter:
- % degradation (O2 consumption)
- Value:
- ca. 2
- Sampling time:
- 28 d
- Key result
- Parameter:
- probability of ready biodegradability (QSAR/QSPR)
- Remarks on result:
- readily biodegradable based on QSAR/QSPR prediction
- Remarks:
- Biowin2 (Biodegrades Fast, p= 0.839), Biowin6 (Not Readily Degradable, p=0.440)
Reference
Description of key information
Ready biodegradability: 2% in 28 days
Key value for chemical safety assessment
- Biodegradation in water:
- under test conditions no biodegradation observed
Additional information
Data are available for 4-methylhexahydrophthalic anhydride (4-MHHPA) whose structure is clearly close to methylhexahydrophthalic anhydride (MHHPA).
Ready biodegradability of 4-MHHPA by a non-adapted activated sludge has been investigated according to OECD/EU test methods using a Manometric Respirometry Test. After 28 days the mean biodegradation was 2% and the test substance must be regarded as not readily biodegradable. A toxicity control containing both test and reference substances demonstrated that degradation of the reference substance was not inhibited by the test substance indicating that the test substance is not inhibitory to STP microorganisms.
4-methylhexahydrophthalic anhydride (4-MHHPA) as well as methylhexahydrophthalic anhydride (MHHPA) hydrolyses almost instantaneously on contact with water, to give 4-methylhexahydrophthalic acid (4-MHHPAc, CAS 57567-84-7). A hydrolysis study according to OECD guideline no. 111 was carried out and the half-life (DT50) at pH 7 and 20°C was estimated to be 1.90 min.
The screening test inherent to the biodegradability of the acid degradation product 4 -MHHPAc was calculated using the software BIOWIN v4.10.The results indicate that 4-methylhexahydrophthalic acid is expected to be readily biodegradable.
Moreover, modelling of possible biodegradation pathways indicate that aerobic degradation is likely, intermediate degradation products being predicted which have been shown to be readily biodegradable.
Although QSAR estimations result in readily biodegradability environmental exposure was assessed by using the term “not biodegradable” as a worst case.
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