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EC number: 225-625-8 | CAS number: 4979-32-2
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
- Endpoint:
- biodegradation in water: ready biodegradability
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1988-12-07 till 1989-01-04
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: basic data given
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.4-F (Determination of the "Ready" Biodegradability - MITI Test)
- Version / remarks:
- Cited as Directive 84/449/EEC, C.7
- GLP compliance:
- no
- Oxygen conditions:
- aerobic
- Inoculum or test system:
- sewage, predominantly domestic, non-adapted
- Duration of test (contact time):
- 28 d
- Initial conc.:
- 100 mg/L
- Based on:
- test mat.
- Reference substance:
- aniline
- Key result
- Parameter:
- % degradation (O2 consumption)
- Value:
- ca. 2
- Sampling time:
- 28 d
- Details on results:
- reference substance (aniline): 71% biodegradation in 28 days
- Validity criteria fulfilled:
- not specified
- Interpretation of results:
- under test conditions no biodegradation observed
- Conclusions:
- 2% biodegradation of DCBS was observed in 28 days according to EU Method C.4-F (Determination of the "Ready" Biodegradability - MITI Test) (Bayer AG 1989); and hence DCBS is considered as "Not Readily Biodegradable".
- Executive summary:
2% biodegradation of DCBS was observed in 28 days according to EU Method C.4-F (Determination of the "Ready" Biodegradability - MITI Test) (Bayer AG 1989); and hence DCBS is considered as "Not Readily Biodegradable".
Reference
Description of key information
Readily Biodagradation:
2% biodegradation of DCBS was observed in 28 days according to EU Method
C.4-F
(Determination of the "Ready" Biodegradability - MITI Test) (Bayer AG
1989); and hence DCBS is considered as "Not Readily Biodegradable". A
hydrolysis half-life of 53 hours at pH 7 and 25°C was observed for DCBS
(Bayer AG, 1997) with Dicyclohexylamine and 2-mecarptobenzothiazole
(MBT) as the main hydrolysis products (MITI, 2005).
N,N-Dicyclohexylamine was reported as readily biodegradable with 96%
biodegradation observed in 20 days according to OECD guideline 301D
(Bayer AG, 1975), but MBT was not readily biodegradable with only 2.4 %
biodegradation observed in 14 days (MITI, 1992). In the Appendix A of
EU-Risk Assessment for CBS (CAS: 95-33-0), information regarding the
biodegardabilities of the main metabolites of MBT, such as MBTS, BT,
BTon and MeSBT, is also summarized and discussed. The described
metabolites are also not readily biodegradable. Only when the inoculi
were adapted under special conditions, certain level of degradation of
MBT, BT, BTon and MeSBT was observed. Such processes are expected in
biological treatment plant, but not in the environment.
Inherent biodegradation:
Report Currenta 2013a describes the inherent degradation of DCBS.
Although performed under GLP and an accepted OECD guideline, there was
one significant deficiency as it cannot be excluded that one of the four
test vessels was contaminated with NaOH solution. Removal of the result
of this test vessel shows degradation rates in the three remaining
vessels of 13, 23 and 50% after 28 days (mean 29%) and 16, 64 and 85%
after 60 days (mean 55%). The substance is therefore considered to be"
Not Inherently Biodegradable" . The reference compound sodium benzoate
showed 94 % degradation after 14 days.
Report Currenta 2014a describes the inherent degradation of DCBS with identification of metabolites.The analytical recovery of the parent compound at day 0 was found to be unsatisfactory low. Nevertheless, MBT as a primary metabolite was found to be too high. Obviously the analytical method at these low concentrations was not stable enough.
Key value for chemical safety assessment
- Biodegradation in water:
- under test conditions no biodegradation observed
- Type of water:
- freshwater
Additional information
Ready biodegradation:
The MITI study (2005) was used as critical study for SIDS endpoint and assigned to be reliability of 1. However here it is only assigned to be a reliability of 2 since the original reference is not yet available for assessment and hence it is not used as key study.
Inherent biodegradation:
The test for its inherent biodegradability potential was determined according with the OECD Guideline 302C “Inherent Biodegradability: Modified MITI Test (II)” (1981) (based on standard operating procedures for OECD Guideline 301F (1992) and the Council Regulation (EC) No 440/2008, method C.4-D “Manometric Respirometry Test” (2008)) (Currenta 2013a). Deviating from the guideline OECD 302C “Inherent Biodegradability: Modified MITI Test (II)”, the test was conducted with reduced amount of activated sludge and test item. The guideline states: If the test material is not soluble at the test concentration, special measures are allowed to achieve a good dispersion. Therefore a reduced test item concentration of 10 mg/L and a reduced amount of activated sludge (33 mg/L) from three different sources were used. A suspension of the substance in a mineral medium was inoculated with 40 % sludge of each of two different municipal sewage treatment plants (STP) and 20 % sludge of an industrial STP and incubated under aerobic conditions. During this period, degradation was followed by continuous automated BOD determinations. The test was prolonged until 60 days as the biodegradation curve showed that biodegradation has started but that the plateau has not been reached. The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures. The oxygen uptake was calculated from the readings taken at regular and frequent intervals, using the method given by the manufacturer of the equipment. At the end of incubation, the pH was measured in the flasks. The degradation rate of the test item was set in relation to its experimentally determined COD. As the COD implicitly covers the oxygen demand for the nitrification process, there was no need to take additional correction measures into account. The test item is an N-containing substance. Therefore, the concentration of nitrite and nitrate was determined at test start. The oxygen consumed by nitrification was not determined after 28 days. Therefore, the substance is considered to be "Not Inherently Biodegradable" but shows a continuous degradation up to 66 % within 60 days. Although the conditions for "inherently biodegradable" are not fulfilled, the phrase "inherently degradable but not fulfilling specific critera" was chosen in order to describe the degradation behaviour.
In their response to this study, the evaluationg member state Germany outlined: The inherent biodegradability tests
(Currenta a/c) show experimental shortcomings. One test vessel with test substance in both
studies has undesignedly and extremely higher pH value (both > pH 9.4) than all the other
test vessels with test substance and those with blank tests (all < pH 7.1). These two test
vessels show extremly high biochemical oxygen demand (BOD) values, which wrongly
indicate a biodegradation of the test substance beyond 100%. This influences the calculated
mean value, erroneously. Following the guideline, these two test vessels have to be
removed from any further assessment and conclusion. The mean value of the degradation
(%) of the remaining three test vessels for both studies was calculated following the
procedure of calculation by the author of the studies. The mean degradation reached after
28 days is 3.3 °h for Currenta 2013c and 28.7 % for Currenta 2013a. It can be therefore
concluded that DCBS is NOT inherently biodegradable.
In a second inherent biodegradation test (Currenta 2013b) DCBS was used in even lower concentrations (67 µg/L). As this is still above the water solubility, Trifluoroethanol was used as a solubiliser. Samples were taken in intervals of 7 days up to 61 days. DCBS and the metabolites MBT, DCHA, MeSBT, BT, BTon and BTSO3H were monitored with a specific LC/MS/MS method. DCBS was found to degrade by 81% within 14 days thus fulfilling the requirement for inherent biodegradability (>60%). After 61 days DCBS and metabolites have decreased to value of 0.1 to 2 µg/L.
In their response to this study, the evaluationg member state Germany outlined:
Two other screening tests on inherent biodegradability (Currenta, 2013b/d) are not reliable
because purity was unclear, the mass balance at the start of the experiment is not
confirmed, and pH values are partly implausible or not reported. Nevertheless, MET (CAS
149-30-4) and Dicyclohexylamine (CAS 101-83-7) were identified as primary degradation
products suggesting that hydrolysis, already before the start of the experiment, is the
dominant degradation process in these tests and not biological degradation.
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