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EC number: 904-551-6 | CAS number: -
- 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
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- 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

Endpoint summary
Administrative data
Description of key information
For Hexalon the following results were derived:
Guideline |
Test species |
Endpoint |
Result |
Remark |
OECD TG 203 |
Cyprinus carpio |
96-h LC50 |
4.1 mg/l |
Data derived from read-across to Galbascone (CAS# 56973 -85 -4). Semi-static conditions and measured concentrations were used. Key study, rel. 1. |
OECD TG 202 |
Daphnia magna |
48-h EC50 |
3.4 mg/l |
Data derived from read-across to Galbascone (CAS# 56973 -85 -4). Static conditions and measured concentrations were used. Key study, rel. 1. |
OECD TG 201 |
Pseudokirchneriella subcapitata |
72-h ErC50 72-h ErC10 72-h NOErC |
5.3 mg/l 2.0 mg/l 1.1 mg/l |
Data derived from read-across to Galbascone (CAS# 5673 -85 -4). Static conditions and measured concentrations were used. Key study, rel. 1. |
OECD TG 301F |
Activated sludge, domestic |
28 -d NOEC |
35 mg/l |
Readily biodegradable at a test concentration of 35 mg/l. Key study, rel. 1. |
Additional information
The aquatic toxicity of Hexalon is based on read across from Galbascone. The read across documentation is for algae, Daphnia and fish and is therefore included in the Endpoint summary of Aquatic toxicity. The accompanying files are also attached in this Endpoint summary.
The read across justification is presented below:
Aquatic toxicity of Hexalon (CAS #79-78-7) based on read across from Galbascone (CAS #56973-85-4)
Introduction and hypothesis for the analogue approach
Hexalon (CAS #79-78-7) has a trimethyl-cyclohexene ring with an alkyl chain to it. The alkyl chain has an alpha-beta conjugated ketone bond (also called a vinyl/allyl group) and has an allyl bond at the end of the chain.For this substance no aquatic toxicity information is available.
In accordance with Article 13 of REACH, lacking information should be generated whenever possible by means other than vertebrate animal tests, i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessing the aquatic toxicity of Hexalon the analogue approach is selected because for a closely related analogue, Galbasconeaquatic toxicityinformation is available which can be used for read across.
Hypothesis: Hexalon has similar aquatic toxicity potential as Galbascone asboth substances are vinyl/allyl ketones and therefore the octanol-water partitioning coefficients (log Kow) are considered to give direct indication of their toxicities.
Available information: For the source chemical Galbasconedata are available from GLP guideline studies with fish, aquatic invertebrates and aquatic algae.Short-term effect values for Galbascone were determined to be in the range of 1-10 mg/L for fish, Daphnia, and algae. EC10 and NOEC values in the algae study were >1 mg/L. All tests are according to current OECD guidelines and have a reliability of 1.
In more detail: For Galbascone, short-term fish study was performed according to OECD TG (203 and GLP, WILRES, 2015). The 96-h LC50 value is 5.0 mg/L in common carp (C. carpio). An aquatic invertebrates study was performed according to OECD TG 202 and GLP, WILRES, 2015). The 48-h EC50 is 4.2 mg/L inDaphnia magna. The data are reliable without restrictions (Klimisch 1). Finally, a freshwater algae study was performed according to OECD TG 201 and GLP, WILRES, 2016). The 72-h ErC50, ErC10 and NOEC values are 6.5 mg/L, 2.4 mg/L and 1.3 mg/L, respectively in green algae (P. subcapitata).
Target chemical and source chemical(s)
Chemical structures of the target chemical and the source chemical are shown in the data matrix, including physico-chemical properties and available ecotoxicological information.
Purity / Impurities
Hexalon contains one main constituent present at ca. 78%, a constituent present at ca. 10% and three additional constituents all present below 5%. Except one (1.3%) all minor constituents of Hexalon have similar structures: a ring with an alkyl chain with a ketone group. This minor one has more a ring type of structure instead of a chain which is not expected to have a more severe aquatic toxicity compared to the other constituents. Galbascone contains two constituents that are isomers. As a result it is not expected that the impurities of the source and target chemicals affect the read-across justification.
Analogue approach justification
According to Annex XI section 1.5, read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. Galbascone was selected for read across because it was the most similar substance when compared to other ionones/damascones such as presented in Belsito et al., 2007. The ECHA guidance (2017) has been considered when appropriate.
Structural similarities and differences:Hexalon has a trimethyl-cyclohexene backbone with an alkyl chain attached to it. The functional group is the alpha-beta conjugated ketone group also referred to as (vinyl/allyl ketone group). At the end of the alkyl chain there is an allyl bond which is not considered to be very reactive as such. Galbascone has a somewhat similar backbone, similar functional group and also an allyl group at the end of the alkyl chain. The difference is that Hexalon has this vinyl/allyl ketone bond just outside the ring while Galbascone has it inside the ring. This is expected not to influence the reactivity because both functional groups are slightly hindered by the ring structure: Galbascone having the group in the ring and Hexalon has this group just outside the ring.
Bioavailability: The molecular weights and the structure of both substances indicate that these substances will be bioavailable. The difference in log Kow is expected to present a direct relation of their toxicity: 5.5 for Hexalon and 4.5 for Galbascone.
Reactivity: Hexalon and Galbascone are expected to have the same reactivity because these substances have identical vinyl/allyl ketone chains with a similar backbone. This backbone is non-specific with respect to ecotoxicity; the contribution to reactivity will be reflected in their contribution to the overall log Kow values of the respective substances.
Conversion of the short -term values to Hexalon from Galbascone:The difference in log Kow between Hexalon and Galbascone will be used for conversion of the toxicity values as follows: Effect value Hexalon in mg/L = (Effect value of Galbascone in mg/L x (log Kow Galbascone/Log Kow Hexalon)).
Uncertainty of the prediction:There is no remaining uncertainty because the aquatic toxicity values of Galbascone were corrected to present the expected higher toxicity for Hexalon based on the higher log Kow of the latter substance. Altogether, Hexalon will present a slightly lower toxicity (higher effect values) based on its higher molecular weight which is counterbalanced by its slightly higher log Kow.
Conclusions for hazard assessment, C&L, PBT and risk characterisation
For Hexalon no experimental aquatic toxicity information is available. Read-across is performed to the structural analogue Galbascone. After correction for difference in molecular weight and log Kow, the lowest short-term effect value is 3.4 mg/L in Daphnia. Long-term data is available only from the algae study from which an EC10 of 2.0 mg/L was derived (also after correction for log Kow). These values will be taken forward to the risk assessment.
Data matrix presenting the ecotoxicological information to read across for Hexalon from Galbascone
Common name |
Hexalon |
Galbascone |
Chemical structures |
||
Chemical name |
1-(2,6,6-trimethyl-2-cyclohexen-1-yl)hepta-1,6-dien-3-one |
1-(5,5-dimethyl-1-cyclohexen-1-yl)pent-4-en-1-one |
REACH registration |
2018 |
2018 |
CAS no |
79-78-7 |
56973-85-4 |
EINECS |
201-225-9 |
260-486-7 |
Smiles |
O=C(C=CC(C(=CCC1)C)C1(C)C)CCC=C |
CC1(C)CC(=CCC1)C(=O)CCC=C |
Empirical formula |
C16H24O |
C13H20O |
Molecular weight |
232.4 |
192.3 |
Physical state |
Liquid |
Liquid |
Melting point |
-20 °C |
-20 °C |
Boiling point |
301.1 °C |
265.8 °C |
Vapour pressure |
0.08 Pa (at 24 °C) |
1.14 Pa(at 23 °C) |
Water solubility |
79.0 mg/L (at 24 °C) |
88.9 mg/L (at 22 °C) |
Log Kow |
5.5 (at 24 °C) |
4.5 (at 25 °C) |
Aquatic toxicity |
|
|
Fish LC50 in mg/L |
Read across from Galbascone: 4.1 (= 5.0 mg/L x 4.5/5.5 (log Kow)) |
5.0 |
Aquatic invertebrates EC50 in mg/L |
Read across from Galbascone: 3.4 (=4.2 mg/Lx 4.5/5.5 (log Kow)) |
4.2 |
Aquatic algae 72-h ErC50 in mg/L 72-h ErC10 in mg/L 72-h NOEC in mg/L |
Read across from Galbascone: 5.3 (=6.5 mg/Lx 4.5/5.5 (log Kow)) 2.0 (=2.4 mg/Lx 4.5/5.5 (log Kow)) 1.1 (=1.3 mg/Lx 4.5/5.5 (log Kow)) |
6.5 2.4 1.3 |
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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