(2E)-2-(4-methylbenzylidene)heptanal

Endpoint summary

Description of key information

In the table below the aquatic toxicity data are summarised.

Species	Guideline	Result in mg/L	Remarks
Desmodesmus subspicatus	Read across from Hexyl Cinnamic Aldehyde (OECD TG 201)	72h-EC50 growth rate > 0.065 72h-NOEC growth rate >= 0.065	Key study, Rel 2
Daphnia maga	Read across from Hexyl Cinnamic Aldehyde (OECD TG 202)	48h-EC50 = 0.247	Key study, Rel 2
Daphnia maga	Read across from Hexyl Cinnamic Aldehyde (OECD TG 211)	21d-EC10 = 0.069	Key study, Rel 2
Pimephales promelas	Read across from Hexyl Cinnamic Aldehyde (OECD TG 203)	96h-LC50 = 1.7	Not a key study, Rel 2, Used for C&L but is not needed for Annex VII

Additional information

For assessing the aquatic toxicity of Acalea the information from Hexyl Cinnamic Aldehyde is used. The read across justification is presented and the accompanying file is attached here:

Acalea (Cas no. 84697-09-6) and its aquatic toxicity for Algae and Daphnia using read across information from Hexyl Cinnamic Aldehyde (Cas no. 165184-98-5).

Introduction and hypothesis for the analogue approach

Acalea is an amyl cinnamic aldehyde with an additional methyl group at the para position. For this substance no aquatic toxicity data are available. In accordance with Article 13 of REACH,lacking information can be generated by means of applying alternative methods such asin vitrotests, QSARs, grouping and read-across. For assessing the aquatic toxicity of Acalea the analogue approach is selected because for one closely related analogue, Hexyl Cinnamic Aldehyde, reliable algae and Daphnia data are available which can be used for read across.

Hypothesis: Acalea has similar aquatic toxicity compared to Hexyl Cinnamic Aldehyde (HCA) based on similar structure and functional group.

Available experimental information: For Hexyl Cinnamic Aldehyde adequate short- and long-term Daphnia test and an Algae Growth Inhibition test are available, though all performed under GLP, the reliability is 2, because effects were seen close or at the water solubility limit.

Algae study (OECD TG 201): The EC50 growth rate and NOEC were >= 0.065 mg/L based on geometric mean concentrations. The substance was not stable under the conditions of the test and the 0.065 mg/l, was the maximum attainable concentration.

Acute Daphnia (OECD TG 202): HCAwas tested in a 48h flow-through acute toxicity test with Daphnia magna following OECD 202 guidelines. The 48h-EC50 was found to be 0.247 mg/L.

Long-term Daphnia (OECD TG 211): The lowest EC10 value for reproduction was 0.069 mg/L.

Fish study (OECD TG 203): Though this study is not needed for Annex VII, the result is included here for deriving the final C&L. The LC50 fish is 1.7 mg/l.

Target chemical and source chemical(s)

Chemical structures of Acalea and Hexyl Cinnamic Aldehyde are shown in the data matrix. Also physico-chemical properties thought relevant for aquatic toxicity are listed in there.

Purity / Impurities

Acalea is a mono-constituent with a purity of ≥ 90%. The impurities are all below 10%.

Analogue approach justification

According to Annex XI 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. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation.

Analogue selection:In the RIFM database and the OECD Toolbox (using Tanimoto on atom pairs > 60%) three closely related structures were found for possible read across, Amyl Cinnamic Aldehyde (Cas no. 122-40-7), Hexyl Cinnamic Aldehyde (HCA, Cas no. 165184-98-5) and Butyl Cinnamic Aldehyde (Cas no. 7492-44-6). In view of HCA having the same molecular formula and weight as Acalea HCA is the preferred analogue for read across to Acalea.

Structural similarities and differences:Acalea and HCA have the same backbone and functional group both being cinnamic aldehydes with an alkyl chain.The main difference is thatAcalea contains a para-substituted methyl groupwhereasHCA contains an additional methyl group in the alkyl chain.

Bioavailability:Acalea and HCA are expected to have similar bioavailability based on the similarity in chemical structure and physico-chemical properties. The molecular weight of both substances is 216.32. They are both liquids, their Log Kow’s are 5.2 and 5.3, and vapour pressures are 0.017 and 0.068 Pa, respectively. It can be seen that the water solubility of Acalea is somewhat higher than HCA (12.7 mg/L and 1.62 mg/L, respectively)which may be due to experimental variability as based on EPISUITE predictions similar water solubility is to be expected.

Mode of Action:Acalea and Hexyl Cinnamic Aldehyde are expected to present a similar mode of action due to their similar backbone and similar functional group. This is supported by the ECOSAR classification of both substances into Vinyl/Allyl Aldehydes.

Uncertainty of the prediction: In view of the reasoning above there are no remaining uncertainties.

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the data matrix below.

Conclusions per endpoint for C&L

When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. For Hexyl Cinnamic Aldehyde (HCA) the lowest acute ErC50 for algae is > 0.065, EC50 for Daphnia is 0.247 and the LC50 for fish is 1.7 mg/l. For algae and Daphnia long-term information is available, the NOEC for algae is >=0.065 and the EC10 for Daphnia is 0.069 mg/l, respectively. These values can be used for read across to Acalea. A conversion is not needed because both substances have the same molecular weight.

Final conclusion on hazard, C&L: For Acalea the following values are derived for short-term aquatic toxicity: Algae, Daphnia and fish, > 0.065, 0247 and 1.7 mg/l, respectively. The NOEC and EC10 for long-term toxicity for algae and Daphnia are >=0.065 and 0.069 mg/L, respectively.These values will be applied for classification and labelling purposes and for risk assessment.

Data matrix of Acalea aquatic toxicity using read across from Hexyl Cinnamic Aldehyde.

Common names	Acalea	Hexyl Cinnamic Aldehyde
Chemical structures
Empirical formula	C15H20O	C15H20O
Cas no	84697-09-6	165184-98-5 / 101-86-0
EC numbers	283-718-9	639-566-4
Reach registration	Registered for 2018	Registered for 2010
Physico-chemical data
Molecular weight	216.32	216.32
Physical state	Liquid	Liquid
Vapour pressure Pa (measured)	0.017	0.068 (ECHA dissemination site)
Water solubility mg/L (measured)	12.7	1.62 (ECHA dissemination site)
Water solubility mg/L (EPISUITE)	2.46 – 5.59	2.75 – 5.44
Log Kow (measured)	5.2	5.3 (ECHA dissemination site)
Acute Aquatic toxicity
Alga (72h-EC50) mg/L	> 0.065 Read across from Hexyl Cinnamic Aldehyde	> 0.065 (OECD 201)
Daphnia (48h-EC50) mg/L	0.247 Read across from Hexyl Cinnamic Aldehyde	0.247 (OECD 202)
Fish (96h-LC50) mg/L	1.7 Read across from Hexyl Cinnamic Aldehyde	1.7 (OECD 203)
Long-term Aquatic toxicity
Algae (72h-NOEC) mg/L	≥0.065 Read across from Hexyl Cinnamic Aldehyde	0.065 (OECD 201)
Daphnia (21d-EC10) mg/L	0.069 Read across from Hexyl Cinnamic Aldehyde	0.069 (OECD 211)