[2-(1-ethoxyethoxy)ethyl]benzene

Endpoint summary

Description of key information

In the table below the aquatic toxicity data are summarised

Species	Guideline	Result in mg/L	Remarks
Fish	ECOSAR	96h LC50 = 7.2	Key result, Rel. 2 based on (Q)SAR calculation
Daphnia magna	Read across	48h EC50 = 15.6  based on measured arithmetic mean concentrations	Key study, Rel.2, based on read across data from Hyacinth body #3, tested in OECD TG 202. Geometric mean of EC0 and EC100
Pseudokirchneriella subcapitata	Read across	72h ErC50 = 8.4 72h ErC10 = 5.8 based on measured TWA concentration	Key study, Rel.2 based on read across from Hyacinth body #3, tested in OECD TG 201
Microorganisms	OECD TG 209	3h EC50 = 307 3h EC10 = 60	Key study, Rel.1

For daphnia and algae recalculation of the ECx values was checked based on MW and log Kow values. These recalculated values did not change the values significantly (factor 1.1), nor would these values impact the classification and labelling. Worst case values of the source substance Hyacinth body #3 were maintained.

Additional information

Read across justification for algae and Daphnia ecotoxicity values:

Hyacinth body (target; CAS no. 2556-10-7) and its aquatic toxicity for freshwater algae and invertebrates using read across information from Hyacinth body #3 (source; CAS no. 7493-57-4)

 

Introduction and hypothesis for the read across

Hyacinth body has a benzyl ring with an ethyl chain to which an acetal is attached and another ethyl chain. For this substance no aquatic toxicity data (algae and Daphnia) are available. Therefore additional information is used in accordance with Article 13 of REACH where it is said that lacking information could be generated whenever possible by means other than vertebrate animal tests, i.e. applying alternative methods such as in vitro tests, SARs, grouping and read-across. For assessing the aquatic toxicity to algae and Daphnia the analogue approach is selected because for one closely related analogue, Hyacinth body#3, aquatic toxicity studies are available which can be used for read across.

Hypothesis: Hyacinth body is expected to have similar algae and Daphnia toxicity as its analogue, Hyacinth body #3.

Available experimental information: For the structurally related source chemical, Hyacinth body #3, both an algae and Daphnia guideline toxicity test are available. The studies are considered reliable (K1 and K2, respectively) and can be used for assessment purposes. The 48h EC50 for Daphnia was concluded at 15.6 mg/L, for algae the 72h ErC50 and 72h ErC10 were concluded at 8.4 and 5.8 mg/L, respectively.

Target and Source chemical(s):

Chemical structures of the target chemical (Hyacinth body) and the source chemical (Hyacinth body #3) are shown in the data matrix below, including physico-chemical properties and toxicological information, considered relevant for the aquatic toxicity.

Purity / Impurities:

Hyacinth body (target) and Hyacinth body #3 (source) are mono-constituents. The impurities in both target and source are all below 2 %.

Analogue justification

According to REACH Annex XI, an analogue approach can be used to replace testing when information from different sources provides sufficient evidence. The result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation.

Analogue selection: Hyacinth body #3 was selected as an analogue, being the very close analogue (it has just one carbon more than Hyacinth body) and being a substance from IFF portfolio, for which the adequate data are available.

Structural similarities and differences: The target chemical, Hyacinth body, and the source chemical, Hyacinth body #3, have the same backbone and have the same functional group: both are acetal. The only structural difference is that Hyacinth body (target) has one aliphatic CH₂group less compared to Hyacinth body #3 (ethoxy compared to propoxy, respectively).

Bioavailability: The target and the source chemical have similar bioavailability. The water solubility and log Kow show the one methyl group difference between these two. The water solubility of Hyacinth body is somewhat higher and the log Kow somewhat lower compared to Hyacinth body3, which can be expected due to the additionalCH₂group in Hyacinth body#3.

Mode of Action and the prediction of the aquatic toxicity information: The target and source substances are expected to have the same mode of action, because they are both neutral organics. The ecotoxicity is driven by the Log Kow.

Remaining uncertainties: There are no remaining uncertainties considering bioavailability and mode of action. In view of Hyacinth body having the lower molecular weight and lower log Kow the ecotoxicity values can be converted. This is not considered necessary because the ecotoxicity values remain roughly the same: The converted results would become for Daphnia and algae: 48h EC50 =17 mg/L; 72 ErC50 = 9.2 mg/L; 72h ErC10 = 6.3 mg/L, respectively. Since the conversion factor was only 1.09 and the results therefore do not change the classification and labelling under GLP, the original (worst case) values from Hyacinth body #3 are used.

Data matrix

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

Final conclusions for aquatic toxicity to freshwater algae and invertebrates

For assessing the acute toxicity to Daphnia and algae and the chronic toxicity to algae, read across is applied for Hyacinth body (target) from Hyacinth body #3 (source). 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, which is shown in the present document.

For Hyacinth body the following information from Hyacinth body #3 can be used: 72h-ErC50 and ErC10 for algae of 8.4 mg/L and 5.8 mg/L respectively and the EC50 for Daphnia of 15.6 mg/L. These values can be directly used for Hyacinth body because the conversion does not result in a significant change in the result (conversion factor is 1.09).

Final conclusion on hazard: Hyacinth body has the following ecotoxicity values: the 72h-ErC50 and ErC10 for algae and the EC50 for Daphnia are 8.4 mg/L, 5.8 mg/L and 15.6 mg/L respectively.

Data matrix for the read across from Hyacinth body #3 to Hyacinth body

CHEMICAL NAME	Hyacinth body	Hyacinth body #3
Molecular structure
CAS	2556-10-7	7493-57-4
REACH registration	For 2018	For 2018
Einecs	219-868-9	231-327-9
Tanimoto*	1	0.93
Molecular weight	194.28	208.30
Physico-chemical properties
Appearances	Liquid	Liquid
Melting point (°C)	<-20 (IFF, 2015)	<-20 (IFF, 2015)
Boiling point (°C)	248.2 (IFF, 2015)	263.4 (IFF, 2015)
Vapour pressure (Pa, at 24^oC)	3.1 (IFF, 2015)	0.60 (IFF, 2015)
Water solubility (mg/L, at 20˚C)	453 (IFF, 2015)	86.0 (IFF, 2015)
LogKow	3.5 (IFF, 2015)	4.1 (IFF, 2015)
LogKow (calculated**)	2.91	3.40
Ecotoxicity values
Acute toxicity
Daphnia 48h EC50 (mg/L)	Read across	15.6
Algae 72h ErC50 (mg/L)	Read across	8.4
Chronic toxicity
Algae 72h ErC10 (mg/L)	Read across	5.8

*The Tanimoto similarity of the selected analogue to Hyacinth body was calculated using Chemmine tools: http://chemmine.ucr.edu/similarity/.

** Calculated in EPISuite