Alcohols, C11-15-secondary, ethoxylated

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. CALCULATION: NOEC= 10e(-0.803 log Kow+4.078) (Boeije et al 2006)

2. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: NOEC for long term toxicity to aquatic invertebrates (based on 21-day studies for training set)
- Unambiguous algorithm: NOEC= 10e(-0.803 log Kow+4.078)
- Defined domain of applicability: the training set includes alcohol ethoxylate mixtures (C9-11AE6, C12-13AE6.5, C12-15AE6, C12-15AE9, C13-15AE5 or C14-15AE7) and with the range of Log Kow is 3.65 to 5.91 (calculation based on Leo and Hansh, 1979). The training set data is summarised by Belanger et al. (2006) and Belanger and Dorn (2004). This data assessment of the Klimisch scores has been presented in the HERA document (HERA, 2009).
- Appropriate measures of goodness-of-fit and robustness and predictivity: For each studied ecotoxicity endpoint, the SSE for each QSAR model
was minimized by optimizing the slope and intercept parameters. The Microsoft Excel Solver routine (GRG2 optimization) (Excel 2000, Microsoft Corp., 1999) was used for this numerical procedure. The resulting SSE could be compared with the SSE obtained with the existing QSARs, to compare the goodness of fit with the underlying data.
- Mechanistic interpretation: based on nonspecific membrane disruption being the mode of action for all AE toxicity, which means that toxicity is related to the hydrophobicity and thus the Kow of the specific AE homologue .

3. APPLICABILITY DOMAIN
- Descriptor domain: log kow of 5.3 (predicted using Episuite which is based on Leo and Hansch calculation). It is difficult to get accurate results for experimental determinations of Log Pow of surfactants.
- Structural and mechanistic domains: C11-15AE3
- Similarity with analogues in the training set: the log Kow is in the middle of the training set range and structurally it has bigger distribution of the alkyl chain length with a shorter ethoxylated chain.
- Other considerations (as appropriate):Although toxicity was found to decrease with increasing ethylene oxide chain length, secondary attachments of the alkyl group were reported to be less chronically toxic than linear primary AE.

4. ADEQUACY OF THE RESULT
The QSAR fitting results described in the Boeije et al (2006) paper show that the deviation of the QSAR predictions from the measurements is less than a factor of 3, which is similar to the normal experimental variability in different ecotoxicological studies (see Table 2 comparing measured and predicted long term EC50 and NOEC outcomes for D.Magna exposed to AE).

Principles of method if other than guideline:

- Principle of test: A new QSAR technique for complex substances, which interprets the mixture toxicity with regard to the‘‘ethoxymers’’ distribution (i.e., the individual AE components) rather than the average structure, was developed (Boeije et al, 2006) using the Log Kow.
- Short description of test conditions: 21-day study
- Parameters analysed / observed: NOEC for chronic Daphnia (survival)

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.2 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: QSAR calculation according to Boeije et al (2006)

Table 2: Measured and predicted long-term EC50 and NOEC outcomes forD. magnaexposed to AE

AE structure	Calculated log Kow based on Leo and Hansch (1979)	Measured chronic NOEC (repro) (μmol/L)	Boeije 21-day model NOEC (μmol/L)	Measured mesocosm NOEC (μmol/L)	Boeije mesocosm model NOEC (μmol/L)
C9-C11-AE6^+	3.65	6.63	14.03	1.73	3.30
C12-C13-AE6.5	4.94	3.72	1.29		0.37
C12-C15-AE6^+	5.54	0.17	0.43	0.03	0.13
C12-C15-AE9	5.1	0.18	0.96	0.17	0.28
C13-C15-AE5	5.91	0.09	0.21		0.07
C14-C15-AE7^+	5.8	0.14	0.26	0.15	0.08
Softanol	5.3		0.66		0.20
Softanol	6.2*		0.13		0.04

All AEs in this table except Softanol used to formulate Belanger’s and Boeije’s chronic models; Boeije 21-day model NOEC =Daphnia NOEC= 10^{-0.803 log Kow+4.078};Boeijemesocosm NOEC =10^{-0.74log Kow +3.22}; *Log Pow of softanol measured using HPLC method.

Validity criteria fulfilled:

yes

Conclusions:

The 21-day NOEC survival value for softanol 30 was calculated as 0.20 mg/L using a 21-day chronic QSAR for aquatic invertebrates developed by Boeije et al (2006).

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

other: Review of the ecotoxicology profile similarity between softanol 30 and the alcohol ethoxylates described in several publications and assessment of data from available studies to waive the execution of a long term aquatic invertebrate study

Adequacy of study:

weight of evidence

Reliability:

other: Review of data extracted from publications

Principles of method if other than guideline:

This is a review of the ecotoxicology profile between softanol 30 and the alcohol ethoxylates described in several publications. The aim is to assess the similarity of the data from available studies with softanol 30 and other alcohol ethoxylates in order to confirm the applicability of the chronic Daphnia QSAR and waive the execution of a long term toxicity study to aquatic invertebrates with softanol 30.
The notifier has performed acute toxicity studies to aquatic organisms with softanol. Long-term toxicity laboratory and field studies to fish and Daphnia and toxicity studies to sediment dwellers are available with other alcohol ethoxylates.

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.11 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: C13-15AE5

Remarks:

in laboratory study

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.187 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: C12-15AE6

Remarks:

in laboratory study

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.35 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: C14-15AE7

Remarks:

in laboratory study

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

0.08 mg/L

Conc. based on:

test mat.

Basis for effect:

other: population densities of Copepoda, Cladocera, Chironomidae, Nematoda, or Annelida

Remarks on result:

other: C14-15AE7 /L

Remarks:

in outdoor stream mesocosms

Description of key information

Chronic aquatic invertebrate endpoint was calculated using a Chronic QSAR algorythm developed by Boeije et al (2006)

Daphnia NOEC= 10^{-0.803 log Kow+4.078} = 0.66μmol/L (0.20 mg/L)

For softanol 30, the log Kow is estimated to be 5.3; molar-to-mass conversions were carried out using its Mw of 334.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.2 mg/L

Additional information

A new long-term toxicity study to aquatic invertebrates with softanol 30 is waived due to availability of data on other ethoxylated alcohols and a chronic QSAR developed for alcohol ethoxylates by Boeije et al (2006). This QSAR was used to calculate the Daphnia NOEC for softanol 30.