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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: quaternary ammonium and saturated or unsaturated alkyl chains with comparable length (corresponding to scenario 2 of the read-across assessment framework)

The read-across hypothesis is based on structural similarity of target and source substances. Based on available experimental data, including key physicochemical properties and data from acute toxicity, irritation, sensitization (human) and genotoxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all substances.

Therefore, read-across from the existing ecotoxicity, environmental fate and toxicity studies conducted with the source substances is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

A justification for read-across is attached to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See justification for read-across attached to IUCLID section 13.

3. ANALOGUE APPROACH JUSTIFICATION
See justification for read-across attached to IUCLID section 13.

4. DATA MATRIX
See justification for read-across attached to IUCLID section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Test organisms (species):
Daphnia magna
Test type:
static
Water media type:
freshwater
Total exposure duration:
48 h
Duration:
48 h
Dose descriptor:
EC50
Remarks:
Water from White river: pH 8.4-8.6, CaCO3 345-363 mgL, 3-5 mg/L susp. solids)
Effect conc.:
1.55 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: extrapolated based on differences in QSAR estimation
Duration:
48 h
Dose descriptor:
EC50
Remarks:
Laboratory water (pH 6.6-7.9, CaCO3 131-163 mg/L, no suspended solids)
Effect conc.:
0.08 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: extrapolated based on differences in QSAR estimation
Conclusions:
Acute toxicity to daphnids varied with the type of dilution water used in the toxicity tests. In laboratory dilution water, the 48-h LC50 values was 0.08 mg/L. However, in river water, acute toxicity was considerably less, with a 48-h EC50 of 1.55 mg/L.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
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 limited documentation / justification
Justification for type of information:
1. SOFTWARE
EpiSuite v4.11, US EPA

2. MODEL (incl. version number)
ECOSAR v1.11

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
average carbon chain length: 14.7
Quaternary Ammonium Surfactants, Mono-alkyl
Quaternary Ammonium Surfactants, Di-alkyl
Quaternary Ammonium Surfactants, Tri-alkyl

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: 48 h LC50 in daphnia
- Unambiguous algorithm:
The QSARs for cationic surfactants are linear and the toxicity potential is related to the size of the hydrophobic component (i.e., number of carbons is greater than C16, or less than C16). Cationic classes may include quaternary aliphatic amines, phosphoniums, quaternary ammoniums, sulfoniums, and other general cationic surfactants. The current QSARs are:
Class Organisms Endpoint Equations
SURFACTANTS, CATIONIC, SURFACTANTS, CATIONIC, SURFACTANTS, CATIONIC, >=C16 FISH 96 LC50 10^((0.023 * AVG_NUM_CARBONS) - 0.092)
SURFACTANTS, CATIONIC, >=C16 DAPHNID 48 LC50 10^((0.115 * AVG_NUM_CARBONS) - 1.64)
- Defined domain of applicability: organic chemicals, molecular weight <1000 g/mol; Quaternary Ammonium Surfactants, Mono-alkyl/Quaternary Ammonium Surfactants, Di-alkyl/Quaternary Ammonium Surfactants, Tri-alkyl

5. APPLICABILITY DOMAIN
- Descriptor domain: special classes: Quaternary Ammonium Surfactants, Mono-alkyl/Quaternary Ammonium Surfactants, Di-alkyl/Quaternary Ammonium Surfactants, Tri-alkyl
- the substance is a quaternary ammonium compound containing mono-, di- and tri-alkyl derivatives
- prediction is solely based on the average carbon chain length

6. ADEQUACY OF THE RESULT
The result is used as supporting information in a read-across approach. The result of this QSAR is in the same order of magnitude as the experimental data obtained with structurally related substances. Thus, the QSAR supports the read-across approach.
Principles of method if other than guideline:
prediction of short term toxicity to Daphnia using EpiSuite v4.11, ECOSAR v1.11
Water media type:
freshwater
Total exposure duration:
48 h
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
1.442 mg/L
Basis for effect:
mortality
Conclusions:
The 48 h LC50 of Di-C12-18 alkyldimethyl ammonium chloride to Daphnia is predicted to be 1.442 mg/L (EpiSuite v4.11, ECOSAR v1.11).

Description of key information

48 h EC50 = 1.55 mg/L (read across from DODMAC)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
1.55 mg/L

Additional information

No experimental data are available for the target substance Di-C12-18 alkyldimethyl ammonium chloride. However, short-term toxicity studies inaquatic invertebrates are available for the closely related source substance DODMAC. A justification for read-across is attached to IUCLID section 13.

 

Acute toxicity to daphnids varied with the type of dilution water used in the toxicity tests. In laboratory dilution water, the 48-h LC50 values for DODMAC was 0.16 mg/L. However, in river water, acute toxicity was considerably less, with a 48-h EC50 of 3.1 mg/L.

 

To further support the read-across a QSAR estimation for both, the target and the source substance were included:

The 48 h LC50 of Di-C12-18 alkyldimethyl ammonium chloride to Daphnia is predicted to be 1.442 mg/L (EpiSuite v4.11, ECOSAR v1.11).

The 48 h LC50 of DODMAC to Daphnia is predicted to be 2.692 mg/L (EpiSuite v4.11, ECOSAR v1.11).

 

From the QSAR data it is deduced, that the target substance should be expected to be more toxic than the source substance DODMAC, and a factor of approx. 2 should be applied to the LC50 obtained with DODMAC. Thus, the 48 h EC50 of the target substance Di-C12-18 alkyldimethyl ammonium chloride is considered to be 1.55 mg/L.