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Ecotoxicological information

Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
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 source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
10.65 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: extrapolated based on differences in QSAR estimation
Conclusions:
The 96 h LC50 of Di-C12-18 alkyldimethyl ammonium chloride to fish is expected to be 10.65 mg/L.

Description of key information

96 h LC50 = 10.65 mg/L (similar to OECD Guideline 203; read-across from DODMAC)

Key value for chemical safety assessment

LC50 for freshwater fish:
10.65 mg/L

Additional information

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

 

DODMAC was tested on acute fish toxicity using two different river waters. LC50 (96h) was 21.3 mg/L for the river water from Dry Fork Creek (TOC 4.6 mg/L) and 36.2 mg/L for the river water from Little Miami River (TOC 6.2 mg/L). The river waters differ mainly in the TOC content. The lower value of LC50 (96h) of 21.3 mg/L was taken in the classification exercise as this river has the lower TOC and therefore a less mitigating effect.

 

The 96-h LC50 values for DTDMAC determined in laboratory high-quality waters ranged from 0.62 to 3.0 mg/L. The acute toxicities of DTDMAC for bluegill in Town River water ranged from 10.1 to > 24 mg/L. The addition of suspended solids to Town River water further reduced the bioavailability of DTDMAC to bluegill. For example, 80% of the bluegill exposed to 10.1 mg/L DTDMAC in test water containing 20 mg/L suspended solids died within 96 h of exposure. However, no mortality was observed when bluegill were exposed to the same surfactant concentration in combination with concentrations of suspended solids of 50 mg/L.

 

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

The 96 h LC50 of Di-C12-18 alkyldimethyl ammonium chloride to fish is predicted to be 0.979 mg/L (ECOSAR v1.11).

The 96 h LC50 of DODMAC to fish is predicted to be 2.1 mg/L (ECOSAR v1.11).

 

The target and the source substances have a low water solubility and form complexes with dissolved organics, especially with anionic compounds. Thus, results with natural river water are considered more realistic and more relevant than the results obtained with laboratory water.

 

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 96 h LC50 ofthe target substance Di-C12-18 alkyldimethyl ammonium chloride is considered to be 10.65 mg/L.