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Short-term toxicity to aquatic invertebrates

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Description of key information

Two acute toxicity studies on marine invertebrates (Acartia tonsa) have been assessed. The results were determined to be: 
- the LC50 value found for the test substance (nominal whole product) after 48 h was 1.7 mg/l. The 95% confidence range was 1.3 - 2.1 mg/l. The NOEC value was estimated to be 0.2 mg/l.
- the LC50 value found for the test substance (based on active ingredient) after 48 h was 0.72 mg/l. The 95% confidence range could not be calculated. The NOEC value (based on active ingredient) was estimated to be 0.13 mg/l.
The results of these studies have been used in a 'geometric mean' approach (see discussion) to calculate the key LC50 value.
Results from a acute toxicity study in freshwater fish have been read-across from a suitable structural analogue substance, Fatty acids, C18 unsaturated, reaction products with diethylenetriamine (also referred to a Tall oil diethylenetriamine imidazoline).
The study resulted in the following EC50 values: 24 h EC50 = 0.42 mg/L, 48 h EC50 = 0.18 mg/L

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.18 mg/L
EC50/LC50 for marine water invertebrates:
1.11 mg/L

Additional information

Marine Data:

Two marine invertebrate studies on Acartia tonsa have been conducted on the substance (Fatty acids, C18 unsaturated, reaction products with diethylenetriamine, acetate salts), the results of which are discussed below:

Study Reference: Kjonno O (2006):

Acartia tonsa testing has been performed on the test substance A01C2 ACETATE based on ISO/CD 14669: "Determination of Acute Lethal Toxicity to Marine Copepods" and PARCOM Ring test Protocol: "Acute Toxicity to the Marine Copepod Acartia tonsa".

The tested concentrations were 0.2, 1.0, 2.5 and 10 mg/l (nominal whole product).

The LC50 value found for the test substance (nominal whole product) after 48 h was 1.7 mg/l. The 95% confidence range was 1.3 - 2.1 mg/l. The NOEC value was estimated to be 0.2 mg/l.

No analytical measurement of test material concentrations in samples was performed.

All control parameters were within recommended ranges and the test considered valid.

Study Reference: Haug S I (2002):

Acartia tonsa testing has been performed on the test substance BL5060 based on ISO/CD 14669: "Determination of Acute Lethal Toxicity to Marine Copepods" and PARCOM Ring test Protocol: "Acute Toxicity to the Marine Copepod Acartia tonsa".

The test substance BL5060 was supplied as a 25.82% solution in water (i.e. active ingredient 25.82%).

The tested concentrations were 0.1, 0.5, 2.5 and 10 mg/l (nominal whole product).

The LC50 value found for the test substance (nominal whole product) after 48 h was 2.8 mg/l. The 95% confidence range could not be calculated. The NOEC value (nominal whole product) was estimated to be 0.5 mg/l.

The LC50 value found for the test substance (based on active ingredient) after 48 h was 0.72 mg/l. The 95% confidence range could not be calculated. The NOEC value (based on active ingredient) was estimated to be 0.13 mg/l.

No analytical measurement of test material concentrations in samples was performed.

Key value for marine water invertebrates:

As two studies in Acartia tonsa have been conducted (i.e. there are two validated short-term/acute toxicity studies available for the same species and end-point), it is considered appropriate to calculate a geometric mean result value, to harmonise the results of the separate studies.

This approach is in accordance with ECHA Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment. This guidance states that multiple values for the same endpoint with the same species should be investigated, looking for differences between results. For equivalent data on the same end-point and species, the geometric mean should be used as the input value.

An assessment of the two marine studies conducted concluded that the results were of a sufficiently similar magnitude to validate a 'geometric mean' approach. The studies were also run to sufficiently similar methods and under sufficiently similar test conditions. The differences in the two results obtained were assessed to be caused by normal biological variation between studies done on the same test substance (studies performed on different batches of test material with minor differences etc). It is therefore considered that the 'mean' approach is justified in this case and no one study should be taken as the definitive result.

The key LC50 value for marine invertebrates is therefore given as the 'geometric mean' result of the two Acartia tonsa studies.

The most sensitive marine species was determined to be algae. The 'geometric mean' algal result has therefore been used as the key result in the environmental assessment.

Freshwater data (Read-across data):

The results of a freshwater acute toxicity ot Daphnia magna study on Fatty acids, C18 unsaturated, reaction products with diethylenetriamine (also referred to as Tall oil diethylenetriamine imidazoline) have been read-across to evaluate the toxicity to freshwater invertebrates of Fatty acids, C18 unsaturated, reaction products with diethylenetriamine, acetate salts.

Study Reference: Gancet, C (2009):

The acute toxicity (inhibition of mobility) of the test item IMIDAZOLINE 4900 for a duration of 48 hours was assessed according to the OECD guideline 202.

Daphnia magna were exposed under static conditions to a range of concentrations of IMIDAZOLINE 4900 dissolved in dilution water. The toxic effect measured during the assay was the inhibition of mobility time periods of 24 and 48 hours.

The tested concentrations, based on Geometric mean measured concentrations were 0.045; 0.068; 0.112; 0.266; 0.355; 0.608 mg/L

The concentration of test item causing a 50% reduction in mobility (EC50) was estimated.

The results were as follows:

Duration of exposure period (h)

*EC50 value, mg/L (95% CI)

24

0.42 (0.33 – 0.61)

48

0.18 (0.1 – 0.35)

C.I.: confidence interval

* results are based on geometric mean measured concentrations.

Analysis of test material concentrations in samples was performed.

Discussion on read-across results:

The read-across results for the freshwater Daphnia magna study are in line with the marine results obtained for the acetate salts. The results indicate that freshwater invertebrate species may be more sensitive to the test substance than marine species. However, it should also be taken into account that the freshwater result is based on measured (geometric mean) concentrations of test material in test samples, whereas the marine studies did not include analytical measurements of test material in samples, so the results are based on nominal concentrations.

It is considered that the results obtained from studies on Fatty acids, C18 unsaturated, reaction products with diethylenetriamine (Tall oil diethylenetriamine imidazoline) are suitable to read-across to and for use in the evaluation of Fatty acids, C18 unsaturated, reaction products with pentaethylenehexamine acetate salts (cas 64754 -93 -4).

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