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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
see "General Justification for Read-Across" attached to IUCLID section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Mutual read across from the AAPBs to one another is justified:

a) Based on the information given in section 1, it can be concluded that all AAPBs mentioned above are similar in structure, since they are manufactured from similar resp. identical precursors under similar conditions and all contain the same functional groups. Thus a common mode of action can be assumed.
b) The content of minor constituents in all products are comparable and differ to an irrelevant amount.
c) The only deviation within this group of substances is a minor variety in their fatty acid moiety, which is not expected to have a relevant impact on intrinsic toxic or ecotoxic activity and environmental fate. Potential minor impact on specific endpoints will be discussed in the specific endpoint sections.

The read-across hypothesis is based on structural similarity of target and source substances. Based on the available experimental data, including key physico-chemical properties and data from toxicokinetic, acute toxicity, irritation, sensitisation, genotoxicity and repeated dose toxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all five substances.
The respective data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see "General Justification for Read-Across" attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see "General Justification for Read-Across" attached to IUCLID section 13

4. DATA MATRIX
see "General Justification for Read-Across" attached to IUCLID section 13
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Duration:
16 h
Dose descriptor:
EC0
Effect conc.:
ca. 3 000 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth inhibition
Conclusions:
The available data point on a low toxicity of C8-18 and C18 unsatd. AAPB to Pseudomonas putida (30 min/16 h EC0 = 3000 mg a.i./L nominal). The obtained results were considered to be valid for the AAPBs.

Description of key information

Data for toxicity to microorganisms are available from 4 reliable studies. 

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
3 000 mg/L

Additional information

No experimental data are available for C8-18 AAPB. However, adequate andreliable results on the toxicity of C8-18 and C18 unsatd. AAPB to microorganisms are available. A justification for read-across is given below.

 

The toxicity of Coco AAPB to Pseudomonas was investigated in four studies conducted according to national standard methods (DIN 38412, part 8 and part 27) and according to EN ISO 10712, respectively.

 

The toxicity of Coco AAPB to Pseudomonas putida was investigated in a study conducted according to EN ISO 10712. Pseudomonas were exposed to the test material (10000 mg product/L nominal) for 16 h under static conditions. A 16 h EC0 = 3000 mg active substance/L nominal was determined.

 

The toxicity of Coco AAPB to Pseudomonas putida was investigated in a study conducted according to DIN 38412, part 27. Pseudomonas were exposed to the test material (10000 mg product/L nominal) for 30 min under static conditions. A 30 min EC0 = 3000 mg active substance/L nominal was determined.

 

The toxicity of Coco AAPB to Pseudomonas putida Migula was investigated in a study conducted according to DIN 38412, part 8 (Pseudomonas Zellvermehrungshemm-Test). The 16 h EC10 was found to be >10000 mg dry residue/L (nominal) which corresponds to >8450 mg a.i./L nominal assuming a content of 29.6% active matter.

 

The toxicity of Coco AAPB to Pseudomonas putida was investigated in a study conducted according to DIN 38412, part 8 (Pseudomonas Zellvermehrungshemm-Test; Draft). The 16 h EC10 and EC50 were determined to be 15000 and 17000 mg product/L nominal, respectively. The active matter content is not reported. Assuming an active matter content of 30%, a 16 EC10 = 4500 mg a.i./L and a 16 h EC50 = 5100 mg a.i./L is obtained.

 

Conclusion

The available data point on a low toxicity of Coco AAPB to Pseudomonas putida (30 min/16 h EC0 = 3000 mg a.i./L nominal). The obtained results were considered to be valid for the AAPBs.

 

Justification for read-across

For details on substance identity and detailed (eco)toxicological profiles, please refer also to the general justification for read-across given at the beginning of the CSR and attached as pdf document to IUCLID section 13.

 

This read-across approach is justified based on structural similarities. All AAPBs contain the same functional groups. Thus a common mode of action can be assumed.

The only deviation within this group of substances is a minor variety in their fatty acid moiety (chain length and degree of unsaturation), which is not expected to have a relevant impact on intrinsic ecotoxicological properties.

 

a. Structural similarity and functional groups

Alkylamidopropyl betaines (AAPBs) are – with the exception of C12 AAPB - UVCB substances (Substances of Unknown or Variable composition, Complex reaction products or Biological materials), which are defined as reaction products of natural fatty acids or oils with dimethylaminopropylamine and further reaction with sodium monochloroacetate. AAPBs are amphoteric surfactants, which are characterized by both acidic and alkaline properties.

 

Their general structure is:

 

R-C(O)-NH-(CH2)3-(N(CH3)2)+-CH2-C(O)O-

R = fatty acid moiety

 

The fatty acids have a mixed, slightly varying composition with an even numbered chain length from C8 to C18. Unsaturated C18 may be included. Consequently, the AAPBs differ by their carbon chain length distribution and the degree of unsaturation in the fatty acid moiety. However, Lauramidopropyl betaine (C12 fatty acid derivate) is the major ingredient of all AAPBs covered by this justification as listed in table 1 “Substance identities” of the general justification for read-across.

 

The substances under evaluation share structural similarities with common functional groups (quaternary amines, amide bonds and carboxymethyl groups), and fatty acid chains with differences in chain length and degree of saturation.

 

b. Differences

Differences in ecotoxicity of the AAPBs could potentially arise from the following facts:

-Different amounts of different carbon chain lengths (carbon chain length distribution):

Higher amounts of higher chain lengths and corresponding lower amounts of lower chain length could result in a rising average lipophilicity. However, the main component for all AAPBs is C12 AAPB. Relevant effects on ecotoxicity are not to be expected.

- Different amounts of unsaturated fatty ester moieties:

Effects may be expected for e.g. physical state, but are not considered to be of relevance for ecotoxicity.

 

Comparison of data on toxicity to microorganisms

 

Endpoints

Source substances

Target substance

 

C8-18 and C18 unsatd. AAPB

C8-18 AAPB

Short-term toxicity to aquatic invertebrates

key.Toxicity to microorganisms: 61789-40-0_9.1.4_Henkel_2004_EN ISO 10712

 

key study

 

EN ISO 10712 (Pseudomonas cell multiplication inhibition test),

Pseudomonas putida, static, freshwater

 

16 h EC0 = ca. 3000 mg/L act. ingr. (nominal) based on: growth inhibition

 

Reliability: 2 (reliable with restrictions), no GLP

No data, read-across

sup.Toxicity to microorganisms: 61789-40-0_9.1.4_Henkel_2004_DIN 38412 part 27

 

supporting study

 

DIN 38412, part 27: Pseudomonas oxygen consumption inhibition test, Pseudomonas putida, static,

freshwater

 

30 min EC0 = ca. 3000 mg/L act. ingr. (nominal) based on: respiration rate

 

Reliability: 2 (reliable with restrictions), no GLP

 

sup.Toxicity to microorganisms: 61789-40-0_9.1.4_Hüls_1995_DIN 38412 L8

 

supporting study

 

DIN 38412, part 8 (Pseudomonas Zellvermehrungshemm-Test), Pseudomonas putida, static, freshwater

 

16 h EC10 > 8450 mg/L act. ingr. (nominal) based on: growth inhibition

 

Reliability: 2 (reliable with restrictions), GLP

sup.Toxicity to microorganisms.61789-40-0_9.1.4_Zschimmer_Schwarz_1991_DIN 38412, part 8


DIN 38412, part 8 (Pseudomonas Zellvermehrungshemm-Test), Pseudomonas putida, static, freshwater

 
16 h EC10 = 15000 mg/L test mat.
(nominal) based on: growth inhibition


16 h EC50 = 17000 mg/L test mat.
(nominal) based on: growth inhibition

 

Reliability: 2 (reliable with restrictions), no GLP

 

The available data point on a low toxicity of Coco AAPB to Pseudomonas putida (30 min/16 h EC0 = 3000 mg a.i./L nominal / 16 h EC10>8450 mg a.i./L / 16 h EC10>4500 mg a.i./L).

 

Quality of the experimental data of the analogues:

The available data are adequate and sufficiently reliable to justify the read-across approach.

The studies were conducted according to DIN 38412, part 8 and part 27 or EN ISO 10712, respectively and were reliable with restrictions (RL2).

The test materials used in the respective studies represent the source substance as described in the hypothesis in terms of substance identity and minor constituents.

Overall, the study results are adequate for the purpose of classification and labelling and risk assessment.

 

Conclusion

Based on structural similarities of the target and source substancesas presented above and in more detail in the general justification for read across, it can be concluded that the available data from the source substance C8-18 and C18 unsatd. AAPB are also valid for the target substance C8-18 AAPB.

AAPBs show a low toxicity towards microorganisms (30 min/16 h EC0 = 3000 mg a.i./L, nominal).