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Ecotoxicological information

Toxicity to terrestrial plants

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Reference
Endpoint:
toxicity to terrestrial plants: short-term
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
Key result
Species:
other: all three test species
Duration:
17 d
Dose descriptor:
NOEC
Effect conc.:
>= 84.6 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: emergence and growh
Conclusions:
A 17 d-NOEC ≥100 mg dry residue/kg soil d.w. nominal (= 84.6 mg a.i./kg) was determined for all three plant species in respect to emergence and growth.

Description of key information

Data from a study conducted according to OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test) are available.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:
84.6 mg/kg soil dw

Additional information

No experimental data are available for C8-18 AAPB. However, adequate and reliable data on the short-term toxicity to terrestrial plants are available for the closely related source substance C8-18 and C18 unsatd. AAPB (Coco AAPB). A justification for read-across is given below.

 

Short-term toxicity

In a study (limit test) conducted according to OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test),Triticum aestivum,Brassica alba and Lepidium sativum were exposed to a nominal concentration of 100 mg Coco AAPB/kg soil. A 17 d-NOEC ≥100 mg dry residue/kg soil d.w. nominal (= 84.6 mg a.i./kg) was determined for all three plant species in respect to emergence and growth. Analytical monitoring was not performed.

 

Long-term toxicity

As recommended in R.7.11.3.1, data obtained from the OECD 208 Guideline study have been used as estimates of chronic toxicity as they cover a sensitive stage in the life-cycle of a plant. The determined NOEC of 84.6 mg/kg (a.i. nominal) was used for PNEC derivation. In addition according to REACH Regulation (Annex X, 9.4, column 2), a study on long-term toxicity on terrestrial organisms does not need to be conducted if no direct or indirect exposure of soil is to be expected. Based on the uses of the test substance, soil is not the target compartment and therefore exposure of soil is expected to be low and furthermore the test substance proved to be readily biodegradable. Therefore additional testing is considered not necessary.

 

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 toxicity datato terrestrial plants

 

Endpoints

Source substance

Target substance

 

C8-18 and C18 unsatd. AAPB

C8-18 AAPB

Toxicity to terrestrial plants

key.Toxicity to terrestrial plants: 61789-40-0_9.4.3_Hüls_1995_OECD 208

 

key study

 

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test),
Triticum aestivum, Lepidum sativum, Brassica alba
seedling emergence toxicity test, short-term toxicity, laboratory study

 
17 d NOEC >= 100 mg/kg soil dw,
dry residue (nominal) based on: emergence and growth
17 d NOEC >= 84.6 mg/kg soil dw,
act. ingr. (nominal) based on: emergence and growh

 

Reliability: 2 (reliable with restrictions), GLP

No data, read-across

 

A 17 d-NOEC>=100 mg dry residue/kg soil d.w. nominal (=84.6 mg a.i./kg soil dw; growth, emergence) was determined for all three plant species in a study conducted according to OECD Guideline 208.

 

Quality of the experimental data of the analogues:

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

The study was performed according to OECD Guideline 208 and was reliable with restrictions (RL2, GLP).

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 substances as 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.

The 17 d NOEC was 84.6 mg a.i./kg soil dw (based on seedling emergence and growth) in the tested speciesTriticum aestivum, Lepidum sativum and Brassica alba.