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Sediment toxicity

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Reference
Endpoint:
sediment toxicity: 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: supporting information
Reason / purpose:
read-across source
Duration:
10 d
Dose descriptor:
NOEC
Effect conc.:
14 248.1 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
10 d
Dose descriptor:
NOEC
Effect conc.:
5 129 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mortality
Duration:
10 d
Dose descriptor:
LC50
Effect conc.:
> 14 248.13 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
10 d
Dose descriptor:
LC50
Effect conc.:
> 5 129 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mortality
Conclusions:
The 10 d NOEC and LC50 values were determined to be 14248 mg product/kg sediment dw (5129 mg a.i./kg sediment dw) and >14248 mg product/kg sediment dw (>5129 mg a.i./kg sediment dw nominal), respectively.

Description of key information

Acute toxicity data from a study in marine sediment to the intertidal amphipod Corophium volutator are available. No long-term data are available.  
However, a long-term toxicity study on sediment organisms is not justified.

Key value for chemical safety assessment

EC50 or LC50 for marine water sediment:
5 129 mg/kg sediment dw

Additional information

No data on toxicity to sediment dwelling organism are available for C12-14 AAPB. However, adequate and reliable short-term toxicity data on marine sediment organisms are available for the closely related source substance C8-18 and C18 unsatd. AAPB.

 

Freshwater sediment

No data are available for toxicity to freshwater sediment organisms.

 

Marine sediment

The acute toxicity of C8-18 and C18 unsatd. AAPB to the intertidal amphipod Corophium volutator was investigated in a study conducted according to OSPARCOM (1995) 'A sediment bioassay using a amphipod Corophium sp.'. Corophium volutator were exposed for 10 d under static conditions to the test item. The 10 d NOEC and LC50 values were determined to be 14248 mg product/kg sediment dw (5129 mg a.i./kg sediment dw) and >14248 mg product/kg sediment dw (>5129 mg a.i./kg sediment dw nominal), respectively.

 

No data on long-term toxicity to sediment-dwelling organisms are available. In Annex IX of Regulation (EC) No 1907/2006, it is laid down that sediment toxicity tests shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate further the effects on sediment organisms. According to Annex I of this regulation, the chemical safety assessment triggers further action when the substance or the preparation meets the criteria for classification as dangerous according to Directive 67/548/EEC or Directive 1999/45/EC or is assessed to be a PBT or vPvB. The hazard assessment of AAPB reveals neither a need to classify the substance as dangerous to the environment, nor is it a PBT or vPvB substance, nor are there any further indications that the substance may be hazardous to the environment. Furthermore, the substance is not persistent in this compartment, due to physico-chemical properties and the proven rapid biodegradability. Therefore, a long-term toxicity study on sediment organisms is not justified.

 

Justification for read-across

For details on substance identity and detailed (eco)toxicological profiles, please refer also to the general justification for read-across 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.

 

Sediment toxicity data

Endpoints

Source substance

Target substance

 

C8-18 and C18 unsatd. AAPB

C12-14 AAPB

Sediment toxicity

key (marine).Sediment toxicity.61789-40-0_9.5.1_Marine_10d_Corophium volutator_Rhodia_Mirataine-BET-C-37_2008

 

OSPARCOM guidelines (1995) A sediment bioassay using a amphipod Corophium sp.


Corophium volutator, short-term toxicity, static

 
10 d NOEC = 14248.1 mg/kg sediment dw
test mat. (nominal) based on: mortality


10 d NOEC = 5129 mg/kg sediment dw
act. ingr. (nominal) based on: mortality


10 d LC50 > 14248.13 mg/kg sediment dw
test mat. (nominal) based on: mortality


10 d LC50 > 5129 mg/kg sediment dw
act. ingr. (nominal) based on: mortality

 

Reliability: 1 (reliable without restriction), GLP

No data, read-across

 

The 10 d LC50 exceeded the highest tested concentration of5129 mg a.i./kg sediment dw. No effects were observed at any concentration level.

 

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 OSPARCOM guidelines and was reliable without restrictions (RL1, 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 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 substanceC8-18 and C18 unsatd. AAPB are also valid for the target substance C12-14 AAPB.

The 10 d NOEC and LC50 values ofC8-18 and C18 unsatd. AAPB to Corophium volutator were determined to be 5129 mg a.i./kg sediment dw (nominal) and >5129 mg a.i./kg sediment dw (nominal), respectively.