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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
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
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 for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Key result
Duration:
72 h
Dose descriptor:
EC50
Remarks:
geometric mean of all available studies
Effect conc.:
1.5 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Remarks:
geometric mean of all available studies
Effect conc.:
0.3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Conclusions:
In a weight of evidence approach, considering all available information for the endpoint aquatic toxicity, the ecotox profile of C8-18 AAPB is characterised by an acute aquatic toxicity in the range of >1 to ≤ 10 mg/L. For practical reasons (to name a value for the algae effect concentration) the algae study with the lowest acute effect result within this range is used for the assessment of algae toxicity: 72h-ErC50 = 1.5 mg a.i./L, 72h-NOEC = 0.3 mg a.i./L.
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2007-04-23 to 2007-05-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Sampling method: Lauramidopropyl betaine and control were analytically verified at the beginning and the end of the test in all test vessels. Separate replicates (all concentrations without algae) were prepared and analysed at 0 h and at the end of the test.
- Sample storage conditions before analysis: All samples were stored at room temperature until start of analysis if necessary
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 100 mg C12 AAPB/L stock solution was freshly prepared and dispersed by agitation
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Desmodesmus subspicatus
- Strain: Chodat SAG 86.81
- Source (laboratory, culture collection): Collection of algal Cultures (SAG), Inst. Plant Physiology, University of Göttingen (Germany)
- Age of inoculum (at test initiation): 3 days old preculture
- Method of cultivation: Fresh stocks were prepared every month on Z-Agar (nutrient medium acc. to Lüttge et al. 1994) at the testing facility. Light intensity was 35 - 70 µE/ m² x s for 24h/d

ACCLIMATION
- Acclimation period: no (preculture was directly pipetted to the test and control replicates)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
Algae from the test vessels of 3.2 - 32 mg test item/L and the controls were transferred into fresh untreated medium (0.5 - 1 mL algae suspension from each replicate were filled up with dilution water to 10 mL) and allowed to grow for further 4 - 6 d to determine whether the effect was reversible.
Hardness:
0.24 mmol Ca+Mg/L (nominal)
Test temperature:
21 - 23°C
pH:
7.67 - 8.05
Nominal and measured concentrations:
0.10, 0.32, 1.0, 3.2, 10, 32 mg/L test material (nominal)
corresponding to
0.03, 0.096, 0.3, 0.96, 3, 9.6 mg/L mg a.i. (nominal)
0.091, 0.31, 0.93, 3.27, 9.70, 33.36 mg/L test material (measured)
corresponding to
0.027, 0.093, 0.28, 0.98, 2.91, 10.01 mg/L a.i. (measured)
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL sterile Erlenmeyer flasks
- Type: sealed with cotton wool plugs
- Material, size, headspace, fill volume: test volume 100 mL
- Initial cells density: 2 - 5 x10E3 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: 24 h/day light
- Light intensity and quality: 60 - 120 µE/m² x s

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Chlorophyll-a-fluorescence, excitation at 435 nm, emission at 685 nm
- Chlorophyll measurement: Each replicate was measured 6-fold, values (flash) no. 3 - 6 were used for calculations
Chlorophyll was measured at the beginning and every 24 h
- at start and at the end cells were checked for unusual cell shape, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and aggregation of alga cells

TEST CONCENTRATIONS
- Spacing factor for test concentrations: square root of 10
- Range finding study
- Test concentrations: 0.1, 1, 10, 100 mg/L (nominal)
- Results used to determine the conditions for the definitive study:
Yield inhibition: -7, 20, 95, 100 %
Specific Growth Rate Inhibition: -1, 4, 54, 100 %
Reference substance (positive control):
yes
Remarks:
potassium dichromate (CAS 7778-50-9
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
3.15 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 2.82 - 3.51 mg act. ingr./L
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
1.31 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 1.11 - 1.48 mg act. ingr./L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.825 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 0.663 - 1.01 mg act. ingr./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.96 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.01 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: yield inhibition
Remarks on result:
other: 0.801 - 1.29 mg act. ingr./L
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
0.558 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: yield inhibition
Remarks on result:
other: 0.396 . 0.603 mg act. ingr./L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.426 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: yield inhibition
Remarks on result:
other: 0.287 - 0.603 mg act. ingr./L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: yield inhibition
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.96 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: yield inhibition
Details on results:
Rate-related inhibition (inhibition of growth rate):
ErC50 (95% confidence interval): 10.5 mg test mat./L (9.40 – 11.7 mg test mat./L)
ErC20 (95% confidence interval): 4.35 mg test mat./L (3.70 – 4.94 mg test mat./L)
ErC10 (95% confidence interval): 2.75 mg test mat./L (2.21 – 3.37 mg test mat./L)
NOEC: 1.0 mg test mat. /L (0.3 mg act. ingr./L)
LOEC: 3.2 mg test mat. /L (0.96 mg act. ingr./L)

Yield inhibition
EyC50 (95% confidence interval): 3.38 mg test mat./L (2.67 – 4.29 mg test mat./L)
EyC20 (95% confidence interval): 1.86 mg test mat./L (1.32 – 2.43 mg test mat./L)
EyC10 (95% confidence interval): 1.42 mg test mat./L (0.955 – 2.01 mg test mat./L)
NOEC: 1.0 mg test mat. /L (0.3 mg act. ingr./L)
LOEC: 3.2 mg test mat. /L (0.96 mg act. ingr./L)

- Observation of abnormalities: no morphological abnormalities were observed by microscopic evaluation at start and at the end of the test
- Any stimulation of growth found in any treatment: A slight stimulation was observed at test concentration 0.32 mg test mat./L

Post exposure observation
The test item effects were observed to be reversible at these test concentrations. There is potential for recovery following exposure up to the highest test concentration of 32 mg/L
Results with reference substance (positive control):
- The effect value (rate related inhibition) is in accordance with the range of data determined in a ring test (ISO 8692)
Rate-related inhibition:
- EC50: 0.92 mg/L (nominal), 95% confidence interval: 0.87 - 0.97 mg/L
Yield inhibition:
- EC50: 0.38 mg/L (nominal), 95% confidence interval: 0.36 - 0.39 mg/L
Reported statistics and error estimates:
EC10, EC20 and EC50 values of growth rate and yield inhibition after 72 h were calculated by sigmiodal dose-response regression. Confidence intervals were calculated using standard procedures according to Clopper and Pearson (1934)

Table 1: Evaluation ofter 72 h

Nominal concentration  [mg test mat. /L]

Mean yield [N/ml]

Mean inhibition of yield [%]

Mean growth rate [d-1]

Mean rate-related inhibition [%]

32

10437

98.50

0.346

78.47

10

63074

90.93

0.835

48.04

3.2

375795

45.96

1.401

12.82

1.0

659085

5.22

1.592

0.96

0.32

851865

-22.50

1.676

-4.29

0.10

684705

1.54

1.605

0.17

Control

695415

1.607

Negative inhibitions = increase of growth

Table 2: Mean cell densities

Nominal concentration  [mg test mat. /L]

0 h

24 h

48 h

72 h

32

5601

7439

13623

16038

10

5601

15030

34508

68675

3.2

5601

27945

119369

381396

1.0

5601

38561

156990

664686

0.32

5601

43055

204051

857466

0.10

5601

46005

197436

690306

Control

5601

38955

193131

701016

No morphological abnormalities were observed by microscopic evaluatuion at start and at the end of the test

A slight stimulation was observed at test concentration 0.32 mg test mat./L

Algae from the test vessels of 3.2 - 32 mg test item/L and the controls were transferred into untreated medium and allowed to grow for further 4 - 6 d to determine whether the effect was reversible. The test item effects were observed to be reversible at these test concentrations. There is potential for recovery following exposure up to the highest test concentration of 32 mg/L.

The study meets the validity criteria of the guideline:

The cell growth increased 125-fold after 72 h in the control (required 16-fold)

The temperature was in the range of 21 -24°C

The difference of the temperature from the mean values was within±2°C

The pH value in the control replicates increased not higher than 1.5 units

The mean coefficient of variation of daily growth rates was 20.45 (required < 35%)

The mean coefficient of variation of average growth during the whole test period in replicate cultures was 2.76 (required <7%)

Validity criteria fulfilled:
yes
Conclusions:
In a 72 hour acute toxicity study, the cultures of Desmodesmus subspicatus were exposed to C12 AAPB under static conditions in accordance with the OECD Guideline 201 (2006).  The 72 h ErC50 value based on inhibition of specific growth rate was 3.15 mg a.i./L, the 72 h EyC50 value based on yield inhibition was 1.01 mg a.i./L, respectively. The 72 h NOEC based on growth rate and yield was determined to be 0.3 mg a.i./L nominal. No abnormalities were noted. The test item effects were observed to be reversible at the test concentrations 0.32 - 32 mg test mat. /L. (0.096 - 9.6 mg a.i./L).
Executive summary:

In a 72 hour acute toxicity study, the cultures of Desmodesmus subspicatus were exposed to C12 AAPB at nominal concentrations of 0.03, 0.096, 0.3, 0.96, 3, 9.6 mg a.i./L / under static conditions in accordance with the OECD Guideline 201 (2006).  The 72 h ErC50 value based on inhibition of specific growth rate was 3.15 mg a.i./L, the 72 h EyC50 value based on yield inhibition was 1.01 mg a.i./L, respectively. The 72 h NOEC based on growth rate and yield was determined to be 0.3 mg a.i./L nominal. No abnormalities were noted. The test item effects were observed to be reversible at the test concentrations 0.32 - 32 mg test mat. /L. (0.096 - 9.6 mg a.i./L).


This toxicity study is classified as reliable without restriction and satisfies the requirements of the OECD Guideline 201 Alga, Growth inhibition test (2006).

Results Synopsis
Test Organism: Desmodesmus subspicatus
Test Type: Static
72 h ErC50:  3.15mg a.i./L                95% C.I.:  2.82 to 3.51 mg a.i./L
72 h EyC50:  1.01 mg a.i./L                95% C.I.:  0.801 to 1.29 mg a.i./L

72 h NOEC: 0.3 mg a.i./L
(all values refer to nominal concentrations) Endpoint(s) Effected: Rate-related inhibition; Yield inhibition

Description of key information

The toxicity of C8-18 AAPB, Coco AAPB and C12 AAPB to fresh water and salt water algae was investigated in 8 valid studies. In a weight of evidence approach, considering all available information for the endpoint aquatic toxicity, the ecotox profile of C8-18 AAPB is characterised by an acute aquatic toxicity in the range of >1 to ≤ 10 mg/L. For practical reasons (to name a value for the algae effect concentration) the algae study with the lowest acute effect result within this range is used for the assessment of algae toxicity: 72h-ErC50 = 1.5 mg a.i./L, 72h-NOEC = 0.3 mg a.i./L.

Key value for chemical safety assessment

EC50 for freshwater algae:
1.5 mg/L
EC10 or NOEC for freshwater algae:
0.3 mg/L

Additional information

One algal toxicity study conducted with C12 AAPB is available as well as further freshwater and saltwater studies conducted with the closely related source substances C8-18 AAPB and C8-18 and C18 unsatd. AAPB (Coco AAPB). A justification for read-across is given below.

 

The toxicity of C8-18 AAPB, Coco AAPB and C12 AAPB to fresh water and salt water algae was investigated in 8 valid studies,7 fresh water algae studies with Desmodesmus subspicatus and Pseudokirchnerella subcapitata (72h-ErC50 1.5 - > 334 mg/L a.i.) and one marine algae study with Skeletonema costatum (72 -h- ErC50 0.97 mg/L a.i.).

 

In a weight of evidence approach, considering all available information for the endpoint aquatic toxicity, the ecotox profile of C8-18 AAPB is characterised by an acute aquatic toxicity in the range of >1 to ≤ 10 mg/L. For practical reasons (to name a value for the algae effect concentration) the algae study with the lowest acute effect result within this range is used for the assessment of algae toxicity: 72h-ErC50 = 1.5 mg a.i./L, 72h-NOEC = 0.3 mg a.i./L.

 

Data included in the weight of evidence approach

1. In a test conducted according to DIN 38412, part 9 (comparable to OECD Guideline 201), the cultures of Desmodesmus subspicatus were exposed to Coco AAPB at nominal concentrations of 0.003, 0.009, 0.03, 0.09, 0.3, 0.9, 3.0 mg a.i./L under static conditions for 72 h. Originally, the data were evaluated according to the test guideline (DIN 38412, Part 9) using the EDV-program of Mr. Holtmann (Henkel KGaA). Based on today knowledge, this calculation model is no longer valid or only valid with restriction. Therefore, a recalculation of the 72 h EC50 values was performed taking into account the OECD principles. The 72 h ErC50, EbC50, and NOEC were found to be 1.5, 0.57, and 0.3 mg a.i./L nominal, respectively.

 

2. In a 72 hour toxicity study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test) and EU Method C.3 (Algal Inhibition test), the cultures of Desmodesmus subspicatus were exposed to Coco AAPB (30.9 % active matter) at nominal concentrations of 0.97, 1.93, 3.86, 7.72, 15.45, 30.9 mg active substance/L under static conditions. The 72 h NOEC, LOEC and EC50 values based on growth rate were 3.86, 7.73 and 9.86 mg a.i./L nominal, respectively. The 72 h NOEC, LOEC and EC50 values based on biomass were 1.93, 3.86 and 5.31 mg a.i./L nominal, respectively. There were no compound related phytotoxic effects. This toxicity study is regarded as reliable without restriction and satisfies the requirements of the guideline.

 

3. In a 72 hour acute toxicity study, the cultures of Desmodesmus subspicatus were exposed to C12 AAPB at nominal concentrations of 0.03, 0.096, 0.3, 0.96, 3, 9.6 mg a.i./L / under static conditions in accordance with the OECD Guideline 201 (2006).  The 72 h ErC50 value based on inhibition of specific growth rate was 3.15 mg a.i./L, the 72 h EyC50 value based on yield inhibition was 1.01 mg a.i./L, respectively. The 72 h NOEC based on growth rate and yield was determined to be 0.3 mg a.i./L nominal. No abnormalities were noted. The test item effects were observed to be reversible at the test concentrations 0.32 - 32 mg test mat. /L. (0.096 - 9.6 mg a.i./L). This toxicity study is classified as reliable without restriction and satisfies the requirements of the OECD Guideline 201 Alga, Growth inhibition test (2006).

 

4. In a 72 hour toxicity study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test), the cultures of Desmodesmus subspicatus were exposed to C8 -18 AAPB at nominal concentrations of 0, 0.098, 0.31, 0.98, 3.1, 9.8, and 31 mg active substance/L under static conditions. The 72 h ErC50 and 72 h EbC50 were 14.7 and 9.2 mg active substance/L nominal, respectively.  There were no compound related phytotoxic effects. This study is regarded as reliable with restrictions and satisfies the guideline requirements for a toxicity study with freshwater algae.

 

5. The toxicity of Coco AAPB to Scenedesmus subspicatus was investigated in a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test), EU Method C.3 (Algal Inhibition test) and ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum). Scenedesmus subspicatus was exposed to nominal concentrations of 0 (control), 1.0, 1.8, 3.2, 5.6, and 10.0 mg a.i./L for 72 h under static conditions. The 72 h EC50 and NOEC based on biomass and growth rate were determined to be 5.6 (growth rate) and 4.66 (biomass) and 1.8 mg a.i./L nominal (growth rate and biomass), respectively. This study is regarded as reliable with restrictions.

 

6. The toxicity of Coco AAPB to Selenastrum capricornutum was investigated in a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test), EU Method C.3 (Algal Inhibition test) and ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum). Selenastrum capricornutum was exposed to nominal concentrations of 0 (control), 0.56, 1.0, 1.8, 3.2, 5.6, and 10.0 mg a.i./L for 96 h under static conditions. The 96 h ErC50, EbC50 and NOEC were determined to be >10 (growth rate) and ca. 8 (biomass) and 3.2 mg a.i./L nominal (growth rate and biomass), respectively. This study is regarded as reliable with restrictions.

 

7. In a test conducted according to OECD Guideline 201, the cultures of Desmodesmus subspicatus were exposed to Coco AAPB at nominal concentrations of 0 (control), 4, 10, 25, 63, 158, and 395 mg dry residue/L for 72 h under static conditions. The stability of the test item was measured via TOC measurements. The recovery rate was >80%. After 72 h, the measured values differed from freshly prepared solutions by < 20%. The 72 h EC50 were determined to be 37.2 (biomass) and >334 mg a.i./L nominal (growth rate), respectively. This study is regarded as reliable with restrictions.

 

8. The toxicity of Coco AAPB to the marine phytoplankton Skeletonema costatum was investigated in a study conducted according to ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum). Cultures of Skeletonema costatum in the exponential growth phase were exposed to nominal concentrations of 0.32, 1.0, 3.2, 5.6, and 10 mg product/L corresponding to 0.01, 0.36, 1, 2, and 3.6 mg a.i./L under static conditions for 72 h. The 72 h ErC50 and NOEC values were determined to be 2.05 mg product/L and 1 mg product/L (nominal each), respectively.

Effect concentrations based on a.i. as named in study report CoA (certificate of analysis) (= solids - sodium chloride) and recalculated for a.i. of registration substance composition (IUCLID chapter 1.2): 72 h ErC50: 0.97 mg a.i./L, 72 h NOEC: 0.47 mg a.i./L.

Effect concentrations based on a.i. as named in study report CoA (certificate of analysis) (= solids - sodium chloride): 72 h ErC50: 0.74 mg a.i./L, 72 h NOEC: 0.36 mg a.i./L.

This toxicity study is regarded as reliable without restriction.

 

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 acute 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 to aquatic algae and cyanobacteria

 

Endpoint

Source substances

Target substance

 

C12 AAPB

C8-18 and C18 unsatd. AAPB

C8-18 AAPB

Toxicity to aquatic algae and cyanobacteria

WoE.Toxicity to aquatic algae and cyanobacteria: 4292-10-8_9.1.2_Betaines consortium_2007_OECD 201


Weight of evidence

 

OECD Guideline 201 (Alga, Growth Inhibition Test),Desmodesmus subspicatus, freshwater, static

 
72 h EC50 = 3.15 mg/L,
act. ingr. (nominal) based on: growth rate (2.82 - 3.51 mg act. ingr./L)


72 h EC20 =
 1.31 mg/L,act. ingr. (nominal) based on: growth rate (1.11 - 1.48 mg act. ingr./L)


72 h EC10 = 0.825 mg/L,
act. ingr. (nominal) based on: growth rate (0.663 - 1.01 mg act. ingr./L)


72 h NOEC =
 0.3 mg/L,act. ingr. (nominal) based on: growth rate


72 h LOEC = 0.96 mg/L,
act. ingr. (nominal) based on: growth rate

 
72 h EC50 = 1.01 mg/L,
act. ingr. (nominal) based on: yield inhibition (0.801 - 1.29 mg act. ingr./L)


72 h EC20 = 0.558 mg/L,
act. ingr. (nominal) based on: yield inhibition (0.396 . 0.603 mg act. ingr./L)


72 h EC10 = 0.426 mg/L,
act. ingr. (nominal) based on: yield inhibition (0.287 - 0.603 mg act. ingr./L)


72 h NOEC = 0.3 mg/L,
act. ingr. (nominal) based on: yield inhibition


72 h LOEC = 0.96 mg/L,
act. ingr. (nominal) based on: yield inhibition

 

Reliability: 1 (reliable without restriction), GLP

WoE.Toxicity to aquatic algae and cyanobacteria: 61789-40-0_9.1.2_Henkel_1992_DIN 38412 part 9

 

Weight of evidence


DIN 38412, part 9: Bestimmung der Hemmwirkung von Wasserinhaltsstoffen auf Grünalgen, Desmodesmus subspicatus (reported as Scenedesmus subspicatus), freshwater, static

 
72 h EC50 = ca. 1.5 mg/L,
act. ingr. (nominal) based on: growth rate


72 h NOEC = ca. 0.3 mg/L,
act. ingr. (nominal) based on: biomass


72 h EC50 = ca. 0.57 mg/L,
act. ingr. (nominal) based on: biomass

 

Reliability: 2 (reliable with restrictions), GLP

WoE.Toxicity to aquatic algae and cyanobacteria: 97862-59-4_9.1.2_THG_1993e_OECD 201

Weight of evidence

OECD Guideline 201 (Alga, Growth Inhibition Test),Scenedesmus subspicatus (new name: Desmodesmus subspicatus), freshwater, static


72 h EC50 = ca. 14.7 mg/L,
act. ingr. (nominal) based on: growth rate

 
72 h EC50 = ca. 9.2 mg/L,
ingr. (nominal) based on: biomass

 

Reliability: 2 (reliable with restrictions), GLP

WoE.Toxicity to aquatic algae and cyanobacteria: 61789-40-0_9.1.2_CEFIC_CESIO_2006b_OECD 201


Weight of evidence

 

OECD Guideline 201 (Alga, Growth Inhibition Test),Desmodesmus subspicatus, freshwater, static

 
72 h NOEC = 3.86 mg/L
act. ingr. (nominal) based on: growth rate


72 h EC50 = 9.86 mg/L
act. ingr. (nominal) based on: growth rate (95% c.i. 9.33 - 10.4 mg/L)


72 h LOEC = 7.73 mg/L
act. ingr. (nominal) based on: growth rate


72 h EC50 = 5.31 mg/L
act. ingr. (nominal) based on: biomass (95% c.i. 5.06 - 5.53 mg/L)


72 h NOEC = 1.93 mg/L
act. ingr. (nominal) based on: biomass


72 h LOEC = 3.86 mg/L
act. ingr. (nominal) based on: biomass

 

Reliability: 1 (reliable without restriction), GLP

WoE.Toxicity to aquatic algae and cyanobacteria.61789-40-0_9.1.2_Acute-algae_Unilever_A19_AL-L17-01

Weight of evidence


OECD Guideline 201 (Alga, Growth Inhibition Test),Desmodesmus subspicatus (reported as Scenedesmus subspicatus),
freshwater, static

 
72 h NOEC = 1.8 mg/L
act. ingr. (nominal) based on: biomass and growth rate


72 h EC50 = 4.66 mg/L
act. ingr. (nominal) based on: biomass


72 h EC50 = 5.6 mg/L
act. ingr. (nominal) based on: growth rate

 

Reliability: 2 (reliable with restrictions), no GLP

 

WoE.Toxicity to aquatic algae and cyanobacteria.61789-40-0_9.1.2_Acute-algae_Unilever_A18_AL-L474-01

 

Weight of evidence


OECD Guideline 201 (Alga, Growth Inhibition Test),Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata), freshwater, static

 
96 h NOEC = 3.2 mg/L
act. ingr. (nominal) based on: biomass and growth rate


96 h EC50 > 10 mg/L
act. ingr. (nominal) based on: growth rate

 

96 h EC50 = ca. 8 mg/Lact. ingr. (nominal) based on: biomass

 

Reliability: 2 (reliable with restrictions), no GLP

 

WoE.Toxicity to aquatic algae and cyanobacteria: 61789-40-0_9.1.2_Hüls_1996_EEC 92-69 C3


weight of evidence


EU Method C.3 (Algal Inhibition test) (cited as Directive 92/69/EEC, C.3,Desmodesmus subspicatus (reported as Scenedesmus subspicatus), freshwater, static

 
72 h EC50 > 334 mg/L
act. ingr. (nominal) based on: growth rate


72 h EC10 = 37.2 mg/L
act. ingr. (nominal) based on: growth rate


72 h NOEC = 10 mg/L
act. ingr. (nominal) based on: biomass

 

Reliability: 2 (reliable with restrictions), GLP

WoE.Toxicity to aquatic algae and cyanobacteria.61789-40-0_9.1.2_Marine_72h_Skeletonema costatum_Rhodia_Mirataine-BET-C37_ISO_2008

 
weight of evidence


ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum),Skeletonema costatum, saltwater, static

 
72 h NOEC 0.36 mg/L
act. ingr. (nominal) based on: growth rate


72 h EC50 0.74 mg/L
act. ingr. (nominal) based on: growth rate (95% c.i.: 0.7-0.78 mg a.i./L)


72 h NOEC 1 mg/L
test mat. (nominal) based on: growth rate


72 h EC50 2.05 mg/L
test mat. (nominal) based on: growth rate (95% c.i.: 1.94-2.17 mg product/L)

 

Reliability: 1 (reliable without restriction), GLP

 

72 h ErC50 values were in the range of 0.74 to >334 mg/L; 72 h NOEC (or EC10) values were in the range of 0.3 to 37.2 mg/L.

In a weight of evidence approach, considering all available information for the endpoint aquatic toxicity, the ecotoxicity profile of the AAPBs is characterised by an acute aquatic toxicity in the range of >1 to ≤ 10 mg/L. For practical reasons (to name a value for the algae effect concentration) the algae study with the lowest acute effect result within this range is used for the assessment of algae toxicity: 72h-ErC50 = 1.5 mg a.i./L, 72h-NOEC = 0.3 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 available studies were conducted according to OECD Guideline 201 or EU method C.4 (marine algae: ISO 10253) and were reliable (RL1) or 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 substances C12 AAPB and C8-18 and C18 unsatd. AAPB are also valid for the target substance C8-18 AAPB.