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Toxicity to microorganisms

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Description of key information

14 d NOEC > 45 mg a.i./L, OECD TG 301 B, GLP, RL1; read-across: C8-10 Alkylamidopropyl betaine

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
45 mg/L

Additional information

No experimental data are available for the target substance Undecylenamidopropyl Betaine. However, relevant and reliable data on toxicity to microorganisms are available for the closely related source substances C8-10 Alkylamidopropyl betaine , C8-18 and C18 unsatd. AAPB (Coco AAPB) and Formamidopropylbetaine. A justification for read-across is given below.

 

The toxicity of C8-10 Alkylamidopropyl betaine (35% a.i.) to microorganisms was investigated during a ready biodegradation study (CO2 Evolution Test) according to OECD guideline 301 B (1992) over a period of 28 days and using an inoculum obtained from activated sludge from a predominantly domestic sewage treatment plant.

Inoculum blank, procedural/functional control with the reference substance Sodium acetate and a toxicity control with 45 mg/L test item and 35 mg/L reference item Sodium acetate were performed.

The reference item degraded normally (68% within 14 days). By the end of the test, the reference item was degraded by 82%.

The biodegradation of the item mixture in the toxicity control was found to be 63% after 14 days of incubation. Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 45 mg/L, as the biodegradation in the toxicity control was higher than 35% within 14 days of incubation.

 

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 a.i./L nominal was determined.

 

The toxicity of Formamidopropylbetaine (40.1% a.i.) to microorganisms was investigated in a study OECD Guideline 209 after a contact time of 30 minutes. The 30 min EC50 was > 87 mg a.i./L.

 

For chemical safety assessment the lowest effect value (14 d NOEC = 45 mg a.i./L) will be used.

 

Justification for read-across

Hypothesis for the analogue approach

This read-across is based on the hypothesis that source and target substances have similar toxicological properties because

·        they are manufactured from similar / identical precursors under similar conditions

·        they share structuralsimilarities with common functional groups:quaternary amines, amide bonds, carboxymethyl groups, and fatty acid chains, differing in length and degree of saturation.

Based on the information given in section 1, it can be concluded that the substances are similar in structure, since they are manufactured from similar or identical precursors under similar conditions and all contain the same functional groups. Thus a common mode of action can be assumed.

 

The content of minor constituents in the substances are comparable and differ to an irrelevant amount.

 

The only deviation within this group of substances is a (minor) variety in their carboxylic acid moiety, which is not expected to have a relevant impact on intrinsic toxicity to microorganisms.

Therefore, read-across from the existing studies on toxicity to microorganisms on the source substances is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

The justification of the proposed read-across approach is elaborated in the next chapters.

 

1. Substance Identity

The target substance Undecylenamidopropyl Betaine is a monoconstituent substance manufactured from undecylenic acid and N, N-dimethylpropylenediamine (DMAPA) and further reacted with monochloroacetic acid.

 

The source substance C8-10 Alkylamidopropyl betaine is a UVCB substance manufactured from fatty acids (C8 and C10) and N, N-dimethylpropylenediamine (DMAPA) and further reacted with sodium monochloroacetate.

The source substance C8-18 and C18 unsatd. AAPB is a UVCB substance manufactured from natural fatty acids or oils with N, N-dimethylpropylenediamine (DMAPA) and further reacted with sodium monochloroacetate. As their origin is from natural sources, the used fatty acids may have a mixed slightly varying composition with an even numbered chain length from C8 to C18, including unsaturated C18 chains.

 

The source substance Formamidopropylbetaine is a monoconstituent substance manufactured from formic acid and N, N-dimethylpropylenediamine (DMAPA) and further reacted with sodium monochloroacetate.

 

Table 1: Substance identities

 

Target substance

Source substances

Undecylenamidopropyl Betaine

C8-10 Alkylamidopropyl betaine

C8-18 and C18 unsatd. AAPB

Formamido-propylbetaine

IUPAC name

Carboxymethyl)dimethyl[3-[(1-oxoundecenyl)amino]propyl]ammonium hydroxide

1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-C8-10 (even numbered) acyl derivs., hydroxides, inner

1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-(C8-18(even numbered) and C18 unsaturated acyl) derivs., hydroxides, inner salts

(3-(Formylamino)propyl)dimethylammonioacetate

EC number

n.a.

n.a.

931-333-8

480-680-7

CAS number

98510-75-9

n.a.

147170-44-3

120128-90-7

Molecular formula:

C18H34N2O3

UVCB substance, not applicable

UVCB substance, not applicable

C8H16N2O3

Molecular weight:

327.48

286.4-314.5g/mol

weighted mean: 297 g/mol

286.4 - 426.7 g/mol

weighted mean: 355 g/mol

188.226 g/mol

Chain length distri-bution

C11

C6: <= 2 %

C8: 53-64 %

C10: 36-47 %

C12: <= 2 %

C6:         <=2%

C8: <= 10%

C10: <= 10%

C12: 40 - 65%

C14: 14 - 21%

C16: 5 - 12%

C18: 1 - 14%

C18 unsatd.:  2 - 20%

C1: 100%

Minor consti-tuents

ca. 15.3% sodium chloride

 

ca. 0.6% glycollic acid

 

ca. 0.8% N-[3-(dimethylamino)propyl]-10-Undecenamide

 

 

11-21% sodium chloride

 

0-3% water

 

0-2% glycollic acid

 

0-0.3% alkylamidopropylamine

 

0-0.0005% DMAPA

<20% sodiumchloride

 

<3% glycollic acid

 

< 0.005%DMAPA

 

<1% alkylamidopropylamine

 

ca. 26% sodium chloride

 

ca. 1.5% glycolic acid

 

ca. 1% formamidopropylamine

 

</=0.02% DMAPA

 

 Figure 1: Molecular structures of the target substance Undecylenamidopropyl Betaine and the source substances C8-10 Alkylamidopropyl betaine, Formamidopropylbetaine and C8-18 and C18 unsatd. AAPB (see attachment)

 

2. Structural similarity

Structural similarity and functional groups (Table 1, Figure 1)

The target substance Undecylenamidopropyl Betaine is a monoconstituent substance manufactured from undecylenic acid and N, N-dimethylpropylenediamine (DMAPA) and further reacted with monochloroacetic acid.

 

The source substance C8-10 Alkylamidopropyl betaine  is a UVCB substance manufactured from fatty acids (C8 and C10) and N, N-dimethylpropylenediamine (DMAPA) and further reacted with sodium monochloroacetate.

 

The source substance C8-18 and C18 unsatd. AAPB is a UVCB substance manufactured from natural fatty acids or oils with N, N-dimethylpropylenediamine (DMAPA) and further reacted with sodium monochloroacetate. As their origin is from natural sources, the used fatty acids may have a mixed slightly varying composition with an even numbered chain length from C8 to C18, including unsaturated C18.

 

The source substance Formamidopropylbetaine is a monoconstituent substance manufactured from formic acid and N, N-dimethylpropylenediamine (DMAPA) and further reacted with sodium monochloroacetate.

 

Differences

Differences in chemical and other intrinsic properties of the target and source substances 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 lead to an increasing average lipophilicity as can be seen from the increasing log Kow from Formamidopropylbetaine (log Kow: -3.3), Undecylenamidopropyl Betaine (-1.38), C8-10 Alkylamidopropyl betaine (log Kow: 2.2), C8-18 AAPB (log Kow: 4.23).

There are clear trends in the physicochemical properties (with regard molecular weight, water solubility, log Kow and surface tension) as demonstrated below. As data on toxicity to microorganisms are available for the upper and lower end of this row similarly showing the absence of toxicity to microorganisms, the differences in C chain lengths obviously do not influence the intrinsic toxicity to microorganisms. 

- Different amounts of unsaturated fatty ester moieties:

The target substance Undecylenamidopropyl Betaine contains an unsaturated C11 chain. Also, the source substance C8-18 and C18 unsatd. AAPB contains considerable amounts of unsaturated C18 chains.

However, as fatty acids independently from their degree of unsaturation are generally considered to be not toxic to microorganisms, a variability in the fatty acid moiety is not expected to have any influence on the intrinsic toxicity to microorganisms.

 

The provided structural similarities and impurity profiles support the proposed read-across hypothesis with high confidence.

 

3. Physicochemical properties

Table 2: Physicochemical properties

 

 

Target substance

Source substances

End-points

Undecylenamidopropyl Betaine

C8-10 Alkyamidopropyl betaine

C8-18 and C18 unsatd. AAPB

Formamidopropylbetaine

Physical state at 20°C / 1013 hPa

Solid

 

Reliability: 1 (reliable without restrictions)

Solid

 

Reliability: 2 (reliable with restrictions)

Solid

 

Reliability: 2 (reliable with restrictions)

Liquid

 

Reliability: 1 (reliable without restrictions)

Melting point

144 -158 °C

 

OECD TG 102

 

Reliability: 1 (reliable without restrictions)

No data

Not identifiable due to decomposition in the range between 208 and 280°C

 

OECD TG 102

 

Reliability: 1 (reliable without restrictions); read-acrossC8-18 AAPB

-50 °C to -20 °C

 

OECD TG 102

 

Reliability: 1 (reliable without restrictions)

Boiling point

decomposition >220°C

 

OECD Guideline 103

 

Reliability: 1 (reliable without restrictions)

No data

decomposition in the range between 208 and 280°C

 

OECD Guideline 103

 

Reliability: 1 (reliable without restrictions); read-acrossC8-18 AAPB

decomposition >250°C

 

OECD Guideline 103

 

Reliability: 1 (reliable without restrictions)

Vapour pressure

1.52E-12 Pa at 25°C

 

Calculation: Modified Grain Method; Episuite v4.11, MPBMWIN v 1.43

 

Reliability: 4 (not assignable)

2E-11 Pa at 25°C (calculation C8 derivative)

 

EPIWIN v3.11, MPBPWIN v1.4

 

Reliability: 4 (not assignable)

<=0.0031 hPa at 20°C, C8/10-fraction

 

OECD

Guideline 104

 

Reliability: 2 (reliable with restrictions)

2758 Pa at 20°C

 

OECD

Guideline 104

 

Reliability: 1 (reliable without restrictions)

Log Kow

-1.38 at 20°C

 

Calculation (ACD/Labs v12)

 

Reliability : 2 (reliable with restrictions)

2.2 at 20°C (weighted mean)

 

Calculation (ACD/Labs v12)

 

Reliability : 2 (reliable with restrictions)

4.2317 at 20°C, mean

 

Calculation (ACD/Labs v12)

 

Reliability : 2 (reliable with restrictions)

-3.3 at 20.1°C, pH 7.1

 

OECD

TG 107

 

Reliability: 1 (reliable without restrictions)

Water solubility

CMC: 3.1 g/L at 20°C

 

OECD

TG 115

 

Reliability: 1 (reliable without restrictions)

CMC: 4.9 g/L at 20°C

 

OECD

TG 115

 

Reliability: 1 (reliable without restrictions)

400 mg/L at 20°C

 

CMC determination

 

Reliability : 2 (reliable with restrictions); read-acrossC8-18 AAPB

> 2160 g/L at 20.2 ± 0.6 °C, pH 5.8

 

OECD

TG 105

 

Reliability: 1 (reliable without restrictions)

Surface tension

28.9 mN/m(surface active)

 

OECD

TG 115

 

Reliability: 1 (reliable without restrictions)

24.4 mN/m(surface active)

 

OECD

TG 115

 

Reliability: 1 (reliable without restrictions)

30.9 ± 0.2 mN/m at 20°C (surface active)

 

DIN EN 14370 (Wilhelmy plate method)

 

Reliability: 1 (reliable without restrictions)

72.9 mN/m at 20°C and 2.77 g/L (not surface active)

 

OECD TG 115

 

Reliability: 1 (reliable without restrictions)

 

Experimental data on melting point, boiling point, water solubility and surface tension are available for the target substance as well as calculated values for vapour pressure.

There are differences in molecular weight among the target and source substances – especially the source substance Formamidopropylbetaine differs from the other substances. But as it represents an extreme with the shortest possible C-chain within this group of substances, it can be regarded as a worst case in terms of reactivity (e.g. for the flammability endpoints). The differences in molecular weights also results in differences in physical state, melting and boiling point and vapour pressure. The shorter C-chain further leads to higher hydrophilicity and thereby a lower log Kow and may also explain the absence of surface activity.

 

Under standard conditions the substances are solid (described as waxy or soapy), with the exception of the source substance Formamidopropylbetaine which is liquid. A melting range of 144 -158°C was determined for thetarget substance; a boiling point was not identified due to decomposition >200°C. A melting and a boiling point were not identifiable via DSC measurements with the source substance C8-18 AAPB due to decomposition of the test substance. The source substance Formamidopropylbetaine has a melting range of -50 °C to -20 °C and undergoes decomposition at >250°C.

The log Kow increases within this group of substances with increasing C-chain length, the presence of double bonds decreases the log Kow, which is in line with the expectations. The water solubility decreases with increasing C chain length, which is also in line with the expectations.

 

4. Comparison of ecotoxicity data (toxicity to microorganisms):

 

Target substance

Source substances

Endpoint

Undecylenamidopropyl Betaine

C8-10 Alkylamidopropyl betaine

C8-18 and C18 unsatd. AAPB

Formamidopropylbetaine

Toxicity to micro-organisms

No data, read-across

key_Toxicity to microorganisms: 73772-45-9 / 73772-46-0_9.1.4._2005_Evonik_OECD 301 B

 

OECD TG 301 B (Ready Biodegradability: CO2 Evolution Test)

activated sludge of a predominantly domestic sewage, static, freshwater

 

14 d NOEC = 45 mg a.i./L (nominal) based on: respiration rate

 

Reliability: 1 (reliable without restrictions), GLP

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

 

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

sup_RA_NOTOX 454106 Toxicity to microorganisms.001

 

OECD TG 209 (Activated Sludge, Respiration Inhibition Test)

activated sludge of a predominantly domestic sewage, static, freshwater

 

30 min EC50 > 87 mg a.i./L (meas., arithm. mean) based on: respiration rate

 

Reliability: 1 (reliable without restrictions), GLP

 

Biodegradation

sup_Biodegradation in water: screening tests: 98510-75-9_9.2.1.1._2016_Evonik_EpiSuite

 

calculation with EpiSuite v4.11, BIOWIN v4.10

 

predicted to be readily biodegradable

 

Reliability: 2 (reliable with restrictions), no GLP

key_Biodegradation in water: screening tests: 73772-45-9 / 73772-46-0_9.2.1.1._2005_Evonik_OECD 301 B

 

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test), ready biodegradability, aerobic

 

activated sludge, domestic, non-adapted

 

% Degradation of test substance: 68 after 11 d / 81 after 28 d(CO2 evolution)

 

readily biodegradable

 

Reliability: 1 (reliable without restrictions), GLP

Sup_RA_Biodegradation in water: screening tests.61789-40-0_9.2.1.1_Stepan_2000_ISO/DIS 14593

 

ISO/DIS 14593, ready biodegradability, aerobic

 

activated sludge (adaptation not specified)

 

% Degradation of test substance: 87.2 after 28 d (CO2 evolution)

 

readily biodegradable

 

Reliability: 1 (reliable without restrictions), no GLP

sup_RA_NOTOX 454051 Biodegradation in water: screening tests

 

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test), ready biodegradability, aerobic

 

activated sludge, domestic, non-adapted

 

% Degradation of test substance: 35% after 28 d (CO2 evolution)

 

Not readily biodegradable; inherently biodegradable

 

Reliability: 1 (reliable without restrictions), GLP

 

No experimental data are available for the target substance Undecylenamidopropyl Betaine.

 

The toxicity of C8-10 Alkylamidopropyl betaine to microorganisms was determined during a biodegradation study according to OECD Guideline 301 B. The 14 d NOEC was determined to be 45 mg/L.

The toxicity of C8-18 and C18 unsatd. AAPB to microorganisms was investigated in a study conducted according to EN ISO 10712. The available data show a low toxicity of C8-18 and C18 unsatd. AAPB to Pseudomonas putida (16 h EC0 = 3000 mg a.i./L nominal).

The toxicity of Formamidopropylbetaine to microorganisms was investigated in a study according to OECD Guideline 209. The 30 min EC50 was 87 mg/L.

 

Further support is given by the predicted ready biodegradation of the target substance Undecylenamidopropyl Betaine. The source substances are also readily (Formamidopropylbetaine: inherently) biodegradable.The assumption that the substance under investigation is not inhibitory to the micro-organisms when dosed in the test system is implicit in ready biodegradability testing. Thus, the prediction ofready biodegradation also indicates the absence of toxicity to microorganisms.

Quality of the experimental data of the analogues

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

The key studies were conducted according to OECD TG 301 B, EN ISO 10712 or OECD TG 209 and were reliable or reliable with restrictions (RL1-2).

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 (identical/similar functional groups) and a clear trend in physicochemical properties (esp. water solubility and log Kow), which is in line with the expectations based on the differences in C chain length, the results obtained with the source substances C8-10 Alkylamidopropyl betaine, C8-18 and C18 unsatd. AAPB and Formamidopropylbetaine are also valid for the target substance Undecylenamidopropyl Betaine.

As fatty acids independently from their chain length and degree of unsaturation are generally considered to be not toxic to microorganisms, a variability in the fatty acid moiety is not expected to have any influence on the intrinsic toxicity to microorganisms.

As a worst case, the lowest of the available effect values to microorganisms will be used as starting point for deriving the PNEC(STP).