1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-(C12-18(even numbered) acyl) derivs., hydroxides, inner salts

Endpoint summary

Description of key information

There is no evidence on relevant intrinsic acute toxic activity of AAPB constituting a hazard to human health. Acute toxicity data on AAPBs are available for the oral and for the dermal route. Acute animal studies by inhalation route are unjustified. Due to its very low  vapour pressure, an exposure  to AAPB  vapour is negligible. Generation of aerosols may be theoretically possible, however the estimated exposure is very low. Furthermore, systemic toxicity relevant to humans did not appear neither in acute nor in repeated dose toxicity studies by other exposure routes. Considering the exposure probability and the available information on the intrinsic toxic activity of the substance, an inhalative risk to humans is unlikely and therefore, the conduct of an inhalative  toxicity study is unjustified. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

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 for cross-reference:

read-across: supporting information

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

Key result

Sex:

male/female

Dose descriptor:

LD50

Remarks:

after 14 d

Effect level:

2 335 mg/kg bw

Based on:

act. ingr.

95% CL:

1 944 - 2 571

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 335 mg/kg bw

Quality of whole database:

comparable to guideline study, pre-GLP

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

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 for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 620 mg/kg bw

Based on:

act. ingr.

Remarks on result:

other: mortality 0/10

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

620 mg/kg bw

Quality of whole database:

OECD guideline study; however no higher dose levels have been tested (2000 mg test material/kg bw), corresponding to 620 mg a.i./kg bw

Additional information

No experimental data on acute toxicity are available for C12-18 AAPB. However, acute toxicity data on closely related AAPBs are available for the oral (C8-18 AAPB / C8-18 and C18 unsatd. AAPB (Coco AAPB)) and for the dermal (C8-18 ans C18 unsatd. AAPB) route. A justification for read-across is given below.

 

Acute oral toxicity

In the key study on acute oral toxicity, performed according to US Guideline Appraisal of the Safety of Chemicals in Food, Drugs and Cosmetics, FDA, 1959, which is comparable to the OECD guideline 401 (1981), 5 male and 5 female Wistar rats were given a single oral dose of C8-18 and C18 unsatd. AAPB (30 % a.i.) as delivered by the sponsor at doses of 5.0, 6.3, 7.94, and 10.0 ml/kg bw. Animals were then observed for 14 days. This study was selected as key study considering reliability, adequacy and relevance including dose scheme and dose level based on active ingredient.

At 5.0, 6.3, 7.94, and 10.0 ml/kg bw 2/10, 2/10, 6/10, and 8/10 animals died, respectively. Most animals died within 24 hours p.a.. Weight gains were normal in all animals. Clinical signs at >= 5 ml/kg bw were decreased motor activity, coordination disturbances, abnormal body posture, piloerection, diarrhoea, skin/mucosa cyanosis and decreased body temperature with dose response relationship. At >= 7.94 ml/kg bw animals showed prone position. Clinical signs were observed at 20 minutes, 1 h and 3 h after application. Except of slight diarrhoea in one animal in dose groups 6.3, 7.94 and 10 ml/kg bw, each, all symptoms were reversible after 24 hours. 7 days after application, all surviving animals were free of clinical symptoms. Gross pathology examination of animals found dead revealed reddened gastric and intestinal mucosa. Animals sacrificed at study termination 14 days p.a. had light reddened intestinal mucosa.

Oral LD50 Combined =  7.45 mL/kg bw after 14 d

Oral LD50 Combined =  8.1 mL/kg bw after 24 h

LD50 determined refers to the test substance as delivered by the sponsor. Amount of active ingredient in test item is 30 %. The density is roughly 1 g/ml. Therefore the calculated oral LD50 combined referring to 100 % active substance = 2335 mg/kg bw after 14 d. Coco AAPB is of low toxicity based on the LD50 in males and females.

 

The low oral toxicity seen in this study is confirmed by a further study in which the tested dose based on a.i. also exceeds the limit dose of 2000 mg/kg bw of the recent EU and OECD guidelines. In this study, performed according to OECD Guideline 401, 1981, 5 male and 5 female Bor: WISW (SPF TNO) rats were given a single dose of C8-18 and C18 unsatd. AAPB (a.i. 35 %) as delivered by the sponsor at a dose of 10000 mg/kg bw (limit test). Animals were then observed for 14 days. 1/5 males and 2/5 females died within 24 hours after dosing. Clinical sings observed 30-60 min after dosing were rough fur, hunched position, slowed motions, aggressiveness, slight sedation and ataxia and strong diarrhoea. 1h - 7 days after dosing: animals showed prone position, diuresis, slight trembling, shrunken flanks and tumbling. 7 days after application, all surviving animals were free of clinical signs. All animals gained weight during the observation period. Gross pathology of the deceased revealed in 1 animal hyperemia of stomach and intestine mucosa, renal pelvis and adrenals and thickened forestomach mucosa an in the 2 further decedents thin and shiny forestomach mucosa. 3/7 animals sacrificed at study termination 14 days p.a. showed focal thickened (in parts chondroic) forestomach mucosa.

Oral LD50 Combined: > 10000 mg/kg bw

LD50 determined refers to the test substance as delivered by the sponsor. Amount of active ingredient in test substance is 35 %. Therefore the calculated oral LD50 combined referring to 100 % active substance is > 3500 mg/kg bw.

Coco AAPB is of low toxicity based on the LD50 in males and females.

 

There are several further supporting acute oral toxicity studies, performed on products containing 30 – 39.2 % a.i. C8-18 and C18 unsatd. AAPB in aqueous solutions, confirming the low acute toxicity. In these studies LD50 was generally greater than 5000 mg/kg bw based on product (i.e., greater than 1500 mg active substance/kg bw). Only one study resulted in a LD50in the range of 5000 mg product/kg bw. As details on the specific composition of this product are not available, a reason for the slightly higher toxicity of this specific product cannot be given.

 

Acute dermal toxicity

In the key study on acute dermal toxicity, performed according to EU Method B.3 and OECD Guideline 402, 5 male and 5 female CD rats (Crl:COBS CD(SD)BR) were dermally exposed to

C8-18 and C18 unsatd. AAPB (a.i. 31 %) as delivered by the sponsor for 24 hours to 10% of total body surface at a dose of 2000 mg/kg bw (limit test). Test sites were covered with an occlusive dressing. After 24 hours, the test sites were rinsed with warm water. Animals then were observed for 14 days after dosing. There were no clinical signs of systemic reaction to treatment. Sites of application of the test substance showed slight or well-defined erythema in all animals on Day 2 and/or 3. On Day 4 and Day 5, slight erythema were seen in three male and four female rats, sloughing in two male rats and one female rat and hyperkeratinisation in three female rats. All skin reactions were completely reversible by Day 6 in all animals. Slightly low bodyweight gains were recorded for three females on Day 8. All other rats achieved anticipated bodyweight gains throughout the study. Terminal autopsy findings were normal.

Dermal LD0 Combined: 2000 mg/kg bw

Dermal LD50 Combined: > 2000 mg/kg bw

 

LD0 and LD50 determined refer to the test substance as delivered by the sponsor. Amount of active ingredient in test substance is 31 %. Therefore the calculated oral LD0 and LD50 combined referring to 100 % active substance is 620 and > 620 mg/kg bw, respectively.

Although, referring to active ingredient, this study does not cover the limit guideline limit dose for acute dermal studies (2000 mg/kg bw), carrying out an additional acute dermal study which covers the guideline limit dose referring to a.i. is not justified. As seen in a reliable in vivo rat study on dermal and oral absorption, the dermal absorption does not exceed the oral absorption. The dermal absorption in a reliable in vitro study on human skin was even zero. Taking into account the information on dermal absorption and the high LD50 values determined in oral studies, it can be anticipated that an acute dermal systemic toxicity leading to classification is highly unlikely.

 

Acute inhalation toxicity

Acute animal studies by inhalation route are unjustified. Due to its very low vapour pressure, an exposure to AAPB vapour is negligible. Generation of aerosols may be theoretically possible, however the estimated exposure is very low. Furthermore, systemic toxicity relevant to humans did not appear neither in acute nor in repeated dose toxicity studies by other exposure routes. Considering the exposure probability and the available information on the intrinsic toxic activity of the substance, an inhalative risk to humans is unlikely and therefore, conduct of an inhalative toxicity study is unjustified. The acute toxicity of the whole group of AAPBs is expected to be in the same range as variability in the fatty acid moiety is not expected to be relevant to the intrinsic systemic toxicity of the compounds.

 

Summary

There is no evidence on relevant intrinsic acute toxic activity of AAPB constituting a hazard to human health. The acute toxicity of AAPB in rats is low, with a dermal LD50 value greater than 2000 mg product/kg bw (i.e., greater than 620 mg active substance/kg bw), and an oral LD50 value of 2335 mg active substance/kg bw in a full acute toxicity study. In addition, several supporting oral acute toxicity limit tests with dose levels of 10000 or 5000 mg product/kg bw are available. Only in one of these studies, which resulted in a LD50 of >10000 mg product (35 % active substance)/kg bw (corresponding to > 3500 mg active substance/kg bw), the effective dose based on active substance covers the guideline limit dose of 2000 mg/kg bw. In the further studies a limit dose level of 5000 mg product was tested, corresponding to 1500 to 1960 mg active substance/kg bw considering the respective active substance content of the products (30 -39.2 %). In these studies LD50 was generally greater than 5000 mg/kg bw based on product. Only one study resulted in a LD50 in the range of 5000 mg product/kg bw. As details on the specific composition of this product are not available, a reason for the slightly higher toxicity of this specific product cannot be given. Other than irritation, there were no clinical signs reported after acute dermal exposure. After oral exposure to high doses the most relevant findings were decreased motor activity, diarrhea, and ataxia. Prominent gross pathology findings in oral studies are hyperemia of stomach and intestine mucosa, and thickened forestomach mucosa.

 

There are no data gaps for the endpoint acute toxicity. No human data are available. However, there is no reason to believe that these results from rat would not be applicable to humans.

 

 

Justification for read-across

For details on substance identity and detailed 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, which is not expected to have a relevant impact on intrinsic acute toxicity.

 

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 toxicity 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 acute toxicity are not to be expected.

- Different amounts of unsaturated fatty ester moieties:

Effects may be expected for e.g. physical state and for some toxicological endpoints, mainly local effects (e.g. irritation), but not for acute systemic toxicity.

 

Comparison of acute toxicity data

 

Endpoints	Source substances		Target substance
	C8-18 AAPB	C8-18 and C18 unsatd. AAPB	C12-18 AAPB
Acute toxicity, oral	Sup_Acute toxicity: oral: 97862-59-4_8.5.1_GCC_1993_FHSA 16 CFR 1500.3   Supporting study US FHSA Federal regulation: 16 CFR 1500.3, rat oral: gavage LD50 > 5000 mg/kg bw (based on test material) LD50 > 1960 mg a.i./kg bw Reliability: 1 (reliable without restriction), GLP	Key_Acute toxicity: oral: 61789-40-0_8.5.1_Th_Goldschmidt_AG_1977   Key study Similar to OECD TG 401, standard acute method, rat oral: gavage LD50 = 7.45 mL/kg bw (based on test material; after 14 d) LD50 = 2335 mg a.i./kg bw (after 14 d) LD50 = 8.1 mL/kg bw (based on test material; after 24 h) LD50 = 2430 mg a.i./kg bw (after 24 h) Reliability: 1 (reliable without restriction), pre-GLP	No data, read-across
	Sup_Acute toxicity: oral: 97862-59-4_8.5_GCC_1993d   Supporting study US FHSA Federal regulation: 16 CFR 1500.3, rat oral: gavage   LD50 > 5000 mg/kg bw (based on test material) LD50 > 1960 mg a.i./kg bw   Reliability: 1 (reliable without restriction), GLP	Sup_Acute toxicity: oral: 61789-40-9_8.5.1_Hüls_1986_OECD 401   Supporting study OECD TG 401, rat oral: gavage   LD50 > 10000 mg/kg bw (based on test material) LD50 > 3500 mg a.i./kg bw Reliability: 2 (reliable with restrictions), no data on GLP
	Sup_Acute toxicity: oral: 97862-59-4_8.5.1_GCC_1992_FHSA 16 CFR 1500.3   Supporting study US FHSA Federal regulation: 16 CFR 1500.3, rat oral: gavage   LD50 > 5000 mg/kg bw (based on test material) LD50 > 1960 mg a.i./kg bw   Reliability: 1 (reliable without restriction), GLP	Sup_Acute toxicity: oral: 61789-40-0_8.5.1_Stepan_1982a_FDRL Supporting study   Similar to OECD TG 401, standard acute method, rat oral: gavage LD50 > 5000 mg/kg bw (based on test material) LD50 > 1750 mg a.i./kg bw   Reliability: 1 (reliable without restriction), GLP
		Sup_Acute toxicity: oral: 61789-40-0_8.5.1_Stepan_1982b_FDRL Supporting study Similar to OECD TG 401, standard acute method, rat oral: gavage LD50 ca. 5000 mg/kg bw (based on test material) LD50 ca. 1530 mg a.i./kg bw   Reliability: 1 (reliable without restriction), GLP
Acute toxicity, dermal	No data	key_Acute toxicity: dermal: 61789-40-0_8.5.3_KAO Corporation_1987_OECD 402   key study   OECD TG 402, rat, Type of coverage: Occlusive LD0 > 2000 mg/kg bw (based on test material) LD0 > 620 mg a.i./kg bw LD50 > 2000 mg/kg bw (based on test material) LD50 > 620 mg a.i./kg bw   Reliability: 1 (reliable without restriction), GLP	No data, read-across

 

There is no evidence of relevant intrinsic acute toxicity of the AAPBs:

-      The oral LD50 was 2335 mg a.i/kg bw in rat.

-      Although the substance has only been tested at 620 mg a.i./kg bw (corresponding to 2000 mg/kg bw in terms of test material) via the dermal route, the consideration of all available data on acute dermal toxicity, acute oral toxicity, toxicokinetics and dermal penetration leads to the conclusion, that the dermal LD50 will be > 2000 mg a.i./kg bw.

 

Quality of the experimental data of the analogues:

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

The key study for acute oral toxicity with C8-18 and C18 unsatd. AAPB was conducted similar to OECD Guideline 401 (RL1, study performed before implementation of GLP).

Several reliable (RL 1or 2) supporting studies according to OECD Guideline 401 or US FHSA Federal regulation 16 CFR 1500.3 are available for both source substances.

The acute dermal toxicity of C8-18 and C18 unsatd. AAPB was tested in a study according to OECD Guideline 402 (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 substances C8-18 AAPB and C8-18 and C18 unsatd. AAPB are also valid for the target substance C12-18 AAPB.

There is no evidence of relevant intrinsic acute toxicity of C12-18 AAPB, thus, classification and labelling with regard to acute toxicity is not warranted.

Justification for classification or non-classification

There is no evidence on relevant intrinsic acute toxic activity of AAPB constituting a hazard to human health. In rats, oral LD₅₀ values are greater than 2000 mg/kg bw based on active substance insofar as tested and generally greater than 5000 mg/kg bw based on product (i.e., greater than 1500 mg active substance/kg bw referring to products with 30-39.2 % a.i. in aqueous solution). The dermal LD50 value is greater than 2000 mg/kg bw based on product (i.e., greater than 620 mg active substance/kg bw). Although, referring to active ingredient, this study does not cover the limit guideline limit dose for acute dermal studies (2000 mg/kg bw), conduct of an additional acute dermal study for classification and labelling purposes which covers the guideline limit dose referring to a.i. is not justified. As seen in a reliable in vivo rat study on dermal and oral absorption, the dermal absorption does not exceed the oral absorption. The dermal absorption in a reliable in vitro study on human skin was even zero. Taking into account the information on dermal absorption and the high LD50 values determined in oral studies, it can be anticipated that an acute dermal systemic toxicity leading to classification is highly unlikely.

The conduct of acute inhalative animal studies is also unjustified, as due to its very low vapour pressure, an exposure to AAPB vapour is negligible. Generation of aerosols may be theoretically possible, however the estimated exposure is very low. Furthermore, systemic toxicity relevant to humans did not appear neither in acute nor in repeated dose toxicity studies by other exposure routes. Considering the exposure probability and the available information on the intrinsic toxic activity of the substance, an inhalative risk to humans is unlikely and therefore, the conduct of an inhalative toxicity study is unjustified.

Thus, AAPB does not comply with the classification requirements regarding acute toxicity outlined in regulation (EC) 1272/2008 or the former European directive on classification and labelling 67/548/EEC.