Oxoaluminium, C16-C18-alkyl esters

Endpoint summary

Description of key information

The skin sensitisation potential of the registered substance is read across from a proprietary, GLP-compliant experimental study on aluminum, benzoate C16-18 fatty acid complexes following OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted 22 July 2010) and Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Regulation (EC) No. 440/2008.

This substance is considered suitable for read-across as it contains a fatty acid moiety coordinated to an aluminium atom. Although it also contains a coordinated benzoate ion, no toxicological effects were observed and therefore it is concluded that the benzoate ion does not contribute any additional toxicity to the substance. Aluminum, benzoate C16-18-fatty acids complexes was tested in the form of an isolated solid and showed no sensitising effects (Harlan 2013). Therefore, aluminium, benzoate C16 -18 fatty acids complexes is considered to be a non-sensitiser and this has been read across to the target substance.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 October 2012 to 06 November 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/Ca (CBA/CaOlaHsd)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Female CBA/Ca (CBA/CaOlaHsd) strain mice were supplied by Harlan UK Limited, Oxon, UK.
- Age at study initiation: At the start of the study the animals were eight to twelve weeks old.
- Weight at study initiation: At the start of the study the animals were in the weight range of 15 to 23g.
- Housing: The animals were individually housed in suspended solid-floor polypropylene cages furnished with softwood woodflakes.
- Diet: Ad libitum (2014 Teklad Global Rodent diet supplied by Harlan UK Limited, Oxon, UK)
- Water: Ad libitum.
- Acclimation period: At least five days.

ENVIRONMENTAL CONDITIONS
- Temperature: The temperature was controlled to remain within the target ranges of 19 to 25ºC.
- Humidity: The humidity was controlled to remain within the target ranges of 30 to 70%.
- Air changes: The rate of air exchange was approximately fifteen changes per hour.
- Photoperiod: The lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.

IN-LIFE DATES: From: Day 1 to Day 6

Vehicle:

propylene glycol

Concentration:

Each group was exposed to the test material at concentrations of 10%, 5% or 2.5% w/w in propylene glycol.

No. of animals per dose:

Groups of four mice were treated for each test item concentration plus vehicle control

Details on study design:

RANGE FINDING TESTS
- Method: Using available information regarding the systemic toxicity/irritancy potential of the test item, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µL of the test item at a maximum attainable concentration (as a suspension) of 10% w/w in propylene glycol, to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Local skin irritation was scored daily according to the scale included as Appendix 4. Any clinical signs of toxicity, if present, were also recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6. The thickness of each ear was measured using an Oditest micrometer (Dyer, PA), pre-dose on Day 1 and post-dose on Day 3 and on Day 6. Any changes in the ear thickness were noted. Mean ear thickness changes were calculated between Days 1 and 3 and Days 1 and 6. A mean ear thickness increase of equal to or greater than 25% was considered to indicate excessive irritation and limited biological relevance to the endpoint of sensitisation.
- Lymph node proliferation response: No signs of systemic toxicity, visual local skin irritation or irritation indicated by an equal to or greater than 25% increase in mean ear thickness were noted. Based on this information the dose levels selected for the main test were 10%, 5% and 2.5% w/w in propylene glycol.

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay in the Mouse. The assay has undergone extensive inter-laboratory validation and has been shown to reliably detect test materials that are moderate to strong sensitisers.
- Criteria used to consider a positive response: The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node(dpm/node) and as the ratio of 3HTdR incorporation in lymph node cells of test nodes relative to that recorded for the control nodes (stimulation Index). The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non-sensitier".

TREATMENT PREPARATION AND ADMINISTRATION
- Test material: For the purpose of the study, the test material was used at concentrations of 10%, 5% or 2.5% w/w in propylene glycol. This vehicle was chosen as it produced the highest concentration that was suitable for dosing. The test item was formulated within two hours of being applied to the test system. It is assumed that the formulation was stable for this duration. No analysis was conducted to determine the homogeneity, concentration or stability of the test item formulation. This is an exception with regard to GLP and has been reflected in the GLP compliance statement. The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest suitable concentration. The mice were treated by daily application of 25 µl of the appropriate concentration of the test material to the dorsal surface of each ear for three consecutive days (Days 1, 2 and 3). The test material formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette. A further group of four mice received the vehicle alone in the same manner.
- 3H-Methyl Thymidine Administration: Five days following the first topical application of the test material (Day 6) all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 3H-methyl thymidine (3HTdR: 80 µCi/mL, specific activity 2.0 Ci/mmol, ARC UK Ltd) giving a total of 20 µCi to each mouse.

Positive control substance(s):

other: Phenylacetaldehyde

Statistics:

None provided.

Positive control results:

One group of five animals was treated with 50 µL (25 µl per ear) of phenylacetaldehyde (>90%) as a solution in propylene glycol at a concentration of 2.5% v/v. A further control group of five animals was treated with propylene glycol alone. The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:
Concentration % v/v in propylene glycol Stimulation Index (SI) Result
2.5 6.48 Positive

Phenylacetaldehyde (>90%) was considered to be a sensitiser under the conditions of the test.

Parameter:

other: disintegrations per minute (DPM)

Value:

ca. 522.69 - ca. 691.12

Test group / Remarks:

DPM per node of 522 to 691 were recorded for the vehicle control and the test material at concentrations of 10%, 5% and 2.5% w/w in propylene glycol.

Remarks on result:

other: The radioactive disintegrations per minute (dpm) per lymph node and the stimulation index (SI) are given in Table 2.

Key result

Parameter:

SI

Value:

1.1

Variability:

Concentration: 2.5% w/w in propylene glycol

Test group / Remarks:

4 animals

Remarks on result:

other: The stimulation index (SI) results are given in Table 4.

Key result

Parameter:

SI

Value:

0.83

Variability:

Concentration: 5% w/w in propylene glycol

Test group / Remarks:

4 animals

Remarks on result:

other: The stimulation index (SI) results are given in Table 4.

Key result

Parameter:

SI

Value:

1.01

Variability:

Concentration: 10% w/w in propylene glycol

Test group / Remarks:

4 animals

Remarks on result:

other: The stimulation index (SI) results are given in Table 4.

Cellular proliferation data / Observations:

- Clinical Observations and Mortality Data: There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.
- Bodyweight: Bodyweight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.
- Conclusion: The test item was considered to be a non-sensitiser under the conditions of the test.

Table 1              Clinical Observations, Bodyweight and Mortality Data – Preliminary Screening Test

Concentration (% w/w) in propylene glycol	Animal Number	Bodyweight (g)		Day
				1		2		3		4	5	6
		Day 1	Day 6	Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
10	S-1	21	20	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 2              Local Skin Irritation – Preliminary Screening Test

Concentration (%w/w) in propylene glycol

Animal Number

Local Skin Irritation

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

left

right

left

right

left

right

left

right

left

right

left

right

10

S-1

0

0

0

0

0

0

0

0

0

0

0

0

Table 3              Measurement of Ear Thicknessand Mean Ear Thickness Changes – Preliminary Screening Test

Concentration (%w/w) in propylene glycol	Animal Number	Ear Thickness Measurement (mm)
		Day 1		Day 3		Day 6
		pre‑dose		post dose
		left	right	left	right	left	right
10	S-1	0.245	0.240	0.230	0.240	0.235	0.245
overall mean (mm)		0.243		0.235		0.240
overall mean ear thickness change (%)		na		-3.093		-1.031

na=     Not applicable

Table 4              Disintegrations per Minute, Disintegrations per Minute/Node and Stimulation Index

Concentration (%w/w) in propylene glycol	dpm	dpm/Node^a	Stimulation Index^b	Result
Vehicle	5012.31	626.54	na	na
2.5	5528.98	691.12	1.10	Negative
5	4181.55	522.69	0.83	Negative
10	5039.56	629.95	1.01	Negative

dpm= Disintegrations per minut

a=      Disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

b=      Stimulation Index of 3.0 or greater indicates a positive result

na =    Not applicable

Table 5              Individual Clinical Observations and Mortality Data

Concentration (% w/w) propylene glycol	Animal Number	Day 1		Day 2		Day 3		Day 4	Day 5	Day 6
		Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
Vehicle	1-1	0	0	0	0	0	0	0	0	0
	1-2	0	0	0	0	0	0	0	0	0
	1-3	0	0	0	0	0	0	0	0	0
	1-4	0	0	0	0	0	0	0	0	0
2.5	2-1	0	0	0	0	0	0	0	0	0
	2-2	0	0	0	0	0	0	0	0	0
	2-3	0	0	0	0	0	0	0	0	0
	2-4	0	0	0	0	0	0	0	0	0
5	3-1	0	0	0	0	0	0	0	0	0
	3-2	0	0	0	0	0	0	0	0	0
	3-3	0	0	0	0	0	0	0	0	0
	3-4	0	0	0	0	0	0	0	0	0
10	4-1	0	0	0	0	0	0	0	0	0
	4-2	0	0	0	0	0	0	0	0	0
	4-3	0	0	0	0	0	0	0	0	0
	4-4	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 6              Individual Bodyweights and Bodyweight Changes

Concentration (% w/w) in propylene glycol	Animal Number	Bodyweight (g)		Bodyweight Change (g)
		Day 1	Day 6
Vehicle	1-1	22	21	-1
	1-2	20	22	2
	1-3	22	20	-2
	1-4	17	18	1
2.5	2-1	18	19	1
	2-2	20	20	0
	2-3	18	19	1
	2-4	21	22	1
5	3-1	19	18	-1
	3-2	19	19	0
	3-3	18	19	1
	3-4	20	18	-2
10	4-1	20	22	2
	4-2	20	20	0
	4-3	18	21	3
	4-4	19	19	0

Interpretation of results:

other: Criteria for classification as a skin sensitiser not met

Remarks:

Criteria used for interpretation of results: Any test item failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitiser".

Conclusions:

The test material, aluminum, benzoate C16-18-fatty acids complexes was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

Introduction

A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The skin sensitisation potential was assessed in a proprietary, GLP-compliant experimental study (Harlan 2013) following OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted 22 July 2010) and Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Regulation (EC) No. 440/2008. The study is considered reliable and relevant for use for this endpoint.

Methods. 

Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 10% w/w, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of four animals, were treated with 50 µL (25 µL per ear) of the test material as a suspension in propylene glycol at concentrations of 10%, 5% or 2.5% w/w. A further group of four animals was treated with propylene glycol alone.

Results. 

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%w/w) in propylene glycol	Stimulation Index	Result
2.5	1.10	Negative
5	0.83	Negative
10	1.01	Negative

Conclusion. 

The test material, aluminum, benzoate C16-18-fatty acids complexes was considered to be a non-sensitiser under the conditions of the test.

Reference 2

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Read-across data

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH

In accordance with the Regulation (EC) No 1907/2006, Annex XI, section 1.5, read-across to aluminum, benzoate C16-18-fatty acids complexes has been used to fulfil REACH information requirements where appropriate and is justified by the chemical structures and common physiological active moieties of the substances. The chemical structures of the target and read-across substances are very closely aligned. The aluminium cation, a long chain fatty acid, and the –Al=O (-AlOH in aqueous solution) moieties are identical in both substances. The key difference is that read-across substance contains a benzoate moiety linked to the aluminium cation, which is absent from the target substance. Benzoic acid and benzoates have been well characterized (eco)toxicologically, but in this case generating experimental data on the aluminium salt containing benzoate would be expected to demonstrate a ‘worst case’ hazard profile when compared to the target substance. Since no intrinsic toxicity could be demonstrated from any of the Annex VII or VIII endpoints with the benzoate-containing aluminium salt, then these results can be read across to the target substance without restriction.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)

Source chemical: Aluminum, benzoate, C16-18 fatty acids complexes (EC: 303-385-6, CAS: 94166-87-7)

See robust study summaries for further details on the identity of the tested substances and IUCLID dataset for further information on the substance identity and the data to support the read across justification.

3. ANALOGUE APPROACH JUSTIFICATION
Aluminum, benzoate C16-18-fatty acids complexes is considered suitable for read-across as it contains a fatty acid moiety coordinated to an aluminium atom. The chemical structures of the target and read-across substances are very closely aligned; both substances consist of aluminium salts of fatty acids. The aluminium cation, a long chain fatty acid, and the –Al=O (-AlOH in aqueous solution) moieties are identical in both substances.

The fatty acids present in both substances are the same, consisting of a mixture of C16 and C18 chain lengths at approximately a 1:2 ratio. The C16 and C18 fatty acid moieties are derived from natural fatty materials, or substances which are chemically indistinguishable from natural fatty acids. The fatty acid moieties are considered not to be hazardous to humans as they are natural constituents of the human body and essential components of a balanced human nutrition. REACH Annex V, Entry 9, groups fatty acids and their potassium, sodium, calcium and magnesium salts, including C6 to C24, predominantly even-numbered, unbranched, saturated or unsaturated aliphatic monocarboxylic acids. Provided that they are obtained from natural sources and are not chemically modified, the substances included in REACH Annex V, Entry 9 are exempt from registration, unless they are classified as dangerous (except for flammability, skin irritation or eye irritation) or they meet the criteria for PBT/vPvB substances. The fatty acid components of the two substances are therefore expected to be exempt from registration under REACH.

Fatty acids are an endogenous part of every living cell and are an essential dietary requirement. They are absorbed, digested and transported in animals and humans. When taken up by tissues they can either be stored as triglycerides or can be oxidised via the ß-oxidation and tricarboxylic acid pathways. The ß-oxidation uses a mitochondrial enzyme complex for a series of oxidation and hydration reactions, resulting in a cleavage of acetate groups as acetyl CoA. Acetyl CoA is used mainly to provide energy but also to provide precursors for numerous biochemical reactions. Alternative minor oxidation pathways can be found in the liver and kidney (ω-oxidation and ω-1 oxidation) and in peroxisomes for ß-methyl branched fatty acids (α-oxidation). The metabolic products can then be incorporated for example into membrane phospholipids.

Comparison of the data for the two substances indicates that they are expected to have similar properties. Neither the target or read-across substance meets the criteria for classification for physico-chemical, environmental or human health endpoints, based on the available data.

On the basis of the physico-chemical results, the substances are not flammable and have similar densities. The low vapour pressure results indicates that hazards associated with the atmospheric compartment or inhalation routes of toxicity are not expected to be relevant. The substances show similar water solubility, without surface active properties, indicating that they are likely to have similar behaviour in the aquatic environment.

Although the read-across substance met the criteria for ready biodegradability and the target substance (tested as a 50% concentration in pharmaceutical white oil) did not, neither substance was inhibitory to micro-organisms at the concentration tested. The difference in biodegradation results is expected to derive from the presence of the base oil in the target substance sample, which is designed to minimise leaching of the grease thickener, and therefore less of the grease thickener would have been available for degradation by the micro-organisms.

There are no results available for the ecotoxicity of the target substance and therefore comparison of the effect concentrations against the read-across substance is not possible. However, leaching studies on grease thickeners in base oils have been used to assess the potential bioavailability of the grease components. The bioavailability potential of the water accommodated fractions (WAFs) of metal (lithium and calcium) soap complex based grease thickeners was assessed using a solid-phase micro-extraction (SPME) method combined with gas chromatography (GC). This approach was complemented with metal ion analysis to determine whether the metal leaches out of the base grease during WAF preparation and the ecotoxicity of WAFs was also monitored using an in vitro Microtox assay. The SPME-GC data confirmed that there was negligible leaching of the thickeners from base oils in the samples tested, with measurements for calcium and lithium below the limit of detection (<0.1 mg/L) and the screening ecotoxicity data also showed a lack of toxicity of the greases.

The results of the bioavailability potential of the WAFs, the metal ion analysis and the screening ecotoxicity of lithium and calcium based complexes have been read across to aluminium based thickeners. All of these metal salts of fatty acids are expected to behave in a very similar manner when entrained within a grease matrix, with high temperature stability indicating that the thickener structure is robust and resistant to diffusion out of the oil. Dissolution of grease thickeners from grease into water is very unlikely as the thickeners are poorly water soluble and the thickeners are embedded in the hydrophobic grease matrix and thus unlikely to leach out. Therefore, although there are no data on the ecotoxicity of the target substance, no effects are expected based on the lack of bioavailability of the thickener.

These data on the potential for leaching of other metal salt complex based grease thickeners have been read across to both the target and read across substances. On the basis of these results, it is expected that neither the target nor the read across substance would leach from the base oil in which they are typically marketed and therefore neither substance would be bioavailable. Thus, reading across data from the source substance tested in its isolated form is considered robust as it provides a worst-case conclusion for the target substance which is only manufactured in an inert carrier, typically base oil. In order to provide further evidence for the lack of bioavailability, it is proposed to undertake leaching studies on the target and read-across substances themselves. Dependent on the results, the two studies would then be used to show the similarity in the bioavailability of the two substances and provide further weight of evidence for the read-across approach.

The available mammalian toxicity data show that neither the target nor read-across substance would be classified as irritating to skin or eyes and would not be classified for acute oral toxicity, with LD50 values of >2000 mg/kg. Although no other data are available for comparison of the potential mammalian toxicity of the two substances, the target and read-across substances are expected to behave in a very similar manner. As grease thickeners are entrained within grease matrices which are robust and resistant to diffusion out of the oil, neither substance is expected to be bioavailable. In order to provide further evidence for the lack of bioavailability, it is proposed to undertake leaching studies in fed state simulated intestinal fluid (FeSSIF) on the target and read-across substances. Dependent on the results, the two studies would then be used to show the similarity in the bioavailability of the two substances and provide further weight of evidence for the read-across approach.

For the skin sensitisation of the substances, read across from the source to the target substance is considered justified. Data available for the both substances show that they are not irritating to skin or eye and have an acute oral toxicity LD50 of >2000 mg/kg bw. The source substance also has a study showing an LD50 of >2000 mg/kg for acute dermal toxicity. Both substances would not leach when in situ in base oil during use as grease thickeners and are not expected to be bioavailable. The substances would dissociate into inorganic aluminium species and fatty acids (plus benzoic acid for the source substance), the organic components of which are readily metabolised. As the fatty acid components are essential nutrients to many organisms and are not expected to be hazardous (and the benzoate component of the source substance is not expected to be hazardous), the toxicity is expected to be driven by the aluminium component, so would be the same in both the source and target substances. As such, read across from the source substance is considered to provide a worst-case scenario for the target substance.

4. DATA

T = target substance (tests were undertaken on a sample prepared as a 50% w.w. concentration in medicinal white oil unless otherwise indicated)
RA = read-across substance

- State: Liquid (T), Solid (RA)
- Melting point: 21°C (T), 224°C (RA)
- Relative density: 0.933 (T), 1.08 (RA)
- Vapour pressure: 0.00015 Pa (T), 0.000044 Pa (RA)
- Surface tension: 72.5 mN/m (T), 72.6 mN/m (RA)
- Water solubility: ≤0.00015 g/L (T), ≤0.00026 g/L (RA)
- Flash-point: 159°C (T), No data available for RA
- Flammability: No data available for T, Not flammable (RA)
- Self-ignition temperature: 374°C (T), 383°C (RA)
- Viscosity: 174.3 mm2/s at 100°C (T), No data available for RA
- Biodegradation: Not readily biodegradable (31%) (T), Readily biodegradable (79%) (RA)
- Acute aquatic invertebrates: No data available for T, EL50 (48 h): > 100 mg/L (RA)
- Algae: No data available for T, EL50 (72 h): > 100 mg/L and NOELR (72 h): 100 mg/L (RA)
- Aquatic microorganisms: NOEC (28 d): 6.7 mg/L (T), NOEC (28 d): 15.4 mg/L (RA)
- Acute fish: No data available for T, LL50 (96 h): > 100 mg/L (RA)
- Skin irritation: Not irritating (T), Not irritating (RA)
- Eye irritation: Not classified (T), Not classified (RA)
- Skin sensitisation: No data available for T, Not sensitising (RA)
- In vitro gene mutation in bacteria: No data available for T, Negative (RA)
- Acute toxicity, oral route: LD50: > 2000 mg/kg (T, test undertaken on solid (isolated) form of the substance), LD50 >2000 mg/kg (RA)
- Acute toxicity, dermal route: No data available for T, LD50 >2000 mg/kg (RA)
- In vitro cytogenicity: No data available for T, Negative (RA)
- In vitro gene mutation in mammalian cells: No data available for T, Negative (RA)
- Short-term repeated dose toxicity, oral route: No data available for T, NOAEL: > 225 mg/kg (RA)
- Reproductive toxicity: No data available for T, NOAEL (P): > 225 mg/kg (RA)
- Developmental toxicity: No data available for T, NOAEL (F1): > 225 mg/kg (RA)

Reason / purpose for cross-reference:

read-across source

Statistics:

None provided.

Positive control results:

One group of five animals was treated with 50 µL (25 µl per ear) of phenylacetaldehyde (>90%) as a solution in propylene glycol at a concentration of 2.5% v/v. A further control group of five animals was treated with propylene glycol alone. The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration % v/v in propylene glycol Stimulation Index (SI) Result
2.5 6.48 Positive

Phenylacetaldehyde (>90%) was considered to be a sensitiser under the conditions of the test.

Parameter:

other: disintegrations per minute (DPM)

Value:

ca. 522.69 - ca. 691.12

Test group / Remarks:

DPM per node of 522 to 691 were recorded for the vehicle control and the test material at concentrations of 10%, 5% and 2.5% w/w in propylene glycol.

Remarks on result:

other: The radioactive disintegrations per minute (dpm) per lymph node and the stimulation index (SI) are given in Table 2.

Key result

Parameter:

SI

Value:

1.1

Variability:

Concentration: 2.5% w/w in propylene glycol

Test group / Remarks:

4 animals

Remarks on result:

other: The stimulation index (SI) results are given in Table 4.

Key result

Parameter:

SI

Value:

0.83

Variability:

Concentration: 5% w/w in propylene glycol

Test group / Remarks:

4 animals

Remarks on result:

other: The stimulation index (SI) results are given in Table 4.

Key result

Parameter:

SI

Value:

1.01

Variability:

Concentration: 10% w/w in propylene glycol

Test group / Remarks:

4 animals

Remarks on result:

other: The stimulation index (SI) results are given in Table 4.

Cellular proliferation data / Observations:

- Clinical Observations and Mortality Data: There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.
- Bodyweight; Bodyweight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.
- Conclusion: The test item was considered to be a non-sensitiser under the conditions of the test.      

Table 1              Clinical Observations, Bodyweight and Mortality Data – Preliminary Screening Test

Concentration (% w/w) in propylene glycol	Animal Number	Bodyweight (g)		Day
				1		2		3		4	5	6
		Day 1	Day 6	Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
10	S-1	21	20	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 2              Local Skin Irritation – Preliminary Screening Test

Concentration (%w/w) in propylene glycol

Animal Number

Local Skin Irritation

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

left

right

left

right

left

right

left

right

left

right

left

right

10

S-1

0

0

0

0

0

0

0

0

0

0

0

0

Table 3              Measurement of Ear Thicknessand Mean Ear Thickness Changes – Preliminary Screening Test

Concentration (%w/w) in propylene glycol	Animal Number	Ear Thickness Measurement (mm)
		Day 1		Day 3		Day 6
		pre‑dose		post dose
		left	right	left	right	left	right
10	S-1	0.245	0.240	0.230	0.240	0.235	0.245
overall mean (mm)		0.243		0.235		0.240
overall mean ear thickness change (%)		na		-3.093		-1.031

na=     Not applicable

Table 4              Disintegrations per Minute, Disintegrations per Minute/Node and Stimulation Index

Concentration (%w/w) in propylene glycol	dpm	dpm/Node^a	Stimulation Index^b	Result
Vehicle	5012.31	626.54	na	na
2.5	5528.98	691.12	1.10	Negative
5	4181.55	522.69	0.83	Negative
10	5039.56	629.95	1.01	Negative

dpm= Disintegrations per minut

a=      Disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

b=      Stimulation Index of 3.0 or greater indicates a positive result

na =    Not applicable

Table 5              Individual Clinical Observations and Mortality Data

Concentration (% w/w) propylene glycol	Animal Number	Day 1		Day 2		Day 3		Day 4	Day 5	Day 6
		Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
Vehicle	1-1	0	0	0	0	0	0	0	0	0
	1-2	0	0	0	0	0	0	0	0	0
	1-3	0	0	0	0	0	0	0	0	0
	1-4	0	0	0	0	0	0	0	0	0
2.5	2-1	0	0	0	0	0	0	0	0	0
	2-2	0	0	0	0	0	0	0	0	0
	2-3	0	0	0	0	0	0	0	0	0
	2-4	0	0	0	0	0	0	0	0	0
5	3-1	0	0	0	0	0	0	0	0	0
	3-2	0	0	0	0	0	0	0	0	0
	3-3	0	0	0	0	0	0	0	0	0
	3-4	0	0	0	0	0	0	0	0	0
10	4-1	0	0	0	0	0	0	0	0	0
	4-2	0	0	0	0	0	0	0	0	0
	4-3	0	0	0	0	0	0	0	0	0
	4-4	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 6              Individual Bodyweights and Bodyweight Changes

Concentration (% w/w) in propylene glycol	Animal Number	Bodyweight (g)		Bodyweight Change (g)
		Day 1	Day 6
Vehicle	1-1	22	21	-1
	1-2	20	22	2
	1-3	22	20	-2
	1-4	17	18	1
2.5	2-1	18	19	1
	2-2	20	20	0
	2-3	18	19	1
	2-4	21	22	1
5	3-1	19	18	-1
	3-2	19	19	0
	3-3	18	19	1
	3-4	20	18	-2
10	4-1	20	22	2
	4-2	20	20	0
	4-3	18	21	3
	4-4	19	19	0

Interpretation of results:

other: Criteria for classification as a skin sensitiser not met

Remarks:

Criteria used for interpretation of results: Any test item failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitiser".

Conclusions:

The test material, aluminum, benzoate C16-18-fatty acids complexes was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

Proprietary data are read across from aluminum, benzoate C16-18-fatty acids complexes. This substance is considered suitable for read-across as it contains a fatty acid moiety coordinated to an aluminium atom. Although it also contains a coordinated benzoate ion, no toxicological effects were observed and therefore it is concluded that the benzoate ion does not contribute any additional toxicity to the substance. Aluminum, benzoate C16-18-fatty acids complexes was tested in the form of an isolated solid and showed no sensitising effects (Harlan 2013). Therefore, aluminium, benzoate C16 -18 fatty acids complexes is considered to be a non-sensitiser and this has been read across to the target substance.

Introduction

A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The skin sensitisation potential was assessed in a proprietary, GLP-compliant experimental study (Harlan 2013) following OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay"(adopted 22 July 2010) and Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Regulation (EC) No. 440/2008.The study is considered reliable and relevant for use for this endpoint.

Methods. 

Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 10% w/w, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of four animals, were treated with 50 µL (25 µL per ear) of the test material as a suspension in propylene glycol at concentrations of10%, 5% or 2.5% w/w. A further group of four animals was treated with propylene glycol alone.

Results. 

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%w/w) in propylene glycol	Stimulation Index	Result
2.5	1.10	Negative
5	0.83	Negative
10	1.01	Negative

Conclusion. 

The test material, aluminum, benzoate C16-18-fatty acids complexes was considered to be a non-sensitiser under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The assessment of skin sensitisation potential for the registered substance is based upon read-across from the Local Lymph Node Assay performed on aluminum, benzoate C16 -18 fatty acid complexes. Aluminum, benzoate C16 -18 fatty acid complexes was subjected to a Local Lymph Node Assay in mice according to OECD Guideline 429. The test material was considered to be a non-sensitiser under the conditions of the test with the highest Stimulation Index of 1.10 recorded at the 2.5% concentration in propylene glycol, and a Stimulation Index of 1.01 at the highest concentration tested of 10% in propylene glycol. Therefore, the registered substance is also considered likely to be a non-sensitiser under the same conditions.

Justification for selection of skin sensitisation endpoint:
Read-across mouse Local Lymph Node Assay study on aluminum, benzoate C16-18 fatty acid complexes. This was a high quality GLP compliant regulatory design Local Lymph Node Assay.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

No Classification for the registered substance is required: Stimulation Index <3 in a Local Lymph Node Assay on the read-across substance, aluminum, benzoate C16 -18 fatty acid complexes.