Adipic acid, ammonium salt

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

22 July 2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

1

Reference substance name:

Adipic acid, ammonium salt

EC Number:

242-809-3

EC Name:

Adipic acid, ammonium salt

Cas Number:

19090-60-9

Molecular formula:

C6H10O4.xH3N

IUPAC Name:

ammonium 5-carboxypentanoate

Test material form:

solid: crystalline

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

Husbandry
Animal health: Only healthy animals (and not showing any sign of skin
lesion) were used
Housing during
acclimatization period: Grouped caging in small groups
Housing during the test: Grouped caging (4 animals/cage)
Cage type: Type II. Polypropylene / polycarbonate
Bedding: Laboratory bedding
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 22 ± 3 °C
Relative humidity: 30 – 70 %
Housing/Enrichment: Mice were group-housed to allow social interaction, and with
deep wood sawdust bedding, to allow digging and other
normal rodent activities.
The same conditions were used for the dose range finding and main test animals. There were
no deviations from these specifications during the experimental phase. The temperature and
relative humidity were recorded daily during the acclimatization and experimental phases.
Before housing the animals, the microbiological status of the room was checked.

Study design: in vivo (LLNA)

Vehicle:

other: ethanol -water (7:3) (EtOH) , acetone, olive oil,

Concentration:

5, 2.5, 1, 0.5 w/w% (EtOH)

No. of animals per dose:

4

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

ca. 1.7

Test group / Remarks:

5%

Results 2

Key result

Parameter:

SI

Value:

ca. 1

Test group / Remarks:

2.5 %

Results 3

Key result

Parameter:

SI

Value:

ca. 1.6

Test group / Remarks:

1%

Results 4

Key result

Parameter:

SI

Value:

ca. 2.6

Test group / Remarks:

0.5%

Cellular proliferation data / Observations:

No significant lymphoproliferative response (SI ≥ 3) compared to the relevant control (EtOH) was noted for Ammonium Adipate at the tested concentrations.

Any other information on results incl. tables

Table 4:Individual Body Weights of the Animals with Group Means and the Body Weight Changes in the Dose
Range Finding Test

Animal	Dose Group	Initial Body	Terminal Body	Body Weight
Number	Weight (g)	Weight (g)*	Change (%)
281	Ammonium Adipate	20.8	20.0	-4
334	5 % in EtOH	18.7	18.3	-2
Mean	19.8	19.2	-3
309	Ammonium Adipate	20.7	19.8	-4
335	2.5 % in EtOH	18.2	17.9	-2
Mean	19.5	18.9	-3
282	Ammonium Adipate	20.8	20.9	0
336	1 % in EtOH	18.4	18.2	-1
Mean	19.6	19.6	0

*Terminal body weights were measured on Day 6.
EtOH = Absolute ethanol:water 7:3 (v/v) mixture

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of the present assay, Ammonium Adipate tested at the maximum
attainable concentration of 5 % (w/v, based on solubility) and at concentrations of
2.5 %, 1 % and 0.5 % (w/v) as formulations prepared with a suitable vehicle (absolute
ethanol:water 7:3 (v/v) mixture, EtOH) was shown to have no skin sensitization
potential in the Local Lymph Node Assay.

Executive summary:

The aim of this study was to evaluate the skin sensitization potential of Ammonium Adipate
following dermal exposure in the Local Lymph Node Assay.
Preliminary tests were performed according to the relevant guidelines to find an appropriate
vehicle and the maximum applicable concentration.
The maximum soluble concentration in vehicles preferred in the LLNA was determined
according to the relevant guidelines. No adequate solubility was achieved with the most
preferred vehicles, but the test item was soluble in absolute ethanol:water 7:3 (v/v) mixture
(EtOH) with a maximum concentration of 5 % (w/v). As no significant adverse effects
(irritation or systemic toxicity) were observed in the Dose Range Finding test at this
maximum soluble concentration the test item was examined in the LLNA at concentrations
of 5 %, 2.5 %, 1 % and 0.5 % (w/v) as formulations in EtOH.
An appropriate positive control (α-Hexylcinnamaldehyde, HCA), furthermore two negative
control groups dosed with the vehicles of the test and positive control groups, respectively,
were employed.
The positive control item [25 % (w/v) HCA in Acetone: Olive oil 4:1 (v/v) mixture (AOO)]
induced significant stimulation over the relevant control (SI = 5.1) thus confirming the
validity of the assay.
No mortality, significant treatment related effect on the body weights or other symptoms of
systemic toxicity were observed during the test. No signs of irritation (monitored by
observation of erythema) or any other local effects were observed at the treatment site (ears)
in any treatment group.
No significant lymphoproliferative response (SI≥3) compared to the relevant control
(EtOH) was noted for Ammonium Adipate at the tested concentrations. The observed
stimulation index values were 1.7, 1.0, 1.6 and 2.6 at test item concentrations of 5%, 2.5 %,
1 % and 0.5 % (w/v), respectively. No dose-related response was observed (p = 0.59,
r2= 0.16, evaluated by linear regression using SI values).
According to the evaluation criteria of the relevant guidelines, the lack of a significantly
increased lymphoproliferation (indicated by an SI≥3) up to the maximum attainable
concentration of 5 % (w/v, based on solubility) as well as the lack of a significant
dose-related response is considered as evidence that Ammonium Adipate is a not a skin
sensitizer.
In conclusion, under the conditions of the present assay, Ammonium Adipate tested at
the maximum attainable concentration of 5 % (w/v, based on solubility) and at
concentrations of 2.5 %, 1 % and 0.5 % (w/v) as formulations prepared with a suitable
vehicle (absolute ethanol:water 7:3 (v/v) mixture, EtOH) was shown to have no skin
sensitization potential in the Local Lymph Node Assay.