Diammonium hexachloropalladate

Endpoint summary

Description of key information

In a GLP mouse LLNA, performed according to OECD Test Guideline 429, significant evidence (a calculated EC3 value of 11.9%) for the skin sensitising potential of diammonium hexachloropalladate was reported (Váliczkó, 2013).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8-14 May 2013 (preliminary experiment was 12-17 December 2012)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, performed to GLP.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

temperature reached 26.2°C (i.e. >25°C) on one occasion. Deviation not considered to impact on validity of study.

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/J Rj

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Elevage Janvier, Route de Chènes Secs B.P. 4105, 53940 Le Genest-St-Isle, France
- Age at study initiation: 10 weeks
- Weight at study initiation: 19.7-21.8 g
- Housing: individual caging (polypropylene/polycarbonate)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 (a maximum of 26.2 was recorded on 30 April 2013)
- Humidity (%): 30-70
- Air changes (per hr):15-20
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: no data

Vehicle:

propylene glycol

Concentration:

Range-finding study: 25 or 50% (w/v)
Main study: 0, 10, 25 or 50% (w/v)

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: short preliminary compatibility test performed in which solubility was assessed in acetone:olive oil (4:1), N,N-dimethylformamide, methyl ethyl ketone, propylene glycol, dimethyl sulfoxide and 1% Pluronic. Propylene glycol gave the highest concentration which was suitable for dosing (50%).
- Irritation: groups of mice (2/dose) were treated topically with 25 or 50% test substance. Mice were observed daily for signs of local irritation, changes in ear thickness, and systemic toxicity up until day 6. No adverse effects were observed.
- Lymph node proliferation response: not performed

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: local lymph node assay
- Criteria used to consider a positive response: the test item is regarded as a sensitiser if both of the following criteria are fulfilled:
1. That exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than recorded in control mice, as indicated by the stimulation index.
2. The data are compatible with a conventional dose response, although allowance must be made (especially at high topical concentrations) for either local toxicity or immunological suppression.
TREATMENT PREPARATION AND ADMINISTRATION: groups of mice were given topical applications to the ear of 25 µl of formulation om three consecutive days (1, 2 and 3). On day 6, animals were injected with tritiated thymidine (3HTdR) and killed 5 hours later. Lymph node cell proliferation was then assessed.

Positive control substance(s):

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

Positive control results:

As expected. See Table 1 in "Any other information on results incl. tables".

Parameter:

SI

Remarks on result:

other: The stimulation index values were 10.6, 14.9 and 1.3 at concentrations of 50, 25 and 10 % (w/v), respectively. Also see Table 1 in "Any other information on results incl. tables".

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: See Table 1 in "Any other information on results incl. tables".

No adverse effects on body weight were observed.

The calculated EC3 value is 11.9% (w/v).

 

Table 1. Results of a mouse local lymph node assay on diammonium hexachloropalladate

Test Group Name	Measured DPM	DPM	Number of lymph nodes	DPN	Group DPN	Stimulation Index
Background (5% trichloroacetic acid)	42 35	-	-	-	-	-
Propylene glycol	227	188.5	2	94.3	38.4	1.0
	104	65.5		32.8
	106	67.5		33.8
	80	41.5		20.8
	59	20.5		10.3
50% DAHP	884	845.5	2	422.8	405.0	10.6
	474	435.5		217.8
	1179	1140.5		570.3
	645	606.5		303.3
	1060	1021.5		510.8
25% DAHP	133	94.5	2	47.3	571.5	14.9
	2516	2477.5		1238.8
	2740	2701.5		1350.8
	223	184.5		92.3
	295	256.5		128.3
10% DAHP	66	27.5	2	13.8	51.2	1.3
	121	82.5		41.3
	325	286.5		143.3
	93	54.5		27.3
	99	60.5		30.3
25% HCA	1137	1098.5	2	549.3	808.2	21.1
	1855	1816.5		908.3
	1186	1147.5		573.8
	2840	2801.5		1400.8
	1256	1217.5		608.8
Notes: 1. DPM (Disintegrations Per Minute) 2. DPN (Disintegrations Per Node) = DPM divided by the number of lymph nodes. 3. DAHP (Diammonium hexachloropalladate) 4. HCA (α-Hexylcinnamicaldehyde) 5. Stimulation Index = mean DPN of a treated group divided by mean DPN of the appropriate control group.

 

Interpretation of results:

sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In a GLP mouse LLNA, performed according to OECD Guideline 429, significant evidence (a calculated EC3 value of 11.9%) of the sensitising potential of diammonium hexachloropalladate was reported.

Executive summary:

The skin sensitising potential of diammonium hexachloropalladate has been assessed in a GLP mouse local lymph node assay (LLNA), performed according to OECD Test Guideline 429. Following a preliminary range-finding study to assess irritancy, female mice (5/group) were treated topically with 0, 10, 25 or 50% diammonium hexachloropalladate (in propylene glycol) on three consecutive days (1, 2 and 3). On day 6, cell proliferation in the local lymph nodes was measured by incorporation of injected tritiated methyl thymidine (3HTdR).

No mortality or clinical signs of toxicity were observed, and there were no signs of local irritation at the application site. Observed stimulation index values were 10.6, 14.9 and 1.3 at 50, 25 and 10%, respectively. The calculated EC3 value (the concentration producing a stimulation index of 3) was 11.9%. Positive and vehicle controls performed as expected.

Under the conditions of this study, diammonium hexachloropalladate should be classified as a skin sensitiser (category 1B) according to EU CLP criteria.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

No human sensitisation data were identified. No in vitro skin sensitisation studies were identified, or are required, as reliable in vivo studies are already available.

The skin sensitising potential of diammonium hexachloropalladate has been assessed in a GLP mouse local lymph node assay (LLNA), performed according to OECD Test Guideline 429. Following a preliminary range-finding study to assess irritancy, female mice (5/group) were treated topically with 0, 10, 25 or 50% diammonium hexachloropalladate (in propylene glycol) on three consecutive days (1, 2 and 3). On day 6, cell proliferation in the local lymph nodes was measured by incorporation of injected tritiated methyl thymidine (3HTdR). No mortality or clinical signs of toxicity were observed, and there were no signs of local irritation at the application site. Observed stimulation index values were 10.6, 14.9 and 1.3 at 50, 25 and 10%, respectively. The calculated EC3 value (the concentration producing a stimulation index of 3) was 11.9%. Positive and vehicle controls performed as expected (Váliczkó, 2013).


Justification for selection of skin sensitisation endpoint:
GLP study, conducted according to OECD guidelines, and the only skin sensitising study available.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

No respiratory tract sensitisation data are available. A new study was not conducted as no standard and validated test method is available and it is not a REACH Standard Information Requirement. Further, the compound is not expected to reach the lungs in appreciable quantities (based on respiratory tract deposition modelling data). Thus, inhalation will not be a significant route of exposure.

Justification for classification or non-classification

Based on the results of the available and reliable mouse LLNA, diammonium hexachloropalladate should be classified as a skin sensitiser (category 1B) according to EU CLP criteria (EC 1272/2008).