Bis[O,O-bis(2-ethylhexyl) dithiophosphorato-S,S']dioxodi-μ-thioxodimolybdenum

Endpoint summary

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

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)

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Females (if applicable) nulliparous and non-pregnant: yes
- Microbiological status of animals, when known: SPF
- Age at study initiation: approx. 10 weeks
- Weight at study initiation: 20.1 - 23.4 g
- Housing: in groups up to five animals
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days
- Indication of any skin lesions: no

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 48 - 69
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12
- IN-LIFE DATES: From: To:

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

25, 50, 100%

No. of animals per dose:

5

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: substance is liquid and missible with the vehicle
- Irritation: no
- Systemic toxicity: no
- Ear thickness measurements: yes
- Erythema scores: no

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA (OECD 429)
- Criteria used to consider a positive response: stimulation index (SI) was calculated based on DPM values; SI >= 3 indicates a sensitising potential

TREATMENT PREPARATION AND ADMINISTRATION:
the test substance was applied on three consecutive days on the dorsal surface of both ears (25 µl/ear)

Positive control substance(s):

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

Key result

Parameter:

SI

Value:

1.8

Test group / Remarks:

25% concentration

Key result

Parameter:

SI

Value:

2.2

Test group / Remarks:

50% concentration

Key result

Parameter:

SI

Value:

3

Test group / Remarks:

100% concentration

Remarks on result:

other: see "Any other information on results"

In this LLNA test at the highest dose of 100% test substance applied to the ears the calculated SI value reached the value of 3.0. However, the vehicle control group of this study showed a very low mean DPM value, amounting to 223 DPM. In a parallel LLNA test performed at the same time, with the same batch of animals and vehicle, in the vehicle control group the DPM value amounted to 532 (copies of the tables showing the DPM values of both studies are attached).

The DPM value of the vehicle control group was very low due to three animals having DPM values between 109 and 154. The two other animals of the control group had DPM values of 358 and 375. The DPM values of the five vehicle control animals of the parallel study had DPM values ranging from 375 to 706. These data show that (1) a brought range of DPM values in vehicle control animals is determined (from 109 to 706) and (2) that the random distribution of animals can lead to high variations of DPM values in control groups. The exchange of just one control animal between the two vehicle control groups would have resulted in a calculated SI value below 3.0. An increase of only 10 DPM of the mean DPM value of the vehicle control group, i.e. from 223 DPM to 233 DPM, results in an SI value < 2.9.

Taking these statistical and mathematical considerations together it is concluded that the SI value of 3.0 as calculated in this study is a borderline case not leading to classification of S-930 as having a skin sensitising potential.

Interpretation of results:

other: no skin sensitising potential

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

No in vitro tests for testing of a skin sensitisation potential could be performed due to insolubility of the substance in test-compatible solvents. Therefore, an in vivo test (LLNA) was performed with the test substance. Based on the result it was concluded that the substance does not have a skin sensitising potential and therefore does not need to be classified according to Regulation 1272/2008.