MMCT

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14 - 17 Mar 2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study followed the standard guideline of reference (OECD 429), which describes a procedure designed to evaluate this endpoint, but with an important protocol deviation. Cellular proliferation was not determined by incorporated radioactivity, thus no disintegrations per minute (DPM). Instead, lymph node cell count was used as direct measurement of cell proliferation and a lower cut-off value of 1.4 times increase of stimulation index was used. The results were reviewed for reliability and assessed as valid, and the study was conducted under GLP condition.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted in 2002

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

adopted in 2010

Deviations:

yes

Remarks:

Proliferation was assessed on Day 4 instead of Day 6, determined by lymph node cell count instead of incorporated radioactivity and the analysis was not part of the GLP study, no Draize scoring, positive control was run in an independent experiment

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

adopted in 2001

Test guideline 4

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

adopted in 2003

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Test material form:

liquid

In vivo test system

Test animals

Species:

mouse

Strain:

NMRI

Remarks:

Hsd Win:NMRI

Sex:

female

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

3, 10 and 30% (w/v)

No. of animals per dose:

6

Positive control substance(s):

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

Results and discussion

Positive control results:

The reliability check with the positive control was done at regular intervals. Data included in the study report were published in 2004 and 2005 by the same authors. The positive control substance alpha-hexyl cinnamic aldehyde (3, 10 and 30% in acetone:olive oil (4:1 v/v)) was considered to be a sensitiser under the conditions of the test.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

0.98

Test group / Remarks:

3%

Remarks on result:

other: SI = Cell count of treated group / Cell count of control group

Results 2

Parameter:

SI

Value:

0.88

Test group / Remarks:

10%

Remarks on result:

other: SI = Cell count of treated group / Cell count of control group.

Results 3

Parameter:

SI

Value:

1.37

Test group / Remarks:

30%

Remarks on result:

other: SI = Cell count of treated group / Cell count of control group.

Applicant's summary and conclusion

Interpretation of results:

other: Skin sens. 1, H317 according to Regulation (EC) No. 1272/2008.

Conclusions:

A local lymph node assay was performed with the test item at dose levels up to 30%. In the applied protocol, lymph node cell count was used as direct measurement of cell proliferation and a lower cut-off value of 1.4 times increase of stimulation index (SI) was used when compared to the current OECD guideline 429 (2015). A statistically significant increase compared to vehicle control treated animals regarding cell counts was observed in the highest dose group. For the 30% formulation an SI value of 1.37 was obtained, indicating slight skin sensitising properties of the test item. The authors state that, based on the experience with the assay, a small increase in the test item concentration would verify classification as weak sensitiser. In addition, the high dose level was set to 30% because an unspecific activation by irritation was expected at higher concentrations. Based on the experimental findings classification as Skin sens 1, H317 is required according to Regulation (EC) No. 1272/2008.