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Administrative data

Description of key information

The skin sensitizing potential of N-Ethyl-2-pyrrolidon was assessed using the nonradioactive variant of the Murine Local Lymph Node Assay (OECD 429). From the results of the study it is concluded, that N-Ethyl-2-pyrrolidon does not have a skin sensitizing effect (BASF, 2005).

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:
other: GLP and guideline study. The study was modified to a non radioactive procedure. But this has no impact on the result.
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
adopted April 24, 2002
Deviations:
yes
Remarks:
non radioactive method, but no impact on the result
Principles of method if other than guideline:
The Murine Local Lymph Node Assay (LLNA) is recommended by international test guidelines (e.g. OECD) as an animal test for predicting skin sensitization in humans.
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)
Specific details on test material used for the study:
Batch No.: 29151288P0
Degree of purity / content: 99.8 corr. area-%
Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
The single housed animals were identified by cage cards. The animals were housed in fully air-conditioned rooms in which a central air-conditioning system ensured a temperature in the range of 20 - 24°C and a relative humidity in the range of 30 - 70%. Deviations from these specifications that would have had an adverse effect on the test results did not occur. Illumination period was 12 h light and 12 h darkness. Acclimatization period 15 days before the first test substance application.
Vehicle:
other: aectone
Concentration:
50%, 10% and 3% w/w preparations of the test substance in acetone
No. of animals per dose:
6
Details on study design:
The study used 3 test groups and 1 control group. Each test animal was applied with 25 uL per ear of the respective test substance preparation to the dorsum of both ears for three consecutive days.
The control group was treated with 25 uL per ear of the vehicle alone.
Three days after the last application the mice were sacrificed and the auricular lymph nodes were removed. Lymph node response was evaluated by measuring the cellular content (indicator of cell proliferation) and weight of each animal's pooled lymph nodes . Moreover, a defined area with a diameter of 0.8 cm was punched out of the apical part of each ear and for each animal the weight of the pooled punches was determined in order to obtain an indication of possible skin irritation.
Positive control substance(s):
other: Alpha-Hexylcinnamaldehyde, techn . 85%
Statistics:
Mean values and standard deviations of the measured parameters were calculated for the test and control groups from the individual values. The indices of lymph node weight, cell count and ear weight were calculated as the ratio of the test group mean values for these parameters divided by those of the vehicle control group.
Positive control results:
As recommended by the respective testing guidelines, the following study was performed to evaluate the sensitivity of experimental animals and the ability of procedures to detect a known mild to moderate skin sensitizer.

Name of test substance: Alpha-Hexylcinnamaldehyde, techn . 85%
CAS number: 101-86-0

The mean indices (fold of change as compared to the vehicle control) for lymph node weight, cell count and ear weight are summarized for each test group in the table below.

Test group Treatment Lymph node Weight Index Cell Count Index Ear Weight Index
1 vehicle acetone 1 .00 1 .00 1 .00
2 1% in acetone 1 .12 1 .28 # 1 .04
3 3% in acetone 1 .37 # 1 .63 # 1 .06 #
4 10% in acetone 1 .96 ## 2 .94 ## 1 .14 ##

The statistical evaluations were performed using the WILCOXON-test ( # for p_< 0.05, ## for p< 0 .01 )
Key result
Parameter:
SI
Remarks on result:
other: see below
Remarks:
The test substance did not induce a statistically significant or biologically relevant response of the auricular lymph nodes when applied as 3% or 10% preparations in acetone. The minimal but statistically significant increase in mice treated with the 50% test substance preparation was too small to be considered biologically relevant.
Cellular proliferation data / Observations:
CELLULAR PROLIFERATION DATA AND DETAILS ON STIMULATION INDEX CALCULATION

Test group Treatment Lymph node Weight Index Cell Count Index Ear Weight Index
1 Vehicle acteone 1.00 1.00 1.00
2 3% in acetone 0.95 0.99 1.05 #
3 10% in acetone 0.92 1.01 1.05 #
4 50% in acetone 1.20 # 1.32 # 1.05 #

The statistical evaluations were preformed using the WILCOXON-test( # for p<= 0.05 ## for p<= 0.01)

CLINICAL OBSERVATIONS:
No abnormalities were observed during general observation .

BODY WEIGHTS
The expected body weight gain was generally observed in the course of the study.

The test substance did not induce a statistically significant or biologically relevant response of the auricular lymph nodes when applied as 3% or 10% preparations in acetone. The minimal but statistically significant increase in mice treated with the 50% test substance preparation was too small to be considered biologically relevant. The statistically significant increases in ear weights, which were concentration independent, indicate irritation of the ear skin at all concentrations. The minimal increase in cell count and lymph node index in test group 4 is considered to be related to ear skin irritation produced by the combination of vehicle and test substance, which starts already at the 3% concentration without relevant lymph node response.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

The skin sensitizing potential of N-Ethyl-2-pyrrolidon was assessed using the nonradioactive variant of the Murine Local Lymph Node Assay (OECD 429). Choosing a non-radioactive variant is not considered to influence the validity of the test. Groups of 6 female CBA/Ca mice each were treated with 50%, 10% and 3% w/w preparations of the test substance in acetone or with the vehicle alone. The test substance did not induce a statistically significant or biologically relevant response of the auricular lymph nodes when applied as 3% or 10% preparations in acetone. The minimal but statistically significant increase in mice treated with the 50% test substance preparation was too small to be considered biologically relevant. Beyond this the statistically significant increases in ear weights, which were concentration independent, indicate irritation of the ear skin at all concentrations. Thus, the minimal increase in cell count and lymph node index in test group 4 is considered to be related to ear skin irritation produced by the combination of vehicle and test substance, which starts already at the 3% concentration without relevant lymph node response.

From the results of the study, it is concluded that N-Ethyl-2 -pyrrolidon does not have a skin sensitizing effect in the Murine Local Lymph Node Assay.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Classification is not warranted according to the criteria of the EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.