4,5-dihydroxy-1,3-dimethylimidazolidin-2-one

Endpoint summary

Description of key information

In a Murine Local Lymph Node Assay according to OECD guideline 429 with the analogue substance Urea, reaction products with formaldehyde and glyoxal (CAS 92908-35-5), the analogue substance was not skin sensitising under the test conditions chosen.

 

In a Murine Local Lymph Node Assay according to OECD guideline 429, the test item (containing 36% 4,5-dihydroxy-1,3-dimethylimidazolin-2-one) was not skin sensitising under the test conditions chosen.

 

In combination with a negative QSAR prediction (Skin sensitization with autoxidation v.21.26, OASIS TIMES v.2.27.19.13), it was concluded that 4,5-Dihydroxy-1,3-dimethylimidazolidin-2-one has no sensitising potential. 

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2010-03-23 to 2010-04-14

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

2008-05-30

Deviations:

yes

Remarks:

No ear thickness and erythema measurements were included in the study. The study was not conducted under GLP conditions.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2002-04-24

Deviations:

yes

Remarks:

No ear thickness and erythema measurements were included in the study. The study was not conducted under GLP conditions.

Principles of method if other than guideline:

No ear thickness and erythema measurements were included in the study. The study was not conducted under GLP conditions.

GLP compliance:

no

Remarks:

This study was conducted to confirm former study results conducted with another product. It was considered sufficient to repeated the study under non-GLP conditions.

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Remarks:

CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories B.V., Postbus 6174, 5960 AD Horst / The Netherlands
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 18.4 g - 21.9 g
- Housing: Single caging in Makrolon Type II cages, with wire mesh top
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period: At least 5 days
- Indication of any skin lesions: Only animals without any visible signs of illness were used for the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 26-65
- Air changes (per hr): Not indicated
- Photoperiod (hrs dark / hrs light): 12/12

- IN-LIFE DATES: From day 1 to day 5

Vehicle:

dimethylformamide

Concentration:

100%, 50% and 25%

No. of animals per dose:

4 female animals per dose group

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: The test item was soluble in dimethylformamide.
- Irritation: At the concentrations tested in the pre-test (50% and 100%), the animals did not show any signs of irritation.
- Systemic toxicity: At the concentrations tested in the pre-test (50% and 100%), the animals did not show any signs of systemic toxicity.
- Ear thickness measurements: No ear thickness measurements were conducted in the pre-test.
- Erythema scores: No erythema scores were determined. Animals were observed for clinical signs within 1 hour and 24 ± 4 hours after each application as well as on day 7 (including systemic toxicity and irritation symptoms).

MAIN STUDY
Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear (left and right) with different test item concentrations of 25, 50 (w/v), and 100% in dimethylformamide. The application volume, 25 µL, was spread over the entire dorsal surface (diameter 8 mm) of each ear once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals). The positive control was tested in a validation- / positive control experiment which was performed with α-Hexylcinnamaldehyde in acetone:olive oil (4+1) using CBA/CaOlaHsd mice in November 2009. Five days after the first topical application, all mice were administered with 250 µL of 78.7 µCi/mL 3HTdR (corresponds to 19.7 µCi 3HTdR per mouse) by intravenous injection via a tail vein. Approx. five hours after treatment with 3HTdR, all mice were euthanised. Lymph nodes were pooled per group and single cell suspensions (in phosphate buffered saline) were prepared by gentle mechanical disaggregation through stainless steel gauze (200 µm mesh size). After precipitation of macromolecules, the level of 3HTdR incorporation was then measured on a β-scintillation counter. The β-scintillation counter expresses 3HTdR incorporation as the number of radioactive disintegrations per minute (DPM). In addition to the sensitising reactions the following observations and data were recorded during the test and observation period: Mortality (once daily on week days from experimental start to necropsy), clinical signs (local / systemic) within 1 hour each application, and 24 ± 4 hours after the first and second application as well as on the day of preparation.

ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: See "Any other information on materials and methods incl. tables"

Positive control substance(s):

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

Statistics:

The mean values and standard deviations were calculated in the body weight tables.

Positive control results:

The sensitivity and reliability of the experimental technique employed was assessed by use of a substance which is known to have skin sensitisation properties in CBA/CaOlaHsd mice. The validation- / positive control experiment was performed with α-Hexylcinnamaldehyde in acetone:olive oil (4+1) using CBA/CaOlaHsd mice in November 2009.

Key result

Parameter:

SI

Value:

0.71

Test group / Remarks:

100% test substance in vehicle

Key result

Parameter:

SI

Value:

0.89

Test group / Remarks:

50% test substance in vehicle

Key result

Parameter:

SI

Value:

0.74

Test group / Remarks:

25% test substance in vehicle

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA: See "Attached background material"

DETAILS ON STIMULATION INDEX CALCULATION: The proliferative response of lymph node cells is expressed as the number of radioactive disintegrations per minute per lymph node (DPM/node) and as the ratio of 3HTdR incorporated into lymph node cells of test lymph nodes relative to that recorded for control lymph nodes (Stimulation Index; S.I.). Before DPM/node values were determined, mean scintillation-background DPM was subtracted from test and control raw data.

EC3 CALCULATION: The EC3 value could not be calculated, since none of the tested concentrations induced an S.I. greater than 3.

CLINICAL OBSERVATIONS: No symptoms of local toxicity at the ears of the animals and no systemic findings were observed during the study period.

BODY WEIGHTS: The body weight of the animals, recorded prior to the first application and prior to treatment with 3HTdR, was within the range commonly recorded for animals of this strain and age.

SIGNS OF TOXICITY: No systemic findings were observed during the study period.

Interpretation of results:

GHS criteria not met

Conclusions:

In a Murine Local Lymph Node assay according to OECD guideline 429, the test item showed no sensitising potential under the conditions of the study.

Executive summary:

In order to study a possible contact allergenic potential of ARKOFIX NZF NEW LIQ, three groups each of four female mice were treated daily with the test item at concentrations of 25, 50 (w/v), and 100% in dimethylformamide by topical application to the dorsum of each ear (left and right) for three consecutive days according to OECD guideline 429. A control group of four mice was treated with the vehicle (dimethylformamide) only. Five days after the first topical application the mice were injected intravenously into a tail vein with radio-labelled thymidine (3H-methyl thymidine). Approximately five hours after intravenous injection, the mice were sacrificed, the draining auricular lymph nodes excised and pooled per group. Single cell suspensions of lymph node cells were prepared from pooled lymph nodes, which were subsequently washed and incubated with trichloroacetic acid overnight. The proliferative capacity of pooled lymph node cells was determined by the incorporation of 3H-methyl thymidine measured in α-scintillation counter. All treated animals survived the scheduled study period and no signs of systemic toxicity or local irritation were observed. A test item is regarded as a sensitiser in the LLNA if the exposure to one or more test concentration resulted in 3-fold or greater increase in incorporation of 3HTdR compared with concurrent controls, as indicated by the Stimulation Index (S.I.). The estimated concentration of test item required to produce a S.I. of 3 is referred to as the EC3 value. In this study Stimulation Indices of 0.74, 0.89, and 0.71 were determined with the test item at concentrations of 25, 50, and 100% in dimethylformamide. The EC3 value could not be calculated, since none of the tested concentrations induced an S.I. greater than 3.

Reference 2

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

other: Read-across, see cross-reference

Justification for type of information:

Please refer to IUCLID section 13 for Read Across Justification.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

SI

Value:

0

Test group / Remarks:

No further test groups were included as the study was conducted as a limit test

Remarks on result:

not measured/tested

Remarks:

No further test groups were included as the study was conducted as a limit test

Key result

Parameter:

SI

Value:

2.31

Test group / Remarks:

60% test substance

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

Control group

Parameter:

other: disintegrations per minute (DPM)

Value:

2 222.9

Test group / Remarks:

60% test substance

Reference 3

Endpoint:

skin sensitisation: in chemico

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
OASIS TIMES v2.27.19.13

2. MODEL (incl. version number)
Skin sensitization with autoxidation; v. 21.26

3. SMILES IDENTIFIERS USED AS INPUT FOR THE MODEL
CN1C(O)C(O)N(C)C1=O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: In vivo: skin sensitization
- Unambiguous algorithm: refer to QMRF
- Defined domain of applicability:
1. General parametric requirements - includes ranges of variation of log KOW and MW. It specifies in the domain only those chemicals that fall in the range of variation of the MW and log Kow defined on the bases of the correctly predicted training set chemicals. This layer of the domain is applied only on parent chemicals.
2. Structural domain - it is represented by list of atom - centered fragments extracted from the chemicals in the training set. The training chemicals were split into two subsets: chemicals correctly predicted by the model and incorrectly predicted
chemicals. These two subsets of chemicals were used to extract characteristics determining the "good" and "bad" space of the domain. Extracted characteristics were split into three categories: unique characteristics of correct and incorrect chemicals (presented only in one of the subsets) and fuzzy characteristics presented in both subsets of chemicals. Structural domain is applied on parent chemicals, only.
3. Mechanistic domain - in SS model it includes: Interpolation space: this stage of the applicability domain of the model holds only for chemicals for which an additional COREPA model is required. It estimates the position of the target chemicals in the population density plot built in the parametric space defined by the explanatory variables of the model by making use the training set chemicals. Currently, the accepted threshold of population density is 10%.
The mechanistic domain is applied on the parent structures and on their metabolites.

- Appropriate measures of goodness-of-fit and robustness and predictivity:
External Validation: For substances in the applicability domain, a predictivity of 100% was found for 100 industrial chemicals for the distinction of non-sensitizers versus sensitizers of GHS Category 1. The evaluation has been published in W. Teubner, A. Mehling, P.X. Schuster, K.Guth, B. A. Worth, J. Burton, B. van Rawenzwaay, R. Landsiedel: Computer models versus reality: How well do in silico models currently predict the sensitization potential of a substance, Regulatory Toxicology and Pharmacology 67 (2013) 468-485

Statistics for goodness-of-fit: For 875 chemicals, the TIMES-SS model was able to predict correctly 90% of the strong sensitizers, 55% of the weak sensitizers and 77% of the non-sensitizers, i.e., an overall performance of 78 %. Sensitivity: 78 %, Specificity: 77 %

- Mechanistic interpretation:
The TIMES-SS (Tissue Metabolism Simulator for skin sensitization) model integrates a simulator of skin metabolism together with a number of “local” QSAR models for assessing the reactivity of specific alerts. A skin metabolism simulator was developed based on empirical and theoretical knowledge (not enough reported observed skin metabolism data). The transformation probabilities (defining the priority of their execution) were parameterized to reproduce skin sensitization data. The simulator comprises of about 420 transformations, which can be divided into four main types: abiotic transformations, covalent interaction with proteins, Phase I and Phase II reactions. Autoxidation (AU) of chemical is also accounted for. Interactions with skin proteins are grouped into three types: leading to strong or weak skin sensitization effect and interactions requiring QSAR models to quantify the potency of sensitization of the alerting groups. The QSAR models were developed by the COmmon PAttern Recognition (COREPA) approach [3]. The skin sensitization model predicts skin sensitization effect in three classes: strong, weak and non-sensitizers.
Reliability of alerts in the TIMES-SS model has been also evaluated to provide transparent mechanistic reasoning for predicting sensitization potential. Alert performance was defined as the ratio between the number of correct (positive and negative) predictions and the total number of chemicals within the local training set that triggered the alert. The alert performance was assessed based on the predictions on parents, autoxidation products simulated by the external AU simulator and metabolites as simulated by the skin metabolism simulator embedded in TIMES-SS model. Four different categories of reliability were defined:
High reliability – alert performance higher than 60% and more than 5 chemical in local (transformation/alert) training set
Low reliability – performance less than 60% and more than 5 chemicals in training set
Undetermined reliability – less than 5 chemicals in training set
Undetermined (theoretical) – there are no chemicals supporting the alert in the local training set

5. APPLICABILITY DOMAIN
- Descriptor domain:
Log(Kow): range = [ -13.2 .. 15.4 ]
calculated: -2.98 (In domain)
MOL._WEIGHT: range = [ 30 .. 738 ] Da
calculated: 146 Da (In domain)
--> Conclusion: The chemical fulfils the general properties requirements.

- Structural fragment domain: The following ACF are identified:
Fragments in correctly predicted training chemicals – 20.00%,
Fragments in non-correctly predicted training chemicals – 40.00%,
Fragments not present in the training chemicals – 40.00%
--> Conclusion: The chemical is out of the interpolation structural space

- Mechanistic domain: Interpolation space
Domain result: N/A
- Similarity with analogues in the training set: not reported

6. ADEQUACY OF THE RESULT
Although the substance does not completely fall into the applicability domain of the model, the model was found to give reliable predictions for industrial chemicals. It is therefore considered to be acceptable for REACH.

The substance is considered to be non skin seniziting.

Qualifier:

according to guideline

Guideline:

other: REACH guidance on QSARs R.6

Version / remarks:

May/July 2008

Principles of method if other than guideline:

TIMES-SS v.2.27.19.13 - Skin sensitization with autoxidation v.12.12 (structure-toxicity and structure-metabolism relationships)
The QSAR is also described in the "Practical guide How to use and report (Q)SARs", Ver. 3.1, July 2016.

GLP compliance:

no

Parameter:

other: Skin sensitization with autoxidation algorithm

Remarks on result:

no indication of skin sensitisation

Interpretation of results:

GHS criteria not met

Conclusions:

The registrant considers this predication as valid because TIMES-SS was validated with 100 substances from the registrant's portfolio (Teubner et al., Regulatory Toxicology and Pharmacology 67 (2013) 468–485). All predictions that fullfilled all domain requirements were correct (Specificity 100%).

The QSAR program calculated a negative sensitization potential of the test substance. The substance is in the paramter domain but does not completely fall into the structural fragment domain of the model.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

WoE, read-across. skin sensitisation in vivo, RL2

In order to study a possible contact allergenic potential of ARKOFIX NZF NEW LIQ, three groups each of four female mice were treated daily with the test item at concentrations of 25, 50 (w/v), and 100% in dimethylformamide by topical application to the dorsum of each ear (left and right) for three consecutive days according to OECD guideline 429. A control group of four mice was treated with the vehicle (dimethylformamide) only. Five days after the first topical application the mice were injected intravenously into a tail vein with radio-labelled thymidine (3H-methyl thymidine). Approximately five hours after intravenous injection, the mice were sacrificed, the draining auricular lymph nodes excised and pooled per group. Single cell suspensions of lymph node cells were prepared from pooled lymph nodes, which were subsequently washed and incubated with trichloroacetic acid overnight. The proliferative capacity of pooled lymph node cells was determined by the incorporation of 3H-methyl thymidine measured in α-scintillation counter. All treated animals survived the scheduled study period and no signs of systemic toxicity or local irritation were observed. A test item is regarded as a sensitiser in the LLNA if the exposure to one or more test concentration resulted in 3-fold or greater increase in incorporation of 3HTdR compared with concurrent controls, as indicated by the Stimulation Index (S.I.). The estimated concentration of test item required to produce a S.I. of 3 is referred to as the EC3 value. In this study Stimulation Indices of 0.74, 0.89, and 0.71 were determined with the test item at concentrations of 25, 50, and 100% in dimethylformamide. The EC3 value could not be calculated, since none of the tested concentrations induced an S.I. greater than 3.

 

WoE, read-across. skin sensitisation in vivo, RL2

A murine local lymph node assay with the structure-related Fixapret CP konz. (CAS 92908-35-5) is available (BASF, 2010). This material basically consists of 4.5 -Dihydroxy-1.3-dihydroxymethylimidazolid-2-one which is also assumed to be a possible metabolic sequel product. Female CBA mice were used. When applied as a 60% preparation of the test substance in 1% aqueous Pluronic, the chemical did not induce a biologically relevant response. Thus, it was concluded, that Fixapret CP konz. does not show a skin-sensitizing effect in the Murine Local Lymph Node Assay.

 

 

WoE, skin sensitisation in silico, RL2

The QSAR program OASIS TIMES v.2.27.19.13 with its module Skin sensitization with autoxidation v.21.26 calculated a negative sensitisation potential of the test substance.

 

Overall conclusion:

The test item or its analogue substance was non-sensitising in the LLNA and in an in silico prediction. 

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. Based on available data, the test item is not classified and labelled for skin sensitisation according to Regulation (EC) No 1272/2008 (CLP), as amended for the eighteenth time in Regulation (EU) 2022/692.