Methyl 3-pyridyl ketone

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-08-05 - 2015-10-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP OECD 439 guideline study without deviations on the registered substance itself.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Version / remarks:

B.46 BIS. “IN VITRO SKIN IRRITATION: RECONSTRUCTED HUMAN EPIDERMIS MODEL TEST”, dated 24. Aug. 2009

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

OECD Guideline for the Testing of Chemicals, Version 439, 26. July 2013, “In Vitro Skin Irritation: Reconstructed Human Epidermis (RhE) Test Method”

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Kaiser-Friedrich-Straße 7, 55116 Mainz, Germany

Test material

Test material information

Constituent 1

Reference substance name:

3-Acetylpyridine

IUPAC Name:

3-Acetylpyridine

Constituent 2

Reference substance name:

Methyl 3-pyridyl ketone

EC Number:

206-496-7

EC Name:

Methyl 3-pyridyl ketone

Cas Number:

350-03-8

Molecular formula:

C7H7NO

IUPAC Name:

1-(pyridin-3-yl)ethan-1-one

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): 3-Acetylpyridine
- Substance type: pure substance
- Storage condition of test material: Room temperature (20 ± 5 °C)
- Homogeneity: homogeneous

Test animals

Species:

other: EpiDermTM tissue consisting of human-derived epidermal keratinocytes

Strain:

other: not applicable

Details on test animals or test system and environmental conditions:

not applicable

Test system

Type of coverage:

other: not applicable

Preparation of test site:

other: not applicable

Vehicle:

unchanged (no vehicle)

Controls:

other: DPBS-buffer was used as negative control, 5 % SDS solution was used as positive control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 30µL

Duration of treatment / exposure:

60 min

Observation period:

42 h postincubation + 3 h incubation with MTT

Number of animals:

in total, 3 6-well plates were used

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Rinsing with DPBS buffer
- Time after start of exposure: 60 min

SCORING SYSTEM: Formazan production as described in OECD Guideline 439

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

other: other: Formazan production

Value:

46.6

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 1 h incubation, 42h postincubation. Reversibility: other: not applicable. Remarks: Test item; below the threshold for skin irritation (50%).. (migrated information)

Results 2

Irritation / corrosion parameter:

other: other: Formazan production

Value:

3.3

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 1 h incubation, 42h postincubation. Reversibility: other: not applicable. Remarks: Positive control; below the threshold for skin irritation (50%).. (migrated information)

In vivo

Irritant / corrosive response data:

The relative absorbance values were reduced to 46.6 % after the treatment. This value is below the threshold for skin irritation (50%). Therefore, the test item is considered as irritant to skin. For details see "Any other information on results incl. tables"

Any other information on results incl. tables

Findings and Results

Measured Values

As blank, the optical density of isopropanol was measured in eight wells of the 96-well-plate. The measured values and their mean are given in the following table:

Table Absorbance values blank isopropanol (OD at 570 nm)

Replicate	1	2	3	4	5	6	7	8	Mean
Absorbance	0.036	0.036	0.036	0.037	0.034	0.035	0.036	0.035	0.036

 

The absorbance values of negative control, test item and positive control are given in the following table:

Table Absorbance Values negative control, test item and positive control (OD at 570 nm)

Designation	Measurement	Negative Control	3-Acetylpyridine	Positive Control
Tissue 1	1	1.925	0.926	0.101
	2	1.922	0.935	0.102
Tissue 2	1	1.830	0.895	0.098
	2	1.857	0.900	0.097
Tissue 3	1	1.804	0.826	0.087
	2	1.800	0.826	0.088

 

From the measured absorbances, the mean of each tissue was calculated, subtracting the mean absorbance of isopropanol. Mean and relative standard deviation (comparison of the three tissues) were also calculated.

Table Mean Absorbance Values

Designation	Negative Control	3-Acetylpyridine	Positive Control
Mean – blank (tissue 1)	1.888	0.895	0.066
Mean – blank (tissue 2)	1.808	0.862	0.062
Mean – blank (tissue 3)	1.766	0.790	0.052
Mean of the three tissues	1.821	0.849	0.060
Relative standard deviation of the three tissues	3.4%	6.3%	12.0%

 

Comparison of Formazan Production

For the test item and the positive control, the following percentage values of formazan production were calculated in comparison to the negative control:

Table % Formazan Production

Designation	3-Acetylpyridine	Positive Control
% Formazan production (tissue 1)	49.1%	3.6%
% Formazan production (tissue 2)	47.3%	3.4%
% Formazan production (tissue 3)	43.4%	2.9%
% Formazan production (mean)	46.6%	3.3%

 

Assessment and Validity

Skin Irritation Potential of the Test Item

The relative absorbance values were reduced to 46.6 % after the treatment. This value is below the threshold for skin irritation (50%). Therefore, the test item is considered as irritant to skin.

 

Validity and Acceptability

Validity criteria and results are stated in the following table:

Table Validity

Criterion	Demanded	Found
OD of negative control	≥ 0.8 and ≤ 2.8	1.8
% Formazan production of positive control SDS	<=20% of negative control	3.3%
Variation within replicates (RSD)	< 18%	3.4% (negative control) 12.0% (positive control) 6.3 % (test item)

 

All validity criteria were met.

Values for negative control and for positive control were within the range of historical data of the test facility.

Therefore, the experiment is considered valid.

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritant) based on GHS criteria

Conclusions:

Testing was performed via a GLP OECD 439 guideline study on the registered substance itself. The present in vitro method is recommended in a tiered testing approach, it was used as follow-up study to an OECD 431 study in which 3-Acetylpyridine was found to be non-corrosive to skin.
The validity criteria are met, making the results sufficiently reliable to assess the irritating potential of 3-Acetylpyridine to the skin. The present in vitro method allows the identification of irritating chemical substances and mixtures.
The relative absorbance values were reduced to 46.6 % after the treatment. This value is below the threshold for skin irritation (50%). Therefore, the test item is considered as irritant to skin according to the guideline.

Executive summary:

In an OECD 439 (in vitro skin irritation) study under GLP, 1 valid experiment was performed.

 

3 tissues of the human skin model EpiDerm^TM were treated with 3-Acetylpyridine for 60 minutes.

30 µL of the test item (using a nylon mesh) were applied to each tissue and spread to match the tissue size (0.63 cm²; as indicated by supplier).

DPBS-buffer was used as negative control, 5 % SDS solution was used as positive control.

After treatment with the negative control, the absorbance values were within the required acceptability criterion of 0.8 ≤ mean OD ≤ 2.8, OD was 1.8. The positive control showed clear irritating effects. Relative absorbance was reduced to 3.3 %.

Variation within tissues was acceptable (< 18%).

 

After the treatment with the test item, the relative absorbance values were reduced to 46.6 %. This value is below the threshold for irritation potential (50%).

 

Therefore, 3-Acetylpyridine is considered as skin irritant in the Human Skin Model Test.