Didodecyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate

Endpoint summary

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29.06.2018 - 20.07.2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

28 July 2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Jul-2012

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Irritation / corrosion parameter:

% tissue viability

Value:

> 50

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

In the present study the skin irritant potential of Didodecyl 1,4-dihydro-2,6-dimethylpyridine-3,5-

dicarboxylate was analysed. The EpiDerm™-Standard Model (EPI-200™), a reconstituted threedimensional

human epidermis model, was used as a replacement for the Draize Skin Irritation Test

(OECD TG 404, [7]) to distinguish between UN GHS “Category 2” skin irritating test substances and

not categorized test substances (“No Category”) which may be considered as non-irritant. Hereby,

the test item was applied topically. Cytotoxicity is expressed as the reduction of mitochondrial

dehydrogenase activity measured by formazan production from MTT after a 60 min exposure and

42 h post-incubation period and compared to those of the concurrent negative controls.

The mixture of 25 mg test item per 1 mL MTT medium showed no reduction of MTT compared to the

solvent. The mixture did not turn blue/purple. Therefore, NSMTT equalled 0%.

The mixture of 25 mg of the test item per 300 μl aqua dest. showed no colouring detectable by

unaided eye-assessment. The mixture of 25 mg of the test item per 300 μl isopropanol showed

colouring detectable by unaided eye-assessment. Therefore, the absorption of the chemical in

isopropanol was measured in the range of 570 ± 30 nm. No absorption was measured in the

relevant range (see Figure 1). Therefore, NSC equalled 0%.

The test item showed no irritant effects. The mean relative tissue viability (% negative control) was

> 50% (109.8%) after 60 min treatment and 42 h post-incubation.

8.2. Conclusion

In this study under the given conditions the test item showed no irritant effects. The relative mean

tissue viability after 60 min of exposure and 42 h post-incubation was > 50%. The test item is

therefore classified as “non-irritant” in accordance with UN GHS “No Category”.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018 -2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Version / remarks:

25 Jun 2018

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EURL ECVAM DB-ALM Method Summary No. 164: EpiOcular™ Eye Irritation Test

Version / remarks:

Summary, 22 July 2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EpiOcular™ Eye Irritation Test (OCL-200-EIT) For the prediction of acute ocular irritation of chemicals For use with MatTek Corporation’s Reconstructed Human EpiOcular™ Model

Version / remarks:

29 June 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Details on test animals or tissues and environmental conditions:

The EpiOcular™ tissues are provided as kits (e.g. OCL-200-EIT; MatTek), consisting of the following components relevant for this study:
1x sealed 24-well plate containing 24 inserts with EpiOcular™ tissues on agarose
1x bottle EpiOcularTM assay medium
1x bottle Ca2+/Mg2+-free DPBS buffer

Vehicle:

water

Controls:

yes

Irritation parameter:

in vitro irritation score

Value:

108

Negative controls validity:

valid

Interpretation of results:

GHS criteria not met

Conclusions:

In this study under the given conditions the test item showed no irritant effects. The relative mean viability of the test item treated tissues was 108 %. The test item is therefore classified as “non-irritant” in accordance with UN GHS “No Category”.

Executive summary:

In the present study the eye irritating potential of Didodecyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate was analysed. Since irritant substances are cytotoxic to the corneal epithelium after a short time exposure the cytotoxic effects of the test item on EpiOcular, a reconstituted three-dimensional human corneal epithelium model, were determined. Hereby, the test item was applied topically. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT after a 6 h exposure period and 18 h post-treatment period and compared to those of the concurrent negative controls.

The mixture of 50 mg test item per 1 mL MTT medium showed no reduction of MTT as compared to the solvent. The mixture did not turn blue/purple. Therefore, NSMTT equalled 0%.

The mixture of 50 mg test item per 1 mL Aqua dest. and 2 mL isopropanol showed colouring as compared to the solvent. Since the mean relative tissue viability of the test item treated tissues (TM) was above the 60% threshold value coloured tissue controls were performed for quantitative correction of results.

NSCliving [%] = [ODTVT/ODNC] * 100 = 0.7%

Difference of NSCliving of the two duplicate tissues must be < 20%, otherwise not accepted.

NSC1 [%] = [ODTVT1 / ODNC] * 100 = 0.7%

NSC2 [%] = [ODTVT2 / ODNC] * 100 = 0.7%

NSC1 – NSC2 = ± 0.0%

NSCliving was ≤ 60% (0.7%) relative to the negative control of living epidermis and could therefore be used for determination of the NSC-corrected mean relative tissue viability (NSCCV) according to the following formula:

NSCCV [%] = viabilityTM [%] – NSCliving [%] = 108.7% - 0.7% = 108.0%

The test item showed no irritant effects. The mean relative tissue viability (% negative control) was > 60% (108.0%, NSCliving-corrected).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Justification for classification or non-classification

No classified on experimental data