[(3,7-dimethyl-6-octenyl)oxy]acetaldehyde

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From September 23, 2019 to February 18, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Deviations:

not specified

Remarks:

There were no deviations from the study protocol during the conduct of this study

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

[(3,7-dimethyl-6-octenyl)oxy]acetaldehyde

EC Number:

231-324-2

EC Name:

[(3,7-dimethyl-6-octenyl)oxy]acetaldehyde

Cas Number:

7492-67-3

Molecular formula:

C12H22O2

IUPAC Name:

2-[(3,7-dimethyloct-6-en-1-yl)oxy]acetaldehyde

Test material form:

liquid

Specific details on test material used for the study:

Batch: VE00601569
Expiration date of the batch: January 12, 2020
Physical Description: liquid colorless to pale yellow
Purity: 92.9%

Test animals / tissue source

Species:

other: Excised Bovine Cornea

Strain:

other: Not Applicable

Details on test animals or tissues and environmental conditions:

Bovine eyes will be obtained from the abattoir of J.W.TREUTH & SONS, Inc., Baltimore, MD.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

The test item was used as supplied (neat), undiluted.

Duration of treatment / exposure:

Three corneas were incubated in the presence of the test article at 32 ± 1 °C for 10 minutes.
Three corneas were incubated in the presence of each control at 32 ± 1 °C for 10 minutes.

Number of animals or in vitro replicates:

Negative control: 3 Corneae
Positive control: 3 Corneae
Test item: 3 Corneae

Details on study design:

The study was conducted using the closed-chamber method as described by the OECD 437 guideline. After the medium was removed for the permeability determination, each cornea was carefully separated from its corneal holder and fixed in formalin. The fixed corneas were transferred to Alizée Pathology, LLC (Thurmont, Maryland, USA) for embedding, sectioning, and staining. Slides were evaluated by John W. Harbell, Ph.D. of JHarbell Consulting LLC (Dallas, Texas, USA).

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

in vitro irritation score

Value:

54.7

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks:

In vitro score: 45.4

Results 2

Irritation parameter:

other: Histology

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Other effects / acceptance of results:

The BCOP assay was accepted when the positive control (ethanol) produced an In Vitro Score that fell within two standard deviations of the historical mean. The current acceptance range for ethanol is 38.1-63.4.

Any other information on results incl. tables

Evaluation of Test Results for BCOP:

The following prediction models were used to evaluate the ocular irritancy potential as described by Sina et al. (1995)2 for non-regulatory purposes or as described in OECD TG 437 (2017).

The prediction model according to Sina et. al based on a wide range of materials (note: While this classification system provides a good initial guide to interpretation of these in vitro data, these specific ranges may not be applicable to all classes of materials or other exposure times. Whenever possible, results should be compared to “benchmark” materials tested under similar exposure conditions.):

In Vitro Score	Sina et al Prediction
≤ 25	Mild irritant
> 25; ≤ 55	Moderate irritant
> 55	Severe irritant

Prediction model outlined in OECD TG 437:

In Vitro Irritation Score (IVIS)	UN GHS
≤3	No Category
>3; ≤55	No prediction can be made*
>55	Category 1

* - Additional testing would be required for a definitive classification of ocular irritation potential according to GHS

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

The test article produced an In Vitro Score of 54.7. According to the prediction model presented by Sina et al. (1995), the test article would be considered a moderate irritant (i.e., In Vitro Score greater than 25 and less than 55). According to the prediction model presented in OECD TG 437, a prediction for eye irritation potential could not be determined, and additional testing would be warranted for definitive classification of eye irritation potential for labeling purposes. To understand the depth of injury to the cornea, additional histology was performed on treated corneas. According to the histological evaluation and the model by Jester and Maurer (2002), these findings would be predictive of a high moderate to severe eye irritation potential.

Executive summary:

The Bovine Corneal Opacity and Permeability Assay (BCOP) was used to assess the potential ocular irritancy of the test article to isolated bovine corneas. Bovine corneas, obtained as a byproduct from freshly slaughtered animals, were mounted in special holders and exposed to the test article. An In Vitro Score was determined for the test article based on the induction of opacity and permeability (to fluorescein) in the isolated bovine corneas. The methods and procedures used in this assay were consistent with OECD Test Guideline 437: Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage (2017)1.

According to the prediction model presented in OECD TG 437, a prediction for eye irritation potential could not be determined, and additional testing would be warranted for definitive classification of eye irritation potential for labeling purposes.

After the BCOP assay, the corneas were fixed in formalin and processed for histological evaluation by Alizée Pathology, Inc. (Thurmont, MD). An evaluation of the histological changes was performed by John W. Harbell, Ph.D., (JHarbell Consulting, LLC, Dallas, TX) to assess the depth and degree of injury.

Histology:

The epithelium of corneas treated with CITRONELLYL OXYACETALDEHYDE showed all layers to the present but probably not viable at the time of fixation. The nuclei showed loss of basophilic components leading to a foamy appearance. The stroma was thicker than the negative control treated corneas. The stroma directly beneath the anterior limiting lamina showed extensive stromal swelling. There was a marked increase in the frequency of keratocytes with hyperchromic (pyknotic) nuclei. The stroma at mid-depth showed marked collagen matrix swelling and a similar increase in keratocytes with nuclear pyknosis. The lower stroma showed an extension of the stromal swelling extending from the mid-stroma. There was a moderate increase in the frequency of keratocytes with nuclear pyknosis. Thus it was not possible to evaluate endothelial function based on deep stromal swelling. The Descemet's Membrane was prominent. The endothelium was physically present and normal in appearance in the majority of fields. Using the prediction model developed by Maurer and Jester, a range of high moderate to severe eye irritation potential was assigned to the test article. The test article produced clear histological changes in the epithelial and stromal layers of the corneas, and with support of the BCOP results, these findings emphasize that the test article has at least a moderate eye irritation potential. A hallmark of a severe ocular injury would be damage extending from the source of exposure (i.e., epithelium), through the stromal layers, and ultimately affecting the endothelium. The endothelium was intact for the corneas treated with this test article, which is one aspect suggestive that the injury may not be severe.