Bis(2-ethylhexyl) phosphonate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 Nov 2017 - 22 Jan 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

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:

28 July 2015

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

22 July 2015

Test guideline 3

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

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP-Landesleitstelle Bayer, Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Bis(2-ethylhexyl) phosphonate

EC Number:

222-904-6

EC Name:

Bis(2-ethylhexyl) phosphonate

Cas Number:

3658-48-8

Molecular formula:

C16H35O3P

IUPAC Name:

bis(2-ethylhexyl) phosphonate

Test material form:

liquid

Test animals / tissue source

Species:

human

Strain:

other: Construct of normal human epidermal keratinocytes

Details on test animals or tissues and environmental conditions:

- Justification of the test method and considerations regarding applicability
The EpiOcular™ human cell construct for eye irritation testing is a nonkeratinized epithelium prepared from normal human keratinocytes (MatTek Corporation). It models the corneal epithelium with progressively stratified, but not cornified cells. The ability to expose the tissue topically is essential to model the same kind of progressive injury expected in vivo. In this assay, the test item is applied to the surface of the corneal epithelial construct for a fixed period, removed, and the tissue allowed to express the resulting damage. Two construct tissues (replicates) are used for each test treatment and each control group; a 6-h exposure with an 18 hour incubation post-exposure. Relative tissue viability post-exposure is determined against the negative control-treated constructs by evaluating the reduction of MTT to a formazan product, determined spectrophotometrically (optical density). A concurrent positive control is used with each assay to determine validity of the test. Based on the "depth of injury model," the EpiOcular eye irritation test (EIT) is intended to differentiate those materials that are nonirritants (would not require a warning label in the European chemical classification systems) from those that would require labelling as either GHS eye irritant category 1 or 2.

- Description of the cell system used, incl. certificate of authenticity and the mycoplasma status of the cell live The EpiOcular™ human cell construct for eye irritation testing (OCL-200-EIT) (Lot No. 27017) was obtained from MatTek Corporation, and tested by MatTek for potential bilogical contaminants, sterility, barrier function and tissue viability, results for which were within acceptable ranges and indicated appropriate formation of the mucosal barrier and a viable basal cell layer.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 50 µL (undiluted)

NEGATIVE CONTROL
- Amount(s) applied: 50 μL
- Lot/batch no.: RNBF7110

POSITIVE CONTROL
- Amount(s) applied: 50 μL
- Lot/batch no.: S694311

Duration of treatment / exposure:

30 ± 2 min

Duration of post- treatment incubation (in vitro):

120 ± 15 min

Number of animals or in vitro replicates:

Duplicate tissues for each treatment, positive and negative control groups

Details on study design:

- Details of the test procedure used: EpiOcular™ was transferred to plates containing assay medium and incubated for 1 h, followed by transferring out the assay medium, adding fresh assay medium, and pre-incubating 16-24 hours at 37°C, in a humidified atmosphere of 5% CO2. After preincubation, the tissues were pre-treated by wetting with DPBS and incubated at standard culture conditions for 30 ± 2 minutes. The tissues were treated with each dose group in duplicate, starting with the negative and positive control. The cultures were incubated for 30 ± 2 minutes at 37°C, 5.0% CO2 / 95% air. After the exposure time, tissues were rinsed with DPBS to remove any residual test material. After rinsing, the tissues were immediately transferred to and immersed in assay medium for a 12 ± 2 minutes immersion incubation (post-soak). The tissues were then returned to assay medium, and post-incubated for an additional 120 ± 15 minutes at 37°C, 5.0% CO2 / 95% air. Then the cultures were transferred to 0.3 mL/well of MTT reagent and incubated for 180 ± 10 minutes. After incubation, the cultures were transferred to new tissue well-plates, and extracted in 2 mL of isopropanol, the extraction plates were sealed to inhibit isopropanol evaporation and carried out after storage overnight in the dark at 2 - 8 °C. Then the extracts were mixed to obtain homogeneous solutions, and duplicate volumes of 200 μL of each extraction solution were transferred to a 96-well plate and their optical density (ODs at 570± 30 nm) were recorded, while 200 μL of isopropanol was used as the blank.

- RhCE tissue construct used, including batch number: Epiocular™ (OCL-200, OCL-212); Test Kit name: OCL-200 kit, OCL-212 kit (manufactured by MatTek Corporation); Lot number: 27017.

- Doses of test chemical and control substances used: test material: 50 μL of test substance (undiluted); negative control: 50 μL of distilled water; positive control: 50 μL of Methyl acetate.

- Duration and temperature of exposure, post-exposure immersion and post-exposure incubation periods: Exposure: 30 ± 2 minutes at 37°C, 5.0% CO2 / 95% air; Postexposure immersion: 12 ± 2 minutes not further specified; Post-exposure incubation: 120 ± 15 minutes at 37°C, 5.0% CO2 / 95% air.

- Indication of controls used for direct MTT-reducers and/or colouring test chemicals: The test substance was tested for tissue-binding in assay medium without MTT, with resultant staining being below 60%. Therefore mean cell viability of the test substance group was reduced by the mean staining ratio. The test substance was tested for direct MTT-reduction and results were negative.

- Number of tissue replicates used per test chemical and controls: Two replicates per treatment: test substance, positive and negative controls.

- Wavelength and band pass used for quantifying MTT formazan, and linearity range of measuring device (e.g. spectrophotometer): Wavelength of 570 ± 30 nm, measured on a spectrophotometer.

- Acceptable variability between tissue replicates for positive and negative controls: OD in the negative control substance group is > 0.8 and < 2.5. The cell viability in the positive control substance group is < 50%.

- Acceptable variability between tissue replicates for the test chemical: Differences of two tissue cell viabilities in each treatment group (test material, positive control, negative control) are < 20%.

Results and discussion

In vitro

Results

Irritation parameter:

other: % tissue viability

Run / experiment:

two tissue replicates per treatment

Value:

ca. 17.9

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Other effects / acceptance of results:

OTHER EFFECTS:
The mixture of 50 µL 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 A. dest. and per 2 mL isopropanol showed no colouring as compared to the solvent. Therefore, NSCliving equalled 0%.

ACCEPTANCE OF RESULTS:
The controls confirmed the validity of the study. The mean absolute OD570 of the two negative control tissues was > 0.8 and < 2.5 (1.904%). The mean relative tissue viability (% negative control) of the positive control was < 50% (2.0%). The inter tissue difference of replicate tissues of all dose groups was < 20% (0.3 – 10.3%).

Any other information on results incl. tables

Table 1: Result of the Test Item

 

Name	Negative Control		Positive Control		Test Item
Tissue	1	2	1	2	1	2
OD570values(blank-corrected)	1.720	1.959	0.040	0.035	0.407	0.274
	1.808	1.952	0.040	0.032	0.384	0.263
mean of the duplicates	1.764	1.956	0.040	0.034	0.396	0.268
mean OD	1.860^*		0.037		0.332
mean sd OD	0.116		0.004		0.074
tissue viability [%]	94.9	105.1	2.1	1.8	21.3	14.4
relative tissue viability difference [%]^***	10.3		0.3		6.8
mean tissue viability [%]	100.0		2.0^**		17.9

*   Corrected mean OD570of the negative control corresponds to 100% absolute tissueviability

**  mean relative tissue viability of the positive control is <50%

*** relative tissue viability difference of replicate tissues is <20%

Table 3: Test AcceptanceCriteria

	Value	Cut off	pass/fail
Mean Absolute OD570nmNK	1.904	0.8 < NK < 2.5	pass
Mean Relative Viability PC [%]	2.0	< 50%	pass
Max. Difference of % Viability [%]	10.3	< 20%	pass

Applicant's summary and conclusion

Interpretation of results:

other: irritating potential (Eye Irrit. 2 or Eye Dam. 1 according to Regulation (EC) No 1272/2008)

Conclusions:

CLP: Category 2
Under the conditions of the test, the test substance was shown to have an irritating or corrosive potential towards reconstructed human epidermis tissue in the EpiOcular™ EIT prediction model. The result does not allow for the classification of the test substance as irritant or corrosive and therefore further evaluation and/or data generation is required. In a further BCOP test it was shown that the test substance has no corrosive potential therefore it can be concluded that the test substance is Eye Irrit. 2 according to Regulation (EC) No 1272/2008